White residue on floorboards of old house? That's because they did double duty

Q: I have a house built in 1949. The basement is unfinished. When looking up at the floorboards, they appear to have a dry white/gray powder or something on them. It has a rough feel to it. In our entire time here we have seen no change. Is this some kind of a fungus or naturally occurring color in the wood? The floors feel plenty strong.

A: Look at your exposed foundation walls and you will see horizontal lines about eight or 10 inches tall. Now look at the size of the floorboards. They will be the same. Back in the days before cheap and plentiful plywood concrete forms, the foundation forms were salvaged and used as floorboards.

Today form-boards are reusable 1-1/8 -inch thick plywood, thereby reducing the required labor, but more important, saving countless saw blades dulled cutting 1-by-10s dipped in concrete. OK, maybe the saw blades weren't such a huge consideration. ...

Q: In adding oak floors to the house, this question arises: Are petroleum-based or water-based wood floor-finish products better? Could you give me some pluses and minuses, please? Also, in terms of durability, would you recommend Pergo-type flooring in a high-traffic area?

A: Oil-base finishes show more grain, and the finish looks richer. Oil is also more durable. Water-base products do not stink out the neighborhood during application; they cure in one-sixth the time, and are not toxic.

Laminate flooring is very durable, but can also be a bit noisier when walked upon, and more slippery when wet than other types of flooring. I am a very big fan of natural woods, and would stick with the type that is used in the other areas and not mix styles, particularly next to each other. The contrast could be striking.

Q: I have an 18-year-old house that has been vacant for quite some time. It has copper plumbing, but I see rust flakes coming out of the faucet in the bathroom when I run it. I thought copper did not rust. What is this? Secondly, one of the bathrooms has some rust visible in the sink, near the overflow opening. It leaks below, near the drain, but not exactly on the drainpipe itself. Could this rust at the top be causing the leak below?

A: The rust flakes in the water are from the hot water tank. The tank needs replacing if it is original to the house, or flushing, if it is a newer model.

The sink has rusted down the overflow spine and needs replacing. This is a very common problem when the welded seams rust and cause a leak near the drain fitting.

Q: Can I safely insulate around and on top of recessed light canisters that are rated "IC"? Must the insulation not touch the metal housing? The 14-year-old house is poorly insulated and has no insulation over the tops of the lights. The bulbs are all at or below rated capacity.

A: Insulate away, my friend. IC means "insulation contact." The lack of insulation may have been precautionary by someone who was not aware of the changeover about that time from older vented units to the sealed IC type.

Darrell Hay answers readers' questions. Call 206-464-8514 to record your question, or e-mail dhay@seattletimes.com. Sorry, no personal replies. More columns and a message board at www.seattletimes.com/columnists.