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Deck Framing Options 

There are several types of deck framing materials and the type selected depends on the elevation of the deck, the local environment, and the aesthetics of the deck with the home. We will help select the under-framing products to go with your deck project, but here is a short overview.

Pressure-treated timber is a popular under-decking material. While it is made from pressure-treated wood, the lumber can be inconsistent to work with.  Pressure-treating dramatically changes the wood’s moisture percentage, which causes the boards to warp and twist. Lumber can show up on the job site warped, but once installed, it may change shape as the moisture content acclimates to the environment. Wood also does not hold up over time to the elements and is prone to rot. 

Engineered pressure-treated beams are better than regular pressure-treated lumber. Engineered wood, also known as composite wood, consists of a range of wood products that are made by joining veneers, fibers, strands, and particles of wood with adhesives to form man-made composites. With traditional wood, the length is determined by the size of the tree. Engineered wood products are stronger and can be made in more sizes and lengths. Glulam, or glue-laminated lumber, also makes a great beam material because it is lighter in weight, low maintenance and offers greater durability over traditional wood. 

Steel under framing is often made of cold-rolled, light-gauge galvanized steel joists. Some of the advantages of steel framing is that the material is lighter than wood and the span capabilities of steel are greater than wood. Steel joists are flat and will stay that way. The joists can be made to a specific length so there is less prep for installation. 

Aluminum Framing, offered by Harmony and other companies,  is a strong material that won't rust, rot or warp. The product comes with a powder-coated finish that provides increased corrosion resistance and a more finished look. Most products are easy to install and come in kits. 

trex steel substructure
Trex Elevations ®

The only deck frame that can stand up to the elements. Wood substructures split, warp and shift over time, leading to an uneven surface in the deck boards above. The dimensionally stable steel of Trex Elevations stays in place, giving you consistently flat decking.

trex steel framing
trex layer breakdown


An unparalleled three layers of protection surround a carbon steel core, ensuring each critical joist, beam and ledger connection holds up to the elements for decades, with a 25-Year Limited Residential Warranty to prove it. And, unlike our interior-grade steel competitors, Elevations is the ONLY one code-listed for exterior use, supported by the CCRR0186 code compliance research report.

Trex Elevations

The first question you may be asking yourself is, "Why would I want a steel-framed deck?" The answer is as simple as it is complex; because it’s BETTER!


Our ancient ancestors came to the realization that steel did a much better job of protecting and providing the foundation for stronger structures, because it was not an organic substance (such as wood). You could change the recipe, so to speak, if you wanted something harder, softer, pliable, etc…where by comparison, you get what you get with wood. That is not to say that pressure-treated wood cannot provide the foundation for a solid deck, because it can and it does in the majority of structures in our yards today. But as with anything organic, there is maintenance, aging and blemishes that appear over time. Wood can also split, warp, and shift over time-leading to an uneven decking surface, as well as structural weak points.


In an effort to combat these and other issues, the good people at Trex set out to develop a system of deck framing that was stronger, more durable, non-organic and maintenance free. The result? Trex Elevations steel framing was born!

by Tim Zwart

trex steel decking

Rot- and termite-proof steel lasts much longer than wood.

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