Bathtub Caulk Basics

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  • Transcript

    LESLIE: Well, you’ve seen the ominous signs of aging caulk, like a brown tinge and the cracks opening the way for all those stubborn colonies of mildew to just take hold or even for water to seep through and make your walls, well, mushy.

    TOM: Well, whether it’s around your sink, between a tub and it’s tile surround or covering the joints of your shower stall, worn caulk has got to go. Tom Silva from This Old House is here to tell us how to get this job done right.

    Welcome, Tom.

    TOM SILVA: Thank you. It’s nice to be here.

    TOM: Now, this is a kind of one of those pain-in-the-neck jobs that everybody’s got to do from time to time. And I’ve seen it done poorly more than I’ve seen it done well. What’s your tricks of the trade for taking this on?

    TOM SILVA: Well, I think the biggest thing is you have to make sure that you’ve got every single bit of the old caulking out before you put new caulking in. I can’t tell you how many times I’ve gone in and see layers upon layer upon layer of bad-done caulking. And it’s all black and mold because the water gets trapped in between it. It’s peeling away from the wall and the tub because it’s done incorrectly. You’ve got to clean it out, you’ve got to scrape it out and you’ve got to remove any silicone that’s there, because nothing will stick to that silicone.

    TOM: Now, getting rid of that caulk without damaging the tub and tile is key. I’ve seen products that are advertised as sort of the caulk equivalent of a paint stripper. It’s supposed to soften the caulk and make it easy to pull out. Have you used this – these materials?

    TOM SILVA: It doesn’t really work great on silicone.

    TOM: Is that right? OK.

    TOM SILVA: Once silicone has hardened, it’s – you’re not going to get anything into it. It’s just – it’s that magical ingredient that they make in there that nothing permeates it except a razor blade.

    TOM: And elbow grease, yeah.

    TOM SILVA: Yeah, yeah. And you’ve got to get in there, you’ve got to scrape it, you’ve got to be careful not to scratch the tile, you’ve got to be careful not to scratch the tub. But you’ve got to get it out. And that’s the longest part of the job is getting the prep.

    LESLIE: So once you’ve got all the old caulk out, what do you do with that opening? Do you take the time to spray bleach in there, clean it, let it air-dry or just go right back at it?

    TOM SILVA: Well, I like all of that. I like to put bleach in there. Bleach will actually cause it to dry a little bit faster. It’s got to be dry. But once you put the bleach in there, you know, you want to make sure that you wipe everything down with a nice, clean rag. Again, you’ll feel if there’s any residue. Get that off.

    And then, before I install a caulking, I like to take some tape and put it on the wall and put it on the tub and create just a little bit of a gap so that I will now be able to put the caulking in. And then push it into that crack and then wet on wet another bead of caulking, if needed. Again, push it in and get the tape off quick.

    TOM: So even the experts don’t rely on the steadiness of your hand to get that line of caulk looking just perfect.

    TOM SILVA: Right, right. You’ve got to – if you’re lucky, sometimes you could do it right.

    TOM: Right. Exactly. But invariably, you’re having to sort of contort your body to get to all those angles, so it’s hard to get it to lay in there without having the tape to guide you.

    TOM SILVA: Well, I mean you’re bringing the caulking gun down. All of a sudden, your elbow will hit the wall beside you.

    TOM: Right.

    TOM SILVA: So now you’ve got to stop and you’ve got to start again to get it smoothed out. And it seems like that little spot, it always bothers me because I can always see it. So I’ve got to redo it again.

    TOM: Now, one of my tricks of the trade is to fill the tub with water before I caulk it so it sort of weighs it down, stretches it out a bit.

    TOM SILVA: Mm-hmm. Absolutely.

    TOM: With the theory being that after the caulk dries, we’ll let the water out, tub comes up and compresses it better or at least doesn’t pull out, when you step in it, quite as easily.

    TOM SILVA: Right. It doesn’t – the tub is – when you fill it with water, you put weight on it so when you – when the caulking has dried, the weight comes off and it’s actually compressing the caulking into that crack. I used to do that all the time. Now, with the new caulking – the polyurethane caulking, just stuff like that – they do have a lot of flex in them, so it’s not needed as much. But in older homes, I would definitely recommend doing that.

    LESLIE: Now, how do you know which type of caulk is the right caulk for the project?

    TOM SILVA: Well, I’m a big fan of polyurethanes or acrylic caulking. You want to make sure that it has a mildicide in it so that it won’t promote the growth of mold or mildew in it. Silicones are good if you’re going on anything that is non-porous. Anything that is porous, silicone really doesn’t stick well to.

    And also, the other thing is you want to use a caulking that is colored. Because if you have a clear caulking and you have a window in that bathroom that is shining down on the sealant …

    LESLIE: They discolor really quickly.

    TOM SILVA: Right. What will happen is if it’s clear, the sun goes through the caulking and it will actually break down the adhesive connection and cause it to curl and break away over time.

    TOM: I’ve also seen if you do get a little mildew that forms underneath that caulk, it kind of permeates right through, almost magnifies.

    TOM SILVA: Yep.

    TOM: And the whole thing ends up looking black very quickly.

    TOM SILVA: Yeah. Oh, yeah. Yeah, mildew is not a pretty thing.

    LESLIE: Is there ever a good place to put the clear caulk? I feel like it just doesn’t ever look good anywhere.

    TOM SILVA: I’m not a big fan of clear caulk. And we use the clear for gluing down marble, granite and stuff like that under kitchen countertops. We’re using like a dab the size of a quarter. And you’re using it as an adhesive but not for water and stuff like that.

    TOM: Now, many times do-it-yourselfers, especially, will turn to acrylic caulk only because it has water cleanup. But if you do use masking tape to kind of guide you, there’s really no reason to use that and you can have the permanence of using silicone caulk instead.

    TOM SILVA: Silicone or polyurethane.

    TOM: Or polyurethane.

    TOM SILVA: Polyurethane, yeah. I prefer the polyurethane because it’s going to stick and it’s got great elasticity and it really holds up well.

    LESLIE: I know we touched briefly on – I feel like every pro just uses their finger to smooth everything and make it look so nice. You’ve seen the tools. They look like little random, triangular, little rubber jobs.

    TOM: Look for the trowel.

    TOM SILVA: Yeah.

    LESLIE: Do you recommend them?

    TOM SILVA: I can never find it.

    LESLIE: Really?

    TOM SILVA: I always find my finger, though.

    TOM: Right.

    LESLIE: True. But do you recommend them for somebody?

    TOM SILVA: Yeah, some people love them. There are guys that I know that do use them. But it’s really a matter of preference.

    TOM: Tom Silva, the general contractor on TV’s This Old House, great advice as always. Thank you so much for stopping by The Money Pit.

    TOM SILVA: Always a pleasure.

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