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Started By
Message
Attic Insulation Questions
Posted on 1/31/23 at 8:23 am
Posted on 1/31/23 at 8:23 am
Good morning.
I have an older house with a smaller attic and I'm looking at re-doing the insulation.
I have old batt insulation up there now but it's compressed in a lot of areas. I can see 2-3 inches of my ceiling joists (actual 6 inch joist) through out. It being an older house, I'm hesitant to blow in 10-12 inches of fiberglass because there's stuff in the attic I'd still like to do (plumbing, electircal, etc).
Looking for opinions on whether or not to go open/closed cell spray foam direct to the decking and remove all the old insulation.
Open cell - my dad got this done on his house and it helped but not as much as he would've hoped. Everything I've read about open cell is that heat still transfers through. Additionally, not sure if I want to go open cell with the it's ability to absorb moisture/humidity.
Closed cell - I'm leaning this, but it's a good bit more. Also reading conflicting reports on how thick it needs to be.
Appreciate the feedback!
I have an older house with a smaller attic and I'm looking at re-doing the insulation.
I have old batt insulation up there now but it's compressed in a lot of areas. I can see 2-3 inches of my ceiling joists (actual 6 inch joist) through out. It being an older house, I'm hesitant to blow in 10-12 inches of fiberglass because there's stuff in the attic I'd still like to do (plumbing, electircal, etc).
Looking for opinions on whether or not to go open/closed cell spray foam direct to the decking and remove all the old insulation.
Open cell - my dad got this done on his house and it helped but not as much as he would've hoped. Everything I've read about open cell is that heat still transfers through. Additionally, not sure if I want to go open cell with the it's ability to absorb moisture/humidity.
Closed cell - I'm leaning this, but it's a good bit more. Also reading conflicting reports on how thick it needs to be.
Appreciate the feedback!
5
Posted on 1/31/23 at 12:12 pm to PureBlood
All spray companies recommend open cell on the underside of a roof. Closed cell for walls and under a floor on pier and beam building.
Posted on 1/31/23 at 12:28 pm to PureBlood
quote:
I can see 2-3 inches of my ceiling joists (actual 6 inch joist) through out. It being an older house, I'm hesitant to blow in 10-12 inches of fiberglass because there's stuff in the attic I'd still like to do (plumbing, electircal, etc).
Looking for opinions on whether or not to go open/closed cell spray foam direct to the decking and remove all the old insulation.
How does this solve your problem?
Is the idea that foam will be less thick so you’d still be able to do whatever additional work?
Open cell foam is similar in R-Value to fiberglass. Closed cell is better, but for R-38 you’re still looking at about 6-7”, which is above your 6” joists.
What’s stopping you from doing the other work first?
Posted on 1/31/23 at 12:34 pm to PureBlood
On all my projects, we do open cell at the roof roof @7" min thickness. However if your house is not adequately air sealed prior, and if your walls are not adequately insulated, it will not make much of a difference.
Posted on 1/31/23 at 12:49 pm to DellTronJon
quote:
However if your house is not adequately air sealed prior, and if your walls are not adequately insulated, it will not make much of a difference.
What profession do you give a call to do an air seal inspection? HVAC? Home inspectors?
I've been wanting to add more insulation in my attic, but I know my house has to be leaky. Just not sure who to call.
Posted on 1/31/23 at 3:09 pm to Baers Foot
quote:
What profession do you give a call to do an air seal inspection? HVAC? Home inspectors? I've been wanting to add more insulation in my attic, but I know my house has to be leaky. Just not sure who to call.
You need a residential energy audit company that can do a blower door test that will determine how leaky your house is, and while the house is under negative pressure they can use a thermal imaging camera and/or smoke pen to identify problem areas that need to be addressed, sealing leaks, including the need for additional attic insulation.
I had one done about 1 1/2 years ago - very helpful in identifying problem areas to correct. Cost about $300 at that time, I think $300-400 is a typical fee.
This post was edited on 1/31/23 at 5:25 pm
Posted on 1/31/23 at 3:15 pm to CrawDude
quote:
CrawDude
Thanks
Posted on 1/31/23 at 4:31 pm to LSUtigerME
quote:
How does this solve your problem?
Based off of OP, it looks like he wants to go spray straight to decking and not on joists.
Energy audit sounds intriguing. I’ve been meaning to spruce up my insulation and doors as well. Did windows recently.
Posted on 1/31/23 at 5:31 pm to TaderSalad
Posted on 1/31/23 at 7:43 pm to PureBlood
No closed cell on a roof deck
Posted on 2/1/23 at 7:05 am to jmkidder
Appreciate the responses everyone.
Can you please elaborate? I have a metal roof, fwiw.
quote:
No closed cell on a roof deck
Can you please elaborate? I have a metal roof, fwiw.
Posted on 2/1/23 at 8:50 am to PureBlood
I think you can use closed cell it's just harder to execute in practice thus the preference for open cell. With open cell your roof deck will be able to dry to the inside. With 2 inches of closed cell you have a vapor barrier and any moisture that finds its way to your sheathing will be trapped. I would also suggest you add a whole home dehumidifier if you go the fully conditioned attic route to ensure you do not have problems with high humidity in your attic. FWIW we have 8 inches of open cell at the roof line and a whole dehum and we love it. I think it really helps moderate the temperature in the house.
Posted on 2/1/23 at 9:17 am to PureBlood
The theory behind it is that closed cell is impermeable, therefore if a roof leak occurs it will collect between the roof deck and insulation and rot the roof deck without you ever knowing.
Open cell is more water permeable and will at least show a waterspot in the event of a roof leak. That waterspot may show up "down stream" and not at the actual leak, but at least you know something is wrong.
Also, closed cell is a much harder product and will be a mess if you have to replace any roof decking. Open cell is a softer product and easier to remove in that situation.
Lastly, your homeowners insurance may not cover you in that scenario above with the closed cell. Just a thought. I am not an insurance agent, just giving my opinion.
ETA: I agree with the above comments about sealing your walls and eaves. You need to treat that attic as part of your house to prevent a domino affect of issues ranging from humidity, mold, inefficient HVAC
Open cell is more water permeable and will at least show a waterspot in the event of a roof leak. That waterspot may show up "down stream" and not at the actual leak, but at least you know something is wrong.
Also, closed cell is a much harder product and will be a mess if you have to replace any roof decking. Open cell is a softer product and easier to remove in that situation.
Lastly, your homeowners insurance may not cover you in that scenario above with the closed cell. Just a thought. I am not an insurance agent, just giving my opinion.
ETA: I agree with the above comments about sealing your walls and eaves. You need to treat that attic as part of your house to prevent a domino affect of issues ranging from humidity, mold, inefficient HVAC
This post was edited on 2/1/23 at 9:19 am
Posted on 2/1/23 at 10:26 am to PureBlood
Replace old batt insulation with Rockwol.
Posted on 2/1/23 at 11:12 am to Man4others
Ive looked into Rockwool for walls and such.
Do you know any companies in Greater Baton Rouge area that work with it? I'd like to get a quote
Do you know any companies in Greater Baton Rouge area that work with it? I'd like to get a quote
Posted on 2/2/23 at 9:12 pm to PureBlood
A&E Insulation can provide Rockwool, although their preference is blown in fiberglass.
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