Most people never give a thought to what's underneath their floor.
They spent a lot of time choosing the finish -- hardwood or laminate, carpet or tile -- and discussing the cost with their contractor. But they won't watch any of the installation or look at the condition of the subfloor. It's all about what it looks like when it's done.
But when it comes to flooring what that finish looks like is largely a result of what's underneath it.
And, if you are considering spending thousands of dollars on new tile, carpet or hardwood, you'd be crazy not to spend some time making sure the subfloor and joists that support that floor are in good shape. If you don't, you're asking to be disappointed in your new floor.
Does your floor slope? Does it squeak? Is there bounce and movement when someone walks across it? Are the tiles or grout cracking? If so, then you need to have your contractor look at the floor's structure and the subfloor and possibly beef it up.
When your contractor removes the old flooring, take a look at the subfloor. If it's in good shape -- not rotten -- then you can probably go over it with the new surface. But if it's in bad shape, it needs replacing. And if it's weak, lay another piece of plywood over it. This is a great opportunity to strengthen the floor -- and it's the only opportunity you'll have before the finish is down.
Do not for a second consider going over the existing finished flooring with the new product. It is never okay to do that.
I still get homeowners telling me their contractor says it'll be fine to go over the old tile with new, or the old hardwood with new, and it'll cost less money. It will never be fine, and if your contractor suggests that, get rid of him -- he doesn't know what he's doing. And, it might cost less money in the short term, but when you need to tear out the whole new floor because it looks like crap, let's see what that costs.
In older homes, you'll often find the subfloor is plywood, laid over two-inch (5 cm.) by 10-inch (25 cm.) joists spaced at 12 inches (30 cm.) apart, and cross-braced every four feet (1.2 m.). Houses built before that used lumber in place of plywood, one inch (2.5 cm.) thick, laid perpendicular across the joists, or on 45 degree angles. The final flooring was laid perpendicular to that, which made for a very strong floor. Tiles didn't crack, floors were solid, though floors are susceptible to boards "popping" when nails loosen.
In new-home construction today, floors are typically 5/8-inch oriented strand board (osb) sheathing as a subfloor, in place of plywood. The osb is laid over two-inch by eight-inch joists at 16 inches apart -- but doubled up at stairwells and floor openings for added structural strength. Code also allows for a one-inch deflection -- that means your joists can sag up to one inch.
In my opinion, that's not good enough.
Sure, your floor isn't going to fall in, but other problems result. That can lead to squeaks, dips, cracked tiles, etc. If you were to stand in the middle of a kitchen and bounce up and down, you'll see the floor move. It's not dangerous, but think about it: every grout line will be flexing, and so will the tiles. That's a recipe for trouble.
That's why I believe in building "over code" -- it's not because I'm trying to overdo it or prove something. Minimum code is in place for safety -- to make sure your house will stay standing and no one will be injured by it. The fact is minimum code sometimes just isn't good enough for quality. If it were, we wouldn't have the problems we do now.
To ensure your floor doesn't bounce or your tiles crack, you really need to strengthen the subfloor. If your joists are sagging or too widely spaced, your contractor should jack up the floor and sister the joists -- that's adding a new joist with glue and screws -- alongside the existing ones. This will reinforce them.
Then, either cross-brace or block the joists to further support the floor. They should be braced every four feet. The better you brace the floor, the stronger it will be. Blocking and cross-bracing do the same job of strengthening the floor, by tying everything together. It also keeps the floor joists from twisting.
If the subfloor is only 5/8 inch osb, I suggest you double it up before you think about tiling. Lay a sheet of 3/4 inch tongue-in-groove plywood over the osb, glued and screwed down to the joists -- not nailed.
Why glued and screwed? Most builders use nails, from a nail gun, because it's faster, and time is money. But, if you take a look from below (assuming your basement ceiling isn't finished), see how many nails missed the joists. That means there are fewer nails actually holding the subfloor down. Squeaky floors are caused when the nails that hold the subfloor to the joist are able to pull away, and they do so whenever pressure is placed on them -- like when someone walks across the floor. That's why we use screws, and glue. Gluing makes that connection and screws hold it -- a screw won't loosen over time like a nail will.
Because it is so expensive to build houses -- both in materials and labour -- developers are always trying to find ways to save money. I get that. But, if in the end the final product just doesn't stand up, then what's the point?
Catch Mike in his brand-new series, Holmes Inspection, airing Thursdays at 8 p.m. ET/PT on HGTV. For more information visit www.hgtv.ca.
