Home & Garden Columns

About The House: It Pays to Pay Attention to a House’s Foundation

By Matt Cantor
Friday July 28, 2006

When I show up with my flashlight, there’s one item that most homeowners are holding their breath about and that’s their foundation. People generally believe that this is: a) the most important system of the house, and b) the most expensive. Well, this is close to the truth in both cases, although I can think of plenty of cases where neither is actually the case.  

Nonetheless, foundations are very important and pretty expensive. Regarding the latter, though, I think it’s important to recognize how cheap they’ve actually become over the last 20 years. 

When I started inspecting houses, many of the houses I saw were valued at roughly $100,000 and the replacement of a foundation was typically about $20,000 or about 20 percent of the total cost of the house. 

At the time, that seemed like such a large amount of money that the notion of acquiring a house that needed a new foundation was often inconceivable for my client. 

I saw quite a few deals fall apart over foundations back in those days and I also saw many a client buy (and keep) the old crumbly foundation with the long-range intent of replacement. Some have done this and many have not.  

Today, a typical house in Berkeley is about $700,000 and the cost of a foundation has risen to about $35,000. In other words, the cost of a foundation replacement has dropped to about 5 percent of the cost of a typical house. Yes, the cost of foundation replacement has risen but it’s risen far less than inflation for a 20 year period. So today, it’s far less excusable to buy a house and keep the crumbly old foundation. Also, the foundation from 1907 (that’s the one I saw today), which was crumbly in 1986 is even crumblier today. 

Beyond that, the standard of care for foundations continues to rise every day. Today, there is a significantly higher percentage of newer, high quality foundations than there were 20 years ago. So we have lots of reasons to want to replace those old foundations now. They’re getting to be a much smaller percentage of the cost of a house, they’re more out of step with current standards and they’re each getting worse as time goes by. 

But what’s wrong with having an old foundation? Why do I want a new one? My old one may have cracks and may be crumbly but it’s still sitting there under my house, right? 

Yes, all that’s true. In the case of most houses, the foundation, even if it’s kind of crumbly or cracked, is bearing the “gravity loads” as my friend, the engineer, Dan Szumsky would say. It’s holding up the house. So that’s not what foundation replacement is about in most case. 

We’re all waiting for an earthquake and, hopefully, getting ready for it. A big part of getting ready for an earthquake is making sure that your house is properly bolted to the foundation so that it won’t slide off during a quake (this actually happens). This is really important and most people know it (even if they’re hiding under the bed avoiding the issue…. Yes, you with the pillow wrapped around your head going ‘LA LA LA LA LA’). 

If the concrete in your foundation is really crumbly, and I see this in a fair number of houses from the early part of the 20th century, the bolts aren’t going to be able to keep the house connected to the foundation. They’ll just shake right through the soft concrete and your house will end up moving to a new address (sans the water service, sewer line….) 

The concrete needs to be at least as strong as the wood otherwise bolting doesn’t work. If you have a foundation that’s soft like this, it’s time to wake up and smell the shear-wall. 

If you’re concerned about the cost of the foundation, there’s a spoonful of sugar I can offer to go with this bitter pill. When you replace the foundation on your house, it’s not going be the same house minus 35 grand. It’s going to be a better house and a more valuable one. 

It might not be worth another $35,000 but it’s going to be substantially more valuable by any measure. Although nobody can say for certain what the actual value adjustment will be, it’s clear that you’re not throwing your money away, even setting aside the seismic issues. 

As houses have grown in value to their wild present heights, the level of scrutiny has certainly risen commensurately 

Twenty years ago, most people didn’t have home inspections and few would argue over an issue like a foundation (and almost never over the presence of bolting and bracing) but today, things are very different.  

With such large amount of money on the table today, most people do a fair amount of investigation into the condition of the house. Many have multiple inspections and issues involving foundation condition and the capability to effectively bolt the house have grown in stature to stand side-by-side with the other issues that buyer’s weigh in the purchase of a house. Things have certainly changed and buying a new foundation just isn’t the dicey financial matter it once was.  

So, how do you know if your foundation is one that should be replaced? Well, deterioration or crumbliness isn’t the only feature one might look at, but with respect to seismic strength, it’s the most important. Foundation strength was something that improved in our houses over the first 40 years of the 20th century and by 1940, most foundations were made of very hard and very long-lasting concrete. 

It’s not about age, it’s about technique. Keep in mind that the Romans built structures in concrete that are still standing today after 2000 years. It’s also not about water, because we built concrete boats and concrete is poured below water for caissons on the bay and the ocean floor.  

If you have a foundation from before 1910, there’s a fair chance that it’s a goner. If it’s from the teens, I’d estimate that there’s about a 20 percent chance that it will need replacement. If it’s from the ‘20s, your changes probably drop to about 10 percent and in the ‘30s they drop to about 5 percent. 

Of course, these are VERY rough numbers and I’ve certainly seen some very good foundations from 1915 (though it’s pretty rare). I should also mention that if your foundation is brick or stone, it should absolutely be replaced. 

You just can’t effectively bolt to these materials without very special and very expensive methods that can’t complete with a simple foundation replacement. 

Some may consider mine an unreinforceable position, but I believe it represents a concrete reality. Of course, you yourself will have to decide if my argument has a solid foundation. 



Got a question about home repairs and inspections? Send them to Matt Cantor, in care of East Bay Real Estate, at realestate@berkeleydailyplanet.com.