drex
New Member
Hi. I have had a bash at plastering and rendering as a diy chap and did a brief course at college a few years ago and now I am in the middle of big indoor project putting some render on the walls in my stripped out kitchen prior to fitting the rest of it.. (first fix electrical back boxes already done)..
So far I have done the ceiling using plasterboard and skimmed over. That was a tricky one because it's hot now and it set far too quickly for my slow pace and I had to rush to an appointment and didn't get my last trowel pass over so it ended up a bit lacking in the smoothness department.. I made the mistake of trying to skim and finish another coat over this several hours later when it had dried in the 30 degree heat, which took even longer than the 3 hours it took to put the previous two coats of skim! And I don't think it even made an improvement. I am guessing because I didn't have enough thickness on that last additional 3rd coat to work it properly over the now hardened two initial coats?
Anyway, on to the wall rendering.. I looked at a few utubes and advice places and it seemed there is a bit of variety in how folks do the job, but basically I gathered this..
1. prepare the wall (brick). pva..
2. first coat 4/1 plasterers sand/cement.. waterproofer/plasticiser in the water at 30/1 (after wetting the wall down).
3. Darby the first coat,
4. Then scratch it with the scarifier.. (It seems to not dig in very well if the render has set too much, and dig in too much if its still too wet! when is the best time to do this?)
5. Second coat.. 5/1 (Not done this yet.. I am wondering how long to wait before putting the second coat on? It seems some folks put it on straight after the first, yet others wait "at least 2 days" before second coat.. I also wonder if I need to pva the first coat before applying the second?)..
6. Float the second coat.. Now I have a few questions.. What should I do after leveling the second coat? Should I just float it with the trowel and rough up the surface or use one of those "devil floats" which seems to be just a plastic float with some screws added to one end..? I am wondering what is the point of this? Is it so the final skim coat can get key? But if that is the purpose, why not use the scarifier on this coat too?
7. Skim coat. finishing plaster. Again, how long to wait before I put the finish coat on?
I have already figured out that rendering walls isn't, despite what I have heard to the contrary, easier than boarding and skimming ceilings. It also seems to use a massive amount of material..
Another thing is, you need to cover up all the pipes, electrical stuff and anything within range of falling plaster, because a bucket full will end up anywhere other than on the wall... (Before being scraped up and used to fill the tricky bits between the electrical boxes etc.. )
Also, cats like to sit on the spot board under the work lamps, because even in a heat wave they prefer the direct heat from the halogen bulbs and don't seem to mind getting messed up and spending half an hour licking themselves clean after and spitting..
Render mix will splash into your eyes every time you pour it out of the mixer.. Goggles are useful unless you want to actually see what is going on in there..
Rendering round multiple electrical back boxes is time consuming and fiddly!
One thing I worked out for myself.. It's a good idea to batten the walls up with the correct thickness of wood to break the job down into more manageable chunks when you are starting out/not too good or speedy at it and because it makes the darbywork easier.. I had the smart idea of screwing the wood in, and I am hoping that I can "raise" the battens higher for the second coat just by putting some folded newspaper or whatever behind, prior to taking the battens out and filling the gaps later?
Well, long intro I know but that's where I am at and I hope you chaps can tell me where I am going wrong and give me a few tips..
drex
So far I have done the ceiling using plasterboard and skimmed over. That was a tricky one because it's hot now and it set far too quickly for my slow pace and I had to rush to an appointment and didn't get my last trowel pass over so it ended up a bit lacking in the smoothness department.. I made the mistake of trying to skim and finish another coat over this several hours later when it had dried in the 30 degree heat, which took even longer than the 3 hours it took to put the previous two coats of skim! And I don't think it even made an improvement. I am guessing because I didn't have enough thickness on that last additional 3rd coat to work it properly over the now hardened two initial coats?
Anyway, on to the wall rendering.. I looked at a few utubes and advice places and it seemed there is a bit of variety in how folks do the job, but basically I gathered this..
1. prepare the wall (brick). pva..
2. first coat 4/1 plasterers sand/cement.. waterproofer/plasticiser in the water at 30/1 (after wetting the wall down).
3. Darby the first coat,
4. Then scratch it with the scarifier.. (It seems to not dig in very well if the render has set too much, and dig in too much if its still too wet! when is the best time to do this?)
5. Second coat.. 5/1 (Not done this yet.. I am wondering how long to wait before putting the second coat on? It seems some folks put it on straight after the first, yet others wait "at least 2 days" before second coat.. I also wonder if I need to pva the first coat before applying the second?)..
6. Float the second coat.. Now I have a few questions.. What should I do after leveling the second coat? Should I just float it with the trowel and rough up the surface or use one of those "devil floats" which seems to be just a plastic float with some screws added to one end..? I am wondering what is the point of this? Is it so the final skim coat can get key? But if that is the purpose, why not use the scarifier on this coat too?
7. Skim coat. finishing plaster. Again, how long to wait before I put the finish coat on?
I have already figured out that rendering walls isn't, despite what I have heard to the contrary, easier than boarding and skimming ceilings. It also seems to use a massive amount of material..
Another thing is, you need to cover up all the pipes, electrical stuff and anything within range of falling plaster, because a bucket full will end up anywhere other than on the wall... (Before being scraped up and used to fill the tricky bits between the electrical boxes etc.. )
Also, cats like to sit on the spot board under the work lamps, because even in a heat wave they prefer the direct heat from the halogen bulbs and don't seem to mind getting messed up and spending half an hour licking themselves clean after and spitting..
Render mix will splash into your eyes every time you pour it out of the mixer.. Goggles are useful unless you want to actually see what is going on in there..
Rendering round multiple electrical back boxes is time consuming and fiddly!
One thing I worked out for myself.. It's a good idea to batten the walls up with the correct thickness of wood to break the job down into more manageable chunks when you are starting out/not too good or speedy at it and because it makes the darbywork easier.. I had the smart idea of screwing the wood in, and I am hoping that I can "raise" the battens higher for the second coat just by putting some folded newspaper or whatever behind, prior to taking the battens out and filling the gaps later?
Well, long intro I know but that's where I am at and I hope you chaps can tell me where I am going wrong and give me a few tips..
drex