Most houses here have a basement, and a basement is a humidity source. That single fact decides the question more often than budget or taste does.
An unconditioned Des Moines basement runs humid all summer. That moisture rises into the underside of the floor above while the living space, air conditioned and drier, pulls the top face the other way. Wood that is wetter underneath than on top curves upward at the board edges. That is cupping, and it is the most common floor failure we see in this metro.
Solid wood, being one piece, has nothing resisting that curve. Engineered wood is built as a cross-laid stack, so the layers fight each other and the board stays flat.
Engineered has a reputation as the budget choice, and in Des Moines that reputation is backwards. Solid runs $7 – $12 per sq ft installed and engineered runs $6 – $10 per sq ft installed, so the saving is real but small. The reason to use engineered over a basement is not price. It is that solid wood there cups, and no amount of good carpentry prevents it.
Above a conditioned upstairs, the situation reverses. Solid nailed down is the right answer, it can be sanded four to six times, and it lasts a century.
A finished basement is not the same as a conditioned one. Conditioned means the space is heated, cooled and dehumidified as part of the house, and holds a stable relative humidity year round. A basement with drywall and carpet but no dehumidifier is still a moisture source.
If you are not sure which you have, put a cheap hygrometer down there and read it in August. Above 60 percent for weeks at a time is the answer.
Whatever goes down. It goes down at the right moisture content or it moves for the rest of its life. The working window in this climate is 6 to 9 percent, measured in the boards and in the subfloor, in the room where they will live, after the wood has sat in the house for a week.
That acclimation week is the step most often skipped, and skipping it is why a floor laid in August opens gaps by February wide enough to lose a coin in. It costs nothing but patience.
We take a reading of the boards and of the subfloor, write it down, and the number goes on the invoice. Not because it is paperwork, but because a floor laid at the wrong moisture content is a problem nobody can prove a winter or two later when it finally shows.
When solid wood is the wrong product for the room below. $6 – $10 per sq ft installed.
Yes, and in Des Moines it is usually the correct choice rather than a compromise. Its cross-laid construction resists the cupping that an unconditioned basement causes in solid wood.
It is at the top of the acceptable band. Wood floors are happiest between 35 and 50 percent relative humidity. Sustained readings above 60 percent, which unconditioned Des Moines basements hit in August, are where cupping starts.
Over concrete or over an unconditioned crawl space or basement, yes. Over a conditioned floor above grade it usually does not, though the underlayment often provides one anyway.
It can only be refinished once or twice, depending on wear layer thickness, where solid takes four to six. That is the real trade. Quality varies more than with solid, so the wear layer thickness is worth asking about.
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