Hardwall on to breeze block

[Captain5691]

Hi

Can you tell me do i need to PVA breeze block before applying Hardwall?

Thanks

 

[joe-90]

I don't think they make breeze blocks any more. Personally I'd say "If in doubt - get the PVA out".

 

[Captain5691]

Hi

It was the wall behind the stairs when i moved them, so it was bare breeze block, i read through a lot of posts on here and most said make sure the blocks are very wet, so anyway i have done half of what i wanted to and it looks good so far....

 

[joe-90]

If it sticks it's fine. If it's too dry your mix will craze before your eyes.

 

[Captain5691]

Hi

No it did not craze, and looks good even if i say so myself, the hardest bit comes next and that's skimming the hall wall, as its full height, i know i need to PVA over the original paint, will also use very rough sandpaper on the wall first as its been painted with vinal silk.....

 

[trowelmonkey1]

slap some WBA on it instead of going to the trouble of sanding

 

[Captain5691]

Sorry to come across as a complete idiot but what is WBA?, google comes up with West Bromwich Albion, but i guess your not telling me to spread a football team on the wall....

 

[joe-90]

You could do. They're a heap of sh*t.

 

[Captain5691]

You mentioned crazing, well have just checked its now 5 hours since i did it and it has got cracks in it c**p
should i take it off tomorrow and redo it or just plaster over the top? and if i redo it, i guess the cracks are a result of it drying out too quick so a coat of PVA sounds like a very good idea......,

 

[Alastairreid]

You could do. They're a heap of sh*t.

 

[NickB_99]

You mentioned crazing, well have just checked its now 5 hours since i did it and it has got cracks in it

should i take it off tomorrow and redo it or just plaster over the top?

Unlucky. Before you hack it off, would give it some taps with your knuckle to check how well it has stuck on (or not) in different places.
I had a small patch with this problem (when I started with Bonding and didn't do it right). If it has stuck on but just cracked, will probably be ok to proceed to skim.
If it sounds hollow to a tapping would prob get it off. Putting skim over loose bonding won't help - would imagine it'll all still come away in parts.

Remember if you've left a significant time between the bonding setting and applying the skim (e.g. 24hrs), you will prob need some PVA/water mix. Even after only 24 hrs, bonding will look damp, but still has lots of suction and your finish will crack too if you do nothing.
Normally you would want to skim immediately as your bonding firms up and darkens. Then there is only minimal suction and you can skim away on top.

if i redo it, i guess the cracks are a result of it drying out too quick so a coat of PVA sounds like a very good idea......,

Guessed right for the reason. PVA won't help if it lost adhesion to the blocks (as described above).

 

[trowelmonkey1]

good reply newbie!

WBA is sold by wickes (wickes plaster bonding agent) made by knauf, has an aggregate built in like sand to give you a good mechanical key to plaster on to.

 

[NickB_99]

good reply newbie!

Thanks TM1. Was hoping I was on the right lines!

 

[Captain5691]

Thanks for all your feedback, newbee have looked again this morning and although its cracked it feels solid, so will carry on with other jobs and see how the time goes, if time is on my hands i may take it off anyway, as i would rather it not be cracked. and anyway its all good practice....