Adding Sleeping Space Over the Garage

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How to Add Guest Space Over the Garage

Get inspired with these tips to max out your sleeping space at the cabin.

Cbn Ta0613 1Garagelead1 2018 07 31 10 46
This 24x24-foot garage has an upper-story space with four single beds plus a table and chairs for late-night card games. Photo: Mike Wilkus
 

Need more sleeping space at your cabin? Consider parking guests in a bedroom over the garage. Most detached garages have a pitched roof with unused space between ceiling and rafters. An attached garage often has an unfinished “bonus room.” In either case, this upper area can make a cozy nest for guests.
 

First Steps

 
First, ask your local building official these questions:

  • What are the code requirements in your area?
  • Do you need a firewall between the garage and the bedroom?
  • If you raise the roof or add dormers, are there restrictions on size and height?
  • Do you need to pull a permit?
  • Are setbacks from property lines, water bodies or easements affected?
 
Next, assess the size and condition of the space. Check rafters for sagging or discoloration (roof leaks).
 

Technical Know-How


  • The bedroom door cannot open directly into the garage. You may need an outside stairway for a detached garage, or a new upstairs hallway for an attached garage bedroom.
  • The bedroom must have an emergency exit. That means either an exterior door, or a window with a minimum opening of 5.7 square feet.
  • Mount a smoke/carbon monoxide detector, and avoid warming cars in the garage.
  • Closed-cell spray foam insulation is the most energy efficient; plastic-sheathed fiberglass batts and/or rigid foam board can also be used. Insulation in walls and bedroom ceilings must touch the back of the drywall; garage ceiling insulation must touch the bottom of the bedroom floor deck. (If possible, insulate the space behind the knee walls before they go up.)
  • Joists almost always need reinforcing; these were meant to support the garage ceiling – not a bedroom floor. Strengthen joists by “sistering” (attaching) equal-sized lumber to existing lumber. While you’re at it, add a vapor barrier between the garage ceiling and bunk space.
  • Most codes require a minimum bedroom height of 7 feet over half of the floor. Since the ceiling slopes, only the part that’s 5 feet or higher counts as useable floor area. To calculate: Measure the width of the space at 5 feet high and multiply by the length to get the useable floor area (A). Then measure the width at 7 feet high and again multiply by length for (B). B must equal more than half of A.
 

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Photo: Mike Wilkus


To make the space comfy and well lit, consider these suggestions:


  • Dormers add head room and useable space.
  • End windows boost light and ventilation, while operable skylights also brighten a garage bedroom.
  • Knee walls are practical in garage bedrooms. These side walls separate bedroom from eaves for a finished look. They also conceal wiring, provide a place for outlets, and serve as backdrops for beds.
  • Make sure your garage bedroom is properly insulated on six sides – floor, ceiling and walls. That way, your guests will be comfy in summer or winter.
 


See also Solutions for Sleeping a Crowd