Floor Tiling on 21mm T & G chipboard

[Penelopejean]

I know there have been similar posts a few years ago but I wondered if new technology has changed ideas.

Our architect/surveyor has specified 21mm T & G Chipboard for our new 1st Floor bathroom floor onto new 195 x 50 joists at 400 ctrs. (No mention of moisture proof chipboard.) We are intending on ceramic tiles on top and our chippie says you can tile straight onto this. The chipboard floor hasn't been laid yet so can be changed if necessary.

Question 1 - Is all T & G Chipboard moisture proof?
Question 2 - Will it need Marineply on the top and if so what thickness?
Question 3 - What tile cement is advisable these days and is any pre prep needed?
Question 4 - What is best grout to use?
Question 5 - Is it best to lay marine ply straight onto joists instead if so what thickness?
Any other useful tips would be great.
Many Thanks in advance.

 

[tpt]

Question 1 - Is all T & G Chipboard moisture proof? - NO (the the moisture resistant stuff is just waxed\treated. dont use it.)
Question 2 - Will it need Marineply on the top and if so what thickness? Not on top, best to just use WBP ply instead of the T&G chip
Question 3 - What tile cement is advisable these days and is any pre prep needed?
Any S1 rated flexi adhesive- i'd suggest granfix rapid (just cos thats what i sell most of) - BAL is also very well thought of
Question 4 - What is best grout to use?
Any flexible - i'd suggest granfix maxigrout (just cos thats what i sell most of)
Question 5 - Is it best to lay marine ply straight onto joists instead if so what thickness? Yes 20mm.

Alternatively you can use a backer board over the chip, but if your starting fresh best to just ditch the chip.

 

[iwaters]

tpt has the bases covered.

One point to pick on the OPs post. Your chippie says you can tile straight on to the chipboard, but what does your tiler say? If he says you can, fire him. Find one that says its a terrible idea and suggests using WBP ply as this is the best option. Especially as the chipboard hasn't been laid yet.

 

[IJWS15]

You might also want to ask for more noggins to stiffen the floor. You know you are going to tile so get it built as stiff as you can.