Error: Solid floor level lower than specified. Redo, top up, or what?

[pb2012]

Hi all,

Bit of an issue. We specified a finished floor level with a flush bi-fold door threshold in mind, and were very clear with the builder about the required floor height. All was agreed.

Insulation was laid, concrete poured and left to set. The floor has come out approx 20-25mm lower than specified. We'll now have a 20-25mm door threshold obstruction. Should we accept this?

I was thinking it could be topped up with self leveler, but as we have underfloor heating, the slab will thicken, reducing efficiency?

The affected area is only approx 9.5sqm, so maybe £250 in self-leveling compound?

It's very frustrating as we agonsied over the floor height and took the punt on achieving flush levels!

What would you suggest? What impact on underfloor heating might an additional 25mm have on a 70mm slab?

 

[Notch7]

Can you not lower the doors?

Im presuming you mean screed, not concrete?

Im surprised the finished floor height does not need match somewhere else like an adjacent floor? -or do you have a step in the house somewhere?

Flush thresholds are a pain in the arris

 

[pb2012]

Can't lower the doors nope. They are in.

Yea I mean screed. UFH pipes are set in it.

We have a large open plan space where there is a single 5x8m section, then a step UP to a 3.5x2.8 section. The latter has the bifold doors at the end. The step up was supposed to be approx 140mm. It is 120mm.

Having a threshold isn't the end of the world, but we were set on near-flush inside to out, and that was specified.

The doors do have a rebate in case you were wondering, rather than one of those crappy brush type threshold! They are set a brick lower on the outside.

 

[Notch7]

Can't lower the doors nope. They are in.

They can probably be moved, and your cheapest option. Although if the reveals and head are plastered, that might need redoing.

Im not you can remove the screed -it may damage the underfloor heating, I dont know.

self levelling can be done, as its such a small area it wont impact on the heat all that much, just making that area have a slower response time.

 

[pb2012]

There's no way the builders would entertain dropping the doors lower at this stage. It would have all sorts of other knock-on effects too.

Digging out the screed to re-pour would be traumatic. The builders absolutely won't want to do it, though in most normal scenarios a supplier should do what has to be done.

I think topping up with self-leveler is is the only option, Vs accepting the raised threshold. I guess I'm mainly wondering A) what will the effect be on the heating aspect, and B) is it reasonable to request that the builder foots the bill for all alterations required?

There is still a lot of work to be done on this job and creating any hostility won't be good.

It's just really frustrating that it has worked out like this. It seems a pretty simple thing to get right!

 

[tomfe]

Thicker floor slab = slower response which does not always equal a worse thing.
I have UFH in 100mm concrete slab, no problems in heating up just takes 3 hours so you have to set the timer back.

 

[JP_]

daft question maybe, but is the screed 20mm lower, or the finished floor level (i.e. tiles, wood, carpet?)
I know you said finished floor, but, surely this difference would have been spotted before putting the final floor down?

 

[pb2012]

Thicker floor slab = slower response which does not always equal a worse thing.
I have UFH in 100mm concrete slab, no problems in heating up just takes 3 hours so you have to set the timer back.

True, thicker slab = a bigger heat store I suppose.

daft question maybe, but is the screed 20mm lower, or the finished floor level (i.e. tiles, wood, carpet?)
I know you said finished floor, but, surely this difference would have been spotted before putting the final floor down?

The FFL has been accounted for yep. So the screed is 20mm lower, and so will the finished tiles. There's been a bit of a miscalculation somewhere in the floor build-up.

 

[JP_]

Well, I have no clue really, never done anything like this, but for speed of install, could you put something like this down, then have a thin latex/levelling layer on top?

https://www.insulationshop.co/18mm_jcw_cement_particle_board.html