Which Substrate to use please?

[cr0ft]

Hi all. Been a while since I posted on here. I now subcontract all the tiling in our bathrooms to a full-time tiler (I do the plumbing only now, my trade). My customer has bought some 9mm thick ceramic tiles (440x300mm). The plasterer is coming in to fix up the solid walls on Monday. The tiler has asked him to use hardwall as the substrate. I have my doubts about this. I would prefer a sand/cement render instead as I don't think hardwall is up to holding the weight.

Can anyone please give me advice either way? The job is for a friend of a friend so I want it done properly of course. I don't want to board the walls as you lose a lot of space doing this and it will be a major pain.

I need to know if this substrate choice is right by the end of tomorrow please, so I can advise the plasterer accordingly prior to Monday.

Many thanks in advance for the advice.

 

[White Room]

Your tile weights are on the limit so should be fine, will he be giving the hardwall a finish

 

[charlie1]

Hi Cr0ft

If space is no ussue then I would agree with your tiler and install either plasterboard or aqua panel if its a shower area, this will give your tiler a straighter / stronger substrate to tile on to! Personally , if it was me, as a tiler i would insist on prepping the area myself. I can understand the tilers recomendations to your plasterer given he has just started working with your team.

Also, if you plaster the walls then they will need about 4 weeks to dry out prior to tiling.

 

[doug boardley]

I wouldn't tile directly onto hardwall. Use either sand and cement or dotand dabbed plasterboard.

 

[cr0ft]

The 4 week thing could be very important as we have 1 week between plastering and tiling. Out of curiosity why is there a 4 week gap between? Plaster usually seems bone dry after about 3 days. Is this not the case? If 1 week is too short then I think we are going to have to use sand/cement.

Thanks for the advice so far.

 

[cr0ft]

Hi Cr0ft

If space is no ussue then I would agree with your tiler and install either plasterboard or aqua panel if its a shower area, this will give your tiler a straighter / stronger substrate to tile on to! Personally , if it was me, as a tiler i would insist on prepping the area myself. I can understand the tilers recomendations to your plasterer given he has just started working with your team.

Also, if you plaster the walls then they will need about 4 weeks to dry out prior to tiling.

The plasterer is going to rough up the hardwall to provide a key for tiling. Is the hardwall stuff the same weight limit as skim and set? I.E 28kg/sq m?

 

[doug boardley]

it might seem dry Croft, but there will still be quite a lot of moisture content in it, this needs to cure properly before tiling.

 

[Aston]

hi croft,
when you say the plasterer is going to 'rough' up the surface to provide a key for the tiling , then that says to me that he isnt going to skim it? you shouldnt tile directly onto hardwall.. it will be too porous when its dried and it will suck the life out of your adhesive. it will need to be skimmed, alllowed to dry for a suitable period, then the walls should be primed with the adhesive manufactures choice of primer or sbr. dont let the plasterer fob you off regarding this. if the plasterer doenst tile professionally, then he wont be fully aware of the problems that can occure!!

ps you should skim hardwall the same day as you apply it, normally within 2-4 hours so it will all set and bond together.

ed

 

[cr0ft]

My worry is that it's the tiler (whose work is excellent normally & I've used on 2 occasions prior) who has suggested he use hardwall.

 

[cr0ft]

How long would sand/cement take to dry?

 

[The Legend; Phil Hobson RIP]

Sand and cement render, depending on thickness, will take about two weeks to cure. But you can get rapid curing ( I think Webber do one)

failing that dot and dab plasterboard, would be the quickest option imo if you go by the book for curing times, render will be the same as screed ( 1mm per day)