Re-Wire With Waterproof Membrane

[pses]

Hi guys

I am starting a re-wire next week and the cutomer has just rung me today to say that the walls have all been covered with a water-proof membrane this week (I know, bloody good of them to tell me now!!).

I'm thinking that now I'll have to cap the cables and fix the capping back to the membrane with some sort of glue rather than nails.

I'm just not sure what I'll have to do about fixing the sockets and switches etc, can I use normal red plugs?

Has anyone worked with this waterproof membrane stuff and how did you 1st fix around it?

Cheers

 

[SLIPSHOD & SLAPDASH]

Theres many types. Some are painted on and some are a hard plastic sheet with dimples. you need to find out whats there and what its being covered with, plaster or plasterboard ?

 

[sellers]

I did one at a school, all the walls were studded out so it was just a case of boxes on battens.

 

[pses]

Its a hard plastic sheet with dimples on the side facing the wall and some sort of mesh on the side facing the room to plaster striaght onto.

 

[SLIPSHOD & SLAPDASH]

On all the jobs i have worked on with that type of membrane the walls have been studed and boarded. You need to raise your concerns with the client pronto about fixing box's & cables and find the total depth in front of the membrane.

 

[sprocketflup]

Did one not too long back, ended up squeezing silicone into every hole we drilled, client was asking for the bare minimum of screws, so saying stuff like "Can you affix that surface mount backbox with one screw?" Needless to say, we didnt.

he hasnt complained yet so i guess it worked

 

[ProDave]

I find it hard to believe they are going to plaster that.

I regularly wire "eco homes" with various layers of membrane like this, and the golden rule is not to penetrate the membrane, or if you have to, to seal the hole afterwards with some special very sticky tape.

In the case of the eco homes there is always a service void that's counter battened and then plasterboarded.

you need to go and have a look at the stuff to see exactly what it is, but more importantly, to establish exactly what goes on top of it and what the final wall makeup is going to be.

 

[Zeespark]

Playing devils advocate here, but, if on the perforated membrane, would it be possible to drill holes in the parts that physically butt up to the wall at all? I only ask as I have seen a similar idea more than a few times on foundation works on Holmes On Homes.

Andy Guinness

 

[philbas]

Is it just me that thinks, this, why not just do things in the correct order, put the electrics in before we add membranes, plaster wall's, tile wall's paint walls, wallpaper walls etc. It would make thinks so much easier.

 

[Sharpend]

At some point the membrane would have to be broken to get cables through or the back boxes fixed/ cut round??

Membrane batten, but how are these fixed?, 1st fixes then plasterboard etc etc?

 

[Manator]

Prodave is correct, the membrane is only certified providing it is not penetrated, if the membrane is installed properly plaster boards can be dot and dabbed directly, however normal procedure is to stud wall leaving a breather in between the membrane and the wall.

 

[steptoe]

Yep, I would ask for battens or something to be left for you to affix to,

You dont want to be the one held responsible for the membrane failing due to your single fixing screw.

Any that I have ever done were battened out and service voids left.

 

[pewter]

sticky back trunking with sticky back , back boxes

 

[Steve3948]

There is a product called waterplug, its powder you mix up a small amount just for fixing you box, it goes off in about 3-5 minutes and is like concrete after that.

Using oval conduit for cable drops set the conduit onto about 4 dabs of water plug hold until set.

Its then ready for render.

 

[Andy™]

sticky back trunking with sticky back

i think just 1 sticky would be enough

 

[SLIPSHOD & SLAPDASH]

Can never have enough sticky !

 

[OnOff]

You can get special "membrane" fixing plugs that theoretically ensure the integrity of the membrane..............but I would guess that if they're not made by the actual membrane supplier then any guarantees would maybe be void. They're also v.expensive - try £60 to 70 for a pack of 200!

http://www.restorationuk.com/waterproof-membranes-for-cellars-and-basments.html

A lot of people seem to favour high performance double sided tape with 3M products being quoted or "in a tube" grip fill type stuff. I'd say if u use tape then make sure the back of the box is grease free ditto the membrane. If using grip-fill etc then I'd rough up the back box.

 

[pses]

The membrane is fixed directly to the wall using the above special membrane plugs.

I have been told that apparntly you use these to fix capping to the membrane and then use the plgs to fix standard metal KO boxes to the membrane with no recessing and then the plasterer skims up to the the box depth....

Good old spreeds, they can hide anything!

 

[SLIPSHOD & SLAPDASH]

I would be interested to see some pics of this being carried out as i have never seen it done this way. Thats going to be a thick bit of muck put on those walls.

 

[Steve3948]

Well 25mm so what they do is a scratch coat, and use comb to form key for next full render coat, then 2 coats of plaster.