Old skim coat is weak and crumbly in patches

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RJW91

New Member
Evening gentlemen. So I recently bought a new house, another old dump in need of major renovations.

Bit of a dilemma concerning the plaster situation. The walls are blockwork and have been plastered with s&c and skimmed with whatever gypsum finish plaster was known as in the early 70s.

The s&c seems fine, little bit weak maybe but not blown other than in a few small areas. The finish on the other hand is another story. An awful lot of it seems to be very poorly adhered, I have quite easily scraped off several sq ft in less than a minute in some spots, before hitting some that seems to actually be putting up a bit of resistance. This has mostly originated from around where something was screwed to the wall or around the many hairline cracks that are all over the place, but I can tell it’s happening in other spots as well by going over the wall and tapping with my fingertip.

I suppose really I’d just appreciate a bit of advice from the pros. I definitely wouldn’t want to hack it all off to just dot and dab, I plan on living here for quite some time and I don’t want to have to deal with the ballache of fixing to dot and dabbed walls every time I want to put up a picture or whatever. I would consider batten and board, but then I would face the same hollow wall issues unless I also lined the walls with plywood, which means more expenditure and a further reduction in room size, so that’s out.

So looking at the different ways forward, I’m thinking I can either:

1.Take everything off back to block, as I’ve said previously the render is somewhat weak and where I have hacked off certain spots it doesn’t take much effort with the SDS chisel. I am quite confident at skimming but never done float and set on entire walls. Seems like a good chance to teach myself, I only ever do small patch ups at work so I doubt I’ll get the chance to learn this anywhere else. I believe the total wall area for the house somewhere in the region of 175m2 so it wouldn’t be a huge expense to buy all the bonding or hardwall.


2. hack off just the finish coat. This is pretty much effortless in some areas and then it can be quite tough in others, so much so that the only way to remove it really is to dig into the s&c slightly. I feel a bit of a necessity to do this, as I know there are weak patches all over the wall and all the walls were papered previously, so it would save washing down anywhere with paste residue and flaky paint left on. I’m finding it pretty frustrating doing just this, takes much longer than just hacking off everything would. Managed to find a scraper attachment thing for reciprocating saws, I doubt it will be much help but I thought I might as well give it a try.

3. Hack off all the areas of loose finish that I can identify, clean up any wallpaper paste residue and dirt etc, go over everything with a bonding agent and hope for the best.

These feel like the only options worth considering, although I’ll listen to whatever the real plasterers have to say. So yeah, let me know what you think!
 

Stewie03

Well-Known Member
If you want to keep costs to a minimum patch up the areas that have blown back to brick,scrape off all the loose finish any finish that is still well bonded and is tough leave on,the backing coat will be quite dusty so give it a good soaking down,2 generous coats of pva,then 2 tight coats of bonding onto the backing plaster to fill out with the existing skim,let it pull in abit give it a float for some key and skim away as normal you will have 2different setting times on your walls so take it into consideration,you can just pva the backing after wetting down and skim but I think you will get caught out by suction
 

Mike Harrison

Active Member
Evening gentlemen. So I recently bought a new house, another old dump in need of major renovations.

Bit of a dilemma concerning the plaster situation. The walls are blockwork and have been plastered with s&c and skimmed with whatever gypsum finish plaster was known as in the early 70s.

The s&c seems fine, little bit weak maybe but not blown other than in a few small areas. The finish on the other hand is another story. An awful lot of it seems to be very poorly adhered, I have quite easily scraped off several sq ft in less than a minute in some spots, before hitting some that seems to actually be putting up a bit of resistance. This has mostly originated from around where something was screwed to the wall or around the many hairline cracks that are all over the place, but I can tell it’s happening in other spots as well by going over the wall and tapping with my fingertip.

I suppose really I’d just appreciate a bit of advice from the pros. I definitely wouldn’t want to hack it all off to just dot and dab, I plan on living here for quite some time and I don’t want to have to deal with the ballache of fixing to dot and dabbed walls every time I want to put up a picture or whatever. I would consider batten and board, but then I would face the same hollow wall issues unless I also lined the walls with plywood, which means more expenditure and a further reduction in room size, so that’s out.

So looking at the different ways forward, I’m thinking I can either:

1.Take everything off back to block, as I’ve said previously the render is somewhat weak and where I have hacked off certain spots it doesn’t take much effort with the SDS chisel. I am quite confident at skimming but never done float and set on entire walls. Seems like a good chance to teach myself, I only ever do small patch ups at work so I doubt I’ll get the chance to learn this anywhere else. I believe the total wall area for the house somewhere in the region of 175m2 so it wouldn’t be a huge expense to buy all the bonding or hardwall.


2. hack off just the finish coat. This is pretty much effortless in some areas and then it can be quite tough in others, so much so that the only way to remove it really is to dig into the s&c slightly. I feel a bit of a necessity to do this, as I know there are weak patches all over the wall and all the walls were papered previously, so it would save washing down anywhere with paste residue and flaky paint left on. I’m finding it pretty frustrating doing just this, takes much longer than just hacking off everything would. Managed to find a scraper attachment thing for reciprocating saws, I doubt it will be much help but I thought I might as well give it a try.

3. Hack off all the areas of loose finish that I can identify, clean up any wallpaper paste residue and dirt etc, go over everything with a bonding agent and hope for the best.

These feel like the only options worth considering, although I’ll listen to whatever the real plasterers have to say. So yeah, let me know what you think!
Floating is a skill mate and wouldn't even attempt it if you weren't capable it will cost you more in the long run dot and dab it.ive been plastering 15 years can do a bit of floating but wouldn't even think off doing my own house
 

Memered

New Member
Evening gentlemen. So I recently bought a new house, another old dump in need of major renovations.

Bit of a dilemma concerning the plaster situation. The walls are blockwork and have been plastered with s&c and skimmed with whatever gypsum finish plaster was known as in the early 70s.

The s&c seems fine, little bit weak maybe but not blown other than in a few small areas. The finish on the other hand is another story. An awful lot of it seems to be very poorly adhered, I have quite easily scraped off several sq ft in less than a minute in some spots, before hitting some that seems to actually be putting up a bit of resistance. This has mostly originated from around where something was screwed to the wall or around the many hairline cracks that are all over the place, but I can tell it’s happening in other spots as well by going over the wall and tapping with my fingertip.

I suppose really I’d just appreciate a bit of advice from the pros. I definitely wouldn’t want to hack it all off to just dot and dab, I plan on living here for quite some time and I don’t want to have to deal with the ballache of fixing to dot and dabbed walls every time I want to put up a picture or whatever. I would consider batten and board, but then I would face the same hollow wall issues unless I also lined the walls with plywood, which means more expenditure and a further reduction in room size, so that’s out.

So looking at the different ways forward, I’m thinking I can either:

1.Take everything off back to block, as I’ve said previously the render is somewhat weak and where I have hacked off certain spots it doesn’t take much effort with the SDS chisel. I am quite confident at skimming but never done float and set on entire walls. Seems like a good chance to teach myself, I only ever do small patch ups at work so I doubt I’ll get the chance to learn this anywhere else. I believe the total wall area for the house somewhere in the region of 175m2 so it wouldn’t be a huge expense to buy all the bonding or hardwall.


2. hack off just the finish coat. This is pretty much effortless in some areas and then it can be quite tough in others, so much so that the only way to remove it really is to dig into the s&c slightly. I feel a bit of a necessity to do this, as I know there are weak patches all over the wall and all the walls were papered previously, so it would save washing down anywhere with paste residue and flaky paint left on. I’m finding it pretty frustrating doing just this, takes much longer than just hacking off everything would. Managed to find a scraper attachment thing for reciprocating saws, I doubt it will be much help but I thought I might as well give it a try.

3. Hack off all the areas of loose finish that I can identify, clean up any wallpaper paste residue and dirt etc, go over everything with a bonding agent and hope for the best.

These feel like the only options worth considering, although I’ll listen to whatever the real plasterers have to say. So yeah, let me know what you think!
First of all, we should start by clearing up a myth: most drywall by itself is not smooth. When first putting up drywall, you screw it in place, tape the seams, and cover them with joint compound. But the paper covering the entire sheet of drywall is typically not smooth. Many brands have a subtle texture like cross hatching, which can create a noticeable difference when you paint over the perfectly smooth seams vs. the sorta textured rest of the drywall.
 
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