[JLawrence08648]

When tiling a wall, should you use joint compound and tape and fill over the drywall screws and prime before tiling with thinset? I saw a YouTube video he used adhesive to set the tiles but did use any joint compound or tape, nor primer.

 

[Brother Antioch]

When tiling a wall, should you use joint compound and tape and fill over the drywall screws and prime before tiling with thinset? I saw a YouTube video he used adhesive to set the tiles but did use any joint compound or tape, nor primer.

I'm assuming you mean on a regular wall and not within a shower enclosure or tub surround. If so, then why bother? It's just added work, and to no added benefit. Mastic or mortar will stick to the dry paper on the drywall just as well as on the primed wall. It also has the added benefit of absorbing the moisture content in the adhesive quicker than a sealed/primed surface.

If it's inside a wet area, it should be properly waterproofed anyway, so again, it's irrelevant. Your waterproofing membrane, be it something like Kerdi or (my preference) a rubber compound like Laticrete Hydroban, it will seal all those imperfections anyway.

Cheers,

BA.

 

[Old Thomas]

I would tape the seams and put 2 coats of compound on. That will reinforce the seam and smooth out the taper of the edges.

 

[Brother Antioch]

I would tape the seams and put 2 coats of compound on. That will reinforce the seam and smooth out the taper of the edges.

Then you'd have to at the very least prime the seams, as mastic or mortar won't stick to drywall compound.

Cheers,

BA.

 

[jeffnc]

Then you'd have to at the very least prime the seams, as mastic or mortar won't stick to drywall compound.

?? Sure it will.

But there's no need to do it. The adhesive itself can fill in any inconsistencies in the drywall. If you're tiling over a tapered drywall joint, just make sure to hold the trowel edges fully over the joint, to completely fill it in. If you're working with a small mosaic, this is probably the only time I'd fill in a tapered joint. But this is not going to be very common in a backsplash situation anyway. If you did want to prefill that joint with something, you could do it with one coat of joint compound, or even the tile adhesive, and then let that dry first.

 

[Brother Antioch]

?? Sure it will.

But there's no need to do it. The adhesive itself can fill in any inconsistencies in the drywall. If you're tiling over a tapered drywall joint, just make sure to hold the trowel edges fully over the joint, to completely fill it in. If you're working with a small mosaic, this is probably the only time I'd fill in a tapered joint. But this is not going to be very common in a backsplash situation anyway. If you did want to prefill that joint with something, you could do it with one coat of joint compound, or even the tile adhesive, and then let that dry first.

You think mastic or thinset will work well over bare drywall compound? Maybe I'll just stick to my 22 years experience that says otherwise...

 

[jeffnc]

You think mastic or thinset will work well over bare drywall compound? Maybe I'll just stick to my 22 years experience that says otherwise...

Pretty vague.


If this is a wet area, then you shouldn't be tiling directly on it anyway. If it's a backsplash or other decorative area, it's just not an issue. The tile isn't coming off and the wall isn't going to fall down. If what you're saying is true, then paint or primer wouldn't stick to it either.

 

[Brother Antioch]

Pretty vague.


If this is a wet area, then you shouldn't be tiling directly on it anyway. If it's a backsplash or other decorative area, it's just not an issue. The tile isn't coming off and the wall isn't going to fall down. If what you're saying is true, then paint or primer wouldn't stick to it either.

Sorry, I guess I could have been a bit more specific. You're 100% correct about not using a mastic in a wet area, or over drywall/compound without waterproofing it first. When I'm tiling a simple backsplash in a kitchen, though, I've always found the mastic or mortar will initially try to peel off the dry compound, unlike over a primed or painted wall. Paint or primer, being much much lower viscosity, will stick to the wall, but even a first initial coat of primer, your first roll on compound is splotchy, until you back roll it out.

It's just proper technique to either leave the drywall untaped and backfill with your adhesive, as you mentioned earlier, or have a coat of primer over the compound.

Cheers,

BA.

 

[jeffnc]

Well, you might be right that it's optimal to prime over the drywall compound. I've never seen the issue you have with it trying to peel off so I don't prime, but I can't say it would be a bad idea.

 

[Old Thomas]

I like a smooth surface without tapered drywall edges. I stand by my comment to tape and mud joints. 50 years of jobs and never an issue with unprimed compound under mastic and tile.