Cold bonus room issues identified, solutions provided

Many new homes are taking advantage of that space above the attached garage for an additional bedroom / bonus room space. It was made possible by the invention of the attic frame truss that is able to span a two car garage and provide a 12′ wide usable room above. However, most bonus rooms have a problem – they are uncomfortable. You can see in this image that a builder has addressed the problem by adding an ugly through wall heating / air conditioner. This will make the room comfortable, but adds to your electric bills, does not address indoor air quality issues, and is usually noisy – not to mention ugly.


This bonus room space is a nice add to the usable space in a home, but has indoor air quality and comfort issues. This is due to the difficulty in getting them air tight as well as difficulty getting supply and return air into the space. A bonus room above the garage needs extra attention from the insulator. In order to get it air tight and efficient, they need to use a LOT of caulk or an open cell spray foam solution. This will also protect against the air infiltration from the garage below. Good planning may also allow for HVAC ducts, supply and return to reach the room through the knee walls. This all needs to be carefully planned and thought through in advance of construction to get it right.

While I prefer this space to only be used for storage in a detached garage, sometimes the lot demands it be attached. If you do take that route, be sure to plan for comfort and indoor air quality solutions that will allow you to sleep knowing you have protected your family.

5 Comments Add yours

  1. Paul Gerber says:

    My master bedroom is above the garage and we have lots of issues with her in the summer and cool in the winter. I agree that these rooms need plenty of attention during construction. I would go so far as to say that the ceiling of the garage should be sprayed with closed cell spray polyurethane foam insulation rather than an open cell. The added density, integral air/vapour barrier that a lot of these products offer and foam’s ability to get into all the nooks and crannies within the ceiling space makes it a very justifiable spend.

    Equally important in this scenario is the insulation of the exterior walls in the garage. Our environment is more extreme than Virginia, but the builder didn’t consider this need in our house so we have to contend with a space that gets down to -20C (-1F) and below directly below a heated living space. We have had instances this past winter where 18L (5 gal) water jugs have frozen solid in our garage.

    Make sure you get it right if you’re considering this option!


    1. Paul Gerber says:

      Wow…that should be a lot of issues with HEAT in the summer…good old autocorrect!


  2. Paul indeed your climate is difficult with the extremes. In your climate I agree that a closed cell foam is appropriate. In our climate however, we don’t use vapor barriers. The added R value for closed cell would be nice and an ongoing discussion I have with our local insulation expert – Elite Insulation – I am just not there yet as it introduces a vapor barrier into the system in a mixed humid climate.


    1. pauldgerber says:

      Ah yes, paradigm shift…I have had vapour retarder/barriers so engrained in my thought process in my climate that I sometimes forget that there are areas where *shutter* they are needed or required by code. I have to turn off part of my brain to make this make sense, as I’m sure you have to do too when considering the need for a vapour retarder/barrier.


  3. John McKinney says:

    Storage or In-Law suite!


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