How to fill behing removed skirting?

bobgroups

Hi,

I removed old skirting and when removing took out nails + big chunks in old wall which is crumbly anyway. An electrician who moved some plug points told me to get a bag of bonding and fill large holes with that. I bought a big bag of british gypsum 25kg thistle bonding purple pack.

bought a bag of bonding from diy shop. I dont have a drill or plaster mixer attachment. Can i mix this bonding with water by hand? Do i need this mixer attachment that you put on end of a drill. If so will need to buy this for 10 quid.

Or is there ready mixed bonding available? it's a small room 10' x 13' square. most of the back of skirting just needs a little filling at the bottom between wooden floorboards and the wall. There are some gaps about 20mm deep where brick is exposed and about 20mm between brick and adjacent areas with old plaster. I am going to pull out some of the old nails still on wall and that may expose more holes.

Help please - thanks Bob.

Sgt_Pepper_2

Can you not just screw some plasterboard to the wall and fill that?

googler

What kind of finish do you want on the wall?

I thought the whole idea of a skirting board was to hide the area where plaster work meets flooring, because of the difficulty of getting a neat joint between the two.

Whenever I've taken skirting off, I've been left with either plaster or plasterboard extending a short way down behind the skirting, then a horizontal wooden spar (to which the skirting is secured/nailed or screwed), with a rough gap below the wooden spar.

I'm curious as to how you're going to get a neat finish on this...

daveb5

you dont need the drill/mixer..just put a couple of pints of water in a clean bucket and mix powder in till its the right consistency...not too wet or it will slump out of the holes...keep adding a little powder and trying it till it works..if its behind the skirting you dont need to worry about how it looks either...if its above the skirting leave it for 20 inutes or so then flick a little bit of water on to it and smooth with whatever tool you used to fill the hole...you can get one coat plaster which finishes better than bonding

Mistral001

Bonding plaster should do this job OK. I have used it sucessfully to fill large holes and gaps in plaster.

You can hand mix small amounts by hand no problem, in say a plastic bowl or even an old soup bowl. It starts to set very quickly though (3 or 4 minutes) so do not mix too much at a time so make sure that all tools are to hand etc ready to go when it is mixed.

I would wet the surface of the plaster/wall to which the bonding is to be applied for greater adhesion

With deep holes bung in a bloob of bonding leaving about 12mm. Wait till it sets and apply the next layer leaving about 2-3mm recess from the wall surface.

When the plaster is set, put a thin skim of finish plaster over it, but I have used Polyila (or B&Q value filler) to do this in the past rather than buying a big bag of finsih coat.

It might be worthwhile investing in a plasterer's trowel to do this job as you need a steel straight edge that will span across the hole that you want to fill for the finishing coat.

Edit: the above leaves a very smooth surface and takes a bit of time. Professional plasterers could probably do this job quite quickly, but unless you have a lot of plastering to do it might not be economical to get in a professional plaster

bobgroups

this is all behind where the new skirting board will go. (Removing old skirting then someone else putting wooden flooring and i will put some new skirting on). So i dont care too much about the finish on the wall. My idea is to smooth and fill the large holes so easier to put new skirting on and wall behind is fairly straight + if I screen new skirting on then I need to fill the gaps as necessary for screws.

Another point to add is that old plaster is really crumbly - it's a grey cement colour - so will bonding or similar stick to the sections of old plaster that are crumbly?

Should i remove all old nails. i'm tempted to leave most there and only remove if really necc. Each time i remove a nail old crumbly plaster comes off with it leaving another hole to file.

Sgt_Pepper_2

You will need to get rid of the loose stuff.

Mistral001

Hard to know without seeing it, but in all restoration work the key is tread gently. In other words do not remove anything that does not absolutly have to be removed. If the plaster is falling off then it has to be removed, but if you think it only might fall off, then perhaps just leave it and remove only the very worst bits. Lots of simple restoration jobs have gone wrong by wanting to "improve" the existing fabric and structure rather than just restoring them.

I have found the key to doing jobs like this is to get a good bond between the plaster and the backgorund. Wetting the existing background will usually do this, though since it is inside work you could apply a PVA adhesive such as Unibond to the background before plastering which might give you a better bond.

PS. If you are sure that the plaster is cement based then maybe you should be using cement mortar rather than bonding. Wetting or PVA still applies

SailorSam

What i've used behind skirting when it's out of sight and basically just to stop any draughts, i'd crush up old newspaper and may mix a bit of filler to hold it together, When you put the skirting back it will be squashed and hidden.

bobgroups

so i guess bonding is the best stuff given there are some gaps and it's old crumbly plaster in front of existing brickwork. gonna see if worth me getting small sections of plasterboard to fill really big gaps - although big gaps are about 6" x 2" in size.

bobgroups

" If you are sure that the plaster is cement based then maybe you should be using cement mortar rather than bonding." hmm not sure it's jsut that it is grey in colour.

Now tempted to leave some of the old nails where they are and maybe cut them with an angle grinder..