Plastering over capped cables

[diynige]

I've just had the leckies in and they obviously hate cutting chases because the top of plastic capping that they've used is virtually flush with the existing plaster in most places. The depth of the capping below the plaster surface varies from about 0.5mm to about 3mm.

How deep does the plaster need to be over the capping to achieve a good plastered surface? Do I need to get the electricians back in before getting the plastering done?

 

[Richard C]

½ mm is not enough to skim over, you need at least 3 or it’s very likely to crack & fall off. I generally allow at least 5mm & either skim with Multifinish if blending in or, which I prefer, initially skim out to the surrounding wall with Bonding plaster (it sticks to the capping better) & then re-skim the whole wall with Multi, then you will never see the join.

 

[diynige]

Many thanks for the reply - I also read elsewhere that PVA should be used to seal the area before bonding. Is it good practice to liberally paint a coat of PVA over the chased area to seal it before applying the bonding coat?

 

[Richard C]

I also read elsewhere that PVA should be used to seal the area before bonding. Is it good practice to liberally paint a coat of PVA over the chased area to seal it before applying the bonding coat?

Yup; give it an initial strong coat (3:1) the day before & then a quick 5:1 & plaster when it goes tacky; don't over brush the capping or you’ll wash off the previous days bonding coat of PVA which helps the plaster stick to the surface of the capping.

Don't use Bonding plaster out to the surface if your only blending in the chase; it's a base coat plaster, very course & you wont get a decent enough finish on it to paint.