Floor prep..

[dboden]

I have a kitchen floor to do.. 26m
Half is floor boards (solid & sound)
half is concrete..
I was going to glue and screw 6mm hardie boards onto the boards, overlapping the concrete by 50-100mm, then make up the concrete depth with flexi SLC.. does this sound the best way?
Thanks in advance

 

[J Sid]

Needs an expansion joint at intersection of concrete and wood or very likely to get a crack form. You may be lucky and not have any problems but your method is not recommended

 

[dboden]

Ok, good point, thankyou....
What about if I do the above, but with the addition of a metre or so of the anti fracture matting over the joining area!! Surely that will cover everything?

 

[J Sid]

If it was me, I would screw the boards down, don't screw into any pipes etc. prime, Ditra the boards if as good as you say or over board with hardie up to intersection of concrete, self level the concrete or Ditra, depending on condition of floor. Tile, with expansion joint, profile or colour match silicon over intersection of the two substrates.
Boarding across the joint, you may be lucky and get away with it if it was your own home, but for a customer, no, not the thing to do.

 

[dboden]

It is brick bond so that messes with the expansion joint really..
What is you opinion on the anti fracture matting idea??.. Isn't this what its for?

 

[J Sid]

No that is no what its for.
Its for lateral movement, you will get lateral and vertical movement at the joint. The vertical movement will do the damage.
I have seen ply and cement boards crack when what you want to do is tried.
Can the bond be turn the other way?

 

[Rich Midge]

I already know I'm going to be slated for this but this is how I tackle these floors and have covered it in other threads. You want to make sure the boards are solid, flat with no deflection. If this means lifting boards, adding noggins or even building piers then so be it. Ply the prepared boards overlapping the concrete by a good couple of feet. I screw this to the joists and the boards and glue it and screw it to the concrete. This means alot of drilling and alot of plugs! I then slc the concrete up to the height of the ply. On top of this I lay a decoupler over the whole floor. Unconventional, yes, costly, yes but I've even layed chipped edge trav with all its holes and veins successfully this way.

 

[J Sid]

Its a lot of work and expense to do away with the expansion joint. If one did fail, even if very unlikely, you have no comeback on any products used, leaving yourself open to a costly retile

 

[Rich Midge]

Fully aware of that mate. I also make my customers fully aware they're taking a risk. It is amazing what lengths people will go to, to avoid using expansion strips! I'll admit I offer no formal guarantee doing floors this way but most are willing to go with it. As my work is pretty much exclusively recommendations I think people know I'd correct any failures.

 

[J Sid]

I wouldn't slate you for your approach, but would be amazed if other don't.