how long for finish coat

[groucho]

had a bit of a prob today refused to tile onto thistle bonding coat. peed everybody off but i know im right. so question now is with a finish coat put on top how long to wait to tile ?? bonding coat been on about a week. thanks

[Alan.P]

The general rule of thumb is a day per mm depth IIRC

[whitebeam]

Was the bonding dry when the finish was put on

[groucho]

bonding is on already been on about a week. finish coat being put on sat

[whitebeam]

The reason I ask is because multi finish should be put on low suction backgrounds, dry bonding can be very absorbant and can suck the water out of the finish and cause crazing or make it very weak. Normally a pva would be put on before the finish is applied to stop to much suction.

[groucho]

funny you should mention that the plasterer said if you put PVA on the bonding coat it can be tiled. Never neard of that before have you? problem now is the bonding coat is level with rest of wall ( only half wall is bonded. just the 4 courses of tiling) so I presume the whole wall will have to be skimmed? rest of wall has paint on. Done a tape test and it was fine but does the plasterer have to do anything to the wall before for the finish to take?

[whitebeam]

Don't tile onto gypsum undercoats with pva, the plasterer should have skimmed the bonding when it had set and was still green. Jointing to the existing wall with the finish and make it flush, which can still be done, plasterers being a bit lazy and it's his job to finish off.