M
markh
Guest
As the title suggests, the recent job of replacing the roughcast on an outside wall didnt work out, quite the way i intended, and i dragged it all off the wall; all of it.
The old stuff was over 50 years old, and much of the wall was blown, and started falling off after being about 2" away from the wall; i removed it right back to the bricks, as they were the last thing that was still solid, the scratchcoat was just powdery.
I made up a 4:1 with soft sand, and used PVA/water mix, after painting a mix of PVA onto the wall. and all seemed to be fine, for a first ever attempt at plastering, it was looking fine. I waited a few days and then got a decent weather window to apply the top coat. I mixed the top coat as 5:1 and mixed it with SBR/water mix; it went on the wall okay, but the dry dash merely bounced off it, not even the powdery stuff stayed on. So i flattened and floated the wall and thought i'd wet dash it. I just made a mess with that and scraped it off.
Have i done anything wrong?
I have now decided to scratch coat it and then apply mortar with a Tyrolean gun; i bought one, as it was cheaper to buy one, and spend some time experimenting with it than to hire it.
I know i will use PVA/water mix in a 4:1 mix to scratch coat it. In other words NO waterproofer!
What have i done wrong, besides doing the job, or thinking i could do the job, or anything like that?
What mix ratio do i use in the tyrolean gun? someone suggested a normal mortar mix, others have said use emulsion with sand in, and others still, have suggested a slurry coat. I have asked this a number of times on other forums, but not had any answers i can use; is it a goverment secret of something; no-one seems to want to tell anyone anything about it?
Can I apply the mortar in the gun straight onto the scratch coat, or will i need a top coat under it?
The old stuff was over 50 years old, and much of the wall was blown, and started falling off after being about 2" away from the wall; i removed it right back to the bricks, as they were the last thing that was still solid, the scratchcoat was just powdery.
I made up a 4:1 with soft sand, and used PVA/water mix, after painting a mix of PVA onto the wall. and all seemed to be fine, for a first ever attempt at plastering, it was looking fine. I waited a few days and then got a decent weather window to apply the top coat. I mixed the top coat as 5:1 and mixed it with SBR/water mix; it went on the wall okay, but the dry dash merely bounced off it, not even the powdery stuff stayed on. So i flattened and floated the wall and thought i'd wet dash it. I just made a mess with that and scraped it off.
Have i done anything wrong?
I have now decided to scratch coat it and then apply mortar with a Tyrolean gun; i bought one, as it was cheaper to buy one, and spend some time experimenting with it than to hire it.
I know i will use PVA/water mix in a 4:1 mix to scratch coat it. In other words NO waterproofer!
What have i done wrong, besides doing the job, or thinking i could do the job, or anything like that?
What mix ratio do i use in the tyrolean gun? someone suggested a normal mortar mix, others have said use emulsion with sand in, and others still, have suggested a slurry coat. I have asked this a number of times on other forums, but not had any answers i can use; is it a goverment secret of something; no-one seems to want to tell anyone anything about it?
Can I apply the mortar in the gun straight onto the scratch coat, or will i need a top coat under it?