Filling deep gap before applying silcone sealant.

sonny liston · 20-03-2017 1:50pm #1

Hi folks,
I am about to use silicone sealant to seal gap between top of sink & the tiles above the sink.
The gap is quite deep. I don't want to just fill up it with loads of sealant.
Any suggestions on how to fill the gap before applying the sealant.
Was thinking of using some newspaper to fill the gap, but concerned about damp in the bathroom rotting the paper.
Thanks.

Steve · 20-03-2017 4:19pm

Use some expanding foam filler.. aka 'no more big gaps'. Then silicone over that.

Or better would be Gyproc joint filler but not worth buying a bag of it just for this job and it can be messy if you don't know how to use it.

the_pen_turner · 20-03-2017 7:47pm

how big is the hole

sonny liston · 21-03-2017 7:32pm

Thanks for the replies.

Gap is about 10mm deep.
Height of gap varies from 2mm to 10mm high due to shape of sink.

the_pen_turner · 21-03-2017 8:38pm

have you a pic.

i would use cheap silicone to fill it.

jack of all · 21-03-2017 9:59pm

I've filled large gaps before caulking with silicone, using a foam filler or backer to support the silicone bead and prevent slumping. I've used a strip of foam floor underlay (the white foam used under floating laminate floors), fold over and position it in the gap, as required.

sonny liston · 22-03-2017 2:41pm

I don't think I can upload pics.
I have some pipe insulation, the cylindrical grey foam type. I might cut that up into strips to fill the gap? Would that be better than stuffing with paper?
Or I might just use the silicone to put in an initial bead, allow to cure, then go over again for a clean finish?

jack of all · 22-03-2017 6:08pm

Any type of foam would be preferable to using paper. The danger with very deep beads is that they can sink so I would prefer a backer followed by a smaller bead, but others may have a different opinion.

sonny liston · 24-03-2017 2:25pm

Are you talking about a "backer-rod". I was reading about them online, used to fill the gaps before calking.
Any experience with these or know where to get some?
Thanks.

jack of all · 24-03-2017 4:48pm

Backer rods can be got but they're a specialist item, used in jointing precast panels etc so I don't know where you'd get them. Trust me, a piece of foam folded over will do the job just as well, I've done it with great success!

sonny liston · 03-04-2017 9:36am

Used the pipe insulation foam(cut into strips) to fill the gap before going over with silicone.
Seems to have worked quite well.
Great tip....if only my skills with the silicone were half as good!
Thanks a lot.

Filling deep gap before applying silcone sealant.

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