First mark all the purlin locations on the deck joists.
Under deck roof pitch.
Make a cutting on one of the sides of the horizontal roof beam on an angle.
The slope or pitch of the under panels can be at any degree that will shed the water.
10 foot deck 10 4 2 5 round down to a whole number.
For a house roof the recommended minimum slope is 2 5 vertical inches for every horizontal foot but a nearly flat roof is fine for under deck installations.
Install the purlin along the house and the outer purlin.
Minimum slope is 1 4 inch vertical in 12 units 2 slope and ideally 1 2 vertical in 12 units 4 slope.
You have to do it thoroughly so that the rafters sit flush on it.
Then stretch a string between them.
After that to make it flush with the roof of the existing house cut the two outer rafters.
Attach the horizontal beam by using a nail gun.
However you can only use this pitch with built up roofing or specialized synthetic roofing.
If you consider it as similar to a roof than according to code.
Find under deck ceiling systems at lowe s today.
Among the newest is the raintight system introduced at deck expo 2014.
Add 1 2 to the pitch rail height at each 4 foot increment.
Lower than the purlin along the house 12 x 1 4 3.
The minimum pitch for a roof is 1 4 12 which translates to 1 4 inch rise to 12 inches of run.
Step 2 install a wood support structure for your panels screwing a row of 2 by 4s running parallel to your wall every 2 feet along the underside of your deck.
What makes the underdeck ceiling so innovative is its simple and efficient system of vinyl gutters and panels which attach underneath the deck.
Measure the depth of the deck and divide the total in feet by 4 since a pitch rail is needed every 4 feet.
If the span under your deck is 12 ft for example the purlin at the outer end of the deck should be 3 in.
The first rail is 1 2 and is placed 4 feet from the house.
While a typical deck is designed to support 55 pounds per square foot psf a roof requires 80 psf of support.
Raintight panels are made of heavy gauge aluminum.
This is for metal roofs that have a sealant between their lapped seams.