Pitched Roof Under Deck

If the span under your deck is 12 ft for example the purlin at the outer end of the deck should be 3 in.
Pitched roof under deck. Install the purlin along the house and the outer purlin. Roof deck framing unlike for decks at ground level doesn t entail a ledger attached to the rim joist of a house. Installing a porch roof over an existing deck is usually not recommended unless the deck was originally designed to support a future porch. The minimum pitch for a standing seam metal roof is 1 4 or 3 inches rise to 12 inches run.
The minimum pitch for shingles is 1 6 which is equivalent to 4 inches rise to 24 inches run. Summer calls for sultry nights under the stars and sun drenched cocktail gatherings making the backyard deck the ultimate destination this season. The project illustrated here was a complete teardown and rebuild so i framed the roof with 2x8s spaced on 16 in. Centers supported by a beam and a ledger as on most decks.
Porch decks require 25 additional psf for roof loads for a total of 80 psf. First mark all the purlin locations on the deck joists. Whenever i install decking over a roof i make sure the framing is structurally sound and properly pitched to drain water. Typical decks are designed to support 55 psf lbs per square foot.
A deck on a sloped roof requires a different approach to the framing underneath the joists. Instead a pair of beams rest on supports called sill plates to create a frame for the deck. Once you have your beams in place everything above them joists deck boards balusters and handrails is the same as for any other deck.