Foam insulation in new construction

Like spray?

ETA

There is some people who don't like it. Main rub is it doesn't allow the house to breath.

When done properly its excellent but expensive.

When done improperly its terrible and expensive.

quote:

---

Foam insulation in new construction

---

yes

quote:

---

Post construction

---

nope

Has to be flexible type foam, not rigid. We did all vertical exterior walls with foam and blow in for the attic. Heard too much about trapping moisture if you foam the attic. Decided not to chance it so we didn’t foam the attic No regrets on my end.

I use shredded newspaper

From what I understand foam insulation works better than just about any other type of insulation.

BUT

The installer MUST know what they’re doing because too much in an area can give off toxic fumes and become a total nightmare. I really wanted to go with this in my attic but I found multiple videos on YouTube about nightmare scenarios people have had with it and quickly decided against it. The risk is not worth the reward for me. I went with a combination of blown in and lay down bat insulation. Made a giant difference in summer electric bills for me.

Great if done right. But windows need to be quality as well. On the HVAC system you need to add a 3” or 4” outside air duct tap as your house can get stale. Bet to install a 24v motorized damper interlocked with fan blower.

If doing attic as well then your gas water heater will need to be forced draft and have a ducted combustion air duct.

I am an estimator at a large insulation company. If you want my opinion on how to go about insulating, post an email address and I'll contact you.

In short, if I'm building in the SE, I would have my attic/crawlspace conditioned - unvented, sealed, and tied to my HVAC. "Venting" in the SE is tricky, as you're bringing in humid air almost always. So I would use a closed cell SPF on the crawlspace up to the decking. An R10 (1.5") is sufficient for stem walls, go R19 (3" at rimjoist). For that attic, spray directly to the roof deck and gable ends. For N. Louisiana, I would go with an R15 (2.5" closed cell to the deck), which is required for air impermeability, then either wire an R19 unfaced batt to the deck, or finish it off with 5" of open cell on top of the closed cell. For your walls, use a 1" flash closed cell in the cavities, and if it's 2x4 framing, an R13 batt on top, if 2x6, an R19.

If you insulate your foundation as previously stated, you do not need insulation under your floor. Just make sure you have a substantial vapor retarder on the ground, rising at least 1' up your stem wall and piers. I definitely recommend spray foam, and going to conditioned attic/crawlspace, but only if you have your HVAC company design your system to remove humidity from said areas.

If you go that route, the air quality and comfort of your home will be phenomenal.

Also, another benefit of insulating on the deck of your roof, you keep the ceiling area clear of insulation.

Also, the closed cell SPF will offer you much better structural integrity, keep pests at bay, and make your house much quieter.

ETA: And if you insulate how I stated, all of your electrical and plumbing is in direct access to you at all times in your crawlspace and attic, and if you need to access in your walls, you only have to pull batt insulation out. The main goal is stopping air infiltration, how I described does just that in the most cost effective manner.

quote:

---

Main rub is it doesn't allow the house to breath.

---

This^^
It really has to be done correctly or you’ll be in for some serious problems. Some say even done properly, the house is still too air-tight. Couple that with the fact that it is expensive as hell - you better plan on living there for a long time to recoup the benefits of the added expense.

I have it in mine and haven’t regretted it at all