Spray Foam Insulation

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monkey_business
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Spray Foam Insulation

Post by monkey_business » Wed Sep 20, 2017 4:38 pm

We're building a new house and the builder is offering to put in spray foam insulation in the walls for about $2,500. This is walls only, as the roof is already going to be spray foamed. The standard insulation is R19 batt insulation.

The house will be in an area with low humidity, very hot summers, and very mild winters, i.e. the key energy expense is running the A/C during the warmer months.

Is spray foam insulation worth it in this case?

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MastersChampion
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Re: Spray Foam Insulation

Post by MastersChampion » Wed Sep 20, 2017 5:03 pm

I would do it.

I have read a lot about the stuff and the consensus seems to be positive. I have no direct experience with it, though.
The issues I have read about include:

- Some foams losing adhesion to walls.
- Some insects loving to eat the stuff.

However, the positives seem to outweigh those remote possibilities. Spray foam not only provides good R value, but also seals small air leaks, making the house much tighter than a batt-insulated house (if the foam is closed-cell, which is usually the case).

I believe most newer homes that are completely spray-foamed usually have some sort of air exchange system to provide make-up air for things like gas dryers or furnaces, so you may want to ask about that. These are provided because the house is so tight that regular air leakage can't provide enough make-up air for combustion.

I wish the stuff had been more available when we added on 13 years ago.

staythecourse
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Re: Spray Foam Insulation

Post by staythecourse » Wed Sep 20, 2017 5:15 pm

I lived in a normal house and then built a new house a year ago. First was normal and second was with spray foam. I haven't realized a HUGE difference in warmth, but did notice a big difference in sound dampening.

That being said, it is best practice at this current time in home building and for $2500 extra on something that would be nearly impossible to change after the fact I would not hesitate to do it.

Good luck.
"The stock market [fluctuation], therefore, is noise. A giant distraction from the business of investing.” | -Jack Bogle

killjoy2012
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Re: Spray Foam Insulation

Post by killjoy2012 » Wed Sep 20, 2017 5:27 pm

Make sure it's closed cell, medium density SPF (like BASF Walltite). Not open cell...

simple man
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Re: Spray Foam Insulation

Post by simple man » Wed Sep 20, 2017 5:32 pm

A few thoughts from my experience:

1. Good for NEW build, less so for retrofit because the chemicals need to air out when it cures. Could be problems on retrofit.
2. Insulation value is MUCH higher.
3. The house stays very tight, so you must have a way to bring in fresh air - such as with the ac air exchanger.
4. Sound dampening is a big plus, especially if you have a metal roof.
5. Take pictures of all your walls down to the studs before they spray so you know where all of your pipes and wires are. You wont be able to see them afterwards.
6. If you ever have to take off the roof, you will lose the foam there.
7. If you have a roof leak, it may be harder to find since the water can travel down the foam in different directions, rather than straight down.
8. Overall, a very good value. Just different than the old ways.

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czeckers
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Re: Spray Foam Insulation

Post by czeckers » Wed Sep 20, 2017 7:12 pm

For $2500, I'd definitely do it. We've purchased two homes and had foam insulation added to the attic in both. For a retrofit, you have to take out old insulation so it's much better up front during construction. Adding an inch of foam topped with cellulose reduced our heating/cooling bills by 25-35%. The house was significantly less drafty and more comfortable in the winter after the foam went in. With the second house which had a much bigger attic, we definitely noticed the air gets a bit more stale and bathrooms stay humid longer due to the reduced air circulation.

If you're foaming roof and walls, then you'll definitely want to have an HRV (heat recovery ventilator) or ERV (energy recovery ventilator) to bring in fresh air. This obviously increases the cost but is money very well spent. HRV Vs ERV depends on climate.

You get the most bang for your buck with the first inch of foam because that does all the air sealing. A lot of places will do that and then fill the rest of the cavity with dense pack cellulose. You get a bit less R value than all foam, but usually cheaper (significantly so in my area bc foam is very expensive here.
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Theseus
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Re: Spray Foam Insulation

Post by Theseus » Wed Sep 20, 2017 7:21 pm

When I finished my basement, I got the spray foam insulation in the basement ceiling for noise dampening. I regret doing that. If I ever have to fish the wire to run the lines, it is nearly impossible. I just ran into this last week. My AC line was punctured by a contractor that was drilling a hole from the garage to the basement. They couldn't find the line as it was hidden in the sprayed foam. If we had fiberglass bats, it would have been easier to remove and check before drilling.

OP's situation may be different since it will be walls and ceiling/attic that will be sprayed.

Purelife304
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Re: Spray Foam Insulation

Post by Purelife304 » Wed Sep 20, 2017 7:39 pm

The exterminator company we use also does insullation installs. They will not do spray insullation even though they get requests to do it. The technician said "have you ever seen an ant farm, that's what rodents will do in your walls. That was enough of a visualization for me to not go with Spray.

:sharebeer

staythecourse
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Re: Spray Foam Insulation

Post by staythecourse » Wed Sep 20, 2017 7:57 pm

Purelife304 wrote:
Wed Sep 20, 2017 7:39 pm
The exterminator company we use also does insullation installs. They will not do spray insullation even though they get requests to do it. The technician said "have you ever seen an ant farm, that's what rodents will do in your walls. That was enough of a visualization for me to not go with Spray.

:sharebeer
Not understanding that comment. Have you seen what spray foam looks like after it is done. There is NO room for anything between the studs. Unless the rodent has a chisel it isn't getting through the spray foam. Even if it did what would the effects be through the much easier pink stuff they used to use?

Good luck.
"The stock market [fluctuation], therefore, is noise. A giant distraction from the business of investing.” | -Jack Bogle

shanefairman
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Re: Spray Foam Insulation

Post by shanefairman » Wed Sep 20, 2017 8:04 pm

Personally I think spray foam has it's places but I would only consider it in locations where is provides the best value.

As others alluded to there are different densities of spray foam. It typically falls to categories closed cell and open cell. Most close cell spray foam is 2 pounds per cubic foot. At that density the foam is vapor impermeable. The other product is open cell and it has a density around .5 pounds per cubic foot.

There is a fine home building article that can explain it better than I can.
http://www.finehomebuilding.com/2012/01 ... spray-foam

Spray foam is great for specific areas of a house. I highly recommend it for sealing the rim joist on every floor, crawlspace walls, unvented cathedral ceilings, and the space between a garage and living areas such as a bonus room. It also can be good in finished basements but there are more cost effective options for finishing a basement. It's pretty good at air sealing areas that are critical to air seal. It's also great at air sealing areas that are otherwise be difficult to air seal.

Spray foam has quite a price premium compared to more conventional insulation. On the other hand the cheapest and most common insulation is fiberglass batts. Fiberglass has an ok R value but doesn't stop air leakage. Also fiberglass is almost always installed poorly and often fails to perform as well as it should.

For walls I think dense pack cellulose, JM Spider, and to a lesser extent mineral wool batts are great.

The major issue is getting a house that has low air exchanges per hour. The best strategy is to seal your house tight and then use mechanical ventilation to ventilate as needed. The benefit of spray foam is that is is pretty good at air sealing. To measure how well your house is air sealed you need to perform a blower door test. A blower door test will depressurize your house and measure the air leakage. There are other ways to help ensure a wall assembly is air sealed. It could be sealed with the external sheeting and a high quality tape. Many builders have gone to using Huber Zip System and tape to help build well sealed walls. Another high value option is air tight drywall. In that system the builder uses special caulks or gaskets to make the drywall the air barrier for the house.

I highly recommend a few building websites to learn more.
https://buildingscience.com/
http://www.jlconline.com/
http://www.finehomebuilding.com/
http://www.greenbuildingadvisor.com/
“You must not only think for yourself, you must plan for yourself, and you must plan ahead, and you must live up to these plans. You must know exactly what you want to do.” -George Carlin, Boston Rant

rebenzer
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Re: Spray Foam Insulation

Post by rebenzer » Wed Sep 20, 2017 8:09 pm

My rural neighbor has his entire house insulated with spray foam and is beginning to have mouse damage. The mice have not had any problem chewing through the foam insulation. Once they make inroads into the insulation, the damage ruins the tightness of the house.

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jabberwockOG
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Re: Spray Foam Insulation

Post by jabberwockOG » Wed Sep 20, 2017 10:04 pm

Spray foaming a house sounds like a great idea on paper but there can be serious negative issues in the long run. I personally would avoid buying or living in a spray foam sealed house unless I could physically confirm that there was adequate ventilation and moisture control inside and outside the foam in the walls and ceilings. Lack of adequate positive ventilation causes problems with humidity, mold, and moisture issues that can be difficult to correct after the fact.

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Sandtrap
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Re: Spray Foam Insulation

Post by Sandtrap » Wed Sep 20, 2017 10:40 pm

My neighbor did an entire "McMansion" with spray foam. This was at the time of new construction.
Temperatures are stable year round. 100 outside and 20 degrees cooler inside. Teens in winder and low 70's inside. This is incredible.
He also had an A/C, Heat system that introduces percentage outside air for adequate fresh air ventilation. A must in a home that is sealed so well.

Beach
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Re: Spray Foam Insulation

Post by Beach » Wed Sep 20, 2017 10:47 pm

I have built two houses with open cell spray foam insulation. My utility bills are about a 1/3 cheaper than other homes that use the pink stuff. A previous poster mentioned adequate ventilation. This is a must and you need to ensure your builder is well versed in mechanical ventilation with your HVAC and Heat. If he balks or doesn't know what you are talking about, don't do it. Do a google search, there are lots of articles out there. Here is the first one I pulled.

http://www.greenbuildingadvisor.com/blo ... entilation

Saving$
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Re: Spray Foam Insulation

Post by Saving$ » Thu Sep 21, 2017 12:10 am

Should you do it? Yes, but only if you do it right. What does that mean?
1. Spray foam will by definition make your house much tighter - it will leak less.
2. A tighter house needs controlled ventilation. You will probably need an ERV or HRV. Most codes technically require them, it is just not yet enforced.
3. Will spray foam be a place for mice? No more so than regular insulation is. Sprayfoam is not a substitute for your builder doing a good job with the exterior sheathing and housewrap/taping to keep critters out in the first place.
4. Someone indicated above you should use closed cell everywhere. Unless you have an extremely unusual circumstance closed cell in the walls could cause horrendous problems. Closed cell is used in many (not all) ceilings. Open cell for walls.
5. There are different bases for spray foam. Some are soy based and have lower VOC's than others. Closed cell is generally considered more toxic than open cell.

b.lock
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Re: Spray Foam Insulation

Post by b.lock » Thu Sep 21, 2017 12:23 am

I would do it. I think the worst part is that running any wires inside your walls afterwards will be harder, but I think it's worth it for the sound dampening and energy efficiency. If you want, you could put some empty 1" conduit in the walls, and then in the future if you need to run wires you can run it through the empty conduit.

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monkey_business
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Re: Spray Foam Insulation

Post by monkey_business » Thu Sep 21, 2017 10:59 am

Thanks for the feedback everyone.

Regarding the air ventilation, I know the HVAC system comes with a fresh air intake. I've also been reading about the ERV/HRV systems, but this is all fairly new to me. Does anyone know how a fresh air intake compares to the ERV/HRV methods of ventilation? It seems like ventilation is the key issue to take care of with spray foam insulation.

parhur
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Re: Spray Foam Insulation

Post by parhur » Thu Sep 21, 2017 4:40 pm

being in the hvac business it is well worth the money. Make sure that your HVAC guys knows they are being foamed and runs a load cal. on it. If he has not done foam housed before he will oversize your hvac system and that will create issues. Might look at an Energy Recovery unit for fresh air if you are going to foam the attic.

nativenewenglander
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Re: Spray Foam Insulation

Post by nativenewenglander » Thu Sep 21, 2017 7:08 pm

Make sure borats are added to the foam before spraying. Boric acid keeps out carpenter ants, otherwise if they get into your walls you'll never get them out. We've used closed cell in two houses and a barn.

Valuethinker
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Re: Spray Foam Insulation

Post by Valuethinker » Fri Sep 22, 2017 10:32 am

monkey_business wrote:
Thu Sep 21, 2017 10:59 am
Thanks for the feedback everyone.

Regarding the air ventilation, I know the HVAC system comes with a fresh air intake. I've also been reading about the ERV/HRV systems, but this is all fairly new to me. Does anyone know how a fresh air intake compares to the ERV/HRV methods of ventilation? It seems like ventilation is the key issue to take care of with spray foam insulation.
Heat exchange ventilation is best practice. It *is* fresh air as the air is genuinely exhaled and inhaled.

You have to hit minimum Air Changes per Hour levels w an airtight house. Also max moisture levels re kitchen and bathrooms.

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M_to_the_G
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Re: Spray Foam Insulation

Post by M_to_the_G » Sat Sep 23, 2017 12:25 pm

https://www.youtube.com/watch?v=0Hh5MYv7lWc

Spray foam is great if done right. If done wrong...
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