My grout is crumbling out!!

[glocko]

I have just laid ceramic floor tiles along my hallway, max width 3feet. this was on floor boards, I put hardboard on boards with clout nails evry 4 inches all over. I used rapid fix adhesive average thickness 7mil. Again I used rapid setting floor tile grout in the 6 mil gaps, as the bag said, to a thick yoghurt consistancy.
It is coming out in places in little strips from between the tiles, what can I do? I think there could be slight movement in the floor which is dislodging the grout, is there a flexible grout that can overcome this?
Was thinking of some sort of mastic maybe.
Thanks in advance

Glocko

 

[masona]

I put hardboard on boards

I think this is where the problem is,shouldn't use hardboard as it's not waterproof,the wet adhesive most likely to swell the hardboard causing the tiles to lift or won't let the tile adhesive to settle.

 

[glocko]

Would i be able to drag out the grout where it has come out, sling a PVA mix in and regrout?

 

[breezer]

probably, dout if it would do any good. i saw mr tommy walsh do it on tv he screwdown plywood first not hardboard, maybe its becasue hardboard flexes too much

 

[ali68]

Just been watching a barn conversion on discovery channel, they were laying tiles on a chip -board floor and they used a flexible adhesive allowed the floor to move without disturbing the tiles and grout

 

[masona]

Would i be able to drag out the grout where it has come out, sling a PVA mix in and regrout?

As you already done the floor tiles and got nothing to lose,like you say use a Unibond + part water and you can get Flexible Floor Grout Adhesive and see what happen but the floor tiles should really be on exterior plywood.

 

[glocko]

thanks for that guys, there does not seem to be any movement of the tileees from the hardboard so will try the PVA mix.