Amitico sub-floor

[n0p]

Need advice on the sub-floor route and cost issue. like others before I have received varying advice.
we are having an extension built and have to decide
a) to have standard sub-floor of chipboard, then get floor fitter to install a 6mil marine ply base and fit the Amitico.
or
b) get the builder to install a 12mil ply sub-floor straight off and get the Amitco fitted directly to this.

Any views on cost and best route to take would be most appreciated

 

[flooringman]

If you go for option a) you will be paying for the chipboard,the installation of the chipboard, the ply and the installation of the ply.

If you go for option b) you will be paying for the ply and the installation of the ply.

Add up the costs and decide but bear in mind you will need 18mm ply (just wbp will do) as 12mm will not be load bearing.

Then if it has been laid ok you can lay the Amtico on to this.

 

[n0p]

Um ! - now worried even more as builder advised 12 mil ply as replacment alternative for chipboard - but advice is for 18mil? Surely the cost would be higher for the extra depth?

Also fitter has advised that the builders finish may not be good enough to lay Amtico on?

The builder has quoted for a sub-floor of blng Regs approved chip flooring, so this is in effect in the cost anyway, the addition would be the difference between ply and chipboard or the additional cost of the 6 mil 'extra' layer.

 

[flooringman]

I am presuming (perhaps wrongly) that the chipboard is going down on joists. If this is the case the 12mm boards would not be load bearing you need a minimum 18mm. The fitter you mentioned - is that the Amtico flitter or the guy who is boarding out?

If it is the Amtico fitter then be guided by him as he will be responsible for the overall finish.

Don't get me wrong - overboarding with 6mm wbp ply on to the chipboard will be fine (use ring shank nails or divergent staples to fix).
The surface should have a feather finish applied anyway before the Amtico goes down.