Decks are for enjoying the outdoors, entertaining friends and family, and escaping everyday life for a few hours at a time. Unfortunately, bad weather can put a damper on that enjoyment. However by building a simple roof structure over the deck itself, you can greatly increase the number of days that you have to enjoy it. This article outlines the steps to take in order to build a simple, yet effective roof over your existing deck. The roof outlined in this article is known as a "lean-to" roof and can tie directly into your house roof or exist as a stand-alone unit.
Build the frame of the roof on the ground. Frame up a box the size of the outer dimensions of your deck using 2 by 4 inch lumber. Then run joists connecting the front of your roof with the rear every two feet along the length of your roof.
Tie your existing deck posts into the roof by extending your corner posts with the 4 by 4 lumber. Make the front of the roof the height of the house roof you are presumably tying into, with the rear sloping at a rate of six inches over two feet.
Lift the box frame you built in Step 1 onto the four corner posts and attach using the lag bolts. When the box frame is secure, install the plywood on top of the frame to provide a flat surface on which to nail your tin.
Install tar paper on the plywood sub-roofing and then follow-up by laying the tin roofing down. Tie the tin roof into your existing roof using metal flashing available at any home supplies store. This will ensure a waterproof seal at the junction of house roof to deck roof.