# Brick Foundation Insulation



## alscich (Jul 9, 2012)

In Des Moines Iowa. Tore out moldy drywall from my walkout basement. Foundation walls are brick. Built in 1923. Dehumidifier runs constantly. Get some very minor seepage during hard rains, more like sweating than trickling. Plan is to patch all small holes and cracks with hydraulic cement, then glue 2" Rigid Foam insulation over that then frame up a 2' x 4' wall with pressure treat bottom plate and regular studs and top plate. Then moisture resistant sheetrock. Anybody see any problems with this approach? Hoping to keep the place warmer and cut down on the humidity to some degree.


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## cleveman (Dec 17, 2011)

I would first try to address all basement moisture problems on the exterior.

I don't know if we have had an unprecedented amount of rain during the last month, but we have had a lot of rain.

My neighbor just had a basement repair guy at his house yesterday and after he left, my neighbor flagged me down and we talked a bit. He asked me what I thought about waterproofing the basement by painting the insides of the walls with some waterproofer. Then we walked along the house and came upon a trough next to his house on a wall where the grade was sloping towards the house, there was a downspout not extended out from the structure, the gutter had some holes in it, and you could see in the grass where the water had been pounding in.

I told him to add 2' of dirt there, slope it down radically, and get some turf growing on top of it. Run the downspouts out a ways, and replace the gutter.

As for you, I would look at the exterior first as well.

I would recommend digging down to the footing alongside your wall in a shallow area. If it is a walk-out, I would be digging on the daylight side. You want to find out what you have for drainage down there. In 1923 there was no black perforated drain tile, so if you have anything, it will be clay tile. You will want to find out where these are draining to if they exist.

You will want to look at your entire lot, and get someone with some experience to help you. If it is a walk-out, then there is some slope. If there is slope in the front, then water will be coming down the hill towards your house. This water needs to flow downhill on the surface, hit a trough, then flow in the trough around the front of your house and drain to the back. 

If things were set up like this in 1923, there could be trees planted in this trough and a multitude of other things could have happened since then to mess up the drainage around your home.

The other thing you can do is dig down to the footings all around the structure, backplaster the walls, waterproof the walls, add drainage tile, fill partially with gravel, then back-fill.

Only after you address the exterior should you look at the interior.


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## alscich (Jul 9, 2012)

Realistically all that digging is not going to happen. I have done what I can as far as gutters, adding dirt, and directing downspouts away etc. Weeping is on the side where the driveway is. The driveway covers all the way up to the house. I'm looking more for tips on which materials to use. Would the use of a dimple mat on the interior side be overkill?


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## cleveman (Dec 17, 2011)

Someone will have to see how much water is coming in. And you'll have to address what to do with that water.

As for the sealing up, I would get the energy company in there (Mid American) to do an energy audit. This spring, they paid for 75 or 85% of 2" of xps in a basement in a property I have. Don't forget your rim joist. They will spec everything for you


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## alscich (Jul 9, 2012)

Energy Audit done last spring. I will use that rebate to have the sidewalls drilled and filled at some point. Who has to see the water coming in? I can see it. It could just be condensation. The amount is very small. The drywall that was put in by the previous owner had been there for some time.There will be moisture contacting whatever I put against the bricks. Water vapor moves through bricks and they dry to the inside. It's an exposed brick walkout basement. I'm not going to plaster over it. I'm not trying to turn this into an expensive whole house redo. My question is whether the materials I have selected in that order are the best possible reasonable (i.e. inexpensive) solution to keeping heat in and will they help to control the humidity somewhat. Also I am open to any other ideas that could help. Dimple Mat 1st?


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## SeniorSitizen (Sep 10, 2012)

You found mold when you tore out the drywall and any insulation you put on the interior will make the condensation problem worse. Don't repeat what you know doesn't work.

The condensation will begin on the interior above the exterior dirt back fill line because of that wall portion being much colder, but in severe cases this moisture will migrate down the wall to the floor. When winter weather arrives you'll be able to check interior wall temperature with an infrared temperature gun and follow the exterior soil back fill line on the interior via temperature readings. That portion of the wall will condense that's reached dew point temperature.

To prevent the interior wall surface from reaching dew point temperature the insulation must be on the exterior. One other choice is to reduce dew point temperature of the air via dehumidifiers to below the coldest temperature the wall will ever experience.

Use the link below, run the numbers to determine when the wall will begin to get wet because of condensation.

http://dpcalc.org/


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## cleveman (Dec 17, 2011)

I would do as I did with my basement. I would put 2" of xps on the interior walls, friction fit. I would put a bottom plate on the floor, squeezing the insulation up against the wall, and the same with a top plate. You can stud out the walls later if you wish.

These sheets need to have the joints taped. I used 2 layers of 1" tongue & groove and staggered the joints.

This will stop the air from getting to your walls and carrying the moisture with it, which is the condensation you are seeing.

I'm surprised that the energy company didn't point this out to you. It was explained to me that they would not cost share anything for the exterior walls if there was ANY insulation already there. In my case, they wanted to pay for the basement walls, rim joist, crawlspace floor, and bringing the attic up to R-50. I think they also helped with sealing ductwork and infiltration to the tune of $100 each.

I would check into this some more. At $25/sheet, the xps cost adds up in a hurry.


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## alscich (Jul 9, 2012)

When the audit from mid america was done there was insulation on the basement wall. He rated the attic as most important, sidewalls second most, and basement walls third. They only rebate up to a certain dollar figure, $800 if I remember right. Did the attic myself with roll out batts purchased discount at the Habitat For Humanity ReStore. Doing basement with 4' x 8' 2" XPS purchased from same and half pieces scavenged from job site dumpster. Will be hiring (and using the rebate) for the drill and fill, It's just me doing all the work and that seems like it would be a lot easier with a crew!! I like the idea of the top and bottom plate holding the board up instead of the glue, but I will be scrapping together some partials to save some dough. Will definately look into any other rebates though.


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## cleveman (Dec 17, 2011)

Keep your eyes open. There was a guy on craigslist last week with about 400 sheets of 4" poly iso which would have killed your basement. He was asking $15/sheet. I bought a bunch of 3" and 1" and used the 3" on the basement in my own home, not the one I had mentioned putting up the two layers of 1" t&g and I still have enough left over for a couple more basements and some above grade sheathing with the 1"

Yeah, it would have been good to know their rules before the home inspection. If you just have some worthless insulation on a wall which will be removed anyway, then you don't qualify for the program. They gave me up to $1000 for the basement wall I was talking about.


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