Rendering roughcast garage wall

[paulmag]

I have a garage that was, I think, wetcast? many years ago and I want to put a render of it and get a smoother finish. The roughcast is ridiculously strong and chisels don't make much of an impact . Am i ok to just render straight onto the existing surface? I've seen the excel doc with the estimated quantities required. What does the lime do?

Thanks in advance

 

[dann09]

If it works why fix it?

Knocking off might give you more difficulties, and going on top of the in-situ might give even more!

 

[Micilin]

If it is sound you can go over it but some things to look out for.

Is there clearance on door and windo reveals and drips on cills and fascia

 

[paulmag]

If it works why fix it?

Because it has been there since the 30's and needs patched in places but mostly because we want to make it look a bit smarter

It would be too big a job a to chisel off the existing roughcast and potentially damage the brick underneath. Can anyone give any advice?

Thanks

 

[Alastairreid]

Yes you can go over it! you need to take heed of what micilin said though.

 

[roy c]

Has the roughcast been painted?

 

[paulmag]

"Is there clearance on door and windo reveals and drips on cills and fascia"

We cut a new side door so yeah should be fine for that, the lintel above both windows needs patched up as well so was going to shutter those and pour in some concrete in there as well to tidy those up.

No the garage hasn't been painted, this'll just be a thin scratch coat onto the existing surface. I thought i'd powerwash it first then paint on some sbr before slopping on some cement render at roughly 10mm thickness