More unfinshed Bonus room over Garage?s

Bloodta · 01-16-2010, 03:12 PM

I am finishing an unfinished bonus room over a garage. My question is: Is it the builder's responsibility to properly insulate the floor of the bonus room? The subfloor is down and the garage ceiling has been insulated and drywalled.
Thanks

Scuba_Dave · 01-16-2010, 03:17 PM

I'm not sure I understand, you say the sub-floor is down & already insulated
What is the question then ?

What was the agreement with the builder ?
Since you are finishing the room then it seems the builder is/was not involved

Bloodta · 01-16-2010, 09:13 PM

Quote:

Originally Posted by Scuba_Dave

I'm not sure I understand, you say the sub-floor is down & already insulated
What is the question then ?

What was the agreement with the builder ?
Since you are finishing the room then it seems the builder is/was not involved

Sorry about that, I don't think I worded that right. The garage ceiling is insulated, not the bonus room floor above it. I've always heard that you put the insulation closest to the living space. As it stands now there is an air gap above the insulation under the bonus room floor. I would assume the builder would know this and do it right. So, is it the builder's responsibility to put the insulation directly under the bonus room floor and not directly above the garage ceiling, or maybe do both? There is about a foot gap above the garage ceiling and the bonus room floor.

Scuba_Dave · 01-16-2010, 09:50 PM

In most cases it really doesn't matter where the insulation is located in a joist space
If it was near the floor it could sag over time & leave air gaps
So putting it where the drywall will support it makes sense
Heat rises, how much insulation is there ?

Bloodta · 01-16-2010, 09:57 PM

Quote:

Originally Posted by Scuba_Dave

In most cases it really doesn't matter where the insulation is located in a joist space
If it was near the floor it could sag over time & leave air gaps
So putting it where the drywall will support it makes sense
Heat rises, how much insulation is there ?

I believe it's r-15 or r-19. All I know is the floor is cold and that room is usually around 10 degrees colder than the rest of the house. I recently added r-30 perpindicular to the r-11 that was in the ceiling and the knee-wall. So I know it's not those at fault.

Scuba_Dave · 01-16-2010, 10:01 PM

Is the rest of the house over heated rooms...or an unheated garage ?
What size are the joists? R15 = 3.5" thick, R19 = 5.5" thick
I'm putting R30 between my garage ceiling & great room floor

Bloodta · 01-16-2010, 10:24 PM

This room is the only room that is not over a heated space. I am willing to bet its R19.

**Gary in WA** · 01-16-2010, 11:30 PM

"Heat doesn't rise. The myth that heat rises was used for many years to justify not insulating floors at all. That led to some very cold feet.
It's hot air that rises. An air mass that is warmer than the air around it will rise in relation to that cooler air. The process of hot air rising is called convection. It's only one way that heat can escape a building. Two others are conduction and radiation."
From: http://oikos.com/esb/38/floorinsulation.html

I would air seal the ceiling below and install foam board at the rim joists from the garage: http://www.rd.com/57548/article57548.html

The best way would be to blow cellulose in from the garage. Or new batts, install foam board, then drywall on the garage ceiling. Try to decouple the cold garage joists from the floor: http://www.buildingscience.com/docum...n-crawlspaces/

The air gap of 1-4 inches has a R-value of 1. Worse, it will allow air movement so the existing batts cannot trap air pockets to do their job. The insulation has to be touching on all 6 sides to be effective. If any holes are present, from wiring, etc., you could easily have convective loops occurring: http://oikos.com/library/insulating_...lls/index.html

Did you block air flow under the knee wall to the floor from outside soffit vents? http://www.simplesavings.coop/simple...ee%20walls.pdf

Be safe, Gary

Bloodta · 01-17-2010, 01:14 AM

Quote:

Originally Posted by GBR in WA;384263
Did you block air flow[B

under[/b] the knee wall to the floor from outside soffit vents? http://www.simplesavings.coop/simple...ee%20walls.pdf

Be safe, Gary

I haven't got to that yet. But It's next.

The problem sealing the rim joists is that I'll have to pull down the ceiling drywall in the garage.

Bloodta · 01-17-2010, 04:37 PM

If I get into ripping the garage ceiling down to seal the rim joists, and put the insulation on the bottom of the bonus room floor, do I need a vapor barrier on the bottom of the bonus room floor?

Here is pic before insulation from inside garage looking up at bonus room floor.

This is the insulation in the ceiling of the garage

This is another looking up at bonus room floor. The area outlined is behind a knee wall and is used as storage.

firehawkmph · 01-17-2010, 06:05 PM

Bl,
What exactly are you after? Are you looking for the proper solution to your problem, or are you looking to try and nail the builder for something? The builder's responsibilty is to build the house to meet code, and also to build it to whatever the prints spec above and beyond code. So if you didn't specify you wanted the insulation in that ceiling/floor system to meet a certain R value or you wanted it done in a certain way, he probably didn't do it that way.
If you end up wanting to fill the space with more insulation, the worst you have to do is remove some of the subfloor or drill some holes for blow in. Neither is a big dollar item. Figure out the best solution and do it.
Mike Hawkins

Quote:

Originally Posted by Bloodta

I am finishing an unfinished bonus room over a garage. My question is: Is it the builder's responsibility to properly insulate the floor of the bonus room? The subfloor is down and the garage ceiling has been insulated and drywalled.
Thanks

Scuba_Dave · 01-17-2010, 06:28 PM

Rather then rip the ceiling down, possibly only to find the Max insulation installed I would:
Put rigid insulation down in the bonus room & new subfloor/floor

If you decide to rip the ceiling down make sure you cut a test hole 1st & verify how much insulation is up there

**beenthere** · 01-17-2010, 07:26 PM

It should have been put at the floor of the bonus room.

But, what he did does pass code. So he did what he was responsible for.

You will find that you will need to also seal that area(rim board). And then insulate it.
Other wise, your central system will not be able to maintain temp in that bonus room.
Its a common problem with bonus rooms/FROGs.

Bloodta · 01-17-2010, 08:13 PM

I'm not looking to nail anyone. I want a solution to a problem. I just want to know if everything is up to code. Also, I want to know my options for making this room a liveable space. Ripping up the floor is not an option as it has already been doubled up and carpeted. (this is a theater room build).
If I have to tear down the garage ceiling and seal rim joists and push the insulation up to the floor, then that's what I will do. I just don't want to do all that work and not fix the problem. Would it be more beneficial to seal the area behind the knee wall or to rip garage ceiling down, seal rim joists, etc.? If I could only do one, which should I choose?
Thanks for all the replies, keep 'em coming.

**beenthere** · 01-17-2010, 08:24 PM

Insulate the floor area behind the knee wall also.

The storage area is leaving lots of cold(no insulation to stop the heat transfer) get into the space between the insulation and the rooms floor.

I would drop the ceiling.

But. You said its a theater room. Then it should have its own heating and cooling system. And not be conditioned by the central unit. Unless the central unit is zoned. And that room has its own thermostat.