Hard wall

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Spreadley

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Hey I need some advice on hard wall under plaster.

I am plastering on to old render, I have removed the old blown skim and primed the surface with Cemtone plaster primer. The old render is all over the place so I need to pull it out with an under coat.

I'm I right in thinking that because the background is of moderate suction I should use hard wall instead of bonding or does it not matter?

Any advice would be appreciated thanks
 
If it's an interior wall it doesn't really matter. If it's an exterior wall with no cavity you should use S+C.
 
Is there a key on the render if not you should use should use a primer with an aggregate in it like thistle bond it
 
martinemj said:
hardwall or any gypsum plaster not really ideal on an older property
with no cavity or dpc ...especially if any signs of damp

not sure what type of property op has
Click to expand...

hardwall replaced renovation plaster ideal for this situation, cavity or not had it confirmed with British gypsum
 
Completely agree mart. Any gypsum product especially bonding or hard wall will draw damp in on properties without cavity.
if there is a cavity wall then hard wall is best.
Why has skim blown/failed?
if because of damp then remove all plaster and re do in lime, how it should have been done in the first place!
 
I thought that cemtone gear had agg in it, but didn't hold back suction but could be wrong.

Never used it.
 
As the guys have said Hardwall is ok ,unless it is an older property , it will cause damp problems :RpS_thumbup:
 
BG must be wrong then ,architects I've worked for spec this for exterior walls especially in older properties,
 
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Dunno who U ve been working for but comman knowledge that gypsum on solid walls draws damp.
if you put a wet bush on hardwall or bonding, as u would before skimming then it sucks it in. Lime breaths and doesn't take in moisture!
Have a look on the lime forum there is some useful info about a similar situation on a stone cott.
 
I'd have to agree with everyone on the gypsum thing but superspread must have a point. BG wouldn't say it was right if it wasn't.
 
On old exterior walls I use a sand and cement scratch coat with hardwall on top - as long as there are no known penetrating damp issues - but I wouldn't use hardwall alone unless it was specified by someone else who was overseeing the job :RpS_thumbup:
 
JVplastering said:
Dunno who U ve been working for but comman knowledge that gypsum on solid walls draws damp.
if you put a wet bush on hardwall or bonding, as u would before skimming then it sucks it in. Lime breaths and doesn't take in moisture!
Have a look on the lime forum there is some useful info about a similar situation on a stone cott.
Click to expand...

Bonding draws in moisture supposedly cos it contains vermiculite ,whereas hardwall doesn't
if you set hardwall next day and give it a fine spray it doesn't soak in and there's a moderate suction can't say they about bonding tho. On Monday ring BG and put your mind at ease
 
A building might not have any damp issues until you put gypsum on ex walls and draw damp in. Hope u use plenty waterproofer!
Could use damp proof like bitumen, but that's not how solid walls were meant to work.
Use lime like how it was originally done and succeeded for 100s years!
 
And if damp or moisture is coming thru 9inch solid brickwork which is sometimes rendered hardwall is the least of your problems, sand and cement won't hold it back.agree with you about lime ,I luv using it but as you well know not practical most of the time,only certain clients will pay for it .
 
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JVplastering said:
A building might not have any damp issues until you put gypsum on ex walls and draw damp in. Hope u use plenty waterproofer!
Could use damp proof like bitumen, but that's not how solid walls were meant to work.
Use lime like how it was originally done and succeeded for 100s years!
Click to expand...

I agree about the lime and how the old solid walls should be allowed to breath but 99% of customers ain't gonna have it and having used a S/C scratch with hardwall(renovating previously) and dry-lining systems for 20+ years without any comebacks I am confident that any walls I have done that way are still nice and dry. Freeflo has never let me down yet :RpS_thumbup:
 
I do agree with u lads lime is king but u have to pay for it. Lucky I've had clients willing to do with it the right way and I rest easy!
Do u ever put air bricks in or and venting to outside? Have any probs with condensation?
Think before putting hardwall on ex walls would have to check no gyp render or pointing outside and chex moisture level in the wall!
 
What about thistle Dri coat?
CArlos, it does contain grit but not as good as other primers in holding back high suction IMO.
 
Something said about injection damp corse with dricoat needs futher reading. However hardwall doesn't look good in the white book in this area, says reduces strength and adhere in moisture and condensation. Also says walls have to be completely dry?!
 
JVplastering said:
I do agree with u lads lime is king but u have to pay for it. Lucky I've had clients willing to do with it the right way and I rest easy!
Do u ever put air bricks in or and venting to outside? Have any probs with condensation?
Think before putting hardwall on ex walls would have to check no gyp render or pointing outside and chex moisture level in the wall!
Click to expand...

I have a job coming in the summer grade 2 listed small house to be completely renovated in lime plaster including lathe ceilings. Only used Myke Wye products before but saw an interesting article by a company that used chalk lime in one thick coat for the lathes.
 
Sounds impressive! Never had any experience with that but I'll look into it. Only ever built out lime in small thin coats. Keep me posted!
 
JVplastering said:
I do agree with u lads lime is king but u have to pay for it. Lucky I've had clients willing to do with it the right way and I rest easy!
Do u ever put air bricks in or and venting to outside? Have any probs with condensation?
Think before putting hardwall on ex walls would have to check no gyp render or pointing outside and chex moisture level in the wall!
Click to expand...

Yeah, there are loads of things to look out for when weighing a job up, ventilation and air circulation being one of the main things on a lot of jobs where condensation is the issue.
I've also seen something which can be a problem with older uPVC windows where there is a damp wall below it. The drainage holes can be blocked and the water build-up finds it's way into the wall via the screw-holes in the cills. Look for rusty screws where the fitter has screwed through the frame into the cill.
And if the window looks dodgy ask the customer to open it :RpS_thumbup:
 
I like the last info flat not straight!

Looks good and makes sense. Got some wool boards to do on a ceiling at the mo, might try it there.

I use Ty mawr south wales but new comp started up called renew some good rates.
 
Ha ha that's one way of ventilation!! Do you ever put insulation boards on over s/c? Heard of a few doing that? Holds back salts?
 
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