Home Addition Separating From Original House – What’s the Cost to Fix?
LESLIE: Now we’ve got John from Iowa on the line who has a question about an addition. How can we help you today?
JOHN: We have an addition that was built onto our home before we bought it. It’s about the size of a two-car garage but this winter, it started separating from the house. You can see where the mud and the tape separated about an inch from the original part of the house and we actually had frost on the inside of the room. So we don’t know what we can do to fix it.
TOM: So, what kind of foundation does this addition have?
JOHN: It looks like – it was built before we bought it but we had a contractor come out and he dug around in a couple places. And it looks like it’s only about 6 inches thick.
TOM: That’s what I was afraid of. It sounds to me like it was kind of like a patio that maybe somebody thought they could convert to an addition. And we see that quite frequently. And unfortunately, this is the same – this is the sort of thing that happens.
Foundations have to be down to the frost line and that usually means they have to be 2 to 3 feet deep. And if you just have a cement slab and that slab is just 6 inches thick, you are going to have movement.
Now, you can minimize that movement by making sure that the soil at the foundation perimeter slopes away and you have good drainage and you have good downspouts that discharge the water away. That kind of thing could make it more stable. But it’s really difficult to try to stabilize a building that’s moving like that when the core problem is that the foundation is insufficient to hold that load.
So, that’s not really what you want to hear. I get that. But it is an issue that’s going to have to be dealt with. So what I would suggest you do is have an inspection done, not by a contractor but by a structural engineer who can maybe design – I’m thinking they may be able to design an underpinning system that could help support that slab.
And then once that repair is designed, then you could take that – those instructions, give those to a contractor to have the work done. Then you have the engineer reinspect the work to make sure it’s done completely and write you a letter that says that. In this way, if you go to sell the house in the future and that comes up, you can prove that you addressed it and you had an engineer design a fix. And that was properly executed as a result of the letter that you can present to a future buyer. That’s probably the best way to get it done correctly once and not have to do it again and to make sure that it does not have a negative impact in any future sale. Does that make sense?
JOHN: Do you have a general idea what something like that would run?
TOM: No. It’s kind of all over the map because I don’t know exactly what kind of fix that they would spec out. But for you, just to pay a consulting fee of – I don’t know – $200, $300, $400 for an inspector to come out that is a structural engineer, not just a contractor. A structural engineer.
JOHN: Yeah, we had a contractor come out and he said it might be the frost in and out that was going to make it shift.
TOM: Well, of course that’s – of course it’s the frost in and out that makes it shift. That’s why you put things below the frost line, you know?
JOHN: Right, right.
TOM: So, yes, he’s correct. But if you minimize moisture, you’ll get less movement. That’s just a very temporary slowdown type of solution but it’s not a permanent one. So I really want to see you get to the bottom of this so it doesn’t impact the future value of the house.
Did you have the – did you have an inspection done, by the way, before you bought the house?
JOHN: There was one done the year before that we had.
TOM: Oh, so you did have your own – you did not have your own home inspection done?
JOHN: No, no.
JOHN: And we’ve been there eight years and this is the – and we’ve had much worse winters. And this is the first time it’s done anything. But the contractor we did have come out offered – he suggested putting a 2-inch-thick Styrofoam around the base of the house and putting that down below the frost line. And he thought that would keep the frost out but he’d want to charge – I think it was $3,500 to do it. And then he said that would be if it works.
TOM: Well, my concern about that, if you start digging around that foundation perimeter and you don’t have a foundation there, you’re just going to loosen up all the soil that’s helping to support that foundation in place where it is. So you might get more movement if you start disturbing that dirt right around the foundation perimeter. Because you’re never going to get it back as tamped and solid as it is right now. And it will hold more water.
JOHN: Alright. I appreciate it.
TOM: Good luck with that project. Thanks so much for calling us at 888-MONEY-PIT.