S01E21 - Concrete vs. Wood: Rethinking Foundation Choices

Transcript

Welcome to Moose Tales. I'm Jon with Two Moose Home Inspections, and I have some short home inspection topics that I have on my mind. So, let's dive right in.

Today's conversation is going to be about permanent wood foundations. Now, if you're unfamiliar with permanent wood foundations, that's because in our area, there really aren't that many permanent wood foundations. I think I've only ever inspected one. And that's it. Normally, what you would see on a foundation is some kind of concrete footing, or you'd see a concrete wall of some sort.

Basically, everything would be made of concrete. It is a material that people understand. It is a robust material, and most of the time concrete foundations far exceed the life span of a normal house. And it is not going to be the first thing to fail. Unfortunately, whenever we think of wood foundations, we think of rot, decay and failure.

And also, could this Wood Foundation actually support the load of the house? And the answer to all of that is, yeah, that's all true. You know, you're going to have your rot, your decay, and it can also support. But as soon as it starts rotting and decaying, then we have issues. However, the reason they put the P on the PWF the Permanent Wood Foundation, is to inform consumers that it is a permanent foundation solution.

How does wood become a permanent foundation?

before anything can be done. Site selection is the most important thing. You have to make sure that the soils are able to drain. Let's say that you're in an area where there is a high-water table or you're in an area where soils are unable to drain.

Then that's just not the right place to build a permanent wood foundation. You need the soils, the surrounding soils, to be able to drain water quickly and effectively to get that water away from the wood and foundation.

Once the geotechnical survey is complete and site selection has been finalized and we've decided exactly where the house is going to be built, then what you need to do is level surface, put down a significant amount of crushed gravel to work as drainage, and then you can start putting wood on top of that.

We're not just using any type of wood. We're using a special pressure treated wood and the type of chemicals that they're using and the quality check that they have to verify that the amount of chemical that needs to be saturated into that wood has been saturated in is all and like a whole other level compared to standard pressure treated lumber.

Now you have that pressure treated. Would you put it down? You start building just like you build any stick frame foundation. But instead of building on concrete, you're literally building on top of gravel.

If you were walking past the construction site, it would look like somebody was framing a house, but they forgot to build the foundation. They literally just set it on top of gravel. That's exactly what it will look like. The next thing is they're going to be putting their wall panels on, and those wall panels are, again, pressure treated and or special type.

And in addition, all of those cracks should be corked. Now, relying on caulk to do something is not something that I feel comfortable with. However, this is the way that it's supposed to be. So, we're just going to continue with this process as we continue, the last step is going to be that we are going to put a waterproof membrane normally like a six-mil plastic.

And what that is designed to do is take any ground water that does make it all the way over to that wood framed foundation. And it is going to take it and it's going to move it out in a way. So basically, if you are running as water straight into the wall, you're going to hit that plastic drop down.

The plastic is going to have a skirt that kind of moves you out and away from the foundation and then you can start dripping into the ground or into the gravel that would be on that drainage field, basically.

So, assuming that everything is done correctly, then we should have a foundation that is never going to see any water whatsoever because you have the foundation put onto a drainage field.

You're building that foundation out of wood; you're putting the plastic on. And then whenever you backfill, not only are there going to be French drains and other drainage system, but there's also going to be a lot of crushed gravel to ensure that we aren't going to get a hydrostatic pressure pushing back on to that foundation wall. So, with all of that being said, water should not be making it to that foundation.

But here's the thing. Water shouldn't be making it to any foundation. You'll see that there are failures in concrete foundations. And of course, there are going to be failures in a wooden foundation because water reaches somewhere that we did not intend. However, the difference is, I believe, that most builders are very much aware of the downfalls that could arise if that wood were to get wet.

And so, the attention to detail is as high as it should be any other time, but in fact it is higher than it normally is.

So if you have a higher than normal attention to detail whenever you're making that drainage field, whenever you're putting up the plastic, whenever you're doing all the waterproof details and whenever you're backfilling and making those French drains and drainage pits, whenever you're doing all of that, you're very hyper focused and I think you're going to have a good product.

Whenever we're talking about concrete versus wood and their longevity, they're going to be the same. They're going to last the lifetime of the House. And really that's all that you need. You just need it to last the lifetime of the house. So now let's say that there is an issue.

Let's say there is a failure. Okay, well, what do we do? Can you as an individual, repair concrete, Do you know how do you know how to drill and tap and put in new rebar and then to put in new concrete on a cold joint and basically build up that foundation wall so it's stronger than it was before?

You know how to do that. Most people don't. So, then the inverse question to that is, do you know how to dig out some gravel and frame out a new wall? Yeah, most people know how to do that. So, from a repair standpoint, it's a belief that, well, concrete is, you know, the end all, be all. It's going to be great.

We're in fact wood frame foundations actually do have a lot of repair ability that concrete foundations do not have.

So why would somebody want a wood frame foundation over a concrete foundation? Well, there are two sides to the story. One is we can talk about the impact of materials on our environment. And of course, concrete

is not as good for our environment as sustainable wood harvesting practices are. And so even that can be contested. But some people might say, well, it is better for the environment to build using wood than it is to build using concrete. Fantastic. So then on the other side of that is money.

Now, I'm not saying that money is the deciding factor for all builders. However, if you can save time and you can save money, I can see that being a really strong incentive to use a wood frame foundation.

So, let's talk about the environment that we're in, a high alpine environment. We have times in the year when pouring concrete just isn't possible.

It could be that it's mud season, meaning it's in between summer and it's in between winter and any of those seasons, everything is just muddy, and we will not be able to get that cement truck up this dirt road to be able to pour the foundation for this house. Okay, so there's mud that's a problem. Let's say freezing cold temperatures, while concrete does not do well, curing in freezing cold temperatures, a lot of care has to be taken,

whereas a permanent wood foundation can be built in the rain, in the mud, in freezing conditions, and additionally, carpenters have to come out and build all of the forms that you're going to be pouring concrete into.

And you need a lot of specialists to be able to pour that concrete, whereas you can just have your carpenters doing the work to build the Permanent Wood Foundation and then they can just keep going from there. It saves them time because they're not waiting for concrete cure. They're not waiting for concrete to be delivered. They're not waiting for specialists to come in and work on the rebar and do all those things and do all the concrete testing to ensure that they're able to move on to the next step.

It is much faster. It can be done in almost any environment at almost any time.

And so, yeah, permanent wood Foundations started in the 1950s, but they're still being built today. Now, would I build a house with a permanent wood foundation? I don't know. That's a good question to ask, because I feel more comfortable with concrete because I feel like concrete is one of those things that I'm I think to myself, yes, that is a strong foundation.

That is something that is going to last. Whereas I think of wood, and I just think again of rot and deterioration.

However, the amount of water vapor that the Permanent Wood Foundation is going to see in comparison to the amount of water vapor that your walls or that your attic or that your roof sheathing are going to see are considerably different. And in fact, a lot of those other materials are seeing so much more water vapor passing through them that rotten deterioration are much more likely.

So why do I feel comfortable with having wood for every other aspect of my house that is just getting so much damage from water? But I'm not comfortable with it being in the foundation. And I think it's just because I'm so used to concrete being the product. Now here's another cool thing, is that you're putting down a water vapor barrier using that six-mil plastic, and in fact, you should be putting that completely underneath that whole like foundation structure.

Now what's interesting about that is tying that in for radon mitigation, because you have all of that crushed gravel and you have that plastic layer, you get really good suction, creating an area of low pressure, allowing for radon mitigation to work better than in almost every other circumstance. So, I am a huge fan, a permanent wood foundation in terms of radon mitigation.

So, when you're inspecting a permanent wood foundation, the main thing to keep in mind is you either stay dry or you die. That's all that there is to it. If you see moisture intrusion, then that wood foundation has some serious issues going on. And there's a lot of ways that this can occur.

If you notice that the grading is moving water towards the house, well, you're definitely going to have a problem as opposed to moving the water away from the house. So, any time that it rains, you could have puddles pushing up against the house and it could be overwhelming the waterproofing that has been installed or the drainage that has been installed.

Same thing if you have a gutter system and you have these downspouts,

but they aren't pushing the water far enough away from the foundation or away from the foundation at all. Well, we're going to have a significant amount of water right there at the base of the foundation.

And let's say something happened to the waterproof plastic that had been installed, that six mil plastic, it could be from roots, from plants, it could have been some kind of mechanical damage. Whenever you're digging for something, whatever it may be, maybe some kind of insect or some kind of rodent or anything like that could have damaged that plastic.

And if that's the case, water could start moving in. So, there's a lot of ways in which the system could fail. In addition, whenever you do have that groundwater, you can have small amounts of dirt going through all of those different layers of rock and eventually clogging the system, preventing that water from going anywhere,

which can also create a hydraulic effect that is pushing against that foundation wall in ways in which it wasn't intended to be pushed against.

But if you're inspecting the house, if you see water, that's bad. If you see signs of moisture, that's bad. But what else can you do? I mean, if you were to cut a hole into the wall, let's say there was a basement or crawl space or whatever, but let's say it was a finished wall and you cut a hole into the wall.

That's only telling you in that one specific spot, it's okay literally in the next stud bay over. That's where we could have issues that just aren't readily identifiable. So even if you did sampling, you wouldn't really know because it's a closed system and you don't have really any idea. But if we go back to the idea of repair ability, the repair ability of a permanent wood foundation I think is one of its strongest selling points that nobody really talks about.

I mean, obviously the price is the biggest selling point. But beyond that, I think repairability is second, in my opinion. So, if we're talking about permanent wood foundations inspecting them, it's kind of difficult. If you see signs of moisture, then great, you've done a good job, but you can't really guarantee that you're going to find signs of moisture.

I mean, thermal camera. Yes. Moisture meter, yes. However, there can be hidden points of water intrusion. So, I would say permanent wood foundations. Perfectly good. If you had good site selection, it was well engineered, well installed.

and everything has been maintained the way that it was designed to be maintained, such as grading and making sure your downspouts are doing what they're supposed to be doing.

I think you can have a permanent wood foundation. Far out lasts the house, meaning that somebody be willing to bulldoze the house and build a new, more modern house prior to that foundation failing. However, I think that the public opinion is that concrete is a stronger, longer lasting type of product, even though that's not necessarily accurate or true.

I mean, if you put a certain type of paint on top of concrete and it's not the right perm rating allowing moisture to travel in and out, you're going to totally destroy that concrete. And a lot of people don't know little tips and tricks about concrete such as that. So concrete isn't the perfect product for foundations. And I think that it's okay to see permanent wood foundations.

And I think it's okay to buy a house with a permanent wood foundation. However, if you're selling a house with the Permanent Wood Foundation, my experience has kind of shown that those are going to be on the market for a little bit longer because people are more hesitant, because they are less aware of the pros that you can find with a permanent wood foundation.

And with that, that's a Pod!