How to Build a Sloped Roof

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A sloped roof is a great way to prevent water from puddling on your roof. Rain and snow which tend to congregate on flat roofs, runs off a sloped roof keeping the lifespan of the roof and appearance intact. For those who have a flat roof and are concerned about leaking and rotting, building a sloped roof over the flat roof is an option. For homeowners looking to add roofing to a new construction or an addition, a sloped roof is the way to go.


Build a Sloped Roof

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Step 1

Raise the laminated veneer ridge beam onto the gable ends. Ridge beams are great because they are one big piece of lumber. You don't have to attach smaller pieces of lumber together to span the length of the roof. The gable ends, which are used as the beam support, provide the higher pitch which gives you the sloped roof you desire. The height of the gables determine the pitch of your slope.

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Step 2

Using 20 foot 2 by 10s for the rafters; mark each one with a ridge cut at the top, and a crowe's foot at the bottom. Position each rafter to both sides of the ridge beam starting at the center; securing each rafter in place using nails and a nail gun. Start by securing a few rafters in place; aligning them properly to ensure they are straight. Once you have your initial rafters nailed to the ridge beam and the top plate, you are ready to add additional rafters.


Step 3

Apply CDX 5/8 in. plywood sheathing material across the top of and covering the rafters. This creates a solid foundation. Add an ice and water barrier over the sheathing and along the eaves, and you are ready for your first layer of shingles. Nail an aluminum drip edge in place before shingling the sloped roof. Start in one corner and move your way up as you apply the shingles. And don't forget to staple down felt paper as an underlayment. The felt keeps the plywood from absorbing heat which causes the shingles to dry out and become brittle.


Step 4

Prevent moisture and heat from building up under your shingles by adding ridge and soffit vents. Proper ventilation of your sloped roof will enhance life expectancy. Excessive moisture deteriorates wood leaving your roof wide open to possible weather damage.


When shooting your nails into the rafters make sure to shoot 3 to 4 into the top plate first and then another 3 or 4 into the joist. Don't nail any rafters in place without first making sure they are straight.


It is important not to skip over any of the additional steps when moisture proofing your roof. Your roof is not just a bunch of great looking shingles, it is a complex system designed to maximize your roofs longevity by keeping out the harmful elements.