# Bonus room above garage freezing in winter



## enochian (Jul 1, 2015)

Bonus room above garage freezing in winter.

Floor is not finished.

Should I cut holes in the OSB boards, blow in rock wool, and then fix the hole with a piece of sheetmetal?


----------



## Windows on Wash (Aug 30, 2011)

How about a picture? 

There should have been insulation in there previously as part of the finishing. 

Are there kneewalls on either side of the bonus room? If so, the air whips in from the sides in these cases where there is a soffit and goes under the floor. You would need to install foam blockers in the joist bays, seal them off, and then insulate (or not) at that point.


----------



## joecaption (Nov 30, 2011)

Is the ceiling in the garage finished?


----------



## enochian (Jul 1, 2015)

yes, garage ceiling has drywall and is painted.


----------



## Windows on Wash (Aug 30, 2011)

How about some pictures?

Most bonus rooms have too much air communication under the joists with the vented soffits and then the knee walls are poorly insulated as well. 

All pretty easy fixes. 

Do you have knee wall access from inside the bonus room?


----------



## enochian (Jul 1, 2015)

Pic of room


----------



## enochian (Jul 1, 2015)

Weird gap in floor perimeter:


----------



## Bud9051 (Nov 11, 2015)

Was this space built and finished as part of the original house or did you do the conversion sometime later?

Bud


----------



## enochian (Jul 1, 2015)

Built by builder with the rest of house.


----------



## Windows on Wash (Aug 30, 2011)

Do you have kneewall access doors built in? 

You would normally access to vertical wall areas via an attic connection of some sort and could address those floor gaps and lack of air seal there.


----------



## Bud9051 (Nov 11, 2015)

Had to as as that gap doesn't look like something a builder would do. Also, the window doesn't look like it meets the egress requirements.

Living space above a garage is an area subject to concern with exhaust fumes from below so codes must be followed in detail. As for being cold, there are many similar posts on the forum. The problem is the cold below and the heat above doesn't like to stay at floor level. Your only defense is to super insulate the floor and seal off air circulation as Wow stated. Try to exceed the code minimums.

I would fill the floor cavities 100% and insulate the back of those side walls plus some house wrap. The warmer the room stays the more it will radiate that heat down to the floor.

Bud


----------



## enochian (Jul 1, 2015)

Windows on Wash said:


> some sort and could address those floor gaps and lack of air seal there.


Couldn't I just spray some stuff in the gap?

Or stuff in some rockwool?


----------



## Windows on Wash (Aug 30, 2011)

In theory...yes, but that does not stop the air movement inside the wall or under the floor. It is only addressing a fraction of the issue at hand and not a permanent repair. If you don't have any kneewall access points, I would suggest making some or cutting a hold and fixing it back after you are done doing what you need to do.


----------



## enochian (Jul 1, 2015)

Windows on Wash said:


> I would suggest making some or cutting a hold and fixing it back after you are done doing what you need to do.


And what do I need to do?

I know nothing about insulation.


----------



## Windows on Wash (Aug 30, 2011)

You will need access to those vertical walls. Once there, you would:


Seal any gaps or cracks in the backside of the wall and around any electrical boxes
Install insulation inside the floor joist cavities so that it flush with the outside edge of the stud wall
Install a foam blocker in the floor joist to negate any air movement under the floor
Install foam board over the outside stud edge of a sufficient thickness to negate air and heat transfer for your climate.
Be sure to check with your local code compliance on what is require for exposed foams in an application like yours that will likely not be used for storage

Here is link that has previously been circulated that speaks to the airtight drywall approach: http://buildingscience.com/documents/information-sheets/air-barriers-airtight-drywall-approach


----------



## enochian (Jul 1, 2015)

There are no wood boards on the lateral stud edge of the walls.

Is that normal?

Its just paper faced batts with nothing behind it.


----------

