Building a Room Addition Over a Garage
Key Items to Consider before Building a Room
Addition above a Garage
By: Mark J. Donovan
Do you have a large attached garage
with vaulted ceilings and lots of wide open space between the garage roof
rafters and ceiling joists? If so, you may have a "diamond in the rough" if you
are in need of more living space for your home.
One of the most cost affordable and
best ways to add more living space to your home is to build a room addition over
your existing attached garage. Room additions over garages include such finished
spaces as bonus rooms, home offices, in-law apartments, and billiard rooms.
If you have a garage that has the
possibility of supporting a second story room addition, there are a few key
items that you first need to consider before jumping into such a project.
into Second Story Room Addition over Garage
If you were to complete a second
story room addition above the garage you first need to figure out how you are
going to ingress/egress it. For example, is there an existing stair well that
already leads to the garage loft area, or does it already have an entranceway
via the main home? If there are no current Ingress/Egresses into the garage loft
area, then you will need to figure out how to enter into the space. For the best
return on investment, ingress/egress should be via the main home, and not via a
stair well into the downstairs garage area.
Garage ceiling joists are frequently
not sized to code for finished living space above them. Thus they cannot support
the weight of a finished room addition. Consequently it may be necessary to
sister (or marry) larger ceiling joists to the existing garage ceiling joists.
You will need to check with your local building inspector to determine if
Sistering will be required.
Story Ceiling Heights above Garage
Due to the fact that you are
planning to create a room addition in an otherwise large attic area, chances are
you will have height / head room issues. Items that will need to be considered
are installing knee walls and collar ties to "square up" the room. Knee walls
will shrink the living space of the room addition, however if done smartly,
built-in cabinets and closets can be melded into these knee wall areas.
Regarding collar ties, collar ties will allow you to create a flat
ceiling in at least a portion of the room addition, and will provide more
structural support to the roof rafters. Where you position the collar ties,
will dictate the maximum height of the room.
Plumbing a Room
Addition over a Garage
If you are planning an in-law
apartment, bathroom, and/or kitchen area in the room addition above the garage,
you will need to consider where existing drains and vent stacks exist within the
home. Adding plumbing to a room addition over a garage can be a tricky endeavor
so make sure you meet with your plumber during the planning phase of your
For more help on Building a Room Addition above a Garage, see
Addition over Garage Bid Sheet. This tool, along with an
accompanying cost breakdown spreadsheet, will enable you to find the right
contractor and manage the costs on your room addition project.
Room Addition over Garage Bid Sheet includes an
extensive questionnaire (Request for Quote) that a homeowner can provide to
prospective general contractors and subcontractors for bidding the room
addition. In addition, the bid sheet also includes estimated costs and time intervals
for constructing a room addition over a garage as well as a list of key home material
manufacturers. Finally, the bid sheet includes an extensive
set of helpful tips and advice on making sure the room addition is built
properly and on time and budget.
Related Information on Building a Garage Addition
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