To solve this problem you can either replace your original deck footings to support your new roof or build your roof separate from your deck to ensure a proper foundation.
Under deck roof pitch.
Then stretch a string between them.
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.
If the span under your deck is 12 ft for example the purlin at the outer end of the deck should be 3 in.
Install the purlin along the house and the outer purlin.
Measure the depth of the deck and divide the total in feet by 4 since a pitch rail is needed every 4 feet.
The first rail is 1 2 and is placed 4 feet from the house.
Lower than the purlin along the house 12 x 1 4 3.
Under deck ceilings a number of recently introduced under deck ceiling systems use corrugated aluminum or plastic panels designed to catch water that drains through decking and channel it away from the area below.
The underdeck ceiling system can turn the ugly space under your deck into an outdoor haven that s dry bright clean and enjoyable without costly reconstruction.
Among the newest is the raintight system introduced at deck expo 2014.
Attach the horizontal beam by using a nail gun.
The slope or pitch of the under panels can be at any degree that will shed the water.
While a typical deck is designed to support 55 pounds per square foot psf a roof requires 80 psf of support.
Make a cutting on one of the sides of the horizontal roof beam on an angle.
Minimum slope is 1 4 inch vertical in 12 units 2 slope and ideally 1 2 vertical in 12 units 4 slope.
After that to make it flush with the roof of the existing house cut the two outer rafters.
What makes the underdeck ceiling so innovative is its simple and efficient system of vinyl gutters and panels which attach underneath the deck.
Raintight panels are made of heavy gauge aluminum.
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.
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.
This is for metal roofs that have a sealant between their lapped seams.
Find under deck ceiling systems at lowe s today.
You have to do it thoroughly so that the rafters sit flush on it.