Spray foam insulation comparison

[CADDOKILLER]

What does it do and prevent?

Long story short it prevents mold which is the biggest health-/maintenance factor with spray foam. Foamed houses are so tight they cant breath. Which is a good thing for energy consumption but a bad thing if moisture gets into your house. Which it will.

Basically it brings in outside air and runs it thru your condenser before letting it in your house. That way you have a constant flow of fresh air in. It also has a major impact on keeping your humidity levels in check which allows you to keep your thermostat set higher in the summer. A dry air is cooler than humid air.

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[RutnBuk]

Anyone ever sprayfoamed the walls and just did blow in on top of the ceilings? I have a customer on a house I’m building that wants this. I’ve never had this requested and not sure about it.

Anyone?

[BertramBass]

Anyone?

Usually we will do the opposite. Spray foam the roof/attic but upgrade the insulation on 2x6 exterior walls on custom homes. Thicker walls can get thicker batts. Higher R factor. Spec homes get r 15 on 2x4 walls and r 30 to 38 blown in with a higher seer rated heat pump and are pretty efficient.

[deerwatcher51]

We foamed with our house at the ranch and have been very impressed with the result.

[MarkV]

Usually we will do the opposite. Spray foam the roof/attic but upgrade the insulation on 2x6 exterior walls on custom homes. Thicker walls can get thicker batts. Higher R factor. Spec homes get r 15 on 2x4 walls and r 30 to 38 blown in with a higher seer rated heat pump and are pretty efficient.

Would doing thicker spray foam on 2x6 walls raise R factor vs spray foamed 2x4 walls.

[double bogey]

What does it do and prevent?

The erv exchanges exhaust air with makeup air using a heat exchange process adding very little heat to the house in the summer, and losing very little heat in the winter. ERV = Energy recovery ventilator.

[MarkV]

The erv exchanges exhaust air with makeup air using a heat exchange process adding very little heat to the house in the summer, and losing very little heat in the winter. ERV = Energy recovery ventilator.

Is there a way to see if I will have one of these? We are building a house that will be spray foamed and they just ran all the ductwork. I noticed 2 return airs but I don't think anything that would bring air in from outside.

[double bogey]

It will be a box with 2 ducts coming from the a/c system, and 2 ducts going outside. 4" to 8" ducts.

https://www.aprilaire.com/whole-house-products/ventilation/model-8100

this is one brand. Search erv

[az2tx]

A foamed house can use smaller AC units also, which are cheaper

[Mike D]

Would doing thicker spray foam on 2x6 walls raise R factor vs spray foamed 2x4 walls.

It will help a little but not enough to pay for the difference. Point of diminishing return.


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[Mike D]

Spray foam insulation comparison

A foamed house can use smaller AC units also, which are cheaper

Yep. Our previous home was not foamed or radiant barrier and had 5 tons of air. On a 100° day it would struggle to keep it below 78° inside. This house is almost twice the square footage and only has 6 tons. And I had them run the calcs for it to hold 70° inside @ 100° outside temperature.


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[Budman68]

I'm building my house now and used radiant barrier with traditional fiberglass insulation. I also installed the baffles in case I want to blow in another foot of loose fiberglass. Currently have 7 tons of air and a mini split in the master bedroom. I guess we will see how it works out.

[bowhntrmatt]

Is there a way to see if I will have one of these? We are building a house that will be spray foamed and they just ran all the ductwork. I noticed 2 return airs but I don't think anything that would bring air in from outside.

Talk to your builder or HVAC guy.

The right way to do it is to run a negative pressure test on the structure to find out how many air exchanges you are getting. The only reason to add fresh air is if the house is too tight (which is common on foamed houses, but not automatic). If it is, the test will calculate how much fresh air is needed so the erv can be set to the proper settings.
Any fresh air being brought in should be put through an erv. Don’t let them just run a raw outside air intake into the return. It’s commonly done and a bad idea.

[bowhntrmatt]

Anyone ever sprayfoamed the walls and just did blow in on top of the ceilings? I have a customer on a house I’m building that wants this. I’ve never had this requested and not sure about it.

IMO, waste of money. In most homes, heat gain from walls is a small percentage of the total.
But by foaming under the roof decking, you all but eliminate ceiling and duct heat gain. If I were to do one but not the other, it would definitely be the roof.

[batmaninja]

Any concerns with spray foam and fires? Any way to make it more fire retardant?