Attic ventilation - real world eye-opener.

[SoonerDave]

What do you deem "so expensive"? Our attic was roughly $6000... on a 40' x 40' house with a pretty good roof pitch.

Well, $6k is a lot of money to me, thus its an expensive proposition. Obviously not everyone would necessarily agree that's a lot of money.

[Servicetech571]

Well, $6k is a lot of money to me, thus its an expensive proposition. Obviously not everyone would necessarily agree that's a lot of money.

It's all about payback time. How long would it take to get teh $6,000 back in energy savings....
Too long if it's a retrofit for most people. When done as part of new construction you could subtract the cost of conventional insulation saving some $$$

[stick47]

So roughly $5 per SF of floor space for the 40 X 40 attic foam insulation application. Our 2200 sf home would run $11,000 at that same cost factor. We had R-50 cellulose put in when we built our home at a cost of > $2,000. Our total electric home's utility costs per month have been under $150. That $9,000 extra costs to go with foam would not have saved us more than $50 a month I'm sure. That's 15 yrs to pay out. I believe the choice to go with cellulose was the correct one for us. YMMV.

[SoonerDave]

So roughly $5 per SF of floor space for the 40 X 40 attic foam insulation application. Our 2200 sf home would run $11,000 at that same cost factor. We had R-50 cellulose put in when we built our home at a cost of > $2,000. Our total electric home's utility costs per month have been under $150. That $9,000 extra costs to go with foam would not have saved us more than $50 a month I'm sure. That's 15 yrs to pay out. I believe the choice to go with cellulose was the correct one for us. YMMV.

How many folks live in your home, stick? Amazed to see total electric home of that size at < $150/mo, so wondering what other variables might be in play...

[stick47]

Just two of us here and I work at home part time in one of our attached garages which has 9 fluorescent lights and a 12,000 BTU mini split system heat pump. My shop also sees a lot of usage of a 2 stage industrial air compressor and several other industrial machines. Our water heat is a 50 gallon Geo Spring Heat pump unit which costs less than a gas water heater to operate. The outdoor HVAC unit is probably oversized at 5 tons but it's a 15 seer heat pump and the attic ductwork is insulated to R8.
Wall insulation is cellulose blown in behind netting fabric. We lived in a house half this size previously but the peak combined gas & electric bills were double what they have been here. ($300 a month in the hottest and coldest months)
I do like the idea of spray foam in the attic just for the convenience of being able to navigate around up there to run wires, etc but the cost payout wasn't workable for us since we're semi retired and the likelihood of being in this house for < 10 yrs is doubtful.

[LakeEffect]

So roughly $5 per SF of floor space for the 40 X 40 attic foam insulation application. Our 2200 sf home would run $11,000 at that same cost factor. We had R-50 cellulose put in when we built our home at a cost of > $2,000. Our total electric home's utility costs per month have been under $150. That $9,000 extra costs to go with foam would not have saved us more than $50 a month I'm sure. That's 15 yrs to pay out. I believe the choice to go with cellulose was the correct one for us. YMMV.

Well, with the pitch of the roof, we actually had about 2300 sq ft of foam installed on the roof deck alone. I forgot that the $6K included foam for all rim joists between the basement and 1st floor and between 1st and 2nd floor. Our home is listed as 3000 square feet (our measurements indicate 2800 square feet).

We also paid another $2K for blow in insulation in all the existing walls, average about 5.5" thick since the home has 2x6 construction.