To caulk or not to caulk?

scraig01

Hi,

I recently installed a new vanity/sink in my rental unit. It went fairly smoothly except that after adjusting the plumbing under the sink I noticed there was approximately a 1/2" gap between the top of the sink backsplash and the bathroom wall.

This gap makes it impossible to caulk the sink to the wall. Is step this really necessary? (other than the aesthetics) Should I unseal the sink from the top of the vanity to fix this?

Thanks…

Brik

Is 90% aesthetic and 10% functional. The functional aspect is to keep splashed water from running down the wall and behind the vanity. I cannot imagine that much water getting back there to cause a problem.

You COULD caulk that 1/2" joint. They make a backer type foam to stuff in there first and then you caulk. Could also use a piece of rope or something. The caulk will likely fail over time regardless.

If it were me? If I was concerned about the look I would caulk it. If I wasn't I wouldn't.

Termite

Brik's right. Foam backer rod should be stuffed in the gap first, and then a thin layer of caulk can be put in over the backer rod. Use a wet finger to smooth the caulk and it will look great and will keep out unwanted water.

jogr

I've never sealed a full top sink to a bath vanity. I always put the new faucet hardware, tailpiece and supply lines on the sink before I put the sink on the vanity. Then set the sink on the cabinet and slide against the wall tight. Hookup the p trap, hook up the supply lines to the shutoff valves, caulk the sink/wall joint and done. Have never had a sink move or seen any reason to seal it down.

The gap would bother me. Someone's going to end up dropping something valuable in that 1/2" gap and 1/2" of caulk would look ugly. I'd unseal the sink, loosen the p trap and slide the sink into it's proper location.

Boston Plumber

Hey everyone..

Hey, just one more idea... I am figuring that this issue is a result of the new sink drain not lining up with the old drain.

One quick fix that works perfectly is a corrugated, flexible 1.25" x 6" tailpiece...see pic. (you may need to purchase an 1.5" x 1.25" nut and washer if have 1.5" ptrap... ).

Here, you would cut the metal or plastic tailpiece coming from sink pop-up assembly and you would cut it so that you could slide the COMPRESSED tailpiece into place. When tailpiece extends will seal joint nicely AND ALLOW FLEXIBILITY TO PUSH THAT VANITY TOP BACK TO THE WALL (add a little bit of caulking and wedge the sink in tight overnight).

That should be all you need to do...If I understood this question right..???

Let me know.

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scraig01

Wow,

Thanks for the quick and knowledgeable responses guys. This was my 1st post and I am impressed.

I don’t have any foam or rope on hand so I will probably go ahead and unseal the sink from the vanity and re-set it as the “lost valuables” is a good point.

I think the drainpipe into the wall (Post P trap) has some give so I think the plumbing can be moved to close the gap. Otherwise I will be off in search of a flexible tailpiece.

Thanks Again.

jogr

The horizontal leg of the p trap assembly can be adjusted some in and out of the horizontal pipe from the wall (after loosening the large nut) It can also be cut shorter if need be to slide it in that 1/2".

Brik

One word of caution with those flex tailpieces. They build up soap scum and gunk and start to stink after a while. BTDT