Spray Foam Insulation

[jgedmond]

My heater went out sometime last night while the low was 26F and the daytime high was about 58F. My house stayed above 68F all night and day. Very pleased with the insulating qualities of the spray foamed attic and blown in fiberglass walls. I know that these are wimpy temperatures for you northerners, but if you can't get a new igniter for your LPG furnace for a few days, it makes all the difference! I didn't feel the need to mess with the forced air fireplace, but I will if I need to.

 

[EddieWalker]

How thick is your spray foam and is it closed cell or open cell?

 

[jgedmond]

The spray foam is ~6" thick under the roof deck and on false walls created to block off uninsulated areas (garage attic, over porch cavities). I am pretty sure it is open cell.

The walls 2 x 4 studs with loose glass fiber blown in. The roof is metal and mostly hipped with two large gables one over the uninsulated garage and the other over the front porch.

 

[Toyboy]

Up here in N WI where I am, the spray foam is getting more popular. Cost wise, it's over double fiberglass insulation but we build with 2x6 outside walls. My house was built in 2001 right before spray foam caught on. If I had to do it again I'd foam it.

 

[jgedmond]

Up here in N WI where I am, the spray foam is getting more popular. Cost wise, it's over double fiberglass insulation but we build with 2x6 outside walls. My house was built in 2001 right before spray foam caught on. If I had to do it again I'd foam it.

I agree, some comparisons from our previous tract built home (1997) in NW Houston to our current custom home about 100 miles north in East TX (2016):

Our new home is ~10% more square feet with higher ceilings (10' - 12'). We now have LPG heat and an electric coop (vs. natural gas and competitive electric suppliers), so our energy costs per BTU and kW-hr are significantly higher. Despite that our peak energy month (August) bills are ~30% lower with the thermostat set lower.

Some mitigating factors for our rural home are metal roof (radiant barrier), more porch overhangs and smarter window placement, "Tyvek" type wrap and window tape, more shade trees, and better orientation of the house to sun exposure. It all works together, but I believe that the spray foam and blown in walls are big factors.

FYI, we did not do foam in the walls to allow more breathability for the structure. With all foam you are basically living in a cooler, so moisture retention becomes a real problem especially in the humid region that we live in.

 

[kenmac]

Last couple of homes around me have used spray foam attic and walls. I can see the advantages of foam vs regular insulation.
The foam will fill all the cracks.
Down side is. If you need to do any wiring /plumbing repairs, it make be more difficult with foam walls

 

[oosik]

I had a friend whose DIY theory was - "If a little is good, a lot is better". His DIY foaming project blew the sheetrock & studs off the walls in his basement. He was lucky. The studs were attached to a poured concrete basement wall. The expanding foam blew the sheetrock & many studs off the concrete wall. If it were an above ground stud wall it could have "blown" outwards. Herb was a good guy though.

 

[AllByteNoBark]

We had spray foam in our last house and sprayed the one we just built a couple of years ago also. It does cost more than fiberglass but is well worth it. We have 6 inch walls with around 5 inches of open cell foam in them. The roofline is foamed and is at least 8 inches and probably closer to 10. Yes it is like living in a large cooler. We have never had issues with moisture even though we live in a very humid climate now. The house is tight but we are in and out a lot and did not put an air exchanger in the house we are in now. We had two of them in the previous house and never used them. Some will argue that you should only use closed cell, others only open cell. We had extremely good luck with the open cell in the last house and when I spoke to the foam guys in our area they recommended the open cell. You want to make sure to use a good vapor barrier with the open cell as it will not act as a vapor barrier like the closed cell does.

Also what you use for HVAC comes into play. We keep the house cool but have a multi speed A/C that runs mainly in the low speed all summer to control humidity while cooling. It is easy to make the house feel like a refrigerator if you don't have an HVAC system that can be used to control the humidity as well as temp.

We have been very happy with the foam and would do it again.

 

[3Ts]

Our house is also spray foam with 2x6 exterior studs. We have the open cell and probably a vapor barrier on the walls and none on the roof. Sizing HVAC is very important with this. To big and it won't run long enough to dehumidify. They were to put in a 3 ton unit, they put in 4 ton. However, we also have a whole house dehumidifier and it runs in the spring and fall. The dehuidifier is independent of the AC & heater and is well worth the extra expense.

This is our second house with spray foam and I'd do it again.

 

[jgedmond]

Our house is also spray foam with 2x6 exterior studs. We have the open cell and probably a vapor barrier on the walls and none on the roof. Sizing HVAC is very important with this. To big and it won't run long enough to dehumidify. They were to put in a 3 ton unit, they put in 4 ton. However, we also have a whole house dehumidifier and it runs in the spring and fall. The dehuidifier is independent of the AC & heater and is well worth the extra expense.

This is our second house with spray foam and I'd do it again.

Good points. Our builder said that 5 ton was enough, but I was skeptical based on our smaller previous home with 5 ton that ran continuously in the summer. I thought that we would need to zone the larger new home to get more tons. It turns out that the 5 ton runs enough to keep humidity at 40 - 50% and while maintaining the temperature where we like it at 72F.