Insulation question. Open cell vs. closed cell vs. fiberglass bats

1,411 Views | 17 Replies | Last: 1 yr ago by tgivaughn
schwack schwack
How long do you want to ignore this user?
AG
We are about to start renovating our small lake house that will eventually be our primary residence. It's a 1100sqft 1960's concrete block house with a metal roof and tons of old, metal casement windows - inefficient, but we love them. The cost & wait time to replace all of these custom size windows has made us decide not to replace them + our HVAC unit already handles the temps just fine.

1/2 of the house is an open living room / kitchen, the other half is a 2 bed with 1 Jack & Jill bathroom. We are planning to vault the ceiling in the LR, replace all of the paneling with sheetrock, stone veneer and re-side the gable ends with Hardie board and batten.

We plan to remove all of the old fiberglass blown-in insulation. Question is, do we spray foam and incapsulate the attic or go back with fiberglass? If we go with fiberglass, we'd prefer to have a ridge vent instead of a gable vent but we were not planning on re-roofing this round - but we could. We are also replacing all of the fascia, soffit & siding so, we would not go back with soffit or gable vents if we foam.

We are in East TX. If we use open cell foam, is moisture migrating to the roof deck a real concern? We have a variable speed HVAC that dehumidifies and the kitchen and bathroom fans vent outside. Should we consider conditioning the attic space with a vent if we go foam?

Obvious cost differences aside, are there any reasons not to use foam?
tgivaughn
How long do you want to ignore this user?
AG
Location? (Near what Texas city)
Appliances in attic? e.g. gas heat HVAC or WH
High utility bills?
Then I can offer an opinion.

In the mean time, you may already know ....
R-values/inch:
Foam: Closed cell 6.5-7 employed where wet/humid or thin walled refrigerators/etc.
Foam: Open cell 3.8 open to moisture invasion ala Fiberglass/min.wool but superior infiltration defenses
Spider: 3.7 superior infiltration defenses, cheaper than above?
Fiberglass/min.wool: 3.0-3.4 least costly
Research all the new varieties
then all the costs/sf
The Money Pit opinion: https://www.moneypit.com/spray-foam-vs-fiberglass-insulation/
IMHO and am sticking to it
schwack schwack
How long do you want to ignore this user?
AG
Quote:

Location? (Near what Texas city)
Appliances in attic? e.g. gas heat HVAC or WH
High utility bills?
Then I can offer an opinion.

Palestine

Heat pump, electric HVAC only thing up there - bathroom & kitchen vented outside. Tankless electric hwh.

Our usage has never been above 1500 kWh/month - most of the year right around 1,000/month (includes running our shop bldg with 1 freezer & 2 extra fridges etc. Of course, higher now with the new electric plans, but not too bad.



Edit: Our west wall is built into a hill & the other 3 sides of the house are windows. The East side has a 12' deep covered porch.
tgivaughn
How long do you want to ignore this user?
AG
Thank you!
You've done everything an Architect could do in passive energy management, kudos.
I predict on this forum you will be over run with the SOP movement toward some sort of foam that coats all the attic and my opinion may be a target for fun. That said, even in all-foam attics many of our new residence designs do opt for a minor vent to offset Aggieland humidity, even though not as bad as Houston.

If this were MY house, the choice this jaded designer would pick is the simple, affordable path of R-38 Spider on attic floor/house ceiling; continuous soffit & ridge venting. The Money Pit has evidence that you should seal off any gable vents "due to turbulence" but that was a course studied in the 70's that makes me doubt sealing off ANY venting ... unless it leaks. The return on your costs will be more immediate and perhaps A.OK forever on.

This does NOT limit your selection of foam sealing later should power bills force you. I expect the foam cost trend to continue to fall over the years with skills rising. For others using roof shingles, this would give those manufacturers time to counter the extra heat foam adds to their shingles (time = heat, so more heat = less time old school shingles last).

The windows - I agree.
An Austin Architect/eng study found even single pane windows that were shaded to compete well with dbl.insul when both first-costs & monthly costs were compared over time.
Hard to find quality, long lasting casements within anyone's budget these days!

Hardie - we were the first locally to employ it; get someone that's done it prior ... should be EZ.
Also get the factory pre-primed Hardie and your final paint coats will last MUCH longer.

Would love to see the Floor Plan, if you have time to google my email or other way
IMHO and am sticking to it
Bronco6G
How long do you want to ignore this user?
Holy High Bills Batman...$1000/mo for a 1100 sqft house? That's crazy talk. Put up a radiant barrier on the underside of the roof and spray foam everywhere that you can.
Martin Q. Blank
How long do you want to ignore this user?
1000 kwh, not $1000.
Quote:

Obvious cost differences aside, are there any reasons not to use foam?

1. You can DIY fiberglass easier than foam.
2. Foam is newish. Probably not a health concern once it starts off gassing, but you never know.
Aggie Apple
How long do you want to ignore this user?
AG
Bronco6G said:

Holy High Bills Batman...$1000/mo for a 1100 sqft house? That's crazy talk. Put up a radiant barrier on the underside of the roof and spray foam everywhere that you can.


I think he means 1,000 kWh per month. Not $1,000 bill per month. That would be insane.
Bronco6G
How long do you want to ignore this user?
Ah, yes, I misread that,,,thought he was saying 1500KWh was costing $1000/month
Just don't know why the new electric plans would cause more usage?
Aggietaco
How long do you want to ignore this user?
AG
Depending on your roof pitch, when you vault the LR, are you planning to go all the way to the underside of deck or are you leaving enough room for R-38?

With that size floor plate, is the climatized storage possible in a conditioned attic a benefit you're willing to invest in? If not, I would lean towards tgivaughn's response and run traditional insulation and vented attic - but coming from someone in a 1500 sqft place, I would think the attic storage would be a huge plus.

Is the existing masonry filled or hollow?
MoreCushing4thePushing
How long do you want to ignore this user?
AG
In my remodel, we chose open cell. Closed cell was quoted to be at 2x that of open cell. Closed cell has greater rigidity and basically water proofs your house.

One of the guys who quoted me mentioned something about the acoustic absorption of open vs. closed cell, and that was the determining factor for me. He equated closed cell to yelling at a brick wall and how the sound basically bounces off. He equated open cell to yelling into a pillow. I chose open cell to reduce noise travel.

schwack schwack
How long do you want to ignore this user?
AG
Quote:

Just don't know why the new electric plans would cause more usage?
Billed amount much higher now that it used to be - not more usage. He asked how much our bill was.

schwack schwack
How long do you want to ignore this user?
AG
Quote:

Depending on your roof pitch, when you vault the LR, are you planning to go all the way to the underside of deck or are you leaving enough room for R-38?

With that size floor plate, is the climatized storage possible in a conditioned attic a benefit you're willing to invest in? If not, I would lean towards tgivaughn's response and run traditional insulation and vented attic - but coming from someone in a 1500 sqft place, I would think the attic storage would be a huge plus.

Is the existing masonry filled or hollow?

3/12 pitch

Plan is to set a beam & run the ceiling joists off of that. Waiting on 2 different framers to get their recommendations. There should be ample room for insulation. We will only gain about 3' of ceiling height but it will make the 8' ceilings feel taller.

Storage is a premium. We have decked attic storage on the other side of the house but the HVAC occupies a lot of that space. We also have a shop building with plenty of storage with it's own HVAC climate control. We actually live pretty minimal in the house - our first house was only 800 sq feet - then we went to 2400, now transitioning back to smaller.

The cement block is hollow.

Thank you for your reply.
schwack schwack
How long do you want to ignore this user?
AG
Quote:

He equated closed cell to yelling at a brick wall and how the sound basically bounces off. He equated open cell to yelling into a pillow. I chose open cell to reduce noise travel.

Very valid argument for open cell.
schwack schwack
How long do you want to ignore this user?
AG
Quote:

Would love to see the Floor Plan, if you have time to google my email or other way
I think I sent an email to your correct address.
CenterHillAg
How long do you want to ignore this user?
AG
Would it be possible to put a clear ceramic tint on the windows? I had 70% tint put on the windshield of my car and it made a huge difference, even with the other windows already done.
schwack schwack
How long do you want to ignore this user?
AG
Quote:

Would it be possible to put a clear ceramic tint on the windows?

The inefficiency is not really a direct sun issue on the windows, but just how the windows crank open & shut. They close and don't leak at all, but the seal is not tight. They are the old 50's-60's metal kind.
MS08
How long do you want to ignore this user?
AG
It is not advised to do radiant barrier on the roof deck as well as spray foam the roof deck. Creates a heat trap and decreases effectiveness of the spray foam. Whenever possible, the answer is to spray foam. It is a wonderful product. Only spring for the closed cell when you are trying to create a vapor barrier up against certain walls.
tgivaughn
How long do you want to ignore this user?
AG
FYI to those following this thread
Source: The Money Pit radio program
Retailer: Home Depot & Lowes or better yet - a pro installer

https://www.homedepot.com/p/Owens-Corning-15-in-x-47-in-R13-Thermafiber-Fire-and-Sound-Guard-Plus-Mineral-Wool-Insulation-Batt-1196588/319880476

https://www.homedepot.com/p/Owens-Corning-R-13-Kraft-Faced-Fiberglass-Insulation-Fiberglass-Insulation-Batt-15-in-x-93-in-10-Bags-BF10/205470785

Various size options other than what links show
Your zip code may affect ease of delivery
IMHO and am sticking to it
Refresh
Page 1 of 1
 
×
subscribe Verify your student status
See Subscription Benefits
Trial only available to users who have never subscribed or participated in a previous trial.