Poor workman blaming his tools

April 30, 2009 1:36 AM

How thin can floorboards go before needing replacing? We used a belt sander to sand the edges of our Cypress Pine floorboards back to bare timber. It looked fine initially, but now that a couple of coats of polish are down it looks rubbish.

We sanded back the main floor areas with a hired drum sander (which is made for the job), and they came up great. We then used a belt sander (rather than the recommended edge sander) which left an uneven finish on the edges. While there are definite differences in depth of the sanding, it wouldn't be any more than 1 millimetre at the very most. This is also the case where we sanded out scratches in the main floor area that the drum sander didn't get. With the polish down and the light reflecting off the areas in question it looks terrible.

If we suck it up and get a tradesman in to redo the floors, what are the chances that he/she can get the marks/gouges/waves/etc out without completely stuffing the floorboards?

posted by ihunui to home & garden (8 comments total)

I'm guessing you are talking about hardwood floors. They are usually 3/4 inch thick and I would imagine you can go down to 1/2 inch with no problem. You have a subfloor under the hardwood, right?
posted by bengarland at 3:55 AM on April 30

assuming that this is 3/4 in tongue-and-groove flooring the top part of the groove is about 1/4 of an inch, so you could sand down maybe 1/8 of an inch.... however, if the floor has been refinished before it may have been thin already.

depending on how large an area the messed up parts take up and what kind of damage you did with the belt sander it might be possilbe to touch up the messed up areas. but honestly, baring a complete resand, i think you're going to have to live with some imperfection. in particular, it's going to be really hard to get those groove made by the belt-sander out.

how bad is it really?
posted by geos at 4:14 AM on April 30

If you sand off all your high gloss urethane polish and use a hard burnished floor oil instead, your floors won't resemble faulty mirrors as they will have a sheen rather than a gloss, so minor imperfections won't matter anywhere near as much. An oiled floor is much nicer underfoot than a urethane polished one, and you can apply touchup oil in wear zones without having to do the whole thing over.
posted by flabdablet at 4:57 AM on April 30 [1 favorite]

Essentially you can sand them down until the top lip of the groove is too thin to hold the mating tongue down. Most flooring has a ~1/4" of lip either from an evenly divided 3/4" thickness or from an offset 1/2".

As a general rule of thumb you can sand a floor three times before you need to replace it. Whether you can get the defects out without sanding too much material off is going to depend on how deep they are.

Alternatively you might want to consider scraping your floor. It's a swack load of work but it removes less material.

FYI If you just refinished your floors defects in the finish are going to be much less noticeable once the floor gets scuffed up. 'Twas me I'd hold off on a decision for a few months.
posted by Mitheral at 6:11 AM on April 30

I got into a similar bind last year (my tale of woe here, with pictures posted down thread). My floors were sanded, refinished improperly, and then had to be resanded and resealed. The planks are about 100 years old, and had been refinished at least twice previously. A professional can actually look at the wood and tell if it can take another sanding. You might as well get a couple of estimates. But for the love of god make sure you get someone good... and who knows how to work with pine. Pine is a softer wood than most and requires different treatement.
posted by kimdog at 6:42 AM on April 30

What is this "polish" you used? If it's a glossy finish polyverathane or polyurethane, get some satin finish of the same stuff and do a top coat with that.

At any rate, it probably won't be nearly as noticeable once you put the furniture back and subject the floors to normal wear for a few months. Even right now, it probably looks worse to you than it would to anyone else who isn't a professional floor finisher.
posted by yohko at 8:24 AM on April 30

Thanks for all the responses. To clear up a couple of points: there is no subfloor underneath the timber. The house is about 30 years old (if that makes any difference), and is stumped with solid timber floors. We used Feast Watson Floor Seal, which is a satin finish Tung oil type product. It isn't a high gloss, but has enough of a shine with two coats on to make the marks stand out in direct light. It's also a penetrating finish so depending on how far it penetrates this will be another factor in how repairable it is.

The marks themselves are mostly around the walls (...all of the walls), but there are a couple of beauties as you walk in the front door that you can see from pretty much everywhere, and one in the living room that crosses four or five boards.

It is our first house so we are possibly being a little precious about it, but just knowing it is there through our own ineptitude is galling. I agree that it will fade over time, possibly to the point where the marks are not really noticeable unless you are really looking for them, but we are feeling quite houseproud and would prefer that they weren't there at all.

I'm going to ring around and see what the professionals say about re-sanding the floors. Fingers crossed they are salvageable. Thanks again for all your responses.
posted by ihunui at 3:22 PM on April 30

With the tung oil finish, all you should need to re-sand are the bits close to where the defects are. You won't need to re-do the whole floor. You'll find that new oil on the freshly exposed bits will blend seamlessly into the oil that's already there on the surrounding bits, provided you're not too heavy-handed applying it.

You'll also find that an oil finish will lose its initial shine reasonably quickly with wear, and that in a couple of months this really won't be an issue. Your best course, I'm sure, is to swallow your house pride for at least a couple months and then spend more money on this only if it's still bothering you by then.

Plus, re-sanding a recently oiled floor is going to gunk up a sander super-quick. Seriously, give yourselves and the floor a couple months to harden up and get used to each other.
posted by flabdablet at 6:57 AM on May 1