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BrianinNC 03-19-2013 01:19 PM

insulation for bonus room over garage
So to start of i have a 7 yr old house which i bought as new constuction. The bonus room is finished and the 2-door garage is finished. At the time i was traveling for long periods of time so i never took notice of it but when things slowed down i notice the same as most bonus rooms above garage syndrome. very cool in the winter and very hot in the summer. I desided to invesigate and found that they put insulation around the room but that was it. None in the open space and no lower rafter vents. Air is just flowing freely thru the joist. I'm really not trying to tear the ceiling down. I figured i could close of the open floor joist with insulated foan and spray foam it to block air flow, install celulose in the open space and put up some foil backed insulation on the knee walls. What can i do about the angled walls?? Any pointers tips anyone can give me? I'm also in the proccess of insulating the garage doors as well. Most of the stuff i found is where the the room is unfinished or the garage joist are open. Here are some pics .

pic behind the long bonus room wall

start of the insulation on the angled walls

notice the air pocket in the insulation. This is why my feet was so cold this winter

Nailbags 03-19-2013 06:10 PM

I would use loose fill in there no need to use spray foam to costly. You want ventlation in there for the roof or your going to have other problems then cold in the winter and hot in the summer. like premature roof failure. there has to be some air movement in the attic space. just use a good loose fill insulation keep the baffels inplace insulate to at least R-48 and you should be good to go!:thumbup:

asinsulation 03-19-2013 07:36 PM

you want to allow the air to travel through the ceiling area, do not close it off. If you really want to see a difference there, address the garage ceiling between the bonus room and the garage with densepacked cellulose, and seal off the edges with foamboard and spray foam. then, tack up foamboard or some type of air barrier over the fiberglass that lays vertical on the wall to stop any windlashing, which kills the r-value of fiberglass. If the situation is how I am imagining it from the pictures, that should help alot.

BrianinNC 03-19-2013 08:32 PM

Here is another pic so you can kinda understand what i'm talking about. Maybe saying foam was the wrong word to say. i want to block air from going under the bonus room I.E cold floor in side of bonus room. Run vents on the bottom of rafters to move air up to roof vent and some how keep the angled walls more insulated as well. to prevent heat/cool air from escaping or minumize it from getting in.

In this pic i an standing in the bonus room looking to the roof/attic area beside the bonus room

This one is pic looking under bonus room between joist. Don't mind the no insulation there. I moved it for reference

Nailbags 03-20-2013 12:11 AM

If those photos are correct yes maybe depends on what is on the other side? siding ect... I would just fill that area the place with the red out line with loose fill and as a after thought I would caulk were the bottom cords of the trusses meet the sheetrock help seal the area better then blow in your loose fill of choice to at least R 48 and you should be a lot happier.

BrianinNC 03-20-2013 12:57 AM

I will update my progress on this issue as i go to make sure i'm not going in the wrong direction. This will be a big help.

747 03-20-2013 01:17 AM

If you plan on using the bonus room. Spray foam. You always spray foam if there is living space above a garage. Yes it more expensive but you will be done with it.

Example holmes on homes. He has showed up. Living space above garage. There is insulation up there but its still cold. Solution spray foam. No more problems.

BrianinNC 03-20-2013 01:44 AM

Well in my case the spray foam i won't need due to the fact even though it is a garage no cars are started in the garage and it's only my classic car in there. i roll the car outside before startup and i only drive it on sunny days. I'm not worries about exhaust fumes entering into the room.

asinsulation 03-20-2013 11:46 AM

you have the right idea.

BrianinNC 03-20-2013 06:31 PM

So the insulation that's under the bonus room i should replace with cellulose before capping the ends off with foam board if i'm understanding right? Just taking measurements to do a my own cost worksheet to see how much it's going to run. Also i was looking at another post that i must have missed when i was searching and saw that Gary had mentioned Roxul. Is this far better then the usual fiber insulation? Anyone used this in there home can attest to the product? I Noticed at the major hardware stores itt has to be preordered.

Nailbags 03-20-2013 07:31 PM

Rockwool or roxul is very good 100% fire proof won't itch won't let vermin live in it and if it gets wet it will dry out. I just got done doing a home with it. It draw backs are it is hard to cut. out side of that it is good stuff. In my opinion.

asinsulation 03-20-2013 07:53 PM

roxul is good, but in your application for under the floors it would be difficult. if you want to see a good amount of your results quick, proceed with the air seal around the floor joists. you can always pop a hole for the densepack later and use one part foam to seal it back up. see what results you get from the airseal and if its worth it to go the extra mile with the cellulose.

Nailbags 03-20-2013 08:01 PM

From the photos it is open area.

BrianinNC 03-20-2013 08:14 PM

Yes. For some odd reason i don't know why they didn't put in a small door there so i'm also going to build one to make the space for storage as well. Funny thing is was before this i had a contractor quote me 2500-3000 bucks to do the job. Kinda was suspect which is why i want to do it on my own

Gary in WA 03-20-2013 11:52 PM

Yes, there should be vents in every rafter bay to rid any moisture/heat from the roof sheathing. Yes, close off below the knee wall and above to prevent wind-washing of the fibrous insulation, yet leaving the baffles open for air movement through them. No foil-faced batts on the knee wall;

Yes, remove the f.g. batts under the room floor, if filling with cellulose at a later date. Yes, add an access door (with weather-strip seal and insulation on door back, solid wood has R-1.25 per inch) to the attic for floor storage but do not insulate the floor or rafters as the space is not conditioned, your thermal barrier stops at the knee-wall.

Add some housewrap to the attic side of the f.g. knee wall frame/insulation batts to prevent wind-washing, degrading your R-value. If no insulation at knee wall now, caulk the drywall/truss vertical member to air seal, also any electrical boxes/wire holes in boxes to ADA the drywall;

Also, caulk or canned foam the drywall butt joint at the sloped ceiling/vertical wall on attic side to prevent air loss there. Hey, while it's Exposed Romex within 6' of the access door requires covering/sandwich between boards to protect from walking on/crushing.

PS. When you dense-pack, replace the access hole for the tubing with 5/8" Type X drywall (use the cut-out with plywood backers, unless using fire-rated foam in the garage ceiling.

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