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Started By
Message
Spray Foam vs. Fiberglass
Posted on 3/12/15 at 9:59 am
Posted on 3/12/15 at 9:59 am
Looking at insulation on my new construction, it's 3700 living sq. ft.
Seems like fiberglass is cheaper, but Foam makes your energy bill less.
Heard foam can have problems with moisture, etc.
Any recommendations in the NOLA area? Thanks in advance.
Seems like fiberglass is cheaper, but Foam makes your energy bill less.
Heard foam can have problems with moisture, etc.
Any recommendations in the NOLA area? Thanks in advance.
8
Posted on 3/12/15 at 10:04 am to Rev1897
Bookmarked.
And fiberglass is without a doubt cheaper.
And fiberglass is without a doubt cheaper.
Posted on 3/12/15 at 10:29 am to Ziggy
quote:
And fiberglass is without a doubt cheaper.
On the front end yes...
Posted on 3/12/15 at 10:30 am to Rev1897
(no message)
This post was edited on 12/21/21 at 10:09 am
Posted on 3/12/15 at 10:32 am to Rev1897
I just built and ended up with fiberglass because it was less than half the cost of spray foam. My electric bill has not been bad at all so far. Couple things I was told when I was trying to decide between the two. Some companies spray foam really thin (same goes for fiberglass), make sure to find out how thick it will be when you get a price. Also moisture should not be a problem if your hvac person knows what they doing. They said some people put to big of a unit and it doesn't run long enough to get rid of moisture.
Posted on 3/12/15 at 10:38 am to Rev1897
I used Star spray foam but Retrofitz spray foam actually did the installation. They were well priced compared to my builder's usual installer.
As far as using it vs fiberglass, you are looking at paying more at upfront but you will save money on the back end. My builder puts it in every house he does and I would do it if you can afford it. Also make sure the A/C installer is aware you are using it because you won't need as much tonnage when using foam.
As far as using it vs fiberglass, you are looking at paying more at upfront but you will save money on the back end. My builder puts it in every house he does and I would do it if you can afford it. Also make sure the A/C installer is aware you are using it because you won't need as much tonnage when using foam.
Posted on 3/12/15 at 10:46 am to saderade
quote:
saderade
Did you use open cell on the roof and closed cell on the walls?
Do you have to ensure that it doesn't void the warranty of your shingle manufacturer?
Posted on 3/12/15 at 10:51 am to Rev1897
Fiberglas - Cheaper
Foam - More expensive
Foam will fill all voids and will not have settling like Fiberglas. Foam will make a tighter building will a lot less leakage or infiltration. However, you will not get as many air changes as you do with the leakage of air and you can get a stuffy smelling house. Easy way to fix this is have the HVAC guy install a 4" round duct pulling in outside air into the return air plenum. This way you will make your house positive.\
Foam - More expensive
Foam will fill all voids and will not have settling like Fiberglas. Foam will make a tighter building will a lot less leakage or infiltration. However, you will not get as many air changes as you do with the leakage of air and you can get a stuffy smelling house. Easy way to fix this is have the HVAC guy install a 4" round duct pulling in outside air into the return air plenum. This way you will make your house positive.\
Posted on 3/12/15 at 10:56 am to Ziggy
quote:
As far as using it vs fiberglass, you are looking at paying more at upfront but you will save money on the back end. My builder puts it in every house he does and I would do it if you can afford it. Also make sure the A/C installer is aware you are using it because you won't need as much tonnage when using foam.
Right, so right now i'm looking at either paying 3 to 4 times as much for foam, but I might need less AC tonnage so there is a savings there.
For example I'm trying to decide for A/C purposes on either Carrier 3.5 and 2.5 Ton Down w/ 2.5 Ton Up: 14 SEER gas heat system:
and a Carrier 3.5 and 2.5 Ton Down w/ 2.5 Ton Up: 16 SEER Variable Speed gas heat system:
Posted on 3/12/15 at 11:01 am to tigeraddict
built in '13, went w/fiberglass. average monthly elec bill on ~2200 sq ft, plus 1000 of unheated/cooled garage, is about $50. builder was exceedingly careful about sealing/taping/insulation placement. yes, that's average...it's gone as low as $35 (several times) and as high as $100 (once).
did not go w/spray foam b/c i didn't want a 'tight' house. did not want to breathe in all the VOCs coming out of building materials/finishes, furniture, etc. did not like the idea of being unable to see what's behind foam. have heard some real horror stories about concealed water damage, termite incursions, etc behind foam in attics. w/fiberglas, i can pull it up if I need to visually inspect and easily replace it.
did not go w/spray foam b/c i didn't want a 'tight' house. did not want to breathe in all the VOCs coming out of building materials/finishes, furniture, etc. did not like the idea of being unable to see what's behind foam. have heard some real horror stories about concealed water damage, termite incursions, etc behind foam in attics. w/fiberglas, i can pull it up if I need to visually inspect and easily replace it.
Posted on 3/12/15 at 11:04 am to Ziggy
quote:Actually open for both. My plan was closed for walls but the installer said the difference was minimal if you spray at least 3" inches of open and more expensive. Advantage of closed cell is it adds to the structural strength of the house. Open cell doesn't but is a much better sound barrier from the outside. If money was no issue, I would have probably done closed in the walls.
Did you use open cell on the roof and closed cell on the walls?
Good news is last month I only used a total 65 hours of heat or A/C even with all the cold weather we had.
Posted on 3/12/15 at 11:09 am to saderade
quote:
Good news is last month I only used a total 65 hours of heat or A/C even with all the cold weather we had.
Posted on 3/12/15 at 11:23 am to Rev1897
quote:
Right, so right now i'm looking at either paying 3 to 4 times as much for foam, but I might need less AC tonnage so there is a savings there.
For example I'm trying to decide for A/C purposes on either Carrier 3.5 and 2.5 Ton Down w/ 2.5 Ton Up: 14 SEER gas heat system:
and a Carrier 3.5 and 2.5 Ton Down w/ 2.5 Ton Up: 16 SEER Variable Speed gas heat system:
Most efficient unit is a unit that never comes on (or at least rarely comes on)
IMO, as an HVAC contractor and HVAC engineer, is spend the extra money of efficient windows and on good insulation. Weather it be an attention to detail fiberglass job or a spray foam job. just make sure the builder hits everything.
Posted on 3/12/15 at 11:36 am to tigeraddict
quote:
tigeraddict
Can you shoot me an e-mail: ziggy.td@gmail.com
Posted on 3/12/15 at 12:42 pm to tigeraddict
quote:Exactly, don't know how much sq footage the OP has upstairs but total we are about 250 sqft apart. I think we have a 3.5 (or 3) ton downstairs and 1.5 upstairs and have yet to turn on the upstairs unit. Definitely get a HVAC guy experienced with spray foam if you go that route. While I'm not very experienced at all with HVAC, I think you may have too much.
Most efficient unit is a unit that never comes on (or at least rarely comes on) IMO, as an HVAC contractor and HVAC engineer, is spend the extra money of efficient windows and on good insulation. Weather it be an attention to detail fiberglass job or a spray foam job. just make sure the builder hits everything.
Posted on 3/12/15 at 1:36 pm to Rev1897
I am in the process of working on plans for my hous. I talked to an energy rater that works in south LA and MS and here is what he recommended. Put Spray foam in the attic and blown in cellulose in the walls. He said that in the deep south in the summertime an attic that is not conditioned can get up to 120 degrees as most of us know. Your HVAC ducts only have R7/R9 insulation at best. As air moves through the duct it gets heated thus the unit having to work harder to cool the house. In a conditioned space with foam the air is cooler and the unit doesn't work as hard to cool the house. Made sense to me.
I talked to a builder who said starting in a few months every house that is built is gong to have to pass a HVAC load test. Part of new code and regs.
I talked to a builder who said starting in a few months every house that is built is gong to have to pass a HVAC load test. Part of new code and regs.
This post was edited on 3/12/15 at 1:41 pm
Posted on 3/12/15 at 2:14 pm to lsufan1971
If the attic is vented properly it shouldn't be getting to 120 degrees.
Posted on 3/12/15 at 2:26 pm to lsufan1971
quote:
and blown in cellulose in the walls.
Any particular reason why he didn't recommend spray foam in the walls?
Posted on 3/12/15 at 3:20 pm to Ziggy
quote:
Any particular reason why he didn't recommend spray foam in the walls?
He said it was basically a ROI issue. Said most spray foam installers only blow 3" in the wall. Blowing in cellulose gives full coverage in the walls for half the money.
Posted on 3/12/15 at 4:49 pm to lsufan1971
Cellulose in the walls is not a good option over time. It will settle, leaving voids resulting in no R value in some locations.
Rule of thumb on A/C sizing is 400 sq per ton. 1200 sq ft space would be 3 ton. Also it is better to undersize then oversize the unit. U will only dehumidify the air when the cooling coil is on. An oversized unit quickly gets the space to setpoint and shuts off. This can leave the space with a higher humidity, which will make the space feel warmer then it actually is.
Rule of thumb on A/C sizing is 400 sq per ton. 1200 sq ft space would be 3 ton. Also it is better to undersize then oversize the unit. U will only dehumidify the air when the cooling coil is on. An oversized unit quickly gets the space to setpoint and shuts off. This can leave the space with a higher humidity, which will make the space feel warmer then it actually is.
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