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John Leeke's Historic HomeWorks™ Question & Answer Column

#33 Floor Refinishing

“What steps would you recommend in refinishing an old strip-wood (fir) floor in a high traffic area? I've already prepped and scrubbed the floor with TSP. What kind of poly-urethane should I use for a hard basketball court-like finish, water or oil? This is my first attempt so I want to do it right the first time. Many thanks.” -- Antiques Journal reader, Bill, in New London, Connecticut

What ever you do, test all of the materials and methods through all of the steps to the end, in a small test area, keeping track of materials and methods with written notes. Then judge the result and if it is acceptable continue with the rest of the floor. If not, do another test with changes.

I would not use polyurethane, and suggest that you may really not want a basketball court finish. Basketball court finishes are formulated for stable hardwoods and are particularly hard, almost “brittle.” You may be thinking that it will be more durable, but really it may not be suitable for your floor. For your old softwood floor you need something more flexible. And a court finish will be more difficult to renew when it does wear out. For a high-traffic area I suggest an oil-based alkyd resin varnish that will be easier to renew in the spots where it does take a lot of wear. You might end up maintaining it every few years, but that can be easier than refinishing the whole floor every several years.

Some of the acrylic water-based varnishes might be good, but I don't have enough experience with them to give you any advice. The manufacturers change their formulas too often for me to figure out how they really work.

“This is my first attempt so I want to do it right the first time.”

That's a great goal, but you're not likely to achieve it on your first try. If this is THE critical floor that must be done right the first time, you really should finish at least 2 or 3 other floors first so you know what you are doing on this one. Sorry, there are no magic tricks that can substitute for authentic first hand experience.

Boring Bugs

“There are signs of wood boring bugs in my timbers. The main concern here in mid-coast Maine are carpenter ants and powder post beetles, not termites, and whether the damage is old versus active. Certainly there have been remnants of bugs, such as surface channels or tunnels, in areas of large timbers with some bark left from the original milling. Since it is in an isolated area and the timber is otherwise sound i have assumed that the damage occurred long ago and is not an issue. Given the many years and variety of ways wood can deteriorate, how can you tell? Exposing the sheathing boards on a late 18th century farmhouse revealed tunneling, sawdust etc. but an exterminator suggested that there was no recent activity and to spray a nest if it was discovered.” – a downeast Maine reader

I'm not sure how far downeast you are, but I, personally have found active termites in Brunswick , Maine , four years ago. They seem to be moving a little further north (and east along the coast) each year.

It is possible to determine if powder post beetles are active by looking for piles or "streamers" of frass (like very fine sawdust) coming out of their surface holes that are about 1/32" to 1/16" in diameter, although the frass may be just sifting out of old holes. You can determine old holes from new holes by marking out a section (perhaps 1' x 1') and marking each hole with a pencil. Then check it again after a time (a month, a year, five years, etc.) to see if there are new holes. New holes indicate active infestation.

I often find active carpenter ants by listening for them with a "mechanic's stethoscope." This device is just like the doctor’s stethoscope, but instead of a cup at the end, it has a long, thin metal rod. Auto mechanics use it to listen for parts knocking inside a running engine. You can get one at most automotive suppliers for about $20. When I use it for detecting ants I place the end of the rod on a board or timber. I can easily hear them chewing on the wood, sometimes 3 to 5 feet away from the stethoscope. This is best done in the middle of the night when they are more active and the ambient noise is less.


John Leeke is a preservation consultant who helps homeowners, contractors and architects understand and maintain their historic buildings. You can contact him at 26 Higgins St., Portland, Maine, 04103; or by E-mail:; or log onto his website at:

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