Cracked Grout on Wooden Step

[dan_l]

Hi,

We have had an indoor wooden step tiled just over a week ago and this morning I have noticed that there are some cracks in the grout. A bit of information about the the job:

The step is about 1.5 inches high and roughly 1.8mx0.3m and it's beech wood screwed down to the concrete floor. The step itself is very sturdy.
Flexible adesive and grout were both used.

Has anybody any ideas why the grout has cracked and what we could do to stop it happening again? Would putting plywood on top of the beech step of helped?

Thanks a lot,
Dan

 

[Richard C]

Does the step flex/move at all? Was the wood treated varnished in any way? Are the tiles loose or is it just the grout that has cracked? What type/size tiles? What make/type of adhesive & grout was used? It should have been flexible powder not tub ready mix.

 

[dan_l]

Hi,

The step doesn't seem to move at all, its pretty heavy and screwed and glued down securely, there was a bit of a finish on the wood though.

The tiles are 15cm porcelain ones, they don't seem loose there is just a crack all the way down the middle of the grout from one side to the other, even on parts where its not walked on.
The grout/adhesive was mapei flexible and the powder version.

Cheers,
Dan

 

[Richard C]

What type of Mapei addy/grout was used specifically? Did it come from B&Q or a tile stockist?

 

[dan_l]

It def came from a proper tile place, I'm not sure of the type of Mapei because the tiler bought it but I'm pretty sure the grout is the ultracolour one.

Thanks,
Dan

 

[Richard C]

Something has obviously gone wrong but without seeing it or more detail it’s impossible to say what. On the face of it, quality products have been used &, it seems, of the correct but more detail would have been better. Its common practice to tile onto WBP ply floors but timber can be problematic. My best guess is that the timber has initially absorbed moisture from the addy/grout, expanded & then contracted after the addy/grout has set, causing the crack. You didn’t say if the step had been varnished or treated with anything, did the tiler use any primer first? If the tiles remain well stuck down, it may be that just raking out & re-grouting will work.

I would definitely call the tiler back to sort it out though, it should last longer than a week.

 

[dan_l]

Thanks for the help with this, he didn't use a primer first, the wood did look like it had some sort of varnished finish on it, it definately wasn't bare wood as it had to be cut down a bit at the front and the finish at the front which was bare wood was definately different to the top part. Could this of made a difference?

The tiles do seem really solid though, its just the grout so do you think I could possibly get away with jut re-grouting?

Thanks,
Dan

 

[Richard C]

The tiles do seem really solid though, its just the grout so do you think I could possibly get away with jut re-grouting?

If the tiles remain well stuck down, it may be that just raking out & re-grouting will work.

I would definitely call the tiler back to sort it out though, it should last longer than a week.