Q: I have a redwood deck that is approximately 30 years old. I’ve read that that is about the life expectancy of a redwood deck, but it still looks good. How do I determine when the deck needs replacing? Is this something I can do? If not, what type of craftsperson should I hire to evaluate it?
A: If it looks good, it probably is good. The useful life of building components is at best an estimate.
A good example of this concept is the depreciation schedule imposed by the federal tax code for rental property. Land has no depreciation schedule because it never wears out. Improvements, on the other hand, are given a "useful life" of between 27-30 years.
We ask you to look around your town and see the number of houses that were built 50, 70 and 100 years ago. They are well beyond their life expectancy and are not only habitable but also prized.
The same is probably true for your deck. Redwood is resistant to bugs and rot because of the tannins in the wood. If the deck is in a somewhat shaded area, away from the ravages of weather, which we suspect it is, it probably has many more years of life in it.
Whatever grade, 30-year-old redwood contains more heartwood than its counterpart of today. Heartwood is red in color. Sapwood is white. Heartwood is resistant to rot, while sapwood is prone to it. If your deck was initially constructed of "select" grade, odds are it is mostly heartwood. This is a large part of what accounts for its good condition today.
We think you should do the initial inspection yourself. Then, after following our suggestions, if you find potential trouble spots call in a licensed structural and pest control contractor to look at it.
Begin your inspection from the bottom up. That means take a look at the base of the posts and work your way up to the tops of the handrails. Hopefully the posts are resting on concrete piers. Poke the base of each post in several areas with a Phillips head screwdriver. If the wood is punky and the screwdriver penetrates, the base of the posts probably have dry rot. If so, there’s no real need to replace the entire post. The rotten piece can be cut away and a new section spliced in.
Next, move up to where the floor joists meet the decking. Do the same probing with the screwdriver. Look for the same thing. If you find damage, depending on the extent, either part or all of the joist will need replacement.
Repeat the same drill with handrails.
Finally, take a good look at the decking itself. Don’t be surprised if the boards are loose. Nails have a way of working themselves loose over the years. You may need to refasten the decking to the joist. Use 3-inch deck screws for this part of the job, two screws per board per joist. Make life easy on yourself and use a drill motor with a Phillips head bit to drive the screws.
If all appears in good shape, we suggest you do a good cleaning, let the wood dry, and apply a sealer. Normally we recommend a pressure washer, but since you report that your deck looks good, a scrubbing with a stiff bristle brush and commercial deck cleaner should be all you need.
The bottom line is just because the deck hit 30 doesn’t mean it’s dead. With some regular tender loving care, it’s probably got many years of life left.