Insulation question

CrawlnYota33

CrawlnYota33

Well-Known Member
Joined
Mar 27, 2005
Location
Winston Salem
I bought a house recently. No insulation in the attic. This was not mentioned in the inspection report. There used to be a flat, tar and gravel roof on it, someone put a normal style pitched roof on top of the flat one. There is about a 12 inch air gap between the ceiling and the flat roof, no insulation in the gap. Can I just get insulation sprayed in on top of the tar and gravel, or will it need to go in the gap between the ceiling and flat roof? The house was built in the 40’s. Thanks.
 
There is another option of insulating under side of new roof with foam
 
These pics are from between the ceiling and flat roof
 

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They should be able to blow in on top of the existing ceiling (most effective place for it to be) if there's access to the space between the two roofs. (Even if there isn't, they can blow in from inside the house)
 
Only access to the space between are a few holes cut in the flat roof that they ran vents through. I’m really wanting to get some insulation in the attic soon with the need for heat comming soon. I’ve had two businesses lined up to quote, but one came and looked but now he won’t return calls, the other hasn’t showed up twice. So, I’m done with them. Anyone know a guy?
 
There is a normal attic space on top of the flat roof. Would insulation be affective with the air gap between the two roofs?
 
Dude, you can get the blower machine for free from Lowe’s or HD (I know, they are a pain but for some things they are ok) if you buy the insulation.

In a 2,000 sq ft house, I spent about $600 and about 4 hours of my time to blow in 12” of attic insulation myself and my wife.

Point is, it may be worth your while to just do it yourself than to spend your time waiting on contractors to meet with and be there for them to do the work. You’ll likely have more time invested doing it that way than just doing it yourself.
 
Need more information. What's going on at the soffit? Are there vents anyplace? Ridge, soffit, etc? How much clear space is there between the underside of the roof deck and whatever is under it (presumably the old roof?) Sounds like the space between the ceiling and the old roof isn't really accessible, except in a few select locations. If that's the case, you won't be able to blow into those voids without drilling a bunch of holes... probably a 2" hole at each end of each joist cavity, then another mid-way through.
 
shawn said:
Sounds like the space between the ceiling and the old roof isn't really accessible, except in a few select locations. If that's the case, you won't be able to blow into those voids without drilling a bunch of holes... probably a 2" hole at each end of each joist cavity, then another mid-way through.
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He may be able to take off the fascia or soffit and blow in and then reattach without drilling holes.
 
Blowing between ceiling and flat roof would be difficult to eliminate voids. Also thickness is limited by ceiling joist height. 2x8 ? Edges would crital area. No insulation would degrade r value for that chase and too much would block attic ventilation. Applying on top of flat doesn’t limit coverage or thickness but edges are not sealed or insulated which would severely degrade r value. Insulating older “air leaking buildings” becomes problematic because stopping air can trap moisture . Air being the number two transporter of moisture in buildings. Also raising the moisture level in fiberglass insulation 1 1/2 % degrades r value 36 %. I can’t offer good solutions but It’s good to think thru before spending money. Two different roof systems on an older structure presents some difficult challenges.
 
rockcity said:
He may be able to take off the fascia or soffit and blow in and then reattach without drilling holes.
Click to expand...

If the soffit is vented, that insulation gets wind washed. It might provide some value, but not nearly what it should. Spraying the underside of the sheathing with closed-cell polyurethane causes other issues, like wetting at the ridge from vapor transfer. Spraying in the cavity between the ceiling and the old roof gives some benefit, but with blown fiberglass or cellulose, the R-value isn't very high for the work involved.

They're all imperfect solutions. I can't determine what the least-bad is, given the information at hand.
 
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I’ll take some more pics when i get home tonight so you guys can see what I’m working with.
 
CrawlnYota33 said:
I’ll take some more pics when i get home tonight so you guys can see what I’m working with.
Click to expand...

I'm going to guess - at the end of the day - you're going to be best off to just go get blown insulation and the machine from Home Depot and fill everything everywhere with it. It might cause other problems, but it'll improve the insulation situation.
 
rockcity said:
Dude, you can get the blower machine for free from Lowe’s or HD (I know, they are a pain but for some things they are ok) if you buy the insulation.

In a 2,000 sq ft house, I spent about $600 and about 4 hours of my time to blow in 12” of attic insulation myself and my wife.

Point is, it may be worth your while to just do it yourself than to spend your time waiting on contractors to meet with and be there for them to do the work. You’ll likely have more time invested doing it that way than just doing it yourself.
Click to expand...
This is exactly what I did when we went through a fairly large remodel at our house a couple years ago now. As a heads up, they (Lowe's is who I went through) will only rent it for free if you buy X amount of insulation. So what I did was just bought the amount of insulation needed to get to X and I was only able to haul about 1/2 of it in my trailer so I told them I couldn't haul it all and would be back to get the rest. Went home, blew about 2/3 of the insulation I actually took home and then returned the other 1/3 plus what I never took with me upon returning the machine.
 
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