There is no better wood to use when repairing an old house than old-growth lumber. Though it is hard to come by (it’s not on the shelves at Home Depot) it is the most appropriate and best performing options especially for exterior wood repairs.
What is Old-Growth Wood?
In this picture you can see a piece of old-growth siding on the left next to a piece of replacement new-growth siding on the right.
Old-growth wood is lumber that was grown naturally in vast virgin forests. The forests of nearly every continent have some areas that are still untouched where trees haven’t been harvested for our use yet.
These trees grew slowly due to limited light and competition from the other trees. Because of this slow growth rate the growth rings on the trees were packed very tightly together which gives the wood some big benefits which I’ll discuss in a just a minute.
In America we began seriously depleting these virgin forests during the industrial revolution and by the 1940s most of them were gone. Lumber prices began to spike as Americans looked for substitutions for our lumber addiction. Enter second-growth and new-growth wood.
Tree farms began to produce lumber for the growing demand and the fastest growing species like Pine were selected for this reason. The trees grew in open areas with little to no competition for sun which caused them to grow very quickly so they could be harvested in 10-20 years as opposed to old-growth wood which may be from trees as old as 200-300 years old before being harvested.
Let’s look back at the picture above. The old-growth siding has 29 growth rings in this 3/4″ thick sample compared with the new-growth piece that has only 7 rings including the pith (the center of the tree). That’s a much faster growth rate, so lets see why this fast growth may not be as good as the slower growth of old-growth wood.
Why It’s Better
Now that you know what it is, here is a short list of its many benefits of old-growth lumber.
- More Rot-Resistant – Sure we have woods like Pressure Treated and Accoya (which I use often) but old-growth wood is the original rot-resistant wood. The slow growth process creates greater proportion of late wood (summer/fall growth) to early wood (spring growth). Late wood is the good stuff that adds this rot-resistance. Also, older trees develop heartwood at their center which is not only beautiful to the eye, but it is extremely durable and resists rot in ways that other wood can’t.
- More Stable – Wood moves. It contracts when it’s dry and expands when it’s wet. This can cause joints to open up, paint and finishes to fail prematurely and a host of other issues. But old-growth wood (due to the tight growth rings you can see in the picture above) does not move nearly as much as new-growth. It is immensely more stable and therefore keeps everything where it needs to be from siding and framing to windows and doors.
- Stronger – The denseness of old-growth wood makes it a much stronger wood able to carry heavier loads across longer spans. The span rating for framing lumber continues to fall each time the lumber industry revisits it. Wood is getting softer and weaker as the years go by so old-growth is definitely worthwhile option especially if you already have it in your house.
- More Termite-Resistant – Termites don’t like hardwoods. Don’t get me wrong here, termite-resistant is not the same as termite proof. Termites will still eat old-growth wood, but they prefer soft, moist wood (read: easy to chew). Old-growth wood is harder and drier than new lumber and it does not make as tempting a meal for termites.
So that’s the deal. If you’ve got an old house then you’ve likely got old-growth whether it’s the framing, siding, windows or some other element.
Before you think about replacing an element of your house think about the fact that you may be replacing resilient old-growth lumber with lower quality new-growth lumber. You may be better off keeping what you have!
If you’re looking for a place to find old-growth wood locally try doing a search online for Architectural Salvage in your town, or try some of these other great sources.