6mm No More Ply over floor boards

[beanz]

I was just wondering if you can use the same fixing method for NMP as you would use for Hardi-Backer? ie. Rapid Set Flexi, and screw to boards.

And.... How do you spread the Rapid Set? Would you use a notched trowel, or a flat trowel (i'm thinking if the boards have serious concaves)? Also, what centres would you use for the screws, and do you think 20mm screws would be enough? I'm just trying to cover all the bases before going to price up a job in the next couple of days. If the floor boards are nice and flat, i'll probably just use the NMP Adhesive...


Cheers guys

 

[White Room]

This will help Broken Link Removed

 

[beanz]

Cheers Whitebeam.

 

[Rich]

Use the "No more ply mega stregth adhesive" Then screw down with 25mm screws. They say 8 screws per board and be carful with the adhesive, it sticks like poop to a blanket!

 

[beanz]

Yeah i've used it with the adhesive before (on a wall), but thought there might be voids underneath if the floorboards are warped. Not sure how much of an issue that is though!?!

 

[Daz]

If you wedge enough of the "mega strength" addy under the boards you should be okay. The addy swells like expanding foam to fill any gaps etc..

How thick are the existing floorboards?

6mm No More ply + 18mm floorboards equals a max screw length of 24mm, to ensure no burst pipes or electrical issues :yikes:.

 

[beanz]

If you wedge enough of the "mega strength" addy under the boards you should be okay. The addy swells like expanding foam to fill any gaps etc..

How thick are the existing floorboards?

6mm No More ply + 18mm floorboards equals a max screw length of 24mm, to ensure no burst pipes or electrical issues :yikes:.

I haven't seen the job yet to be honest.. Just wanted to get some prices together before i go round, so i can give them a rough estimate. I was gonna play safe with 20mm screws, especially as the screws will pull into the boards, so i'll probably end up with even less than 24mm, if the boards are 18mm (which i imagine they will be).

 

[nudge]

Hardie's are/were an Ausi. Company for over 100 years old and started off selling a French product way back when. I think Officially the have now incorporated in the U.S.A. for Taxation/marketing/legal reasons etc. But i did work for them as a sales person many years ago in Oz. and it always makes me laugh when i read some of the differences in their tech notes here to over there. In there market of origin, screws are an absolute NO. NO. and ( although no one ever really uses it ) 3mm of mastic is all you need over timber floors plus there would need to be quite a few more than 8 nails even on walls - p.s. if boards have cupped a bit then hire a sander. here there site over here if your interested James Hardie :smilewinkgrin:

 

[brian c]

Hardie's are/were an Ausi. Company for over 100 years old and started off selling a French product way back when. I think Officially the have now incorporated in the U.S.A. for Taxation/marketing/legal reasons etc. But i did work for them as a sales person many years ago in Oz. and it always makes me laugh when i read some of the differences in their tech notes here to over there. In there market of origin, screws are an absolute NO. NO. and ( although no one ever really uses it ) 3mm of mastic is all you need over timber floors plus there would need to be quite a few more than 8 nails even on walls - p.s. if boards have cupped a bit then hire a sander. here there site over here if your interested James Hardie :smilewinkgrin:

personally i wouldnt trust MASTIC alone.

 

[nudge]

personally i wouldnt trust MASTIC alone.

Sorry Brian - bad wording thats should be read - instead of the 6mm spec'd over there. I takes nearly 100 nails per 1800 x 900 ( 6' x 3' ) sheet as well - but definately never - never screw down !

 

[beanz]

Interesting post Nudge.

We're a bit less trusting of nails over here, as they have a tendancy to work themselves loose; although whether they can do that under a bed of addy, i don't know!?!

 

[jay]

interesting nudge personaly wouldnt use mastic as it holds no strength in way of deflection and have been screwing down sheets for over 7 years now no problems to date as nails wont hold not even the ring type :8:

 

[nudge]

the main reason for not srewing is in an effort not to shear or break through the face of the board - ( especially a problem with counter sunk screws ) which would greatly weaken the overall bonding of the sheet but rather to have a flat headed nail completely hold it down from the surface of the board itself - if that makes sense ? -

with regards to using an addy as well, that is only required ( over here ) when using the fibro cement board over other than real/untreated timber flooring such as particle board flooring which is basically a pulp of all bits of rubbish wood glued together and therefore doesn't have the internal strength of strip boards to hold a nail tight an so the fastener can work its way to/thru the surface an become loose over time if not also glued - having said that i know for a fact that almost no tilers actually do it ! and yet we don't seem to get any problems.

 

[jay]

nudge we must be in different parts of the world as i know quite a few that glue and screw but each to their own it workes for me and i have seen a few failures first sighns are grout cracking closley followed by tiles cracking :8:

 

[Gazzer]

What i am thinking about is knocking in 100 nails per panel and what i would find if i looked at the ceiling in the room below :yikes: