Tiling on floorboards and marine ply

[Tyrian30]

Hi,
I've agreed to do a tiling job for a friend who got fleeced by a couple of cowboys. The job is tiling the walls and floor of a bathroom, the floor is partially covered in 25mm marine ply (supplied by my friend, but only half of the 8' x 4' sheet was used) the cowboys left a small part of the floor covered with two runs of old but solid floorboards and attempted to tile over that (I checked the level of the floor and it seems to be level and without ridges or height discrepancies so i'm thinking of leaving the floorboards there..).
The walls above the bath were taken down (old, rotten plaster board) and hardibacker 12mm was put up badly, it's been screwed down well onto the wall joists but the wall is not level i.e. i put a long piece of wood against it and there are 15mm gaps...

My friend supplied the cowboys with bags of Mapei flexi adhesive and ultra color grout, floor and wall tiles and Mapegum liquid membrane, Mapetape and primer g. The cowboys put down the marine ply and disappeared with the other half and never returned, but worst of all they took all the tiles and the adhesive, my mate is distraught. I said i'd help him out but i'm not sure how to proceed.
He wants the bathroom floor tanked with the Mapegum and tape, but i've never used this stuff before.

my questions are:
1. Do i paint the mapegum straight onto the marine ply and floorboards? (There are only two lengths of floorbaords, the rest is marine ply)
2. How should i go about levelling the hardibacker wall? I believe the wall joists are not level so should i put some kind of spacers behind the HB to level out the wall, or can i apply flexi adhesive to the HB and "skim" the wall with it to make it straight?
3. the floor is solid and noggins have been fixed (no noticeable movement), what is the procedure for tanking application and tiling?

This is how i'm thinking of proceeding:

paint primer g onto ply/floorboards, then apply mapetape to corners and wall joints using Mapegum as "glue", use roller to apply Mapegum liquid tanking with roller onto floorboards/ply, leave to dry and re-apply, tile with flexi adhesive straight onto dried Mapegum.
But i'm not sure if i should skim the wall with flexi adhesive.

What do you guys think?

[Scott]

The first thing is making sure that the floorboards are fixed properly and thereis no movement. Second you really need to put something over the floorboards as you cant tile straight onto them. Tanking them is a waste of time as any water will get between the gaps in teh floor.

I think id put a decoupling membrane over the whole lot, (Ditra matting) If done right the ditra will also waterproof the floor.

As for the wall not being plumb, is that vertiacally or horizontally? For vertical you can add a new stud and fix it tot eh side of the exsting to straighten it up or for either way you can buy plastic packers for this purpose but can be a bit laborious getting it flat.

[faithhealer]

they took all the tiles?, theft innit

[Tyrian30]

Hi Scottley,
Thanks for the reply.
I was thinking of closing up the gaps between the floorboards with silicone and then applying the Mapegum over the whole lot. I know it's not perfect but i can't spend alot of time on it, i just want to help my mate out a bit because he's really depressed. But i don't want him to get more depressed if the tiles start getting loose! I know it's not a good idea to tile over the floorboards but they are very solid and the whole floor is solid, it would make little sense to take out two long boards and fix plywood strip in their place, I'd have to fix at least six noggins where the floorboards were (to support the plywood replacement strip...).

Would it be ok to silicone the gaps and apply the mapegum (or should i seal the gaps with Mapei tape and then apply Mapegum).
Should i prime the ply before i apply the mapegum?

The wall is not plumb vertically and a little horizontally (not more than 15mm). I'm thinking of skimming with adhesive, do you think this is ok?

[faithhealer]

I would hardie backer over the lot to cover the floorboard area

[Tyrian30]

they took all the tiles?, theft innit

They took all the tiles and all the adhesive, the tea leaving *****, my mate had to shell out again but only bought half the amount of tiles as he is skint. i told him i'd help him out, his missus just had a baby as well.

[faithhealer]

They took all the tiles and all the adhesive, the tea leaving *****, my mate had to shell out again but only bought half the amount of tiles as he is skint. i told him i'd help him out, his missus just had a baby as well.

speechless if the police can't be called, who were these guys

[Tyrian30]

I would hardie backer over the lot to cover the floorboard area

Thanks for your advice faithhealer. i'll look into the costs of 6mm HB and adhesive (is that correct?) but i have to balance the "cost to bodge" ratio i.e. I don't want the costs to escalate but i don't want to bodge it either.

Do you think i should tell him to ditch the mapegum tanking idea?

[Tyrian30]

speechless if the police can't be called, who were these guys

Total scumbags. the police were called but ...registration of their van not known, mobile phone not in use anymore (i don't know if they can trace that anyway). They were recommended by another tradesman but he insists that he hardly knows these guys and met them on a job he was on...my mate's not only out of pocket but him and his missus/baby don't have a proper bathroom they can use....

[Gazebo]

What van was it and what colour, whereabouts did this happen, maybe if you know this and post it someone reading this thread may stumble across them in future.

[faithhealer]

Thanks for your advice faithhealer. i'll look into the costs of 6mm HB and adhesive (is that correct?) but i have to balance the "cost to bodge" ratio i.e. I don't want the costs to escalate but i don't want to bodge it either.

Do you think i should tell him to ditch the mapegum tanking idea?

No need to tank if it's only a std bathroom with no wet areas and hb is water resistant.

these cowboys want tracking down and sorting out, try the local newspaper with this story and see if anybody wants to help out.

What area are you in?