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Insulating old brick house


chimpywrench's Avatar
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IL

04-17-16, 09:08 AM   #1  
Insulating old brick house

I'm considering buying a house in central IL. It's a 100+ year old 2.5 story brick house. I've renovated 3 other houses on that same block and am well familiar with the framing and build styles of homes that old. I was able to blow-in cellulose in those houses and reduce heating costs by over 50%.

I am not familiar with how a brick house would have been constructed. I'm guessing it's 2x4 balloon framed walls sheathed with 3/4 to 7/8" thick wood boards like all the other old houses I've seen in my area, but how would the the brick have been attached?

I was able to remove a couple outlets (there aren't many) and peer inside. Difficult to see, but I believe I was looking at the back of wood sheathing within a 3.5" deep wall bay.

The point of my question is to figure out if I can blow insulation into the walls of the house. Do I have to worry about the cellulose infiltrating and contacting the masonry exterior?

 
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04-17-16, 09:20 AM   #2  
I have little experience with brick buildings but have had to advise on insulation issues. Here is a link I found helpful.
BSI-047: Thick as a Brick | Building Science Corporation

Bud

 
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04-17-16, 11:59 AM   #3  
Hi Bud,

Thank you, that article was great. That helps me understand what is going on with the brick itself, but I'm also concerned about the wood structure.

I expect the walls inside will look a lot like what this fellow had: http://www.doityourself.com/forum/in...-veneer.html#b

Unlike him, I don't want to tear down any plaster, I want to do blown-in. I'm thinking if the gaps between sheathing boards are big enough the cellulose will blow into the airspace. In that case, I could have cellulose against porous brick. My experience in other houses is that the cellulose may only blow through the gaps a little bit before clogging in the gap. However, a little bit through each gap of a 20ft wall bay could mean a little pile of cellulose at the bottom. If there are any parts of wall bays that aren't completely sheathed, you'd get a lot of cellulose blown into the brick air gap. If the brick is particularly moist, the cellulose could then transfer that moisture to the wood structure.

My best guess here is that if you can blow-in and keep the brick air gap relatively (not necessarily perfectly) clear, the system should work fine. As other building science articles point out, the lack of a vapor barrier is irrelevant since painted interior walls accomplish that task just fine.

 
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04-17-16, 12:31 PM   #4  
I think your concerns are valid. One of the points explained in the article is how a lack of insulation is keeping those bricks warmer and dryer. Once you insulate between the bricks and the warm house, regardless of how you achieve that, the bricks will freeze and IF they are bad bricks you're dead. The damage will be done before you can correct it and even correcting it would be extremely expensive.

One old building I was evaluating had a false wall extending above the roof where it was not protected by the heat inside. In that case, those bricks were perfect, thus we concluded that insulation on the inside would be ok. Another historic brick building has been suffering spalling for decades and obviously has bad brick. The lower 8' of brick had already been replaced and the brick just above that area was in need. Being historic I referred the decision to an engineer with more knowledge and insurance.

I'm not sure why you are looking at this building, but for a flip, there are many others with less risk. Old is the first red flag and along with that comes a LONG list of issues from asbestos and lead to knob and tube wiring. Is there any K&T in those walls.

I've run blower door tests on newer homes with board sheathing and they leak like mad. In a couple of places we were able to inspect those boards and they had shrunk to allow 1/4 to 1/2" gaps. Ugh!

Best I can do.

Bud

 
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04-17-16, 01:42 PM   #5  
Bud,

I own the neighboring house and then found that the owner of this brick house had recently passed away. It's an interesting investment opportunity to me as I'd be making a house+contents (he was a hoarder) bid before any realtor even gets involved, and unlike many of the old houses in this area, this one hasn't seen ANY updates in about 40 years (besides the roof). That leaves me a pretty clean slate to bid low and renovate the house. Before I do that I get to play estate salesman which could also be lucrative. My area fetches pretty good rent and I'd likely keep the house long-term since I can easily maintain it being so close. I have money saved and am looking to put it into something.

Insulating old houses is one of my favorite upgrades to do.

The house has 200A service with a breaker box and grounded wiring but I'm sure there's still plenty of knob & tube in the walls & ceilings. I've rewired a couple houses already. I really don't see the concern with knob & tube wire going to overhead lighting fixtures - the wires carry so little current and in my view it's safer to bury them with fire retardant cellulose than to leave them to open air.

BTW, the house does have parapets as mention in that article. They looked great to me, but I'll revisit and look more closely.

 
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