Worktop to wall (sealing)

[John Greenwood]

Hi,

The walls in my kitchen are far from square and after fitting my worktop there are gaps between the worktop and the wall of differing sizes at various intervals along the 3m length. I didn't have the patience or skill to plane the worktop to fit the wall.

I don't know the correct way to seal a worktop to the wall but I was going to seal it to the wall with transparent silicone before tiling. After tiling should I then run a bead of silicone along the tile/worktop edge or will the grout be sufficient considering I have already sealed the worktop behind the tiles.

But now that I have large gaps how do I seal the worktop to the wall or should I forget this and just tile, bringing the tiles out from the wall with large lumps of grout to cover the gaps.

Or should I fill the gaps with something and then seal with silicone and then tile. If so what can I fill the gaps with so the silicone does not just disappear down the back?

BTW, the exposed chipboard on the worktop edges have been sealed with PVA.

I don't want a rotten worktop in 2 years!

Thanks,

John

[John Rumm]

Depends a bit on just how big the gaps are!

Normally you could tile and then run a bead of silicone sealant along the tile / worktop joint. If your gaps are so big as to be bigger than the thickness of a the tiles (i.e. you wouls still have a vertical gap at this point) then you have a bit more of a problem.

Perhaps one of the worktop sealing strips would do the trick. Fix in place as directed and then ensure that is well sealed in with silicone top and bottom.

[The Natural Philosopher]

Don't panic. We all have the same problems.

If you are tiling, then you have the perfect finish to solve gap problems. If you are tliling up to cupboards, its even greater happiness, because you can just skling some MDF between the cupboards and the worktop, and tile over the now perfectly flat surface.

Experience of trying to get a suite of vertical tiles flat on an uneven wal suggests this is a better option.

Somehw you have to bodge out the gaps to get a smooth tiling sufarce. You camn skim plaster, or use board with various spacings of battens, or indeed shape the rear of the board itself to fit the wall.

In my case, the presence of a nice gap behind the MDF akllowed me to run cables where there were none previously, and hide a nasty piece of trunking... In fact it looks to neat, I haven't tiled it yet.

If you have almost no movement between worktop and tiles, no need for silicone either - Just use grout. I am tending to use silicone first to seal, then tile over, and make grout the final fine finish.

[Simon]

A relatively simple task of scribing, place the wortop in position so that it's front edge is equal distance from the carcasses ..... calculate what overhang you require and subtract that from the current distance, then either using a block of wood cut to size and a pencil, or a pair of compass set to the right distance, you scribe along the back edge

the second sealant will stop the tiles and worktop seperating and looking ugly with later movement

You haven't said how large .. you might, now, have to either resort to dry lining that section if the gap is too big, or building it out with plaster. Don't try and build it out with adhesive, it won't work.

sounds like a BIG gap ...... maybe you should have taken it slower and asked these questions BEFORE fitting the worktop

[Simon]

I hope you sealed the MDF before tiling NP ;-P

[The Natural Philosopher]

Nah. I don't spray my tiles with steam and high pressure hoses.

I have extractor fans and insulated walls and central heating.

[robgraham]

The best way is to plaster the wall to fit the worktop. It doesn't matter if you are no good at plastering - you'll be tiling over it. Get some plaster, how much depends on the size of the gaps, and having distressed the wall to provide a key, put it on level with the back of the worktop, tapering the plaster up the wall. One coat should do it, and when it's gone off a bit (say 1 hour) level it at much as possible.

Rob Graham

[Simon]

That wasn't it ..... MDF is like a sponge and will suck the moisture out of the adhesive before a full cure is reached and won't adhere too well.

[The Natural Philosopher]

If you MUST do this then het some pattens and batten out teh wall to level with vertical strips packed oiut with scrap to make a guide for plastering.

IME trying to get plastering level is hard for professionlas, let alone us D-I-Yers.

[The Natural Philosopher]

? Always worked for me?

Coat of PVA should fix anyway.

[Simon]

slap a piece of plasterboard up, much easier ... stick a dollop of bonding every 8 inches or so and squeaze it in place and let it set, then tile over and if it's on a run of wall where the tiling is to finish, you'll just have to put up with a larger step from wall to the tiling, a nice bevelled grout edge should finish it off.

[robgraham]

Yes, I agree basically. However, here the OP has got an existing wall that just needs modification and then he's going to tile over it anyway. I would have thought the guide consisting of the back of the worktop would have been adequate.

Rob

[stuart noble]

IIRC the face of mdf is not at all porous. The edges are though.

[stuart noble]

Quite often there are just a couple of high spots on the wall that throw the worktop out. Chopping those out can reduce the gaps to tile thickness.

[stuart noble]

You only need a piece of wood to get the surface level. The difficult bit is getting it flat and smooth for decorating, which is not required for tiling.

[The Natural Philosopher]

I am good at many things D-I-Y. Plastering is not one of them :(

[Simon]

"stuart noble"

[Simon]

Better still, simulate the effect of wet tile adhesive under NON porous ceramic tiles by putting a wet rag on the MDF and covering it with plastic and leaving it for a day

[Toby]

Seconded. Just chop away at the plaster high spots, a non-critical if somewhat rough and ready approach. Way easier and quicker than cutting the worktop. This may have the effect of recessing the worktop into the plaster which will aid sealing the tiles.

[stuart noble]

Neither pva nor mdf will withstand "prolonged exposure" to water. Sure, I wouldn't line a pond with it, but it's a good enough base for tile adhesive, and superior to plaster and most ply.