Find out how to refinish a wood floor. Get tips on first prepping the room, get sanding tips and learn what finish to use and what to apply it with.
LESLIE: Well, wood floors are a great selling point in any home but if yours aren't looking so hot, bringing them back to their original glory can be a great do-it-yourself project.
TOM: That's right. And aside from the hassle factor of having to empty the entire room to do this project, refinishing a wood floor is not as hard as it might sound. Here with some tips on how to do just that and do it the right way is This Old House  general contractor, Tom Silva .
TOM SILVA: Thank you. It's nice to be here.
TOM: So, Tom, the idea of refinishing a floor really scares people but it's not that hard to do, is it? And it really all begins with the prep, correct?
TOM SILVA: Right. The prepping is the first step; removing everything from the room that's going to collect dust. That's the furniture and paintings and all that kind of stuff. You want to cover the doorways with plastic and tape and you want to seal up all your registers.
TOM: Now, I guess that's especially important with a return duct, huh?
TOM SILVA: Absolutely because that returned air will get sucked in and blow dust all over the house.
TOM: So once we've got it all sealed off, then it's time for the sanding step and that really is the most critical part of this process. But there's some different equipment that's easier for DIYers, isn't there?
TOM SILVA: Right. There's floor sanders  that will really sand the floor real fast but you've got to know what you're doing; they'll do some major damage that's …
LESLIE: If you don't, that's right.
TOM: That's right.
TOM SILVA: Yeah. That's called a drum sander. That'll make your floor look like the ocean.
But the best type that I recommend for a homeowner is the oscillating type. There's four, little, round heads underneath the sander and you can sand away. You can take your time; it gets right up close to the edges and it does a real nice job.
LESLIE: So, Tommy, do you have any tricks of the trade, especially if this is going to be my first time renting this type of sander to work on the floor?
TOM SILVA: Yeah. Number one, take your time. Start in the corner, start with a real coarse paper. You want to keep the sander moving, alright? You don't want to go and stop and have a cup of coffee with the sander (inaudible at 0:23:47).
LESLIE: Don't get distracted.
TOM SILVA: Yeah, exactly, exactly. Keep a steady pace and change the paper regularly and you'll actually see how the sander's doing; you'll actually see the finish coming off.
TOM: Now, when you use an oscillating sander, does it have sort of a vacuum attachment to it that helps draw off some of the dust that you're generating?
TOM SILVA: Well, it has its own built-in vac system that will go into a bag but I like to use a separate vacuum system along with it and it really picks up the debris really nice.
TOM: So what does that consist of when you say a separate vacuum system?
TOM SILVA: Well, it's a longer hose and then you have a vacuum that's like a big Shop-Vac that you can actually put outside the door, so you have like a 25-foot hose.
TOM: OK. OK.
TOM SILVA: Put it outside the door, that'll suck the dust, put it in the Shop-Vac and then the other dust will just blow away – the fine dust – so you won't even get it in your house.
LESLIE: Now, you mentioned starting with a coarse paper. Do you sort of progress through to fine or do you just go to coarse and you're done?
TOM SILVA: Yeah, depending on the age of the floor, the condition of the floor, you can start with 36, you can start with 80. You know, it really depends on how aggressive you have to be. And then gradually work your way up through the coarseness until you end up with about 120, 150-degree.
TOM: Alright. So we've cleared the furniture from our room, we've sealed everything off and we've just completed a very successful sanding job. Now it's time to apply the finish. Any tips on that project? Where do people go wrong when applying floor finishes?
TOM SILVA: Well, I think you've got to decide on which kind of polyurethane you want to use. There's water-based and there's oil-based.
TOM: Now, what's your opinion on that? Because I've got to tell you, I've used the latex before and I just found that it wasn't nearly as durable as the oil finishes.
TOM SILVA: Well, the water-based, you have to use a lot more coats.
TOM SILVA: And the benefit to that is you can put a lot more coats on in one day, so your finish is dry; you can usually walk on it with no problem the next day.
TOM SILVA: On oil-based finishes, definitely more durable. You're going to have a smell in the house for a few days and it's going to take you longer to put that finish on. It's also going to give a little bit of an amber color. The water-based is going to – what the color of the floor is, is the color you're going to get before you put the finish on.
TOM: And one thing I've learned on the oil-based finishes, despite what it says on the can label, there's no such thing as quick-dry polyurethane.
TOM SILVA: Yeah. No, no. And you don't want to rush that either.
LESLIE: Now, if you do rush and apply a second coat before that first one is really cured, it's possible it'll never dry, right?
TOM SILVA: Well, it takes a lot longer for it to dry. It can become gummy or tacky and you can actually get some rippling in the finish, also. So you've got to be careful.
LESLIE: Then you have to do everything all over again.
TOM SILVA: All over again. And you want to sand lightly between each coat, too, to keep it nice …
LESLIE: Using the same orbital sander or …?
TOM SILVA: No, you can sand with a stick, like a drywall stick. Put some sandpaper on it; use 100 to 120-grit paper. And change the paper regularly, because it will gum up a little bit.
TOM: Now, when you're all done, is it important to wait some period of time before you kind of reload and start really using that room heavily? I mean does it take some number of days for it to really cure and get hard?
TOM SILVA: Well, I don't like to put anybody in a room at least for about 48 hours. You can walk on it. I always tell people to walk on it with your socks; not bare feet, just socks. No shoes, no high heels and – because that finish is going to be soft for a while.
TOM: He was looking at you, Leslie. It's OK.
LESLIE: I know. No, he was really looking at you, Tom.
TOM SILVA: Hey, I wasn't looking at you, Tom.
LESLIE: Now, what about if you've just got to make a spot repair? Maybe there's a burn or a gouge mark or a scuff. Is it possible to make a repair to such a small area or do you really have to go big?
TOM SILVA: It's possible to make a repair and polyurethane but it is always going to be a patch and you are going to see it. If you've got a burn, you can go after it with a razor blade, you can go after it with a sharp edge, a sharp chisel and scrape it away. And then you can just drop a dab of polyurethane in there and hopefully it'll level itself.
But it can always look like a patch; it's very difficult to do.
TOM: And Tommy, the refinishing process is such a big job. One of the things that I've always done in my homes is instead of renting the entire sander and going that rate, if the floor is not terribly, terribly worn, how about just renting a floor buffer with a sanding screen? Is that an option?
TOM SILVA: It's absolutely an option. I put a new kitchen in my house in 1985 and I still haven't refinished that floor  except recently when I just did an addition. And I basically screen the floor about every three years and basically laid two layers of urethane on top of that. And I have a lot of traffic.
TOM: Yeah, that sanding screen just takes up enough of the old finish and the dirt and the grime to give you a really fresh start.
TOM SILVA: Right, right. You're breaking the finish; you're not sanding the wood.
TOM: Great advice. Tom Silva from TV's This Old House, thanks so much for stopping by The Money Pit.
TOM SILVA: My pleasure.
TOM: And for more tips just like that, visit ThisOldHouse.com.
And Ask This Old House is sponsored by The Home Depot. The Home Depot, more saving, more doing.