How to Build a Garage Roof


Authored by Douglas Mefford in Home Improvement
Published on 12-30-2009

Just as with the roof on your house, your garage will need an equally good roof installed in order to protect your vehicle or work/storage area from inclement weather. The basic construction for building a garage roof is much the same as any other roof. There are preformed kits that can be bought that fit standard sized garages but for custom sized garages or additions to one’s house, the do-it-yourself approach can be more satisfactory.

The first thing you should do when contemplating building a garage is to check with the local building authority to see if there are specific regulations or codes that must be maintained. Once the formalities are attended to you can begin drawing up the plans for your garage roof. This will help you determine just what supplies and materials will be required. Included in these plans would be the strength of the roof and the pitch, or angle of slope, it will be constructed with. In arid climates a low pitch or even flat roof is acceptable while a wet climate or one prone to snow will require a steeper pitch to prevent overweighing the structure during snowfall.

After the walls of your new garage are completed you will need to measure where the trusses are to be placed. Most garage roofs are set to 24″ centers with the first truss being positioned flush with the outer edge of the walls. The actual construction should begin on the ground. To maximize the consistency of the angle of pitch you should cut a template board for the beams of the trusses that will hold the garage roof up. Once you have completed the construction of the required number of trusses you should carefully raise them to the top of your garage structure and set each one in place, fastened to the cap plate. A few temporary 2×4 bracing boards should be put on each truss to support it until the ridge line is put in place to finish the framing of the garage roof.

If your new garage is being connected to your existing home structure you will have several methods of fastening the crossbeam to the supports in the building’s walls. You will be mitering the boards in your garage’s roof to the existing structure at three points, the ridgeline and at both points where the roof connects to the walls of the garage structure. You can use either metal plates or slot-cut the boards to fit over the home structure’s bracing beams.

The next step will consist of adding the sheathing over the truss supports. In a lightweight garage roof this could consist of plywood sheets. For a sturdier roof you can use 1×6 boards. Whichever method you use, you will eventually have the entire roof covered over with the sheathing material.

The most common roof covering uses vinyl shingles. To install these you will first need to spread a underlay sheet of either felt or plastic to help protect the subsurface from moisture. Shingling starts at the outer edge of the roof and progresses towards the ridgeline with each successive row of shingles overlapping the one below it. Use a minimum of four nails per shingle with at least six each in areas where high winds are a normal occurrence.

You can now put on any extra touches you want. Guttering can be added to the outer edges of the roof to divert water run-off. The interior of the garage roof can be insulated if you are planning on heating the interior of the garage. This will be very important if you are including a work area in the new garage.


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