Anyone had spray foam insulation done? or blow in? for attic

[JDMMAN]

Just wondering if anyone's had experience in getting their attic insulated with spray foam? What's the cost compared to blow-in fibreglass? Looking to increase the R value from R15 to R40 in the attic. Not sure which route to go.

[gram]

$1.25 to $1.50 per board foot. It is not really an insulation for an attic space but it's great for exterior facing walls and inside of garage trusses etc. You would want to blow in insulation for an attic space. Blown in will be much much cheaper in that application.

[kenny]

Are you topping up insulation in your attic or insulating from scratch? You mention R15 to R40 so I'm assuming you already have insulation in there. Probably wouldn't make sense to remove it and redo.

If going from scratch, Mike Holmes would spray closed cell foam then layer on blown insulation on top of it.

[ExtraSlow]

I had blown-in done on an older home about five years ago. I believe the company was called Affordable Home Insulators. Cost was around $1/foot, but I assume prices have risen since then.
It took the guys about an hour to do an 800 square foot home. Very very hassle free from my perspective.

If you have an older home, sealing off air leaks will give a bigger result.

[gram]

Kenny brings up a good point, you could also spray foam between the trusses and then have some regular blown in insulation put on top of the spray foam. Just make sure you don't only use spray foam or you will have to spray a layer over the top of the studs to eliminate any risk of thermal bridging(expensive) Spray foam is also very dense and if not done correctly can actually put outward pressure on the base plates of your trusses (which can lead to extra pressure between the trusses. This doesn't matter much in vertical walls because they are generally under 10 ft in length but laid over a horizontal surface pushing against a truss that can be upwards of 30 feet long this pressure/lack of expansion can be bad(nail pops in your celing etc with hot/cold expansion and contraction) Make sure you get a good contractor to do this if you decide to use spray foam.

[78si]

I just looked into spray foam. Its $3.80ish sq ft

[JDMMAN]

Thanks for the info guys. Currently there's blown in fibreglass insulation that's in the attic sitting on top of the ceiling. Its not enough according to today's specs. I was thinking of spray foam on the bottom side of the roof to provide additional insulation. This home was built in 1978; already has high efficiency furnace and low-e windows. Want to have the garage door + seals replaced for better heat insulation and also ensure that the attic has the proper insulation to maximize the heat retension.

[1963Corvette]

Originally posted by JDMMAN
Thanks for the info guys. Currently there's blown in fibreglass insulation that's in the attic sitting on top of the ceiling. Its not enough according to today's specs. I was thinking of spray foam on the bottom side of the roof to provide additional insulation. This home was built in 1978; already has high efficiency furnace and low-e windows. Want to have the garage door + seals replaced for better heat insulation and also ensure that the attic has the proper insulation to maximize the heat retension.

You don't want to do that. The attic is a cold zone. No one would spray the roof anyway, unless they want to steal you money. Forget about spray foam in the attic, use blown-in as it is the best for attic.

[Tik-Tok]

http://forums.beyond.ca/st/321673/bl...ion-providers/

[ExtraSlow]

As mentioned, nobody would spray the underside of your roof, that's a terrible idea.

If you have existing blown-in insulation, just get some more blown-in on top and call it a day.

[2LOW4SNOW]

Originally posted by ExtraSlow
As mentioned, nobody would spray the underside of your roof, that's a terrible idea.

If you have existing blown-in insulation, just get some more blown-in on top and call it a day.

Most of the time this is true, However, due to the high R-value of spray foam (and some other reasons), some new high efficiency homes are built with spray foam against the underside of the roof. The r-value is so high that a vented attic is no longer required.

I was a bit surprised when I first heard of this. My boss has it in his house and says it works very well. He had humidity sensors installed in the attic to monitor for moisture as he was also a little worried (never detects anything significant). He also said it cost something like $20-30K to have it sprayed in.

Although in this case, extra blown in would be the most practical solution.

[ExtraSlow]

Wow, so I assume that means these "warm" attics would be unvented? Interesting.

[2LOW4SNOW]

Originally posted by ExtraSlow
Wow, so I assume that means these "warm" attics would be unvented? Interesting.

That's my understanding. There is a bit of information about it on the net. I'm considering it for my detached garage, makes the attic a little more usable.

I have also seen the entire underside of the roof covered with insulation baffles right up to a ridge vent, then spray foam over top. That way it is still vented, not sure how effective either technique is.

[JDMMAN]

Looks like the blow-in fibreglass will be the way to go. The attic is still vented, I wonder where the diminishing returns come in relative to bringing R15 to R35/40/50?

Looks like I should try Zero Draft for a quote I've probably got 1850sqft of attic space though