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3 Tips for Building a Deck on Concrete

It’s become more and more common over recent years for homeowners to replace their concrete patios with something more attractive and easier to maintain, such as a composite deck. Some may wonder if you can lay Trex composite decking over concrete. The answer is yes but, first, we suggest you check with your local building office for any code requirements.

Here are a few key factors to consider when building a deck over concrete.

1. Evaluate the concrete’s condition

Cracks and craters with minimal growth may still be covered without issue, but be cautious if an area of your patio sinks year after year. If the damage to your concrete patio appears too far gone, consult with a local TrexPro®. They’ll assess the project and help you make the Trex decision that’s right for you—decking that won’t warp or splinter like its timber counterpart.

2. Protect against water damage

Ground-level decks are particularly susceptible to moisture build-up, so hard-working water management and air circulation is a must. With a steel substructure, you’ll benefit from the durability and peace of mind that only rot-proof materials can provide. 

For those working with a timber substructure, Trex® Protect™ joist and beam tape is an easy-to-use option that can help shield your under-deck from the elements that lead to dampness and decay.

3. Avoid DIY mistakes

Thinking of being your own builder? A standard deck may take as few as four working days to finish—and isn’t as daunting a task as you may think. Take note of these deck-building basics before you get started.

Post positive. Posts should be anchored to the existing concrete to help stabilize the framing.  Consult with your local building code official on the best methods for attachment.

Gap like a pro. Proper gapping is necessary for water drainage and expansion and contraction, and also allows for shrinkage associated with wood joist systems. Consider using Trex Hideaway® Hidden Fasteners, which create proper gapping when used with our grooved-edge boards.

Pre-drill. Worried about splitting boards? Try pre-drilling surface screw holes to avoid damaging the end of your composite boards.

Know your local laws. In most cases, building permits are required before you start construction. Ensure your deck plan meets local building codes and safety standards. In addition, some states require stamped construction drawings from engineers when applying for a permit.


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