Hi, Bryan. We have a small, three-season cottage built above a boathouse. The floor is insulated with pink fiberglass insulation; it has two thin layers of plywood subfloor and underlay, on top of which is carpet. We’d like to replace the carpet with vinyl plank flooring. The manufacturer says to install it directly on top of the plywood underlay, but I’m considering a thin foam underlay first — or will this cause moisture to form since it is over water?
Andrew T., Toronto
Hey, Andrew. It sounds like a nice place. If you’re installing laminate, typically it’s pretty resistant to moisture. Generally, we install laminate on top of a couple different types of underlay. There’s a quiet walk underlay, which is a felt-type material you can put down if the subfloor isn’t perfectly flat.
Or, if your subfloor isn’t in good shape, your floor could flap around a little bit. It could get dips, valleys and all of that stuff. Foam will absorb some movement, as well, and act as a bit of a vapour barrier as well. Putting the foam down and taping those joints will also actually act as a vapour barrier.
Some floors have an underpad built directly into them, of foam or rubber. Some have an underpad or underlayment of cork already attached to the flooring itself. Those are generally the higher quality laminate floors. If your laminate floor doesn’t have a rubber or cork underlay, installing that foam underpad is certainly a good idea. Once you’ve got it laid down, you can tape those joints with some red tape, which will also provide an effective vapour barrier and soften up the floor a little.
Hi, Bryan: I have a basement room and hallway that is carpeted; I am considering replacing it with stone tile but when I walk on the carpet, it seems the floor beneath may not be flat. If I go ahead with the stone tiles, what steps would I have to take to level the cement floor under the carpet? I don’t really want to put down a sub-floor as this would raise the level of the floor and cause issues in intersecting doorway, etc. Can you give me some advice? Thanks!
Reg M., Toronto
I certainly can, Reg! I’m generally not a fan of carpet directly on the concrete because it will, at some point, have moisture or condensation coming through it. So, putting in stone tiles is a great idea.
You’ve got a couple options to level that floor before you install tiles. But there are things to consider — basically, your concrete pad in the basement sucks the heat out of your house and will cool it down.
So you’ve got the option of using a self-leveling cement, or what’s called a “dry pack” — that is, a dry pack mortar that’s put down and screeded perfectly flat and level before you install the tiles. That’s a little more difficult than self-levelling, which can be used but must be mixed very runny and then dumped into place and screeded flat right away because it sets very, very fast. So you want to make sure you read the instructions on self-leveling cement to fill any low spots.
For high spots, generally, or if there are bumps in your floor, you can rent something called a scarifier — a machine with carbide teeth that will sand down the concrete.
What I’d also recommend is installing some in-floor heating beneath those tiles. Warmup makes a great product where you can glue down these plastic strips and run wires between them to warm up the floor. But keep in mind that heat will go down into the pad unless you put some type of insulated underlayment underneath the tiles. If you don’t want to raise the height, you can certainly put that heat in there and it’ll take the chill off the floor.
Bryan: We have a semi-detached house (built 1928) separated from our neighbour by a firewall which has fiberglass insulation, faced with drywall. The problem is noise transmission — from either side. Where can I get detailed instruction on soundproofing this wall? And maybe add some fireproofing? Could you recommend a contractor for such work or a website where we can choose one?
Herber L., Markham, Ont.
I can certainly recommend looking at the BaeumlerApproved.com website. You might want to call your municipality’s building and planning department to ask what the firewall requirements are. Typically, two layers of 5/8th-inch drywall will give you a proper burn time. What you could do is remove that wall, install a Roxul Safe’n’Sound, which is a sound-deadening insulation in that space, and then put resilient channels on that wall.
The goal is to reduce the solid material from wall to wall, because sound travels through solid connection points. So, install your Safe’n’Sound, which is fire resistant and a sound dampener, and then put your resilient channels on, which are metal channels that attach to the studs. Then attach your drywall to the metal channels, not the studs themselves. Put your second row of drywall over top of that — it will give you fire suppression and added noise reduction. But again, you should find out exactly what’s required in your municipality. You can also go a step higher and there are sound deadening drywall products available, but they come at a significant cost and are typically used for music studios.
Hello, Bryan: During this winter I have noticed cold air coming through the pot lights in our dinette. The dinette, a single storey, is a 28-year-old addition to the house. Do I insulate the pots and, if so, how do I do it? Should I blow insulation (what type) into the attic or is there an easier way? I’d appreciate your opinion and any suggestions.
Matt H., Mississauga, Ont.
Well, Matt, with air coming in through the pot lights, my first concern would be that they are retrofitted — popped into place and without a proper vapour barrier. What’s required is an IC (insulation contact) pot light — they typically come with a metal box that’s installed in the attic space. The box is there so insulation can be put directly over top of it with enough air around the light inside so it doesn’t heat up to cause a fire or make the temperature probe turn it off.
The other problem there, with cold air coming in, means that hot air is escaping into your attic space — it’s a circular problem. And it’s going to condense in the attic space, make the insulation wet, reduce the R-value and keep getting worse.
You’ll have to get up into the attic and make sure they are IC pot lights. If they are, you’ll want to make sure there’s a proper vapour barrier over top of them, because there shouldn’t be air coming through. Once you’ve sealed them, you can either blow in cellulose or get a chopper that will chop up fiberglass and blow it into the attic to increase R-value.
Hi, Bryan: I really need help! We installed a new inverted flat roof in September, 2014, to our 1978-built home. We had an undetected roof leak and had to remove three bedroom ceilings; we found no interior insulation. One professional has said we should insulate but only with Type 4 Styrofoam, one-inch, and that too much insulation would cause mould. Others have told us you shouldn’t insulate an inverted roof. We are stuck and hope you can help.
Lisa L., Toronto
Lisa, typically you see inverted roofs on commercial and industrial buildings. So it’s interesting that they’ve put one on a house.
The lack of interior insulation is actually standard with an inverted roof — the insulation is actually on top of the roof deck and will be roofed over and held down with a ballast. Something like tar and gravel or stones, depending on the roof membrane itself.
The only thing I would do is open up the ceiling and spray foam it with two-pound, polyurethane, closed-cell spray foam. It’ll eliminate any airspace in that roof. The problem, again, that you can run into there when you insulate like that with foam, whether it’s an inverted roof or you spray foam underneath the deck, is that any leak in the roof membrane will be difficult to detect until it’s really working its way into the house.
Whether you decide to insulate inside, on an inverted roof, really depends on the R-value that was initially installed. The only thing I would recommend would be using a two-pound polyurethane spray foam underneath the joists to eliminate any airspace. But the risk there is you’ll make it more difficult to detect a roof leak until it’s been going on for quite some time.