Green chipboard preparation

[Silver Birch]

Hi AGAIN
Prior to laying hardi over green chipboard, will I need to prime or sand before laying hardi on thinset??
Cheers

 

[Stef]

Yeah, clean up boards & prime using a suitable primer not PVA.
Mix your adhesive slightly wet to fix your Hardie down & screw using 25mm turbo golds or similar.
Easier to dry lay your boards & draw round them then you can fix one at a time, I walk all over my boards before screw so they are well fixed..

 

[Qwerty]

^^^^^ What he said!!! ^^^^^ [emoji6]

Make sure the boards are suitably fixed and free of deflection too [emoji106]

 

[CJ]

Yup......as above plus 1.

 

[Just Rizzle]

instead of using hardy have u thought of using ditra matting
prime chip board apply flexi addy on 4mm bed roll in pre prepared ditra matting staple down with galvenised staples. i use this method for past 10 yrs. if the floor is uneven skim over the matting with flexi leveler such as weber flex. as i do most of my work on a price basis this method takes about a quarter of the time it takes to put down hardi. also the matting acts as a dpm and is totally water proof use shulter tape over joints. ideal for wet rooms

 

[White Room]

instead of using hardy have u thought of using ditra matting
prime chip board apply flexi addy on 4mm bed roll in pre prepared ditra matting staple down with galvenised staples. i use this method for past 10 yrs. if the floor is uneven skim over the matting with flexi leveler such as weber flex. as i do most of my work on a price basis this method takes about a quarter of the time it takes to put down hardi. also the matting acts as a dpm and is totally water proof use shulter tape over joints. ideal for wet rooms

You cannot be serious

 

[Just Rizzle]

5 yrs ago had a contract for 52 wet rooms every one the same green chip board floors and walls tanked every one with ditra and kerdy matting had to give 3 year guarentee.the tiles we used were 25mm mosaic 3mm thick consulted with shulter for advice. jobs done. zero failures. the germans have been using these systems for years.it also reduces the hight of the job nothing looks worse than a large step up on to a tiled area

 

[White Room]

Nothing wrong with Schluter but stapling them to the floor is the issue...

 

[Just Rizzle]

Nothing wrong with Schluter but stapling them to the floor is the issue...

why holds the matting down when get to end of roll. using a decoupling membrain is a far better method than using a backer board on floor substrates which have deflection and movement

 

[Andy Allen]

why holds the matting down when get to end of roll. using a decoupling membrain is a far better method than using a backer board on floor substrates which have deflection and movement

I was under the impression a decoupling membrane was for lateral movement and not deflection..?

 

[Stef]

I was under the impression a decoupling membrane was for lateral movement and not deflection..?

If anything Hardie backer glued & screwed to the deck will make the floor more rigid than a bit of Ditra.
Hardie state that their boards offer no structural strength but they certainly help the floor & make it feel more secure.

 

[trustiling]

I'd be intersted in this method Ray, but in my opinion it just doesn't sound right....because most new builds joists are not at 300mm centres and more than likely 400+
Even more so the chipboard could be 18mm and it's only glued together at the ends and doesn't always land on a dwang, so putting down sutra or equivalent wouldn't meet the adhesives companies requirements for strength surely?
Also if these bathrooms do need replacing ten ultimately when you lift the ditra the whole subfloor will be destroyed too.

 

[trustiling]

Ditra not sutra!

 

[Stef]

Prob find the new build joists are sitting at 600 centres & as you say they only glue the caberdeck down now, no screws near it.

 

[Andy Allen]

I think ray must have part shares in ditra..lol

 

[Dave]

Using Ditra for deflection is a joke surely ? .... And as for stapling it down ?. Is this all over ? , as that will anchor the polyethylene to fleece through to the substrate hence no lateral stress movement in the fleece to polyethylene bond.

has to be a wind up .:lol:

 

[Ian]

Using Ditra for deflection is a joke surely ? .... And as for stapling it down ?. Is this all over ? , as that will anchor the polyethylene to fleece through to the substrate hence no lateral stress movement in the fleece to polyethylene bond.

has to be a wind up .:lol:

Not to mention puncturing it making it about as waterproof as a sieve [emoji1]

 

[Just Rizzle]

read the history of why you should be using decoupling membrains by going to www.schluter.co.uk

go to technical advice and learn about "Force transfer"

 

[White Room]

We know about Schluter membranes, would they advise stapling to the floor though....I doubt it.

 

[Just Rizzle]

We know about Schluter membranes, would they advise stapling to the floor though....I doubt it.

i know there a bit flimsy were using 4 in nails from now on lol