Answering Your Questions About Roofing

Tips For Designing And Installing A Water-Tight Rooftop Deck

by Donald Evans

If you are building a custom home and have decided you want a walk-on roof deck where you and your family can watch sunsets, then keep each of these important tips in mind during the design and building process:

Tip: Ensure the Rooftop Deck has an Adequate Slope for Drainage

A rooftop deck must have an adequate drainage slope. This is very important because if water is allowed to puddle on the deck, then it will cause moisture damage below it in the form of dry rot and mold.

Thankfully, your local building permit department will give you specific calculations when you apply for your roofing permit. You will need to use this information to ensure the slope of the deck is significant to prevent puddles from stormwater.

Tip: Keep Other Roof Drainage Water Off of the Deck's Surface

While you can't prevent the rooftop deck from getting wet, it's advisable to proactively keep as much excess water off of the area as possible.

Since your rooftop deck very likely has other sections of your home's roof above it, it is very important you slope those sections away from the deck.

In addition, any elevated roof areas need to have rain gutters installed to keep as much additional stormwater off of the deck as possible.

Tip: Correctly Install an EPDM Membrane Under the Finish Decking Materials

As with other parts of your home's roof, you must install a waterproof membrane under your new walk-on rooftop deck. The industry standard material to use for this application is a man-made membrane made of EPDM, which stands for "ethylene propylene diene terpolymer".

EPDM is a rubberized decking membrane installed by rolling adhesive onto the roof's plywood sheeting and then sticking the membrane material on the top. Once dried, you will need to apply another layer of adhesive to the top surface before installing the deck's finish materials.

Tip: Install a Metal Flashing Drip Edge Along All Exposed Areas of the Rooftop Deck

Finally, as with other areas of your new home's roof that drip water off of the side of the house or into a rain gutter, you need to install a metal drip edge along all exposed areas of the rooftop deck as well. The drip edge is a simple angled piece of flashing that forces water to drip off of the edge of a roof rather than sit on the edge where it could be absorbed and cause damage.

If you are interested in getting a new deck, you can find out more here.