Shuttering for a concrete floor

[Nick1c]

Like @Visti we are having a power floated concrete floor on the ground floor of our house. This is being done before the frame goes up, there are benefits to this but also problems.... 

The two major ones  are shuttering related - the front & sliding doors need a rebate to allow a flush threshold and we need 2 shower trays to be fitted in the floor later. As far as I can see the options are either to shutter the voids accurately or not shutter the door thresholds & make the shower void too small & use a diamond cutter to make them later. 

If we go for the accurate option I am worried about getting a clean release at the edges & the door shuttering’s stabilty as it can’t be supported on the inside edge (& getting it right!). If we cut after the floor is in the inside corners will be hard to finish cleanly, but a multitool might do the job. 

Visti, did the shower tray method you showed work and is there any tips you can offer?

If anyone else has started with a finished concrete floor before the frame went up what did you do?

 

[Jeremy Harris]

Our power floated concrete floor went down before the house went up.  The door thresholds didn't need to be rebated into the slab, as we just bought Part M compliant doors, that had shallow thresholds that were compliant.  We did need to cut small sections out of the 200mm thick upstand insulation where the door thresholds went, though, (before the slab was poured) to ensure adequate support for their outer edge (they all sit wholly within the insulation of the walls, to minimise thermal bridging).

 

One thing you may wish to consider is allowing for mat wells inside the external doors.  We have found that a Part M compliant door opens with only a small clearance over the floor, not enough for conventional door mats.  We get around this by using very thin super-absorbent mats, which work well, but out of preference I wish we'd made a rebate in the floor to allow a proper doormat to be let into it.  We couldn't do this afterwards by cutting out a recess, as we have the UFH pipes within the floor.

 

I can't seem to find the thread, but there's one here that shows a timber mould being used to shutter a rebate for a shower tray, that might give some ideas as to how to go about it.

[HerbJ]

I think the info   was by me  , originally from ebuild.  The useful info can  be found in a thread called "Wetroom in Kore slab".

 

On the question of mat wells, we have porcelain tile floors directly laid on a poured MBC slab and we created matwels using standard metal tile edging strips, which us matwells approx 15mm deep, which is sufficient for entrance mats. The suitable matting can be bought by the metre to suit

 

[Nick1c]

Thank you @JSHarris, a mat well is something I had originally thought of & promptly forgot. I am struggling to see how to make one though. 

@HerbJ I searched for that phrase in the forums & generally & nothing came up. 

[Mr Punter]

If you are doing polished concrete, don't bother with a mat well.  Just use the thin rubber backed mats - they are less than 4mm.  You will not need to cut them to fit the well either.

[HerbJ]