How to Build a Roof Deck with a Wind Screen

Adding a roof deck to your house is an inexpensive way to create outdoor living space that is very functional. You can create a garden oasis, a furnished outdoor living room or an area to BBQ and entertain. This project will enhance your life.

You must have a flat roof on top of your home or building.

Layout the area on your roof where you want to build your deck. Check where the roof drain(s) is located and note the slope of the roof. You CANNOT block the flow of rain water with your roof deck. I'll explain how you do that in a later step.

Mark the outline of the deck on the roof with a carpenters chalk line. Verify that your layout is square. Now determine the direction your 6x6 wooden beams, which will act as the base for your deck. The rule is that these wooden beams, known as "sleepers", cannot block the flow of water. So, your sleepers need to go in the direction of the slope of the roof.

Cut your sleepers to size based on your layout and install them.  You simply lay these down on the roof where your deck will go. DO NOT fasten these into your roof in any fashion. They are to be "floating". This maintains the integrity of waterproof roof membrane. Lay the sleepers down every 24" on center.

To keep your sleepers in place prior to the next step, lay a piece of decking across all of the sleepers and fasten it down to each one. This will keep the sleepers in place and save you frustration.

If you have the funds to hire a glass company to make a windscreen that borders your deck, such as the one pictured on the left, fantastic. If not, you will need to install your own. Start by cutting your posts out of the 6x6 material. The post height should be no less than 38"above the deck and if you get a lot of wind you may want to install 44" high posts that will accommodate a larger wind screen. Install your posts at all corners and every 48" on center in between. If necessary, adjust this dimension to make the distance equal between posts. More about cutting these posts in the next step.

Cut the posts to the height you want them plus 5-1/2". So, if you want a 38" post then you will make a 43-1/2" cut. Create 2" x 5-1/2" notch at the bottom of each of your 6x6 posts. The 5-1/2" part of the notch runs long ways up the post. It is the reason you had to add 5-1/2" to the length of your cut.

Slide the notch of the post over the outside face of the sleeper and fasten the post into the side of sleeper. Use two 3/4" x  6-1/2" hot dipped galvanized threaded bolts with hex heads. Offset the bolts diagonally from one another so the wood does not split.

Once your posts are installed, go ahead and install decking. Good deck materials are Redwood, IPE, Trex and Cedar. IPE is exceptionally strong and that makes it the most difficult to install. Put two 1-1/2" stainless screws in each location that the deck material laps over a sleeper. Use care when installing these screws so that they are consistent in spacing and location. This will make your deck look professional.

The most economical, do it yourself windscreen product is plexi-glass. Take the measurement between all of your posts and write those dimensions down. The height of the plexi-glass should be the height of your post minus 6". This 6" is the added dimension of your top and bottom rail thickness, your top and bottom offsets plus a notch in the rails. Ah, trust me on this.

While you are waiting for those pieces to be fabricated, install a 2x4 bottom rail between your posts that sits  2" above the deck. Use a router and and make a 1/2" x 1/2" notch all the way down the middle of the 2x4 prior to installing it. Make the exact same piece to be installed at the top of the post. Screw the lower 2x4 into the post, but wait to install the top piece.

Install the plexi-glass. Slide the plexi-glass piece in between the post and into the groove of your bottom rail. Take the top rail and slide the notch over the plexi-glass. Screw the top rail into place and check level. Once you have the rails and plexi-glass set, add some 1" x 1" wooden stops to all of the sides (front and back) in order to keep the plexiglass from moving when it is windy.

Now that all construction is complete, you can do a light sanding and stain/seal your deck.