Tiling onto new plaster

[John the tile]

Hello,

Just wondered how long after new finish plaster has set can you tile onto it.

ta

[david campbell]

usually give it 4-6 weeks depending if it is a skim or a new coat!

[enduro]

And it will need priming, not with pva use Bal SBR or similar

[doug boardley]

is it onto plasterboard or plaster basecoat?

[bitter&twisted]

When u need too as long as its dry lol

[John the tile]

either plasterboard OR backing coat,.

6 weeks, why? I thought skim plasters dried out within a week. On domestic properties I cant see customers beeing to happy if you said it cant be done for 4/6 weeks. Thay will be wanting to get their kitchen or bathroom back to normal??

any comments

[doug boardley]

either plasterboard OR backing coat,.

6 weeks, why? I thought skim plasters dried out within a week. On domestic properties I cant see customers beeing to happy if you said it cant be done for 4/6 weeks. Thay will be wanting to get their kitchen or bathroom back to normal??

any comments

a gypsum base coat will retain its moisture far longer than a plasterboard,it breathes moisture!, as a rule of thumb I'd tile skimmed plasterboard after 2 weeks, basecoat and skim probably about 5 weeks before tiling. Ideally tho' I wouldn't plaster onto skim because of the weight bearing (20kgm2) issues.

[John the tile]

sorry doug, i didnt understand wat you meant when you said you wudnt plaster onto skim? did you mean tile onto skim?

so can you explain why a backing coat that still has a bit of moisture in it will effect a tile being stuck onto its top coat?

just trying to get me head round the reasons!

[david campbell]

either plasterboard OR backing coat,.

6 weeks, why? I thought skim plasters dried out within a week. On domestic properties I cant see customers beeing to happy if you said it cant be done for 4/6 weeks. Thay will be wanting to get their kitchen or bathroom back to normal??

any comments

would you rather wait or do it twice?

[doug boardley]

sorry doug, i didnt understand wat you meant when you said you wudnt plaster onto skim? did you mean tile onto skim?

so can you explain why a backing coat that still has a bit of moisture in it will effect a tile being stuck onto its top coat?

just trying to get me head round the reasons!

yes, that is what I meant!!

[doug boardley]

all sorts of reasons golddigger, latent residual moisture being one of them, which will unbond your adhesive, to be honest there's lot's of reasons why not to tile onto fresh skimed plaster..................

[mikethetile]

When u need too as long as its dry lol

no no no

leave a minimum of 4 weeks

[John the tile]

ok so basically moisture in the backing coat will make the adhesive unbond. fair enough. but


plasters only 3mm ish thick on boards and old walls e.g unibond and skim - there no moisture left in skim after 3 or 4 days. the old walls and boards suck the water out of the skim. ???

[mikethetile]

bb

ok so basically moisture in the backing coat will make the adhesive unbond. fair enough. but


plasters only 3mm ish thick on boards and old walls e.g unibond and skim - there no moisture left in skim after 3 or 4 days. the old walls and boards suck the water out of the skim. ???

if you unibond and then skim the skim can only dry forward

if you tile and grout then the molsture is trapped behind your tiling which can only mean one outcome

4 weeks minimum is reccomended for a reason and thats good enuogh for me and most other people

others try reinventing the wheel at their own peril

its your behind that it will bite if the jobb fails

[grumpygrouter]

Though not a plasterer, I also understand that it can take several weeks for the plaster to gain sufficient strength to cope with the loading of tiles, not just being "dry"!

[John the tile]

i dont think i said i wanted to change anthing, the rules are good enough for me also as well as most other people.

I mereley would like to know the science behind it.

As i said in my previious post tiling onto a skim which is onto a wet backing coat then this takes weeks to dry out - the backing coat that is, so fair enough this may have an adverse effect on the tiling if not fully dried out properly.

as for the "skim drying forward"? I think youve made a mistake there. if thats the case your entering into a whole new world of problems. e.g skim falling off the wall totally not just the tiles

I think the 4 week rule must be a worst case scenario e.g skim onto wet backing coat. therfore skim onto board at lot less than 4 weeks.

?

[andy tiler]

I think this will answer any of your questions



tiles.org.uk/help/answer-gypsum.shtml

[John the tile]

sound - thats one for the bookmarks.



it doesnt say anything about tiling onto skim which is onto boards. or am i blind.

also when it keeps refering to concrete backgrounds what does it mean?

[andy tiler]

golddigger fone british gypsum 08705456123 this is the manufacturer of the skim.

[lucius]

Yes Andy apreciate what they are saying but ive worked on hundeds of sites in differant countries over the years and i cant think of any of these recomendations being adhered to especialy nowadays where the site manager is under pressure to stick to unrealistic targets or lose his job.
Lucius.

[mike111]

Ive just done a lot of tiling for a customer,kitchen floor,splash backs,downstairs toilet,and conservatory,as i was tiling the conservatory with ufh the customer had a well known company come in and totally refit and tile the bathroom, They stripped out old suite first day, 2nd day stripped tiles off two plasterboard walls and left tiles on the other two walls and fitted new suite, 3rd day where they stripped tiles off the plasterboard walls and took some of the board with the tiles they just skimmed over this , two walls about 3m2 each , 4th day tiled over tiles and 5th day tiled the skimmed plasterboard walls, so they left to dry one day only before tiling, this was not the way i would of done things but has anyone else seen this type of work before

[whitebeam]

Float and set was 6 weeks thats why dry linning was used for fast track work, skimming, can't see anybody waiting 4 weeks to be honest. I was on a large refurb at a girls school during the school holidays, the tilers had no time to dwell on 4 weeks drying time for skim work, if it looked dry they tiled

[Rob Z]

It seems like everything here is on the fast-track. Now I don't know what they should call the new fast-track, because the old regular way is now the speeded up way, and that is considered normal.

[Colour Republic]

I would and have tiled over skim (single not double coat) after 3-4 days if that is the only new coat of plaster and I know it's only a couple of mm thick, If the walls have been bonded then finished I would wait anything from 2-4 weeks depending on thickness and if the whole wall was bonded or just patched up

Where some of you are quoting 4 weeks, this applies to plaster with an undercoat

From TTA
10. Gypsum plaster must be thoroughly dry before tiling. New plasterwork consisting of undercoat and finish coat should have been completed at least 4 weeks before tiling is commenced. Tiles should never be fixed to plaster which is not dry throughout. Where drying is assisted by space heating or dehumidifying, care should be taken to ensure that the plaster is not just dry at the surface. The heater or dehumidifier must not be directed at the plasterwork.

[mikethetile]

thanks cr

i dont take chances, if four weeks is the reccomendation ,then thats what i do