The author of this article was on the committee that developed Standard Plan A and another committee that created a building code/standard out of FEMA P-1100. However, the opinions expressed here are solely those of the author and do not reflect the opinion of the International Code Council, the Federal Emergency Management Agency, other agencies or those of any group or individuals.
You may have been accepted into the CEA Earthquake Brace and Bolt Program and qualified for a $3,000 grant if you retrofit your home. This webpage is a comparison between 2 qualifying guidelines approved by the CEA Program. The first guideline is the brand new FEMA P-1100 guideline and the second guideline is the decades old Standard Plan A. Reading this material will help you decide which guideline you want to use. There is A LOT of material here. The essential information you need for making the choice between the two guidelines can be found if you scroll down until you get to the paragraph MAKING THE DECISION: COMPARING THE GUIDELINES.
Otherwise if you are interested in knowing how the two guidelines were created, the author’s role in creating them, and how $24,000,000 was spent in FEMA P-1100/ICC 1300’s development, the rest of this article will be of interest.
About the Author
This study actually began after the 1989 Bay Area Loma Prieta Earthquake when the author worked as a residential earthquake damage assessor for the Federal Emergency Management Agency (FEMA). He saw a lot of damage and spoke to a lot of people who lost everything. He never met a family where a family member had died but he may have if he also worked after the 1994 Northridge earthquake where 24 people lost their lives in hillside homes. For many years he has been sounding the alarm on these dangerous houses both as a member of the Berkeley Disaster Commission and as an adviser to the Association of Bay Area Governments. His efforts have up to now gone unheeded though he still does his best to alert the public with a webpage that describes how dangerous these homes are.
He has designed and installed thousands of retrofits over the past 25 years, including those with living areas above a garage (soft story), and homes on steep hillsides, though probably 95% of the houses he works on are crawl space retrofits. He or his company currently design approximately 6 retrofits and installs 3 retrofits a week. Throughout the years he has applied the research skills he developed in graduate school to all aspects of seismic retrofitting and is in the unique position of not only understanding the theory behind residential wood frame retrofits, but has also applied this theory to thousands of homes.
The authors of FEMA P-1100 consisted of a stellar group of scientists and engineers with access to thousands of pages of research papers and extensive laboratory testing. Even though I was not on the original FEMA P-1100 committee, I was assigned to a committee that was tasked with molding it into a standard called ICC 1300 for the International Council. I do not have a copy of the final draft of ICC 1300 and this study only looks at the FEMA P-1100 because as of now ICC 1300 has not yet been published.
FEMA P-1100 was ratified by its 38 authors and FEMA P-1100/ICC 1300 are used synonymously because so few changes were made in the transition from FEMA P-1100 to ICC 1300. This study only applies to FEMA P-1100 because as of now I do not have a copy of ICC 1300. If I see any major changes once it is published I will revise this page. While on that committee I did a thorough cost analysis on FEMA P-1100 and out of this cost analysis this webpage arose. Over the past 2 years I sent all the material in this study to the other committee members but have only received 3 comments from one of the engineers. It must therefore be understood that this study has not been peer reviewed.
I was on this committee as well as the Standard Plan A committee to represent seismic retrofit contractors who would be building these retrofits and homeowners who would be paying for them. The thinking here is analogous to making sure a committee tasked with writing a book about bicycling includes at least one member who has ridden and continues to ride a bicycle.
Though I tried to make this comparison between FEMA P-1100 and Standard Plan A easy to understand, I know my skills at making technical subjects clear to laypeople are limited. I am not a professional writer, website designer, or videographer. If you find any of this material boring or difficult to understand just skip to one of the videos or skip ahead and find something more interesting to read.
This study is written from a contractor’s and homeowner’s point of view for the benefit of contractors, homeowners, and building departments who want to learn how to use FEMA P-1100/ICC 1300. If you think this website, and this webpage in particular, can be improved upon, please write to me at to let me know what I can do and I will do my best.
Introduction, History, and Background
There are currently 3 rather similar seismic retrofit guidelines in use: the 2 page Standard Plan A, the 14 page guideline Appendix Chapter 3 in the 2022 CEBC, and the 1 page Los Angeles Standard Plan Number 1. Why these guidelines should be replaced with the enormous 290 page FEMA P-1100/ICC 1300 guideline or how its addition to the cannon will better serve the cause of public safety are questions I hope to answer.
FEMA P-1100 is called a pre-standard because it was understood that at some time in the future it would become a minimum standard for retrofitting homes called ICC 1300. In itself it would be not legally binding. It serves rather as a “model” for legal jurisdictions to utilize when developing statutes and regulations.
The ~$22,400 worth of research and the 7,000 pages of test reports at the disposal of the 38 engineers, scientists, and other professionals who formed the FEMA P-1100 committee culminated in a practical guideline called FEMA P-1100 that gives contractors step by step instructions on exactly how to retrofit a house. FEMA P-1100/ICC 1300 should therefore be seen as a how-to guide. The author’s task on the ICC 1300 committee was to make sure this how-to guide was as contractor-friendly as possible, while keeping homeowners’ pocketbooks in view. He made close to 100 suggestions and produced 25 videos to this end.
The development of FEMA P-1100 has a long history, dating back to 1997. This video outlines that history.
1) THE HISTORY OF SEISMIC RETROFIT GUIDELINE FROM 1997 – 2024
The Standard Plan A committee worked on Standard Plan A for several years, and we published it in 2006. Since the day of its publication it has been used extensively in the San Francisco Bay Area seismic retrofit industry. It was written by an ad hoc committee of volunteers consisting of ~3 engineers (it seemed like the number and personalities were different at every meeting), 3 building officials, the entire San Leandro building depart, 1 seismologist, and an Association of Bay Area Governments involved in hazard mitigation who guided the National Science Foundation’s publication of Shaken Awake. Engineer Jim Russell chaired the Standard Plan A committee, and years before chaired the committee that developed the 14 page retrofit standard originally published in the 1997 UCBC. I represented seismic retrofit contractors so that this how-to manual had at least one has-done member. I remember Jim Russel telling me how delighted he was that Standard Plan A would be different from the other guideline he had worked on because now the committee had a member who had personally retrofitted numerous homes.
Standard Plan A only addresses crawl space retrofits where the cripple walls are less than 4 feet tall. The only resources we used were the 2001 California Building Code, the 1997 Uniform Code For Building Conservation (UCBC), a study done by the National Science Foundation, and the expertise of a seismologist. Over the years I have written a great deal and produced a few videos about Standard Plan A. Rather than repeating this information I suggest you go to this webpage to learn more about it.
2) PART 1 IN THIS 5 PART SERIES: INTRODUCTION
On the other hand, the FEMA P-1100 is based on a tremendous amount of research. The FEMA P-1100 development committee had access to ~4500 pages of research reports in 30 volumes produced by the 1999 CUREE-Caltech Woodframe Project, the $3,400,000 161 page PEER Report, Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings, and the 422 page FEMA P-1100-3 Background Documentation for Vulnerability-Based Seismic Assessment and Retrofit of One- and Two-Family Dwellings. The latter research project was specific to providing FEMA P-1100 with an accurate engineering framework to justify and inform its how-to suggestions. I do not know the actual cost, but if we extrapolate from the 161 page PEER report, it must have cost at least $5,000.000
In addition, the 20 FEMA funded seismic retrofit research publications totaling ~2000 thousand pages, including the 571 page FEMA P-547 Techniques for the Seismic Rehabilitation of Existing Buildings research report, and the FEMA funded 267 page Training Manual for Contractors and Building Inspectors were available information sources. I think it is safe to these 20 FEMA publications cost at least $3,000,000. I can’t help but think this research included a lot of shear wall testing but remarkably the testing had the exact same results as tests done by the American Plywood Association in 1993. TABLE 1 in the 1993 APA Research Report 154 is identical to TABLE 4.3.A in the 2021 Special Design Provisions For Wind And Seismic which means the building code did not change. For those of you who do not know, the values in TABLE 4.3.A must be divided by 2.8 to equal those found in TABLE 1 of Research Report 154. Since 1993 shear walls have been tested numerous times and the building code has remained the same which makes one wonder why these later tests were done at all.
Quantity and Cost of This Research
Jim Russell was a participating member in the CUREE-Caltech Wood Frame Project, and told me FEMA had provided 6 million dollars for this undertaking. In 2023 dollars, this probably equals $12,000,000. By the way, Jim Russell was the chair of the Standard Plan A committee, and had been the committee chair that created Chapter 3 of the 1997 UCBC (Uniform Code For Building Conservation) Prescriptive Provisions for Seismic Strengthening of Cripple Walls and Sill Plate Anchorage of Light, Wood-Frame Residential Buildings which is currently part of the IEBC.
All this research equals ~7,000 pages at a cost of ~$22,400,000. A substantial part of this research targeted crawl space retrofits.
What Did FEMA Get For Their Money?
FEMA P-1100/ICC 1300 was born out of a combination of brilliant minds, advanced computer modelling, abundant funding, cutting edge research and access to every imaginable resource, which should have produced the most cost-effective, best-engineered, contractor-friendly, and easy to understand crawl space seismic retrofit guideline in existence.
I hope to show exactly how FEMA P-1199/ICC 1300 translated its superior resources into a practical guideline for contractors like myself who actually do the work and for the homeowners who pay for them. As stated earlier, this end will be achieved by comparing it to the much simpler, minimally researched, poorly-funded seismic retrofit standard, Standard Plan A, created by an ordinary group of people who were not brilliant minds by any measure. The difference between the standards is not surprising.
Cripple Wall Retrofits
As mentioned earlier, this study compares cripple wall retrofit strategies found in both of these guidelines because cripple wall retrofits are by far the most important and common types of retrofits and the ones I am most familiar with. If you are unfamiliar with cripple wall retrofits I suggest you watch the 10 minute video below.
3) THE FUNDAPARTALS OF CRIPPLE WALL RETROFITS
4) PART 2: READING THE TABLES IN FEMA P-1100/ICC 1300
FEMA P-1100/ICC 1300 uses a table called the EARTHQUAKE RETROFIT SCHEDULE. The table tells us how many linear feet of plywood are needed, the nail spacing to the top, bottom, and sides of the plywood (called Panel Edge Nailing in the table), the number of bolts, and the number of “Type E Connectors” required on each wall to retrofit a light, medium, or heavy construction house. Light, medium, and heavy construction are defined here.
Comparing the images below, the quantities of plywood and hardware in the EARTHQUAKE RETROFIT SCHEDULE are all reflected in the foundation plan to the right of the table. The magenta box on the left tells us TWO 12′ lengths of plywood are required on each wall line. Correspondingly, in the foundation plan we see TWO 12′ lengths of plywood on each wall line.
The green box tells us our retrofit will need (12) 5/8 bolts on each wall line. Again, on the foundation plan we see 12 bolts on each wall line. The red box tells us the nails on the edges of the plywood need to be 4″ apart. The blue box tells us we need 25 Type E Connectors on each wall line. These are the same as L-90 shear transfer ties. The dark red box on the far left tells us that we must use this particular row and column when retrofitting a 1201-1500 square foot light construction single story house.
Are We Comparing Apples to Apples?
Even though the table called the EARTHQUAKE RETROFIT SCHEDULE is the basis of the cripple wall chapter in FEMA-P-1100/ICC 1300, we will not be comparing it to a similar table in Standard Plan A because its table is so outdated and flawed it is unusable for a study like this. Instead, we will compare the EARTHQUAKE RETROFIT SCHEDULE to Standard Plan A’s engineering calculations. Nevertheless, the Standard Plan A table does have some advantages over the EARTHQUAKE RETROFIT SCHEDULE in FEMA P-1100/ICC 1300 as illustrated in the video below because it is not handcuffed by the proprietary hardware restrictions placed on FEMA P-1100/ICC 1300.
5) COMPARING THE TABLES IN STANDARD PLAN A AND FEMA P-1100/ICC 1300
The Case for Balanced Engineering
The earthquake resistance of each component, i.e., the bolts, plywood, and L90s, should be more or less equal to create a balanced and money saving retrofit. The thinking behind this is that a retrofit is only as strong as its weakest connection. The plywood, bolts, and L90s work as a system. If one component fails the entire system fails. For example, if the plywood can resist 1000 lbs. (#) of shear force, the bolts 5000 lbs. of shear force, and the L90s 20,000 lbs. of shear force, the retrofit will still fail when subjected to 1,000 lbs. of earthquake force because the plywood can only resist 1,000 lbs. of force. Any quantity of bolts or other hardware that exceeds the 1000 lbs. of plywood capacity are purely decorative and a waste of money. Here is a 3:40 video that explains how balanced retrofits work.
6) HOW MUCH EARTHQUAKE FORCE SHOULD A RETROFIT RESIST?
MAKING THE DECISION: COMPARING THE GUIDELINES
Below Is A FEMA P-1100 vs. Standard Plan A Comparison For a 1350 Square Foot 1-Story Light Construction House
Let’s See How Balancing Affects Price
The red numbers on the FEMA P-1100/ICC 1300 foundation plan on the left tell us the total earthquake resistance of the plywood is 36,480 lbs., while the total earthquake resistance of the bolts is 72,000 lbs., and total resistance of the L90s is 92,520 lbs. These numbers are not even close to being balance. In short, we have 35,520 lbs. worth of excess bolt strength ($1,823.00) and 58,020 Lbs. worth of extra L90s strength total ($2,446.00). These extra bolts and L90 and make this retrofit far more expensive than it needs to be.
A 1350 Square Foot 1-Story Medium Construction Comparison
These two figures compare a FEMA P-1100/ICC 1300 retrofit (on the left) with a Standard Plan A retrofit (on the right) for a medium construction 1,350 square foot house. A Standard Plan A retrofit will cost $6,644, compared to $17,784 for a FEMA P-1100/ICC 1300 retrofit. Notice how grossly out of balance the FEMA P-1100 retrofit is. The 21,000 lbs of bolt capacity found in this FEMA P-1100/ICC 1300 retrofit exceeds the 11,760 lb. plywood capacity by 9,240 lbs. We also find 15,065 lbs. of excess (and expensive) L90 capacity. These excess bolts and L90s cause this P-1100 retrofit to be far more expensive than it needs to be.
On the other hand, the Standard Plan A retrofit is balanced with 6,600 lbs. of plywood, 6,000 lbs. worth or bolts, and 6,475 lbs. of L90s on each side. This balanced Standard Plan A retrofit costs considerably less simply because it is balanced.
A 1350 Square Foot 1-Story Heavy Construction Comparison.
These two figures compare a FEMA P-1100/ICC 1300 retrofit (on the left) with a Standard Plan A retrofit (on the right) for a heavy construction 1,350 square foot house. A Standard Plan A retrofit will cost $7,432 compared to $19,592 for a FEMA P-1100/ICC 1300 retrofit. Again, notice how grossly out of balance the FEMA P-1100 retrofit is.
Comparing 2-story Retrofits
FEMA P-1100/ICC 1300 two story retrofits use the same EARTHQUAKE RETROFIT SCHEDULE as 1-story houses. The only difference is that these retrofits often use holdowns, (called tie-downs in the table), which resist overturning forces.
A 3150 Square Foot 2-Story Light Construction Comparison
Applying the same thinking process we used in evaluating 1-story houses, we see the P-1100/ICC 1300 retrofit on the left will cost $49,384, compared to a $9,158 Standard Plan A retrofit shown on the right.
Notice how grossly out of balance the FEMA P-1100/ICC 1300 retrofit is where the capacity of the plywood is 18,240 lbs., the bolts almost twice that amount at 18,240 lbs., and the L90s almost three times that amount at 44,000 lbs. Compare this to the almost perfectly balanced Standard Plan A retrofit with 8,800 lbs. of plywood, 9,000 lbs. worth or bolts, and 9,250 lbs worth of L90s on each foundation line.
Notice how the available foundation on the foundation plan is less than the linear footage of plywood required by FEMA P-1100. In my experience with designing seismic retrofits for two story houses, I cannot think of a single instance where P-1100 would work on a two story house. Fully half of the tables in FEMA P-1100 which took a lot of effort and money to create are therefore unusable and irrelevant.
3150 Square Foot 2-Story Medium Construction Comparison
Assuming 2-story houses where FEMA P-1100 will work actually exist, when we apply the same thinking process used for 1-story houses to this house we discover that this FEMA P-1100/CC 1300 retrofit will cost $47,284 compared to a $22,530 Standard Plan A retrofit. The same problem with balance applies here. Notice how the Standard Plan A retrofit is almost perfectly balanced.
3150 Square Foot 2-Story Heavy Construction Comparison
When we apply the same thinking process to this house we discover that the FEMA P-1100/ICC 1300 retrofit will cost $55,276 compared to a $24,392 Standard Plan A retrofit. The same problem with balance applies here.
No Cripple Wall Retrofits
Here we compare a 2-story 3,150 square foot medium construction P-1100 retrofit of a house without cripple walls. In this retrofit we are using the Type B Connector (the brand name is the Simpson Strongtie FRFP) from the EARTHQUAKE RETROFIT SCHEDULE which is FEMA P-1100/ICC 1300 approach and compare it to a 3,150 square foot 2-story Standard Plan A retrofit no cripple wall retrofit (on the right) which uses the Simpson StrongTie URFP. The FEMA P-1100/ICC 1300 retrofit will cost $42,793, compared to a $6,438 Standard Plan A retrofit.
In this last part of our study we look at what happens when a FEMA P-1100/ICC 1300 construction detail seen on the lower right is applied to a medium construction 1,350 square foot single story house. A construction detail is a drawing that shows a contractor how to build something.
The dark and light blue lines in the detail are 4 foot long shims called “runners”. The red lines are Type B Connectors (Simpson FRFPs). This is another case where the linear footage of foundation is not long enough for the length of the plywood required by the EARTHQUAKE RETROFIT SCHEDULE. The detail has many other problems, including a building code violation. This is fully described in this video.
The Construction Details in FEMA P-1100/ICC 1300
Construction details are drawings that show a contractor how to build something. These details are based on the science that produced complex tables like this one found on page 1-3 of FEMA P-1100-3. These details should provide contractors ideas that reflect the millions of dollars in research that produced them. I have created 15 videos that look very carefully at the construction details in FEMA P-1100/ICC 1300 which are based on $22,400,000 of research.
GRAPH FROM FEMA P-1100-3 BACKGROUND DOCUMENTATION.
GRAPHS LIKE THIS PROVIDE THE ENGINEERING BASIS FOR FEMA P-1100/1CC 1300 CONSTRUCTION DETAILS.
7) THE IMPORTANCE OF EXISTING BUILDING MATERIALS
As mentioned earlier, some scientists can be prone to looking at retrofitting homes as a math problem, while contractors look at it as a construction and math problem. If a retrofit is viewed as a math problem, all you need to do is plug some numbers into a formula, and assume the connections that attach the floor to the foundation have zero earthquake resistance. That spits out a number that predicts the earthquake resistance requirements for the plywood and oter hardware. Another approach is to build a mock up of a house with new building materials, measure its reactions on a shake table, and based on very limited testing will assume existing houses will respond in the same way.
If seismic retrofits are viewed as a formula with a high base shear factor, it is no wonder FEMA P-1100/ICC 1300 retrofits are so expensive.
This video looks at the performance of cripple wall retrofits on homes with stucco, and contrasts them to houses with wood siding. This video confirms the accuracy of TABLE (BS) A1-D in Chapter A1 Seismic Strengthening Provisions for Unreinforced Masonry Bearing Wall Buildings and supports it with empirical evidence. This evidence confirms that the inherent strength of existing houses should be considered and that stucco houses should have fewer retrofit components not more than the amount specified in FEMA P-1100/ICC 1300
On the other hand, contractors are dealing with construction problems they find while working with old houses, not a mock up houses on a shake table or figure on a computer screen. They look at the all the existing connections with a view to strengthening each one as needed. Once you crawl under a house, you often find weak connections that cannot be corrected with bolts, plywood on the cripple walls, and floor to top plate connections. In these cases a contractor must use his experience, available details and tools to figure out what to do. Remember, earthquakes will find all the weak connections. One weak connection and the retrofit will fail.
Sometimes a contractor will advise the client to do nothing at all because the house is sufficiently braced with diagonal sheathing. Only those who have crawled under a few houses will know that diagonal sheathing is not all that uncommon. Contractors know from working on these old houses, studying old building codes, and the well established evidence that relatively few houses fall from their foundations in large earthquakes that old houses have a lot of inherent strength. The tremendous amount of effort required to tear down a plaster wall or remove stucco from an old house is all the convincing a contractor needs to confirm an existing house has a great deal of earthquake resistance before any retrofitting takes place.
Learning From Videos
Contractors are doers and want to see how something is done so that it is effective and he can still make a profit. I created the following series of videos to convince other committee members that alternate details existed that were often easier to build and cheaper than those provided in FEMA P-1100. In some instances I made the case that some details should be removed. Contractors will find these videos extremely helpful.
8) CONSTRUCTION DETAILS – HOW DO I BUILD A RETROFIT?
I made almost 100 suggestions for changes to the ICC 1300 committee. I will not know which ones were accepted until ICC 1300’s final publication. Most of the committee members did not agree with my suggestions; probably because I did not understand the tested engineering principles found in their 7,000 pages of research. On the other hand, I viewed their approach as being impractical. These disagreement reveal the all too common disconnect that often exists between contractors and engineers. After watching the following videos you can decide for yourself.
9) THE T-BLOCK DETAIL
This was the first detail I looked at, and I was puzzled by what I saw because it was contrary to everything I had seen or studied before. I have been studying and building shear walls for a long time and could not help but think these 38 world class experts in shear wall design knew more than I did. I am not a research scientist, I do not have a laboratory, for me this detail was something revolutionary. As it turns out, these experts had made a mistake. Fortunately at a sub-committee meeting I presented my case just as I did in this video. The T Block detail was readily removed and no one knows how it got there.
10) WHY ADDITIONS ARE IMPORTANT
Older homes were much smaller than they are now. It is not uncommon for an older home (such as the 1955 house I live in) to have originally been 900- 1200 square feet. Over time demand for larger homes increased considerably and this was met by building additions on the back of the house. I would guess 1/4 of the older homes we retrofit have additions. The building code does not tell a contractor how to connect an addition to the main house. Nor do retrofit guidelines point out that the addition needs to be retrofitted independently from the main house. Apparently the More field investigations would have brought this to light and perhaps FEMA P-1100/ICC 1300 would have considered this.
11) MECHANICAL ANCHOR BOLTS: BREAKING WITH PRECEDENCE
Many, if not all, seismic retrofit contractors use mechanical anchor bolts, also called wedge anchors, to bolt a house. The main reason is that they are cheap and easy to install. This makes it easier for a contractor to provide a cost-effective retrofit which he can then pass onto his client. They are not allowed in FEMA P-1100/ICC 1300 but are allowed in all the other seismic retrofit guidelines. I asked a member of the committee why mechanical anchors were not allowed and they said it was because one of the engineers heard from a contractor that they can break out the concrete. No reference to testing was cited, only this hearsay. Fortunately, tests performed by the Structural Engineer’s Association of Southern California validated the effectiveness of wedge anchors. This report was provided to the committee along with my own testimony where I recounted my experience of installing ~50,000 wedge anchors without seeing the concrete break out even once.
12) THE DANGER OF CHEMICAL ANCHORS
In spite of potential health risks, the FEMA P-1100/ICC 1300 committee chose to ignore the serious health risks posed by silica dust created when drilling holes for chemical anchors (also called epoxy bolts). OSHA has very stern warnings about the safety precautions required when drilling into concrete. The committee must have believed that contractors are as a rule very safe when handling carcinogenic dust, will minimize dust in work areas, that OSHA is very diligent, and contractors will gladly pay a cleaning service to remove all the carcinogenic dust that inevitably appears inside a house when chemical anchors are used. I found this puzzling because public safety is the purpose of this standard.
13) TABLES AND DETAILS WITH HARDWARE THAT DOES NOT EXIST
This hardware has not been available since the late 2005 or so. It was known as the Simpson FA6 or FA8. We used them before the Simpson UFP10 (currently superseded by the Simpson URFP) when a mudsill was buried in concrete and it can only be accessed from the top. Once Simpson StrongTie realized no one was buying them they discontinued the product. However, the hardware manufacturer USP based in the Midwest still makes them. They lack an ICC test report and sales have been miniscule. I asked the USP sales rep how many they had sold between 2019 and 2020 and this is what he sent me. Note only 28 were sold in a seismic zone and there is no telling what they were used for because at that time the had the Simpson UFP10 (a precursor to the URFP). We have a few left over from earlier days which we use as book ends.
++++++“It is my opinion that devoting an entire column and row in the tables along with various construction details to a hardware that is virtually non-existent will date the standard to before 2005. In other words, it will look obsolete on the day it is published and contractors will tend to discount it.
14) THE TYPE B CONNECTGOR (SIMPSON FRFP) – HARDWARE THAT IS NEVER USED
The Type B Connector (Simpson FRFP)
This hardware is virtually unused in the seismic retrofit industry. I have used this hardware only once in the past 25 years when I was forced to bolt a house from the outside. This is a sales report from the largest hardware supplier in the Bay Area and shows on average it sells 17 FRPP each year, probably as door stops.
As mentioned earlier we do 150 retrofits a week and always come up against something new. In one case in San Francisco the crawlspace clearance was insufficient for us to bolt the house from the crawl space. In this case we ordered some FRFPs and bolted the house. This has happened only once in 25 years. We would never use it in a crawl space. If FRFP connectors are used it should be assumed the they will be used on the outside of a house and the standard should specify that the hardware is special ordered with a Zmax coating to make sure they do not rust. A few years ago a committee member sent me a photo of a house that had been bolted from the outside with FRFPs but they were not coated with Zmax and have probably rusted out by now.
This video examines how the Simpson FRFP is used in FEMA p-1100/ICC 1300 and why it is used so seldom.
15) A COMPARISON BETWEEN THE SIMPSON URFP AND THE FRFP
I made this companion video that compares the Simpson URFP to the Simpson FRFP
16) SHOWING CONTRACTORS THE HARD WAY
This construction detail confirms that the authors of FEMA P-1100/ICC 1300 are not familiar with the tools seismic retrofit contractors use on a daily basis.
17) IS THIS REALLY A WEAK CONNECTION?
During deliberations about this detail no one mentioned any test data that justified its inclusion in ICC 1300. FEMA P-1100/ICC 1300 though this does not mean there is testing data somewhere in the 7,000 pages of data. Never the less, some reason should be provided as to why FEMA p-1100/ICC 1300 is the only guideline that has this detail.
This image is part of a table the FEMA P-1100 plan set which are step by step instructions contractors telling a contractor how many retrofit components he needs to retrofit a house. When I first saw this table I recognized it was an illustration of a type of hardware that Simpson StrongTie stopped making years ago (see video 13), the hardware manufacturer KC Metals no longer exists, and the TYPE C connector produced by USP hardware is not a code approved hardware and is impossible to find. Not only that, but the image was mistakenly identified as a Simpson FRFP. This is what a FRFP looks like.
As you can see, the flat FRFP looks quite a bit different than the bent non-existent/unavailable TYPE C connector. I am pleased to say that my expertise as a contractor who purchases hardware on a consistent basis would have known This confirmed the important role I could play in this project.
The Type A connector is the most versatile bolting hardware used when clearance under a house is minimal. Here the capacity is listed at 1530#. The actual capacity is much lower that that because all mudsills on older homes along the entire west coast are made of redwood. This is because it is decay resistant and will not rot when touching concrete. However, wood species have a big impact on hardware capacity. Simpson StrongTie actually lists this hardware as being 1180 lbs.
This is again something only a contractor would understand after removing, cutting, and replacing mudsills on a regular basis.
IMAGE FROM SIMPSON STRONGTIE CATALOG SHOWING THE ACTUAL VALUE OF THE URFP IS 1180 LBS.
18) TOP PLATE CONNECTIONS IN P-1100/ICC 1300
FEMA P-1100/ICC 1300 uses steel straps to make a critical connection to bridge breaks in top plates. Steel straps are labor intensive and expensive both in material terms and labor. A few nails is all one really needs.
Straps are meant to be used on the exterior of a building which will be covered with stucco or some other siding. Siding does not cover anything in crawl spaces so 2 x 4s can can also be used to connect top plate or other framng members together. These alternate methods will help contractors do it faster, better, cheaper, and save money that he can pass on to the homeowner.
19) BALLOON FRAMING IN FEMA P-1100/ICC 1300
We see balloon framing in homes built at the turn of the century up until about around 1915. Some contractors may find FEMA P-1100/ICC 1300’s detail very labor intensive compared to the standard of care developed by seismic retrofit contractors. This video looks at both approaches.
20) THE PLYWOOD TO BOLT CONNECTION IN FEMA P-1100/ICC 1300
There are 5 different ways to connect plywood to the bolts. In order to do this the plywood must be connected to the mudsill. The 5 different methods were evaluated for the Standard Plan A committee by the American Plywood Association in Tacoma, Washington. This is the leading shear wall testing laboratory in the world. FEMA P-1100/ICC 1300 decided the oldest, and probably the least effective methods is the best method of them all. This video explains what all these methods are and why FEMA P-1100/ICC 1300 chose this particular method in spite of its subordinate standing compared to the other methods.
21) NO TOP PLATE DETAIL IN FEMA P-1100/ICC 1300 VS. CONTRACTORS
There are a very large number of older houses in the San Francisco Bay Area that do not have top plates on the cripple walls. Rather, the end joists sit directly on the studs. FEMA P-1100 is the only retrofit guideline that contains a construction detail that shows how a cripple wall without top plates can be retrofitted. The only other place you will find a detail for this is on Bay Area Retrofit’s detail webpage. This video looks at both construction details which are equally effective but one is far easier to build.
22) UNUSUAL BLOCKS IN FEMA P-1100/ICC 1300
FEMA P-1100 requires blocking between the 2 end joists every 4 feet, even though this is not a requirement for brand new houses built directly on top of a fault. The reason must lie somewhere in the 7,000 pages of research and frankly I don’t have time or desire to look for it.
23) THE IMPORTANCE OF PORCHES
Quite a few houses have foundations that follow the front of the foundation rather than the front of the house. If FEMA P-1100/ICC 1300 is followed as prescribed such that bracing is put on all exterior cripple walls, the front of the porch will be protected but the front of the house will remain unprotected. This is something we see fairly often. It would be useful if FEMA P-1100 developed a way to warn contractors, such as in a construction detail like this one, to look out for this.
24) FEMA P-1100/ICC 1300 HAS A DETAIL FOR A COMMON FLOOR CONNECTION; CONTRACTORS HAVE A SIMPLER WAY
There are many ways to make most connections but the simplest method is usually the quickest method and requires fewer materials and saves on cost. If this video we look at the way FEMA P-1100/ICC 1300 makes a connection using nails and steel and compare that to a detail contractors use that only uses nails.
More On Construction Details
Here are ~60 construction details Bay Area Retrofit uses on a regular basis. This is an ideal detail that includes a link to a YouTube video where you can see another contractor building the detail. Unfortunately, the FEMA P-1100/ICC 1300 development committee did not have the funding to create more details like this. If you are a contractor you should be able to use these ~60 details in combination with these engineering principles and these house weights you should be able to retrofit a house without the complex research and extensive testing that are the basis of the FEMA P-1100/ICC 1300 prescriptive system .
One of the engineers on the committee was kind enough to review this material after I asked him if he saw a reason for the cost discrepancies. This is what he wrote me.
Note: I have absolutely no idea what this engineering lingo means, but have kept it here in case someone who reads this article does. The conclusion, however, is clear.
“I think the LOG (living area above a garage) retrofits use an R of 5.0 (which is more restrictive than ASCE 7 where wood structural panel shear walls have an R of 6.5). The seismic response coefficient Cs = Sds/R = 1.25/5.0 = 0.25 and the base shear is 0.250w. For Standard Plan A the Cs is 0.186, thus FEMA P-1100 and ICC 1300 are generating a base shear 1.34 times that of Standard Plan A.
Interestingly 1.25/6.5 = 0.192 which is still a bit higher than 0.186. Not sure what Standard Plan A is assuming? Maybe Sds=1.17 which used to be the trigger for SDC E in the IRC. Which gets you Cs=0.180 for R=6.5, close to Standard Plan A’s 0.182.
I forget whether FEMA P-1100/ICC 1300 adjusted the resistance side for LOG retrofits too or applied other factors. There was that 1.5 factor Phil Line was concerned about with cripple walls because it was making the results more conservative than a complete engineered design using ASCE 7 and AWC’s standards.
The weights are higher, but I’m not sure that is entirely responsible for the difference. P-1100 is 18% higher on the roof weight (13psf vs 11psf for a light roof assembly) and 33% higher on the floor weight (12psf vs. 9psf for a light floor assembly). And P-1100 isn’t entirely unreasonable as assumptions go, it tracks with other industry resources like the HUD Residential Structural Design Guide.
Put that weight together with the 34% increase in the respective Cs values and you’re getting to a 60-70% increase in base shear. But we know there are other conservative assumptions embedded deep in P-1100’s modeling and calculations. I haven’t spent anywhere near enough time rooting around under the hood to find them.”
This perhaps unlocks much of the mystery. From what I can tell P-1100 is working with a base shear of 0.316 – 0.35.
Outside of what we have seen here, probably the number 1 reason for the cost of FEMA P-1100/ICC 1300 being so high is because it is designed to resist force levels that exceed that required for new houses or Standard Plan A.
Heavy On The Theory, Light On The Practice
It was apparent to me that the scientists on the FEMA P-1100 committee had not spent much time crawling under houses, drilling holes in concrete, beating bolts into 100 year old concrete, reacting to customers when the first floor of their house is covered with carcinogenic concrete dust after chemical anchors are installed, worked with palm nailers etc.. Nor had they flush cut mudsills, tried to drive lag screws dead center into joists, used dust vacuums for holdowns, replaced rotted mudsills, discovered that code recommendations such as (4) 10d nails in 14 1/2″ block splits, realized staples are often needed because old wood spits, tested paint to see if it is lead-based, or known that 2 x 4s work more effectively than steel straps and are far cheaper. They do not know how plywood is repaired if nails break the outer skins of the plywood, and that a large part of a seismic retrofit contractor’s job consists of repairing existing poorly installed shear walls. In short, they were developing a guideline about something they knew practically nothing about except in theory. FEMA P-1100/ICC 1300 is by all accounts an engineering marvel, from a practical point of view it is a complete failure.
FEMA P-1100/ICC 1300 assumes all the lumber under these houses was 1 1/2″ Douglas Fir because that is what modern houses are made of. In fact they are made of redwood and Douglas Fir and the framing is 2 inches thick. Only a contractor who retrofitted these old houses on a regular basis would know this and the impact of species and size is significant.
25) THE IMPACT OF WOOD SPECIES ON HARDWARE.
The Two Worlds of Contractors and Scientists
Research scientists are rarely aware of problematic conditions such as additions or porches that are a common occurrence in many houses. This misconception is quickly dispelled after looking at a few random houses. But if you don’t look, it is impossible to know. A huge problem with P-1100 is that the committee members did not spend time looking at actual houses,; rather the houses were theoretical in nature. I remember going to an Existing Buildings Committee meeting and one of the structural engineers telling me the houses they learned about in school were called “the professor’s house” because they only existed in the mind of the professors and not the houses contractors work on everyday.
Scientist live in a world of theories, computer models, tables, graphs, and test reports informed in part by shake table tests. This research manifests as mathematical analyses such as the ones we saw made by the kind engineer. This is the world they live in so it is only natural that research and testing will take precedence over practical application. Practical application is not the world they live in, nor is it one they would find comprehensible. To a large extent contractors and engineers are trying to solve completely different problems. For the engineer the questions is “how do I make the numbers work?”, while for the contractor it is “how do I build an effective retrofit my client can afford where I can make a profit”?
Engineers need contractors so they understand cost and practicality, contractors need engineers to make sure load paths are solid and equal to the task. Both groups need seismologists to make sure the retrofits are not resisting too little force such that they will fail or too much force because of the added cost.
Standard Plan A Will Work With Revisions
You have learned about the ineffective weak connections in Standard Plan A such as the double top plate nailing, the importance joining upper top plates together, and the incorrect hardware capacities in the table. If you apply these changes to a Standard Plan A retrofit and consult the detail library as needed, you will be n good shape.
If a seismologist tells you Standard Plan A is not strong enough or you simply want to make a Standard Plan A cripple retrofit more earthquake resistant, put in more plywood, bolts, and framing anchors to create the resistance you want. Just be sure they have an equal amount of earthquake resistance. The earthquake resistance of various retrofit components can be found on this webpage and should help you. Home retrofitting really isn’t that complicated. Certainly not 290 pages and 422 pages of back ground documentation complicated.
One of the problems the original 38 member committee had was they were asked to give contractors how-to guidance on something they had never done themselves. It would be like me writing a guideline on how to change a tire, perform a heart transplant, bake a cake, ride a bicycle, climb a mountain, engineer a bridge, etc. without ever having done it myself. The result is very predictable.
A case in point is this detail, which has been unnecessarily duplicated in numerous other government guidelines, was created by highly educated scientists who did not understand the simple principle that nailing exclusively into the lower top plate creates a shear wall with almost no earthquake resistance. This detail can be found on page 19 volume W-17 of the 30 volume set of CUREE studies. When it was peer reviewed no one noticed what contractors would see as a glaring deficiency. On top of that the detail itself is a case spending government money on a detail that has already been drawn in numerous government publications .
After looking at actual top plates and seeing toenails connecting the floor joists to the top plate the principle of edge nailing comes quickly to a contractor. It is interesting to note that this erroneous top plate nailing is both in the 2008 Standard Plan A revision, which I was not part of, and FEMA DR-4193-RA2 . These committees also consisted of engineers and scientists.
I am certain FEMA P-1100/ICC 1300 will become one more of the 21st FEMA publication that no one uses. Over a span of time the Applied Technology Council or a similar organization will convince FEMA that they need several million dollars to produce another guideline for wood frame seismic retrofitting. This is as it should be because protecting the public from earthquakes is FEMA’s whole purpose.
What Would Contractors Have Done With $22,400,000 Dollars?
Contractors would have done a completely different set of tests. We would take older homes apart and see how various connections were made, we would want to know if they were built the same all over the country such as was the conclusion of the research behind the National Science Foundation’s study of masonry buildings. We would want to see why there is not a single case of a mudsill sliding on the foundation, we would want to know why cripple walls in stucco houses rarely collapse, we would like to test holdowns in concrete 100 year old foundations that are 12″ deep or less. We would want to see a house mover transport an older home and shake it on a shake table and see what happens. We would want to bring all the research into the real world, into the houses we work on, not to houses in laboratories.
At some point FEMA might realize that it is better to have “how to” guidelines written by “have done” authors as a team effort with consulting engineers. Together I think they could develop an excellent guideline that would certainly cost less than $100,000 Next time rather than performing tests that have been done many times in the past and using millions of dollars of grant money for experiments that have already been performed elsewhere, that have no practical value, give the money to practical contractors who are in touch with the real world couple them with scientists and engineers so something practical is produced.
The first question that needs to be asked before spending money on a shake table test and writing a 150 page test report is to ask the contractor “will this test provide you with something that will help you protect people’s homes? If the answer is “no” use the money for something else. Maybe when someone practical minded finds out FEMA P-1100 has been relegated to to the list other rarely owned, read, or used publications, they will use the next multi-million dollar grant to create something that will protect the public.
I sent the follow letter to the West Coast FEMA regional manager who was very helpful and told me she did not have any power to make any changes. She advised me to contact two senior managers in Washington D.C. who should have the power. I did not receive a response. This is question is the summation of the letter I sent.
How This Study Was Performed
The webpage is based on this written study that compares FEMA P-1100 with Standard Plan A from a cost point of view. Some of the material is different from what you see here and it does not have videos. I believed the most effective way to conduct this study was to try apply the two guidelines to the same house where the existing construction materials, square footage, and weight of the house were the same.
Throughout this study the pricing per piece of hardware and price per linear foot of plywood is based on Bay Area Retrofit’s current price schedule shown below.
|Plywood < 4 feet
|Plywood > 4 feet
The table below contains the earthquake resistance measured in pounds of the plywood and hardware used in this study. These capacities can be found Special Design Provisions For Wind And Seismic, the National Design Specification, and the Simpson StrongTie Catalog.
|5/8” Bolts in 2” Close Grain Redwood
|Light Construction Rated Plywood
|Medium Construction Rated Plywood
|Standard Plan A 3” o.c. Structural 1 Plywood
|Heavy Construction Rated Plywood
List of Research Projects The FEMA P-1100 Committee Could Draw Upon.
6 Pages ATC-14 EVALUATING THE SEISMIC RESISTANCE OF EXISTING BUILDINGS
190 PAGE FEMA P-50 Simplifed Seismic Assessment of Detached,Single-Family Wood-Frame Dwellings
168 Page FEMA_P-50-1 Seismic Retrofit Guidelines for Detached, Single-Family, Wood-Frame Dwellings
Page Count Unknown ( I won’t pay $25 tp find out) FEMA 276, Example Applications of the NEHRP Guidelines for the Seismic Rehabilitation of Buildings
21 Page FEMA DR-4193-RA2 Earthquake Strengthening of Cripple Walls in Wood Frame Buildings.
44 Page PEER Framing Hillside Home Retrofit Decisions
225 Page FEMA 232 Homebuilder’s Guide to Earthquake Resistant Design and Construction
Unknown Page Length A Methodology for Seismic Design and Construction of Single-Family Dwellings
Unknown Page Length FEMA 237, Development of Guidelines for Seismic Rehabilitation of Buildings, Phase I
21 Page FEMA_274, NEHRP Commentary on the Guidelines for the Seismic Rehabilitation of Buildings
15 Page ATC-50TOC Simplified Seismic Assessment of Detached, Single-Family, Wood-Frame Dwellings
267 Page FEMA Publication Seismic Retrofit Training For Building Contractors & Inspectors
84 Page DR-1664-HI Structural Seismic Retrofits For Hawaii Single Family Residences With Post and Pier Foundations
Page Length Unknown A Methodology for Seismic Design and Construction of Single-Family Dwellings