Rendering a retaining wall

[Grenage]

Hi guys,

Our front garden has a retaining wall, as do our neighbours. All were rendered, but when we moved in, ours was so blown it needed removing sharpish.

I need to replace the top courses and add a couple more, and repoint the truly wrecked areas of the wall, but it will certainly need rendering.

I have skimmed a couple of small areas in the last house, and it was ok. Would I be completely mental to have a crack at two coats myself?

https://tinyurl.com/ydan77qp

 

[roy c]

You will have to take off the top two coarses of bricks, then knock down the pillar and the brickwork that is attached to it and get that rebuilt and tied into the brickwork. After that is all done you can give the old brickwork a rub over with a wire brush and get the loose stuff off. Then cover the whole lot with stainless steel mesh (fixed with galvanised nails). When you come to render it you will have to make up a "scut" mix ( which is measured out at 4 sand 1 cement and instead of water- proofer use pva in your water. Give the whole area a good wetting with water. You then "scut" (throw) the mix over the whole area. You want the consistency of the scut mix to slap on the wall and stick well to the mesh. I used to throw the muck on and go back and check any highs or lows and run a hard road broom over it and straighten it out and leave the brush marks to give a key for the "scratch" coat. So for the scratch coat you can mix it at 5-1 (sand-cement) with water proofer in the mix.. Then give it a few days to cure. You can wet it down as it cures just to hydrate it ( fine spray of water from a garden sprayer all over) but be careful not to put too much on that it brings the scut mix off!! Then when its firmed up I would knock a mix up ( 5 sand 1 cement 1 lime ) and render it up and float it out when it's ready then a light sponge all over it.. Also before you do your rendering I would get some copings on top of your wall, make sure they over hang the wall either side by about an inch an half, you could put these on when you have rebuilt the bricks on top of the wall. Instead of floating it out you could dash it instead, but that's another option .. Always measure your mixes out by the bucket ...Good Luck!!

 

[Grenage]

What an in-depth answer, cheers!

 

[roughcaster]

You will have to take off the top two coarses of bricks, then knock down the pillar and the brickwork that is attached to it and get that rebuilt and tied into the brickwork. After that is all done you can give the old brickwork a rub over with a wire brush and get the loose stuff off. Then cover the whole lot with stainless steel mesh (fixed with galvanised nails). When you come to render it you will have to make up a "scut" mix ( which is measured out at 4 sand 1 cement and instead of water- proofer use pva in your water. Give the whole area a good wetting with water. You then "scut" (throw) the mix over the whole area. You want the consistency of the scut mix to slap on the wall and stick well to the mesh. I used to throw the muck on and go back and check any highs or lows and run a hard road broom over it and straighten it out and leave the brush marks to give a key for the "scratch" coat. So for the scratch coat you can mix it at 5-1 (sand-cement) with water proofer in the mix.. Then give it a few days to cure. You can wet it down as it cures just to hydrate it ( fine spray of water from a garden sprayer all over) but be careful not to put too much on that it brings the scut mix off!! Then when its firmed up I would knock a mix up ( 5 sand 1 cement 1 lime ) and render it up and float it out when it's ready then a light sponge all over it.. Also before you do your rendering I would get some copings on top of your wall, make sure they over hang the wall either side by about an inch an half, you could put these on when you have rebuilt the bricks on top of the wall. Instead of floating it out you could dash it instead, but that's another option .. Always measure your mixes out by the bucket ...Good Luck!!

That's what you call a reply. I agree with every word Roy says.

 

[Bilabong007]

Just out of interest, why would you use pva in the scut coat instead of sbr?

 

[lostinthelight]

Just out of interest, why would you use pva in the scut coat instead of sbr?

And, go to the expence of ss mesh and use galv nails to fix it?
litl

 

[roy c]

I would and have done all the above for years. The reason between pva and sbr is that they both do more or less the same job (SBR) is more expensive and PVA is a lot cheaper and will both do the same job.. SBR was brought in a few years ago when everyone had "Dry Rot" and "Wet Rot" and the chemical companies made the chemicals that was going to "kill" and eradicate dry rot and wet rot and rising damp.. And SBR was the new (PVA) I still think that both brands still do more or less the same job. I worked in the treatment and irradication business in the 80's when "everyone " had dry rot. And a lot of people made a lot of money out of it. I would always use Stainless steel mesh and l galvanised nails to hold it on. The reason being is that the galvanised mesh, will sometimes rust through (Not always) so I don't take the chance of that happening...

 

[lostinthelight]

I would always use ss mesh but why not use ss fixings?
I have just ss meshed parts of the outsde of my house and fixed it with over a thousand 2" ss screws and penny washers.
The rest was sbr slurry coated before rendering, used sbr because its more waterproof than pva.
litl

 

[roy c]

I have seen rusted galvanised mesh but not galvanised nails. There is also the cost of nails against ss/screws and washers. Depends on who is paying the bills.. Also a time factor with screws as opposed to nails,,,

 

[Grenage]

Couple of quick question if I may; how deep does the scut mix need to be - just enough to cover the mesh? Also, measuring by the bucket, do you mean to only mix one bucket's worth at a time?

 

[roy c]

Your scut coat is to give your scratch a good surface to go on. When I say mix by the bucket it means that all your mixes must come from the same sized bucket or what ever you use to gauge your mixes correctly...

 

[Grenage]

Ah makes sense. Thanks again!

 

[roy c]

As a matter of interest are you using a mixer for your mixes? If not I will tell you another way of mixing your mortar..

 

[Grenage]

I've got a paddle mixer and a drill, but that's about it!

 

[roy c]

Ok. I used this trick (I don't know anybody else who has done it) (Only the lads I have shown) What I did was get a piece of thick gauge polythene and if I was doing this on my own I would only use a piece about six foot by six foot square (if there were two of us I would use a bigger sized piece of Poly) and lie it on the ground then I would find a container to gauge my mix and put it on the edge of my poly sheet and grab two corners of the sheet and walk it to the other side of the poly and I would do this (side to side) till all the gauge had mixed. Then I would put some water (not too much) (with an additive in it) over the mix and move it from opposite corners of the poly and pour more of my gauging water over it till the consistency got to what I wanted .If you over water it you can make a measured gauge up and mix that up (dry) and add it to your mix till you get the consistency that you want. Don't forget you can split your mix up ( but keep the gauge right) if you want smaller mixes,,Let us know how you get on ..