Pebbledashing/Roughcasting a new block garden wall.

[Can-do]

Hi All, new to this site and have scanned for various bits of the info I need, however, here's my challenge. (I hope I haven't posted this twice but it didn't seem to work first time?)

I've built a 17 foot wall between my house and garage to screen of the drive from a new sandstone patio I'm laying to the rear of the house. The wall is 6 ft high made of 190 width Topblocks on a 2 ft concrete footing. I tied the damp course into the house and garage and used the strip wall ties to connect to the house and garage walls. It has a 215 width brick and tile arch doorway through the middle and a tiled and round brick capping (@3.35 a brick I nearly passed out!). The house was built in the mid-30s and has exposed brick bands and white painted rough cast which to me appears to be a sort of pebble dash but then with a cement and sand final coat to soften the surface texture?? Various builders have tried to persuade me that it is just pebbledash with years of overpainting but I'm sure the "pebbles" were either mixed into the dash or a final coat of sand/cement overcoated.

Everything looks really great this far and now I want to roughcast both sides of the wall to match into the original house and garage finish. Effectively I have four panels of about 6'8" x 6ft (both sides/either side of the gateway) to render/roughcast. Previously where I have had to patch previous areas where windows have been moved etc by previous owners I have been most successful applying a PVA adhesive coating at 1:1 and then using white waterproof cement based tile adhesive, then pebble dashing on to that while wet, then applying a further coating of tile adhesive thinned to a goop with PVA adhesive once the pebbles had set. However this is the first time I'll have worked from a large area of bare blocks and I don't want to c*ck it up!. Here's my questions:

1. It seems from other topics and responses I should soak the blocks prior to rendering a first coat in 3/1 sharp sand to cement and then scratching the surface in wavy lines -- correct??
2. Should I add waterproofing to this first coat mix?
3. How thick should the first coat be roughly?
4. Should I use my tile adhesive approach prior to pebble dashing or should I use more 3:1 sharp sand to cement mix to pebble dash into?
5. Many of the smaller areas I've overcoated with tile adhesive/PVA have now been up for more than five years successfully -- but is there a better way of "rounding off" the rough profile of the initial pebble dash?

Any advice welcome.

[diyisfree]

4:1:1 for scratch coat,

Thats 4 plastering sand (not building sand)
1 part cement
and 1 part hydrated lime

DO NOT use P.V.A. if you do want to use an adhesion promoter then i would suggest SBR for exterior use.

Second coat (top coat )should be 3:1:1

wet bricks/blocks with a hose first, leave for a few mins for excess water to run off then go for it..

good luck

[onion]

diyisfree wrote:

4:1:1 for scratch coat, Thats 4 plastering sand (not building sand) 1 part cement and 1 part hydrated lime DO NOT use P.V.A. if you do want to use an adhesion promoter then i would suggest SBR for exterior use. Second coat (top coat )should be 3:1:1 wet bricks/blocks with a hose first, leave for a few mins for excess water to run off then go for it.. good luck

top coat should be a weaker mix try 5-1-1

you dont have to put lime in first coat

agree with everything else

[noseall]

summertime: use waterproofer in the scratch coat.

the dead of winter: no waterproofer in the scratch coat.

always use wp in the float coat.

[diyisfree]

Onion,

Well spoted mate not sure why i suggested a stronger mix for top coat. Must have had an hard day when i responded to that one

Thanks for putting it right.

[Can-do]

Thank you all for your advice and sorry for delay in saying "thank you" -- this was my first time using this site.

I've never used "plastering sand" before -- it really makes a difference to the ease of applying without picking up on stones etc. The hardest part was the physical effort of casting the pea shingle into the top coat before it hardened too much.

End result looks great and looks as if it was all built with the house in the 1930s. I've still got to fit a frame and door into the arched brick and tile doorway and paint to match the house but even my wife who hates the DIY mess thinks it was all worth the effort.

[decopete]

have you seen - - - - - - - - - , they have a lime based spray on render that looks like stones????
very clever. saw them at Grand Designs in NEC last month, I thnk they are in Manchester,

[Moderator 11]

one of many advertising posts edited