Can a house fire affect the structural integrity of the home’s foundation?

- Thursday, December 08, 2022

A house fire is bad enough but depending on the severity of the damage, you might be able to save the home.  But what about the foundation?  How does a fire affect it?

Narrator: It’s time once again for the “Crack Man Podcast” hosted by A1 Foundation Crack Repair. I’m Darren Kincaid here with the Crack Daddy himself, Adam Tracy. Adam and The Crack Man Rich have over 30 years’ experience in the construction industry. Rich as over 25 years as the president and founder of A1 Foundation Crack Repair. This podcast provides expert basement waterproofing, concrete repair, and preventative maintenance tips for homeowners and businesses. A1 Foundation’s valuable insight will help avert a disastrous flood within the basement, health problems associated with water infiltration, and protect your biggest investment….your home. The topic of today’s podcast: How does a house fire affect its foundation?

Narrator: Adam, a house fire is bad enough, but depending on the severity of the damage, you might be able to save the home. But what about the foundation? How does a fire affect it?

Adam: Yeah, this is an often-overlooked part of a house fire incident, obviously it can be a traumatic experience for any family or even if it’s a multiple unit dwelling. But the biggest issue with fires, beyond, obviously, the tragedy of fires and rebuilding everything, it can really destabilize a foundation. And most people don’t think about that as they may be take on a property that has had a fire, or looking at buying a property that had been burned down, and try to save the foundation. And fire has some very unique characteristics when it comes to foundation, specifically talking about concrete foundations.

This would be a conversation specifically around concrete foundations, rather than block and stone. There are two major things that happen with concrete when you have a fire, most house fires, if you’re talking about a full engulfing fire, where you potentially lose the entire property, you’re going to see fire temperature somewhere between 1,500 degrees Fahrenheit and 1,800 degrees Fahrenheit, and that can cause some major issues with the concrete itself. Most times, you’re not going to see those temperatures but in certain cases when the house totally burns down on the ground, maybe it was a remote property, maybe it was a fire that started in the basement and they got out of control quickly, you’ll see some issues with this.

We actually had this case this week in a house in Southern New Hampshire. It was a house that, unfortunately, burned down to the ground, and the people who bought the property after the fire were looking to rebuild on top of the foundation. But as they inspected the foundation, they started seeing a lot of cracks in the foundation and that is one of the signs of an issue where there was a fire here.

The two main things that can happen are mechanical changes of the actual physical concrete, and also chemical changes to the concrete. Most residential doesn’t have any rebar in it, but it will have tie rods in there, and those tie rods are steel and they can be affected, just like rebar would. The biggest thing that we see mechanically or visually with the concrete from a fire is spalling of the concrete, where you have large pieces of the outside edge of the concrete that have, kind of, fallen away from it, cracking due to thermal expansion in the dehydration of the concrete. Remember, concrete always has water content in there, it’s part of the strength of the Portland cement bond, so as it dehydrate, it becomes brittle and is subject to cracking. And the other thing that you can see in this would be a discoloration, and typically what we’ll see is the color pink.

Concrete, after the charred has been removed, will have a pink hue to it due to the iron that is inherent in the minerals of the concrete. So visually, if you are unsure if there was a fire there, you could always check that, you know, you’ll see some spalling, you’ll see cracking of the concrete and then you’ll also see some pink hues around the foundation. Beyond the visual aspect of it, it can actually dramatically change the chemical structure of concrete, which can become very dangerous from, you know, load bearing. Quartz, that will be in the minerals of the aggregate, increases in volume. If you have Limestone, it totally decomposes. If you have certain temperatures above 1,000 degrees Fahrenheit, the Portland cement that glues the concrete together, can actually become brittle and fall away, which is what we would see with the spalling. And then the other issue that you’ll have is you’ll see alkalinity changes, so this is, again, very fancy in speaking regarding concrete chemical but that will affect the rebar, or in the case of most homes, all of the tie rods.

You’ll see tie rods leaking, and you’ll see them become brittle, and you’ll see them rusting excessively and causing issues there. And a lot of times, the cracks will start to chase tie rod to tie rod hole because you have the steel in there. So, in this particular house that we had the fire repair, it was relatively okay, there were three cracks that were deemed structural repairs that we used a combination of carbon fiber structural epoxy to give it strength again, and there were two other cracks that were non-structural in nature, and we were able to use a closed cell polymer resin to bind it together and to waterproof it for any further expansion.

This particular house, the foundation was deemed with us and with another engineer to be safe for construction, and we have to make the repairs, and under new homeowners right book, basically start construction this week once the repairs are made. So cautionary tale for anyone who happens to pick up a property after a fire, but you know, it’s one of those rare things that concrete is susceptible to cracking and damage due to temperature extremes, mostly caused by fire events. So, always something to keep an eye out for.

Narrator: Well, thanks Adam for explaining how fire can affect a home’s foundation.                                 

Narrator: If you have a basement water problem and think you need a professional, or, if you’d like more information on foundation crack repair and basement waterproofing topics, please visit or call Rich at (866) 929-3171. Or you can email Rich at Thanks for listening and keep that basement dry.        

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A-1 Foundation Crack Repair, Inc. is a fully registered home improvement contractor. Contact us today to talk to a knowledgeable, master waterproofing professional.

Toll Free: 866-929-3171

Call Us Today at 866-929-3171

A-1 Foundation Crack Repair, Inc. is a fully registered home improvement contractor. Contact us today to talk to a knowledgeable, master waterproofing professional.