A wood deck to weather the elements

Engineered product a sturdier, longer-lasting alternative
By: Bill & Kevin Burnett: Inman News
Q: I am replacing a rotted-out deck at home and would like to know if I should use redwood or treated wood and also whether I should stain the deck.

The structural engineer who drew the plans recommends using all redwood, including the support posts. A general contractor says the posts should be treated wood.

The engineer also recommends the redwood be stained every two years. The contractor says the treated wood needn't be stained.

Where I live, in San Francisco, it's often foggy and damp. I want a deck with less maintenance but want to be sure that the deck will last 10 to 15 years. I'm willing to pay a little extra for the right type of wood.

A: We understand your confusion. There truly are a lot of choices out there. We've built and maintained many decks over the years and have formed some strong opinions about the pros and cons of various materials and methods in deck building and maintenance.

We disagree with your structural engineer's recommendation of a deck made entirely of redwood. Redwood is very expensive and while it is rot-resistant, it is high-maintenance. If you don't clean and treat it regularly, it won't be long before it will look shabby. And, depending on the amount of sapwood – the white wood in the boards – it will eventually rot.

So, the way we see it, you want your new deck to look good, last a long time and need little maintenance. You're considering just two materials for the decking and the supporting structure – redwood and treated wood. We suggest you consider a third choice, one that is not wood at all. Give some thought to using an engineered wood product, at least for the decking.

Remember that decking, whether redwood or treated wood, should be sealed or stained every couple of years to maintain its look and help prevent rot.

Sealers are clear, while stains are colored. Stains can be transparent, semitransparent or opaque. Over the course of time as it weathers, wood loses moisture. Stains and sealers help stabilize this moisture loss and help maintain the look of the wood. In untreated wood, stains and sealers also help prevent decay.

Treated wood is usually a soft wood, such as fir or hemlock, which has been impregnated with a chemical preservative. We've seen brown and green treated lumber. So, if you are planning on staining, you should take into account the color of the treatment when choosing a stain.

We agree with your general contractor that treated lumber does not require regular sealing or staining to prevent decay, but you'll probably want to do it anyway to preserve the look of the wood.

If we were doing your job in the moist climate of San Francisco, we'd use treated lumber for the posts and joists.

You don't mention handrails, but if any part of the posts will be exposed above the deck and are part of a handrail system, specify S4S treated lumber. This means "surfaced four sides" and is smooth – no splinters. If none of the support structure is exposed, rough or smooth grades work equally well.

For the decking itself we'd use an engineered product, such as TimberTech or Trex. Because this "lumber" is made of everything from sawdust to plastic to peanut shells, it tends to be more stable and wears better than wood.

Engineered decking looks and feels like real wood and cuts and installs like regular lumber. Also, it's easier on the environment. Begin your research at www.timbertech.com or www.trex.com.

Whichever way you go, do plan on cleaning the deck at least once a year. Get out the pressure washer and give it a good bath to get rid of the dirt and debris that gets in the nooks and crannies. Pick a warm day and cool off.