cement rendering

[iaith]

i'm looking for a bit of help as I need to render an external breeze block wall.I've done a fair amount of plastering with bonding and multifinish etc. and the finish I achieve is reasonably good, but I've done next to no work with cement.I would like to know how thick the scratch coat should be, How long you should wait before the top coat, sand/cement ratios, wall preparation, admixes, how thick the top coat should be, when to poly float etc. in fact I need to know everything but any Help would be greatly appreciated. Thanks

 

[noseall]

an external decorative render, (top coat not scratch coat) will look better the swifter you work. if you're not up to speed, the finished product may look like a patchwork quilt.

hose the wall down prior to applying the scratch coat. some spreads say use waterproofer in the top coat only, as the waterproofer denys the final coat any suction. some slower spreads welcome the lack of suction! you may need to damp the scratch coat too.

hydrated lime as is a must when rendering. mix the scratch coat 4:1:1 and the float coat 5:1:1 (rinsed sand, cement, lime).

 

[iaith]

Thanks noseall. I often wondered what hydrated lime was at the builders merchants. unfortunately I've done the scratch coat already without lime, is it too late to get some and use it on the top coat? the scratch coat went on quite well I used a plastersizer and painted the wall first with sbr slurry mix. should I wait for the scratch coat to be totally dry before top coating? Thanks

 

[noseall]

Thanks noseall. should I wait for the scratch coat to be totally dry before top coating? Thanks

not necessarily no. but damping the wall down prior to applying the second coat may be useful.

don't worry too much about the lack of hydrated lime in the scratch, but be sure to include it in the float coat. spreads use a sponge to just to finish the render off, though this is used long after the wood float and only to napp up the surface. don't get on the sponge too early.

 

[iaith]

Great . Thanks.

 

[diyisfree]

Edit,

Double post sorry getting excited

 

[diyisfree]

Agree with noseall,

I always use a poly float to rub up not a wooden one, but i finish off with a large sponge to give a nice finish.

Your finished surface should look something like this

 

[noseall]

i use the term 'wood' float generically, as i too use a poly float. same as fairway woods etc when referring to golf clubs.

 

[iaith]

Thanks guys. I have a poly float, I also have a sponge float , could I use this or should I get one of those big sponges?

 

[The-brickie]

B&Q's have a pack of 5 household sponges that are cheap and do the job very well, nice and square without any holes in them.

 

[noseall]

Thanks guys. I have a poly float, I also have a sponge float , could I use this or should I get one of those big sponges?

as i said earlier, you need both poly float and sponge to do the job properly.

 

[diyisfree]

And a shoulder like arnnies to spread all that heavy render

Give me internal jobs anyday with lovely Browning or Bonding Nice ang light

Noseall,

What are fairway woods ? Is that a country walk near to where you live

 

[noseall]

oooooh diyisfree if only you new. golf is.....well..... such a gentlelmans sport. and a great way to get away from that ubiquitous, ever present, pestering, mobile phone!

 

[diyisfree]

I was at a local golf club a few months ago doing a site survey, It was ****ing it down and i mean torential down pore,

I couldnt beleive my eyes when i saw people milling about with their bats in their hands oblivious to the fact that they were wading through water to get to the ball so they could smack it again

Must be SO hypnotic this game of golf.

 

[WabbitPoo]

B&Q's have a pack of 5 household sponges that are cheap and do the job very well, nice and square without any holes in them.

A sponge with no holes? That'd be a lump of plastic, then!