Frequently Asked Questions About Retrofitting Single-Family Homes

What is retrofitting? I have read that some of the retrofits in the Bay Area have not been done properly. What should I check for?


Retrofitting for most single-family homes involves strengthening the walls of the crawl space under your home and making sure that it is attached to the foundation (with bolts or anchors) and to the floor framing above. While many homes continue to be retrofitted, we have become increasingly concerned about the quality of retrofits, including the workmanship and the work actually performed. Somewhere between 25% and 75% of currently retrofitted homes need additional work. Make sure that your contractor addresses all three of the following:

1. The mudsill-foundation connection – Adding bolts and washer plates will prevent the house from slipping off the foundation.

2. The cripple wall – Adding plywood panels on all four walls will prevent collapse of the outside wall of your crawl space (the cripple wall) to resist collapse, or “shear.”

3. The cripple wall-floor framing connection – Adding framing clips to attach the plywood shear walls to the floor framing above.

Specific directions on how to do a retrofit (including the kind and number of bolts, feet of plywood, types of nails to use, and number of anchors) are contained in the model retrofit plan set.

A qualified engineer or other design professional is usually needed to evaluate larger split-level or two-story homes.

Can I do any of this work myself?


Yes, homeowners who have done other home improvements can do it themselves. If you plan to do the work yourself, you need to take a training class. San Leandro offers a class open to all Bay Area residents.

Remember that the area under your house can be an unpleasant work environment!

How do I find an experienced contractor?


Visit ABAG’s page with guidance on how to find a contractor. Then follow these seven simple steps to choosing the right contractor for you.

Will I need to hire an engineer or other design professional?


Sometimes you need to hire a design professional, such as an engineer or architect specializing in seismic retrofitting, particularly if your home is more than one story (even if the home is only a split level), has a bedroom or other living area over a garage, or is on a steep hillside. The engineer will charge $1,000 to $5,000, depending on the complexity of the job. Use the ABAG list of engineers that perform retrofit work.

How do I select the engineer or design professional?


The engineer should be a licensed civil or structural engineer with experience in designing retrofits for homes. A good design professional will not add unnecessary strengthening and will add the strength where it is least expensive for the contractor to install. In addition, some architects may have the expertise to design a retrofit.

ABAG provides guidance on how to find engineers who perform seismic retrofits.

Do I need a building permit from the city or county?


Yes, permits are required by law. When you obtain a building permit, you also have some assurance that the work will be completed correctly. You really need that permit to protect your investment.

How much do permits cost?


Typically, cities and counties charge very little for retrofit permits. Some cities do not charge at all. A typical permit costs about $250. Call your city or county.

How much will a retrofit cost me?


Although costs vary, the typical home retrofit that does not require an engineer costs about $4,500. A lot can be done for $2,500.

How can I get the money to pay for this?


Home equity loans are available from banks. A five-year loan from a bank for $5,000 for 5 years at 9% will cost you about $104 a month, far less than putting this home strengthening on your credit card. Homeowners with low fixed incomes may be able to get help in paying for the work from their city or county or from the California Department of Insurance. Some cities have financial assistance available to their residents for retrofitting.

Last updated: 07.05.2017