I need a recipe for render

[wombat47]

Keef .. I impressed with the idea of rendering over corrugated iron. Who'd a thought it would stick. Perhaps that's why he used rusty.

I you have a search around the net, I'm sure you will find information on the mix you need - with or without the addition of cement. I think you will find that you will have to soak your lime, whether or not you need clay (and that needs to soak anyway) .. but use it straightaway once you have put the cement in.

It is my understanding that cement isn't needed anyway.

I used a mix of only hydrated lime and sand (soaked overnight) for interior patching on old (cementless) mortared bricks. Just out of curiosity, I used the leftover to patch an exterior wall where a pipe had been taken out, and added a couple of bricks to a garden wall. This was done about two years ago and the exterior mortar shows no sign of deteriorating.

[ndru]

Keef

This may be useful...

http://barney.webace.com.au/~agstraw/render.html

[Snoopy]

I'm looking at rendering the brickwork on our house. Now I know this is bound to cause some arguments, but can someone suggest a suitable mix? Now on all the DIY TV shows, they love to quote these mixes - but do you think I've ever bothered to write it down?

I imagine that the same mix would work for Keef, as he is applying onto an existing rough finish render.

[ndru]

Snoopy

Try this page
http://www.diydata.com/materials/cement/cement.htm#lime and click on the "render" link.

[ozwinner]

I looked at the link, and even I was confused, so render mix.
3:1:1
3 sand :1 lime: 1 cement.
Use sharp sand ( washed sand ) NOT brickies sand, brickies sand has too much clay in it, and will drag when you try to trowel it..

Life wasnt ment to be a drag unless your name is Miriam..............:eek:

Cheers, Al

[ozwinner]

Keef .. I impressed with the idea of rendering over corrugated iron. Who'd a thought it would stick. Perhaps that's why he used rusty.

It wont stay stuck for too long, maybe just long enough for the cheque to clear.
What with expansion and contraction, it will all be on the ground before too long.


Al

[Snoopy]

Thanks all. As I don't know one good mix from another, I'll take Ozwinners word for it and go for the 3:1:1 mix - maybe just a little plasticiser??.

Any other handy hints? I would imagine that you should wet the brick wall down first to stop the bottom of the coat drying too fast and to help with binding. Our bricks are moderately well textured, but I would still be tempted to fix a layer of chicken mesh to the walls first. Is this a good idea or is the risk of cancer too great?

As for drag, I will leave that topic well alone. Just what sort of 'wood-work' are we talking about here?

Matt

[ozwinner]

Save the chicken wire for the chicken run.Wet the brick first to stop the moisture being drawn out too quickly, unless the bricks are of the hard brittle type.
Plasticiser/detergent, same thing, only use a drop, literally.

Al

[Danster]

Just on the 3:1:1 mix...What would the detergent do?
Would there be any advantage in lobbing in some bondcrete? I'm thinking of rendering my brick house too and if this is a nice mix, I'll use it. My bricks are VERY uneven with knobbly bits - I think they're descibed as "rolled".
Also, trawling the web for info on how to apply, it was suggested to fix vertical timber battens, say 10mm-15mm thick to the bricks (how?) and apply the render between the battens using them as a screed guide. Is this the way to go? If so, is there a point to be made for horizontal batten thingos or best go for vertical?
There was also some advice about starting from the top and working down - suggestions here? I reckon starting at bottom is better.

If screeding the mortar between timber strips, then does the timber then get removed and just pop some mortar mix in the cavity left behind? Would this show up as a vertical (or horizontal depending on which way the wood was) line because of the different times when applied? I'd assume I'd need to leave the mortar to go off for a few days before removing the timber?

cheers all
Danster

[ozwinner]

Just on the 3:1:1 mix...What would the detergent do?

The detergent gives mortar " life", with out it you will find it dead and lifeless, its hard to explain. Try it both ways and see which way you like it.

Would there be any advantage in lobbing in some bondcrete?

No

Also, trawling the web for info on how to apply, it was suggested to fix vertical timber battens, say 10mm-15mm thick to the bricks (how?) and apply the render between the battens using them as a screed guide. Is this the way to go?

Yes

If screeding the mortar between timber strips, then does the timber then get removed and just pop some mortar mix in the cavity left behind? Would this show up as a vertical (or horizontal depending on which way the wood was) line because of the different times when applied? I'd assume I'd need to leave the mortar to go off for a few days before removing the timber?

When you use battens, fix them to the wall vertically with concrete nails then remove the battens as soon as you have covered the section with render, and fill in the gap straight away.
If you leave it until later you will have all kinds of trouble, like, a ridge where the battens were, uneven cover over different sections, battens stuck in the wall. :mad:
The list goes on.
Start from the bottom, you realy need to practice some where before you tackle the house.

Cheers, Al

[Danster]

Thx ozwinner. Much clearer now.
BTW, what makes you so knowledgable? Is rendering your job or part of it?
I assume I'd fix the timber strips into the mortar between bricks?

What sort of spacing between timber - 2 bricks wide? Maybe 3 or 4?

When the timber is removed, and the render to the left & right is still wet, how do I apply the render into the gap without damaging the just-applied render?

cheers, Danster

[ozwinner]

Thx ozwinner. Much clearer now.
BTW, what makes you so knowledgable?
Is rendering your job or part of it?

I did my apprenticeship with my Dad, who was a builder and we used to do reno's, before they became the flavour of the month.

I assume I'd fix the timber strips into the mortar between bricks?

Yes, into the mortar joint.

What sort of spacing between timber - 2 bricks wide? Maybe 3 or 4?

Mmmm, try maybe 2.4M spaceings, you need to get a straight edges, best if its aluminium with a sharp edge, this is your screed, you apply the mortar to the wall, then get your screed and with a left to right action move up the battons over the render, you will get depresions in the render, fill them, and repeat the screeding, etc, etc, until the render has no more hollow spots in it.


When you have finished with the screeding you need to go over the whole lot with a wooden float, so the render becomes, " whole", as one, so it all looks the same.

When the timber is removed, and the render to the left & right is still wet, how do I apply the render into the gap without damaging the just-applied render?

You will always have some damage, but it will fill up and be repaired as you go.

As I said earlier, practice first.

Al