# Taping cement board / drywall seams



## jlhaslip (Dec 31, 2009)

Mesh tape and drywall mud works fine there.


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## mark sr (Jun 13, 2017)

Generally the lay out of the cement board is such where the tile will bridge the gap between the cement board and the drywall but if it's exposed, j/c and tape will work fine.


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## jaketrades (Mar 2, 2017)

What do you do when the transition bw drywall and cement isn't perfectly flat. Smooth it out as best you can with joint compound?


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## mark sr (Jun 13, 2017)

Yep, basically treat it like you would any other ill fit with drywall. You'll just need to feather the mud out further.


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## jaketrades (Mar 2, 2017)

Cement board inside corners - tape them as well? With cement board mesh tape?


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## mark sr (Jun 13, 2017)

If it's to be painted - use paper tape.


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## jaketrades (Mar 2, 2017)

Is it fine to use mesh in the non-painted corners? And paper in the painted corners?


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## mark sr (Jun 13, 2017)

Yes but the mesh or sticky tape has a bad track record when used with regular ready mix joint compound, it does fine when covered with a setting compound like Durabond or EasySand.


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## jaketrades (Mar 2, 2017)

So first time using thinset for the cement board seams and joint compound for the cement board to sheet rock transitions. It's not easy to get it right. Now I now why sheetrock needs to be perfectly flush.

Got a few questions-->

1. How do I fill in these large voids of space

2. How do I patch large holes? Cut out a larger piece and replace with fresh sheetrock?















































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## mark sr (Jun 13, 2017)

It generally takes 3 coats of mud to finish a wall. Applied correctly only the final coat needs sanding. Large gaps can be prefilled with joint compound [thinset if behind tile] A patch piece needs to be used to fill that hole. I'd square up the hole and then cut a piece of drywall about 2-3" larger than the hole, back cut it removing the excess gypsum, just leaving extra paper on the front and then mud it in place.


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## jaketrades (Mar 2, 2017)

I replaced large holes with new Sheetrock pieces.

With he smaller gaps in the curved areas I used mesh tape->mud -> multiple small strips of prefolded tape to follow the curve without creating bubbles. 














Now I've got a couple more problem spots to fill in. 




























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## Nealtw (Jun 22, 2017)

I am only seeing part of those pictures.


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## jaketrades (Mar 2, 2017)

How do I deal with taped seams that bubbled?



















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## mark sr (Jun 13, 2017)

Usually you just cut out the bubble and remud but since it appears to be in the middle of a joint you'd be better off removing the tape and starting over. You want enough mud under the tape to 'glue' it in place with pretty much all the excess removed from the top of the tape. Never apply the 2nd coat of mud until the tape coat is completely dry!


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## jaketrades (Mar 2, 2017)

How do I tape the seams between the Sheetrock and door frame?

Same as all other seams?











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## mark sr (Jun 13, 2017)

If you mean where the casing meets the drywall - that doesn't get taped, it will be caulked once the drywall finishing is done.


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## jaketrades (Mar 2, 2017)

I'm going to paint part of the cement board. Should I skim coat with mud first?

When Painting over thinset seams, should i sand them down first and then apply mud to get it smooth?

For the holes near the copper, can I put mesh tape and some mud, followed by redguard? Or do I need to use thinset?








Thanks.














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