I have plastered walls and ceilings before and do a pretty decent job. I thought rendering would a piece of cake, how wrong was I. As winter was approaching, I was hoping to get the render done around all the openings so I could order in the glazing. While they were in the process of manufacture, I would have the time to complete the render all around that week. Whilst doing the brick work, I kept the external concrete blockwork 15mm recessed around openings just in case any windows or door get damaged, it would save me breaking off the render to get the new frames in. I had to first get the galvanised edging in position. I used a couple of clout nails and started with the top edging. Best to get a proper cutter.
Once they have been temp nailed I dabbed a render mix to hold these is the correct position permanently.
I started with the scratch coat, a 4 plastering sand to 1 Portland cement mix. I mixed in a waterproofer. This went on quite easy. I leveled it using a straight piece of timber roughly. After a few hours when it was almost harden I scratched the surface to make a key for the next coat.
Take out any stones you may find in the render once it’s on the wall as when you run the float over at the final stage it will scratch the surface.
The best procedure I found was this:
1. Get all thew edging in place using nails.
2: Mix the render.
3: Slap it on a quick as you can roughly.
4. Using a feather edge roughly level the render.
5. Allow 3-4 hours to dry
6.Scratch the surface to provide a key
7. The next day scratch of any bits using your trowel.
8. Mix another mix and apply it to the wall approx 3mm over.
9. allow it to dry for a few hours
10. Run the smoothing float in circular motion to flatten the surface.
11. Wet the wall and run over the trowel or wet sponge.