New Addition Floor Insulation


Old 03-15-03, 04:31 PM
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New Addition Floor Insulation

We just added a 2 car garage to our ranch home and above it will be the new master bedroom/bath. The supports are engineered beams every 12 inches and the garage itself is regular concrete block. I worry that even with insulated garage doors the floor in the bedroom will be cold in the winters, if I was going to insulate the floor would I use a non vapor barrier insulation? I know when using the vapor barrier type the facing goes towards the heated area, in this case the garage would be colder than the bedroom so I was not sure how to install it.

Any suggestions?

Thanks in advance
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Old 03-15-03, 08:47 PM
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You are correct.

The vapor barrier should always be on the warm side of the insulation. The reason for this is that all heat has moisture in it. Since you will be heating the bedroom above and not the garage the way heat will transmit through the insulation during the winter is from the bedroom to the garage.

There is another concern with the floor of the bedroom above a garage. In the U.S. the ceiling and walls in a garage must be covered with a fire-proof material, usually sheet rock. In Canada they go a step further and mandate gas-proofing. Gas-proofing is not mandated in the U. S. but is a logical and prudent application for rooms adjacent to a garage. Gas-proofing is an application that prohibits fumes and/or fire from penetrating the walls and ceiling of the garage into the living quarters of the structure. What the Canadian code does is mandate that all the joints must be taped and spackled. Any penetration in the sheet rock must also be taped and spackled. Ductwork must also be taped, insulated and sheet rocked over. Both countries mandate a self-closer on Man-door and at least a 6 inch step down from inside the home into the garage.

The insulation in the floor of the bedroom will make the floor more comfortable in the winter.
Old 03-15-03, 09:43 PM
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One project that I designed and drafted just got done, which is on my web site is similar to what you describe. We removed the roof system and installed 14" web floor trusses 16" O.C. for a clear span. Worked great to hide all duct work, plumbing and electrical. It now is master bedroom, 5 fixture bath with walk in closet over a 2 plus garage. Garage is unheated with seperate furnace located in garage for the new second story.

I assume that your engineered beams are TJI's or what? What is depth of your joists?

Builders often put the floor insulation on the garage side of the sheetrock, when it should always be next to the part of the house thatís warm in the winter. Because the insulation is lying on top of the garage-ceiling sheetrock, a gap is formed below the bonus-room floor where air can move. Moving air doesnít have any insulation value, and in summer, that space forms a path for warm air to rise to the bottom of the floor. While the insulation should fill in the entire void, uou may want to have a contractor blow in additional insulation between the garage and above unit. Filling the void does not require the use of a vapor barrier.
This procedure can be costly, but you could do this yourself. If you used a rigid insulation and a vapor barrier in conjunction with your garage slab, the issue of moisture is almost non existent. Side walls are another story but if you sealed your concrete block you have resolved that issue as well.

Hope this helps, if you have questions e-mail me.
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