September 25, 2023
A deck built on top of an existing roof might be a lovely addition to your home. The challenge is that it will require some form of supporting structure, as well as waterproofing and any penetrations. We’ll go through how to build a deck over an existing roof in this guide. Because installing a deck on top of an existing roof might be difficult, it’s important to do your homework before getting started. As a result, we will go over a few key points.
Things to Consider
Professional Inspection Needed
So, if you’re considering installing a roof deck on an old flat roof, be sure it’s been professionally assessed before you start. The roof you intend to build a deck on must be capable of supporting 55 pounds per square foot of weight. It’s usually preferable to consult an engineer if you’re unsure.
- Verify Existing Roof Integrity
Consider how you intend to finish off your flat roof, including water run-off, deck access for maintenance, drainage, and so on. Flat roofs leak regardless of whether they are decked or not due to design flaws, insufficient materials, and bad installation. When installed, many roof decks exacerbate roof damage, resulting in even more severe leaks and drainage issues.
Flashing the deck supports and rail penetrations, as well as adding an EPDM membrane, are all part of deck waterproofing. This is generally accomplished by slipping EPDM rubber boots over the openings. EPDM is a rubber-like material that is used to make surfaces watertight. Because poor drainage can lead to leaks, the roof must slope at a quarter of an inch every 12 inches to shed water.
- Allow Future Access
Deck panels should be constructed in such a way that they can be easily lifted for cleaning and repairing the membrane beneath them. To put it another way, you must be able to easily access the membrane underneath for any necessary maintenance or repair.
- The roof below should be cleaned and inspected regularly for debris such as leaves. A deck on a roof under pine trees, on the other hand, will require significantly more maintenance to keep debris from accumulating over time than a rooftop deck on top of a high-rise.
How To Build A Deck Over An Existing Roof
A professional builder would typically do this by erecting two columns – one at each end – beneath the new deck and laying beams across the top. If you’re doing this on your own, you’ll need to figure out how to support these columns with post-tension cables or pier blocks.
Then you will need a platform made of right-angled planks that can support the weight of your deck, as well as enough space between each board for water to run off and a layer of insulation.
To avoid water infiltration, a water-tight EPDM rubber membrane should be put on top of the roof deck. Before dealing with the decking, make sure you’ve installed “sleepers,” or flat 2x6s laid flat on the roof. This will provide you a flat platform on which to install the decking.
Adding a deck to your existing roof expands your living area and provides a great place for family get-togethers and barbecues. It not only boosts the value of your property but also expands your outdoor living space, allowing you to enjoy your deck for three to four seasons, depending on where you live. A roofed deck allows you to enjoy an outdoor lifestyle away from the elements when the sun is blazing down relentlessly or the rain is driving you in from the yard.