Levelling Compound or No More Ply

[Alex3874]

Hi all. Newbie here so please go easy

I've not laid self levelling compound before but am a confident DIY'er so would like to give it a crack.... just trying to do as much research as possible before hand...

I have ripped/stripped out an old bathroom suite (inc stud wall splitting cupboard & shower enclosure). It's at the point where the walls need re-plastering (where old tiles have been removed) and the old flooring has been taken up.

The old flooring was vinyl sheet (on top) but was laid over old 70's style Marley Tiles (which I have now removed as well). This has revealed some black, Bitumen which appears to have been used as an adhesive for the old tiles. Once I removed the old skirting, there was also signs of a plastic membrane (only on the wall which joins the downstairs bathroom to the garage next door, not on the other 3 sides). Please see pic attached.

I would like to install 2msq of electric underfloor heating (once subfloor sorted) and then, finally have new Vinyl floor laid over the top.

My main question is, after priming the existing surface with something like an SBR Primer for adhesion ( & given the above):

1. Would I be better using a levelling compound to achieve a nice smooth, flat surface? Would it be an issue if the compound touches the plaster at the bottom of the walls...? Will this drawn moisture up? Will this be ok laid over the Bitumen?

OR

2. Use something like No More Ply instead and trim to fit. If so, any suggestions on best adhesive to fix this to the existing concrete floor? Can I lay underfloor heating underlay directly into this (after priming)?

Thanks in advance for any help

 

[Old Mod]

Remove as much of the bitumen as you can and then prime with a slurry coat or with either Mapei or Tilemaster's prime and grip. They're suitable for priming bitumen.
Then stick down insulation boards with tile adhesive.
Stagger the joints then tape the joints with a wide scrim tape and smooth tile adhesive over the tape.
That way you'll heat the room and not the screed.

 

[Uheat - Jake]

Exactly as @3_fall said, however as you're using a vinyl make sure you have enough height for a 10mm self levelling compound over the top of the cables.

 

[Alex3874]

Thanks Guys, much appreciated.

I have been advised I could use a 2msq foil (electric) kit and was planning on laying this over the top of the matching reflective underlay (links to both below)...

Foil Underfloor Heating | Under Carpet Heating | Warmup - http://www.warmup.co.uk/underfloor-heating/electric/foil-heater

in conjunction with

http://www.theunderfloorheatingstore.com/warmup-insulated-underlay

The Manufacturer website says:

Simple to install, the foil heater delivers a consistent and even heat distribution. It can also be installed under the floor finish in wet areas without the need for additional earth grids. The thermal properties of the reinforced aluminium foil used in the heater help to spread the heat evenly.

Apparently the foil is so thin, the final Vinyl flooring can be laid straight on top.... I have an off-cut off the vinyl so was going to test the feel of this prior to install.

 

[Uheat - Jake]

Thanks Guys, much appreciated.

I have been advised I could use a 2msq foil (electric) kit and was planning on laying this over the top of the matching reflective underlay (links to both below)...

Foil Underfloor Heating | Under Carpet Heating | Warmup - http://www.warmup.co.uk/underfloor-heating/electric/foil-heater

in conjunction with

http://www.*************************.com/warmup-insulated-underlay

The Manufacturer website says:

Simple to install, the foil heater delivers a consistent and even heat distribution. It can also be installed under the floor finish in wet areas without the need for additional earth grids. The thermal properties of the reinforced aluminium foil used in the heater help to spread the heat evenly.

Apparently the foil is so thin, the final Vinyl flooring can be laid straight on top.... I have an off-cut off the vinyl so was going to test the feel of this prior to install.

Wouldn't be able to speak for other manufactures however our foil mat can have a engineered wood or laminate laid directly on top of it, however a vinyl would need a special layer over the top of the mat, this layer allows the vinyl to then be stuck down as required for vinyl. Unfortunately we don't do such a small foiled mat, therefore we could do a 160w/m2 mat covered with a 10mm flexible self levelling compound.