Help - plaster crumbling near skirting board!

kaboo

cattom said:

ask a plaster if he wants a cash in hand job one weekend.

Probably a wiser option, but no fun in that plus losing the chance to learn something new! 

Thrugelmir

1930's houses are generally well built. As they are approaching a 100 years old. Make a budget for some maintenance. You'll need it. 

FreeBear

Thrugelmir said: 1930's houses are generally well built. As they are approaching a 100 years old. Make a budget for some maintenance. You'll need it. 

Some of us owners would disagree..

As for tools, for small areas, I'd use a jointing knife - It is like a paint/wallpaper scraper, but available in larger sizes. A plastering trowel would be a bit unwieldy.

kaboo

FreeBear said:
Some of us owners would disagree..

Disagree with what - 1930s houses are well built or save for maintenance?

stuart45

I would buy a few tools and start to learn some basic skills. Times are different nowadays to years ago when you had to rely on Barry Bucknell, and trades secrets were just that.

kaboo

Well yeah, that has been the plan. I will try to learn and do as many internal repairs as possible. I am a first time DIYer, but trained as engineer (different discipline and never worked as one), so tend to learn technical stuff quite quickly.

Just finished fitting a new kitchen myself, painting walls ceiling and joinery, but I was not counting on fixing plaster yet

Already have collected tools for these things, now plaster!

I will let you all know how it goes. Many thanks, if anyone has any new ideas please share, I will only be able to get to it on Sat.

Jeepers_Creepers

kaboo said:

Hi all,
I am in need of some wisdom. I bought my first home, a beautiful 3 bed semi built in 1930s. While repainting I found that in the reception room, at one of the corners, old paint was looking funny. It felt very uneven and upon plaster felt soft and spongy! Knocking with my knuckles produced a very hollow sound. I tapped quite hard and a small chunk of plaster came off!!! Crumbling plaster was being held back by layers of paint!

I then thought that I need to fill this hole again and bought a small tub of polyfilla for deep gaps. As per the instructions I tried to get rid of any loose material. I did not try too hard and did not use much force, but just simple prodding with putty knife brought down good chunk of material. If I try I can break off more material but I stopped when the plaster seemed more sturdy. I am attaching pics. The plaster is over a brick wall.

My plan is, dust with a wire brush gently, clean with damp cloth, paint with VPA primer, then fill with Polyfilla Plaster Repair, smooth with a trowel, and sand after drying. Does this make sense?

But my main question is, as you can see in the pic, there is a gap behind the skirting now. Looks like plaster between the bricks and skirting has fallen through into the floor below the floor boards. What should I do here? Can't just keep filling with plaster repair filler!

Many thanks

 

Hi Kaboo.

You've pretty much got this sussed. And a job of that size is going to be pretty straight-forward since the hole is narrower than the filling knife blade you'll be using to finish it off with.

Yes, any obviously loose wobbling plaster, remove it. But, you need to balance this with 'I need to stop somewhere...'. If I see an obvious crack around the missing section which suggests a further piece has completely dislodged from the brick, then I'm inclined to remove that too or it'll always be a problem. Yes, once the 'hole' becomes larger than the width of the wide filling knife, then you are in to the realms of 'plastering', but in reality that's no big deal... :-)

Yes, scrape/wire-brush the surfaces so all the old loose & crumbly plaster is removed from the bricks, or else the new filler will only adhere to that 'dust', and then comes loose again.

Then nicely thin the PVA - a good 25% water - stir thoroughly, and brush this liberally on to the exposed surfaces, making sure you also focus on where the edge of the remaining plaster meets the bricks - because if that is loose or separated at all, you'll want the PVA to be drawn up between the plaster and the bricks in order to seal and bond it. Keep applying this wet PVA mix - whenever you see it being drawn into a surface - say the mortar gaps, or the edges mentioned before, apply another heavy splash. Keep working it in with the brush, until you are confident no more is being 'sucked' in, and then brush off the excess and let it dry fully.

Another important point - make sure you also brush the exposed bare edges of the remaining plaster, but have a damp cloth with you at all times and use this to wipe away any PVA with comes on to the front painted surface. Don't let the PVA dry on any surface that will be visible afterwards or else it'll cause a nuisance. So, liberally soak the exposed sides with the thinned PVA right up to, and on to, the wall surface to ensure it's all covered, and then - before it dries - wipe the top wall surface clean, allowing the cloth to go over the edge by a mm or two so you know there ain't any remaining up there. Phew, I hope that makes sense?

As said above, pack that gap with anything you like in order to stop the filler slumping down there. Tuck it down a good half-inch, tho', 'cos you do want to fill down a bit behind the skirting board.

Which filler to use? Doesn't really matter, and you've had some good suggestions above. I tend to use 'powdered' filler that you mix up with water and then it actually 'sets' chemically, as opposed to ready-mix stuff which works by drying out. Not a biggie, but the 'setting' type can usually be applied in much thicker layers, with subsequent layers being added as soon as the one below has set - after 30 minutes or so. Ready-mixed stuff needs each layer to dry out fully before subsequent layers are added, or else it all remains damp and soft. Not a biggie, tho', and ready-mixed should dry out PDQ in this weather!

Stuart's suggestion of the Knauf Fill&Finish seems good to me as - from my recollection - it'll both give a very good finish and dry pretty quickly. But that will definitely be a 'apply in thin layers' type - I dunno, 5mm thick? But, any decent-brand filler should work (don't get 'fine surface' filler, as that's usually only designed for really thin layers...! Or, get a wee tub for other 'fine' jobs too...).

Buy yourself a set of filling knives - at least three sizes. The widest should ideally be wider than the hole you are filling, because you then use the surrounding wall surface as your levelling-off guide. Don't fixate on getting this perfect, tho', as you will almost certainly be sanding it afterwards in any case, and also anticipate having to fill any undulations, marks or gaps afterwards too.

And get a good comfy sanding block, and paper to match - nice ali oxide stuff, 80 grit for fast removal, 120 grit for levelling off (and possible good enough for a finish if done lightly) and perhaps some 180 grit too for a really fine finish.

Finally, the first coat of emulsion on these filled parts should be 'mist' coat - ie thinned by around 10% water (read the instructions). Don't be surprised/upset if the edge of the filled area appears obvious after the paint has dried - the plaster can often absorb the paint and swell slightly. Just let it dry fully, and 180-grit it perfectly smooth again. It should be fine after that.

Oh, and post your results as we need a good laugh on this forum.

:-)

stuart45

Screwfix do a set of 3 continental filling knifes for £3, which are good value for DIY.

kaboo

Jeepers thank you so much, and everyone else too. You all are awesome

So I started as you said, removed all lose bits but stopped where I was having to use more force to remove the plaster. Then cleaned off few times with a brush. Wiped down with a damp cloth. Then put in expanding foam behind skirting and cut only a bit below level (I hope that would be enough - I forgot that part a bit). I then put a 1:4 diluted coat of a PVA. I am not sure how liberal I was with it but I made sure I was covering all the surfaces and yes did wipe down the walls around the edges.

then next day undiluted coat of PVA and while it was still tacky, put on a layer of plaster repair (roughly 0.5 cm because thats what the tin said). I have left it to dry for now. I used Polycell's plaster repair ready-mix for now because I already had it. For the next time I will definitely go for the powdered stuff as that is preferred by everyone. 

I have left it to dry for now. Between the job and a child I am unlikely to find time before the next weekend again. So it has plenty of time to dry. For the next iteration of plaster repair layer, should I repeat the process starting with PVA or go straight to plaster repair? 

I am feeling a bit more confident after the first round Also already had a set of cheap plastic putty knives, a set of two Purdy putty knives. But also bought a bucket trowel and stainless steel 11" trowel - both of them from Amazon and not very expensive. Might not need them this time but I will be in this house for many years and definitely use them at some point.  

FreeBear

kaboo said: Wiped down with a damp cloth. Then put in expanding foam behind skirting and cut only a bit below level (I hope that would be enough - I forgot that part a bit). I then put a 1:4 diluted coat of a PVA.

The danger of using expanding foam is squirting too much in and having the skirting pushed away from the wall. Using the foam with an applicator gun is best as you have much better control over the amount being squirted out. The cans with a built-in nozzle tend to be all or nothing.. Should you ever wish to remove the skirting, you'll find the foam makes for a very good adhesive so you end up doing damage either to the skirting or the wall. Those factors were behind my original suggestion to use newspaper as a gap filler.

No need to apply any more PVA. It's primary purpose is to stabalise any loose material and give a bit of extra grip between filler, wall, and old plaster. Now that you have a layer of filler (or plaster) on, it will provide a good surface for subsequent layers to stick to. Give it a quick spray with water when you come to apply the next layer, and it shouldn't suck up all the moisture from the fresh filler.