Rigid Foam Insulation in Garage (apartments, homes, to buy)

[Knepper3]

Ok so doing a few smaller projects while I have time. One thing that has been low on my list since I bought: My 1 car garage has a study/office area above it which at one time way back was likely an open porch. That room gets colder in the winter partially because of the cold garage below. The garage ceiling is open with metal beams spanning the width. Between the beams are some very old insulation traditional fiberglass that is wedged in and somehow stays. It looks like crap and not sure it really helps but I want to replace with something that might work better and look better.


I could have it all spray foamed but wondered about swapping out for sheets of rigid foam? They would be easy to install and being rigid would stay in place better/easier. It's about 11x18 so rigid foam should save a $200+ over spray foam but I also dont mind spending more. I just have a cluttered garage so worry about cleaning needed to spray foam.

[guy2073]

I always liked using rock wool in garages. It is fire proof and moisture resistant. If you keep a car in the garage it maybe a better option than spray foam

https://www.lowes.com/pd/ROCKWOOL-SA...7-in-L/3394032

I have used this kit for doing additions, it works very well. You can buy the kit in a smaller quantity if needed. They also make a fire resistant foam kit.

https://www.amazon.com/Froth-PAK-Sea...dDbGljaz10cnVl

[Knepper3]

Thanks, I do not keep a car in. Even if I kept it completely empty few modern cars would fit and let me open a door so I've built various benches, just a workshop area really. I'm pretty handy though I've never done spray foam, I picture it being messy on a ceiling? Is there a big benefit using spray?



The rockwool looks a little more rigid than regular, plus it would be about 1/2 the cost of even DIY spray. The issue is there is about 4 foot spans between each steel beam which are parallel to the garage door with a few wood slats that semi hold up the current insulation. I don't want to put up a real ceiling but maybe I get more slats to better hold the insulation up.

[Catia]

Knepper3,
before you begin, PLEASE consider that this is a garage & that you have adequate ventilation in/out of the garage before you begin tightening it up.
You want to seal off the garage completely from the study.
If the study was previously an open porch, & converted to a closed space, there is good reason to believe that this was not done back when it was converted. There are specific code requirements to address this.
The reason for this is because there is a real risk of carbon monoxide poisoning.


Usually if there is a habitable space above or beside a garage, meaning attached in any way, you need to completely seal the garage off from the habitable space, & double up the sheetrock/drywall, which has to have a specific fire rating as well. There are special caulkings for this sealing as well.


The good news here is that you can do the sealing off of the garage as part of your project, & the additional work & materials will also increase the comfort & safety of the study above. I understand you are not using it as a garage, currently, but you may sell some day, & the next person might use it with a compact car for it's intended purpose.


I am stating this because:
I am a survivor of carbon monoxide poisoning, which caused traumatic brain injury, with permanent affects.
As a result, I have a severe life threatening disorder I must deal with daily.




I 2nd using rockwool for this project. There are other types of rockwool that you can get special order that may suit you better, specifically, there are rockwool panels. The batts are more rigid than fiberglass, but less rigid than panels. There are also acoustic panels.
here is a link to roxul's site, whick is now called Rockwool:
https://www.rockwool.com/products/

[guy2073]

Originally Posted by Catia

Knepper3,
before you begin, PLEASE consider that this is a garage & that you have adequate ventilation in/out of the garage before you begin tightening it up.
You want to seal off the garage completely from the study.
If the study was previously an open porch, & converted to a closed space, there is good reason to believe that this was not done back when it was converted. There are specific code requirements to address this.
The reason for this is because there is a real risk of carbon monoxide poisoning.


Usually if there is a habitable space above or beside a garage, meaning attached in any way, you need to completely seal the garage off from the habitable space, & double up the sheetrock/drywall, which has to have a specific fire rating as well. There are special caulkings for this sealing as well.


The good news here is that you can do the sealing off of the garage as part of your project, & the additional work & materials will also increase the comfort & safety of the study above. I understand you are not using it as a garage, currently, but you may sell some day, & the next person might use it with a compact car for it's intended purpose.


I am stating this because:
I am a survivor of carbon monoxide poisoning, which caused traumatic brain injury, with permanent affects.
As a result, I have a severe life threatening disorder I must deal with daily.




I 2nd using rockwool for this project. There are other types of rockwool that you can get special order that may suit you better, specifically, there are rockwool panels. The batts are more rigid than fiberglass, but less rigid than panels. There are also acoustic panels.
here is a link to roxul's site, whick is now called Rockwool:
https://www.rockwool.com/products/

Unfortunately no matter how sealed a garage is it won't prevent carbon monoxide from entering other areas of the home. The minimum code for a residential garage is 5/8 fire rated drywall that is fire taped. Fire taping is basically a first coat of drywall compound with paper tape. The best way to prevent carbon monoxide poisoning is to buy multiple detectors, i have actually been in apartments where one detector in a unit with a problem didn't go off but one in the neighbors apartment did.

[guy2073]

This study had a 40% failure rate on co2 detectors

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3222366/

[Knepper3]

Thanks, when I pull down the old insulation I will check things out. This being an old porch (I am pretty sure) I think the actual flooring is a solid piece. I've seen them do concrete as a garage ceiling thus the steel supports I see. I will check for an leakage points but this does make me think of how unsafe things were for the prior owner who did use this as an actual garage. There is actually a duct into the garage area for heat/ac. If the unit wasn't running any CO2 would have easily gone through the home. That was one item I was planning to address anyway, not from a safety standpoint (now it is that I think of it) but simply wasted AC/Heat since even closed it wasnt 100%.

[Catia]

Originally Posted by guy2073

Unfortunately no matter how sealed a garage is it won't prevent carbon monoxide from entering other areas of the home. The minimum code for a residential garage is 5/8 fire rated drywall that is fire taped. Fire taping is basically a first coat of drywall compound with paper tape. The best way to prevent carbon monoxide poisoning is to buy multiple detectors, i have actually been in apartments where one detector in a unit with a problem didn't go off but one in the neighbors apartment did.

Huh?! Please reread what you wrote with fresh eyes.
The best way to prevent CO is to not have CO in the 1st place.
To not have CO, & to lessen the risk, you ventilate the areas with CO. You absolutely CAN control contaminant migration through the garage-house interface. It's done all of the time, not just in homes, but commercially as well.


Relying on the poor quality made in China $20 CO detector that often fail is maybe better than nothing.
There are better CO detectors out there, but not everyone can afford them. Yes, do your research on them & purchase the best quality you can afford. The good news is that at least nowadays you have the ability to buy them. The CO detector you can buy off of the shelf took a lot lives & making people aware of after the fact to get them on the market.


Since I have survived, for the past 20 years, I have become very educated in this subject, I have done a lot of research. I have worked with many fields on the issue of CO poisoning. Years back, I have spoken publicly to inform about it, while working with & for an HVAC engineering company, which aligned with the ACCA regarding IAQ, so I respectfully disagree.


The goal is to PROPERLY VENTILATE the garage, which allows the CO out, while sealing the air infiltration to the habitable space.
Ideally, this would be done in tandem with quality CO detectors, as a back up.


(by the way, co isn't the only contaminant coming from car exhaust in a garage, it's just the silent killer)


https://www.ncbi.nlm.nih.gov/pubmed/27444389