Hello - and 1930s black ash mortar advice!

Vix79

New Member
Hi all

I’m a decently skilled DIYer looking for some advice...

I have a bedroom (outside) wall with large patches of blown plaster in my 1930s London house. The background is black ash mortar (horrible stuff!) that isn’t damp anymore but is very crumbly and dusty. After loads of research I’m thinking of PVA - bonding coat - skim as a solution. I’m looking for any advice relating to this: e.g product recommendations, how to prep the very dusty black ash, how to apply PVA coats etc.? The black ash is obviously v.high suction, but presumably if I PVA I can then use a low suction bonding coat?

Looking for majority opinions as there’s so much contradictory advice out there and I’ve started going round in circles!

Oh, and don’t say get a professional in. The quotes I’ve had are ££££ and I can’t afford it. The wall is small enough for me to at least have a go.
 

Monkey Boy

Well-Known Member
Bonding - lovely to use but ain’t for high suction backgrounds but you can PVA the heck out of the wall and then PVA on top of the bonding if it is feathered in at the edges or not getting skimmed same day
Why don’t you get a professional in to advise you and pay him for his time because snippets of info can be misleading
 

Stewie03

Well-Known Member
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bof

Well-Known Member
Hi all

........30s London house. The background is black ash mortar (horrible stuff!) that isn’t DAMP anymore

Looking for majority opinions as there’s so much contradictory advice out there and I’ve started going round in commando
The quotes are probably high because it's not a cheap fix

Why was it damp
 

Vix79

New Member
The quotes are probably high because it's not a cheap fix

Why was it damp
Yeah. The quotes weren’t *too* high, per se. Just I can’t afford them!

Damp had come in from rainwater on outer wall thanks to dodgy gutter. Fixed now.
 

Monkey Boy

Well-Known Member
Have you added up the cost of the tool’s you’ll need?
trowel, hawk, handboard, (you need both of those on this site) buckets, mixer paddle, drill, spot boards etc
And compared it with the cost of a quote?
 

Vix79

New Member
To clarify, it’s not that I resent paying a pro, it’s just that lockdown hasn’t been kind to us financially, we’ve just had a second baby 6 weeks ago and this wall is in the room our older boy needs to move into. Atm it’s exposed black ash (I’ve removed the blown plaster to check for any remaining damp in the background) and I need to get it sorted. No time to find the funds to pay a pro and as I’ve done many (admittedly simpler) patching/rendering jobs before I need to, and can, do it myself.

Any advice on the techniques I mention would be much appreciated.
 

ChrispyUK

Well-Known Member
Be a good time to upgrade the insulation as it’s an external wall. Easiest way for you would be to batten it and screw on insulated plaster board. Just needs skimming then.
 

Vix79

New Member
Problem is there’s original plaster coving that won’t come off without disintegrating so it’s not an option. Otherwise plasterboarding definitely would’ve been my first choice!!
 

Monkey Boy

Well-Known Member
You’re going to do it aren’t you?
Techniques:
Watch loads of YouTube videos on rendering and plastering then try to do a practice wall somewhere even if you get a small sheet of plasterboard and fix it to the wall you’re going to work on in the end to give you a feel for technique then remove it after but the gear will react/behave different on ashen block than it does plaster boards
Oh and do post pics pls
 

Vix79

New Member
You’re going to do it aren’t you?
Techniques:
Watch loads of YouTube videos on rendering and plastering then try to do a practice wall somewhere even if you get a small sheet of plasterboard and fix it to the wall you’re going to work on in the end to give you a feel for technique then remove it after but the gear will react/behave different on ashen block than it does plaster boards
Oh and do post pics pls
Like I said, I’m experienced with rendering and patching. It’s more tips regarding prepping / PVAing the ash wall etc. as it’s not a straight forward job. Basic rendering and plastering skills I’ve already got down
 

Brimstone

Well-Known Member
Have you added up the cost of the tool’s you’ll need?
trowel, hawk, handboard, (you need both of those on this site) buckets, mixer paddle, drill, spot boards etc
And compared it with the cost of a quote?
Tools? Tools? Who knew? You have'nt seen the foreigners - bucket and a bucket trowel to mix and finish with, no probs, cash please.
Ignore the coving, leave it alone, fix the board up to it, and keep your boy warmer. He doen't care about how it looks, sort it later whne he leaves home or you're flush.
 
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