Roughcasting Applied to Wall and now Cracking as it Dries?
Brickwork, drystone walling, render are a few subjects covered here. Click here to post questions and get answers

2 posts   •   Page 1 of 1
markh75
Labourer
Labourer
Posts: 2
Joined: Wed Jul 15, 2015 9:44 am

Roughcasting Applied to Wall and now Cracking as it Dries?

by markh75 » Wed Jul 15, 2015 10:03 am

Hi folks, i'm new to the forum, and have a question about roughcasting. I recently removed the roughcast and scratchcoat from a blown wall; i have cleaned the wall and slurry coated it; and since then have applied the scratch coat. I used three 4:2:1 mixes, with water and SBR at 4 parts water to 1 part SBR. I used sharp sand, cement and lime. I painted an easily coverable area (700 x 700mm) with the SBR mix and applied the render, and kept going like this until the job was finished. I gave it a screed across and up and down, polished it and scratched it. I gave it a good 12 - 14mm depth.
Okay up to now?
My problem is that there are very small cracks appearing as it dries; this is despite keeping an eye on it and wetting it; it wasn't very warm, but it was a nice day when i did the job.For my first attempt its looks brilliant, if only for the cracks. Is the job ruined? will it all fall off now?
What can i do to save the job?
I thought about a slurry coat (with PVA) at the cracked areas, brush it in well and leave it until the next coat. Will this work? Or is the job a gonner?
I think there's one crack that needs attention before i top coat it; it'll need digging out and resetting (there is a difference in sound when i tap the area with my finger), Is it okay to do this? or should i just leave it?
I'd very much appreciate any suggestions and/or advice guys!

markh75
Labourer
Labourer
Posts: 2
Joined: Wed Jul 15, 2015 9:44 am

Re: Roughcasting Applied to Wall and now Cracking as it Dries?

by markh75 » Thu Jul 16, 2015 11:17 am

The job has now dried and the job looks good; i made up a slurry mix with a water/PVA mix and cement, and brushed it into the cracks. Many of them were just superficial surface cracks, not worth worrying about, but a couple were slightly larger, once I'd done them i used up the rest of my mix by going all around the edge and over any cracks that were needing more. The job is fine, looks good and is solid!
My question is: I intend to put on a second coat before a wet dash (which i will apply with a Tyrolean Gun); do I wet dash it on the second coat while still setting (wet)? or can i scratch the second coat and apply the wet dash on the dry scratched surface?
I know i need to use a plasticiser in the second coat; do i put plasticiser (PVA) into the roughcast dash?

Thanks guys!

2 posts   •   Page 1 of 1
It is currently Mon Feb 05, 2024 6:30 am