Rendering a new house,

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johniosaif

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Hi, I am rendering a house built with concrete block . I normally scud blockwork firstly, then a day or so later scratch it with s/c at four to one using fine sharp and opc and additives containing plasticiser /waterproofer(contradiction I know) I will leave it to dry for five days before adding a five to one /one sand /cement/ lime coat. I will also use fibres and I am inclined following been on here to use a mesh in the scratch to reduce likelyhood of cracking. What mesh do I need to purchase as I know little of that end of things,, Any thoughts advice appreciated ..
 
6-8mm mesh if you can get it. There is Chinese crap on ebay if you don't have a conscience. I use 8mm 210g for sand and cement.
 
I always scudd as well...............its not a bad habit though.......................:RpS_thumbup:
 
I have no more info than what I posted but it seems to be all normal standard concrete block ,85p a block so nothing special..
If your blocks are less then 7 newton ,mesh the lot ,i only base my info on monocouche weber renders ,there are guys on here that do s/c render day in day out ,that can give you alot more info ,best of luck ...come on Mark where are you !lol
 
If your blocks are less then 7 newton ,mesh the lot ,i only base my info on monocouche weber renders ,there are guys on here that do s/c render day in day out ,that can give you alot more info ,best of luck ...come on Mark where are you !lol
I expect that the are less than 7 newton.
 
Really? A concrete block less than 7 newton?
Have to admit ,I am not an expert on blocks, I have bought them on occasion of course and have asked for certain types of blocks but have a memory like a old gold fish. I take it that 7 is the standard newton rate for a concrete block then...
 
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Have to admit ,I am not an expert on blocks, I have bought them on occasion of course and have asked for certain types of blocks but have a memory like a old gold fish. I take it that 7 is the standard newton rate for a concrete block then...

No, I am wrong. Just read that some concrete blocks are 3.5 newton. I would mesh these.
 
No, I am wrong. Just read that some concrete blocks are 3.5 newton. I would mesh these.
We all learn something every day the say, all I know is he bought them fairly cheap, the are solid concrete blocks and look fit for purpose, I am fairly sold on the mesh idea now. any good ways of applying it? fit as you go while it is still soft.../
 
Most new jobs I come across are 3.5n blocks. 5:1 sand and cement scratch, never had a problem. I have in recent years though got to be crack conscious so I either mesh stress points or chuck some 12mm fibres in that area.
 
Most new jobs I come across are 3.5n blocks. 5:1 sand and cement scratch, never had a problem. I have in recent years though got to be crack conscious so I either mesh stress points or chuck some 12mm fibres in that area.
So 5 to 1 scratch /6 to 1 float with lime 6/1/1 then. would you put fibres throughout the render? meshing stress points? not meaning s/s mesh I take it or movement beads?
 
We all learn something every day the say, all I know is he bought them fairly cheap, the are solid concrete blocks and look fit for purpose, I am fairly sold on the mesh idea now. any good ways of applying it? fit as you go while it is still soft.../

whack your scratch on flatten it , get you mesh on the surface, trowel it in, scarify
 
Most new jobs I come across are 3.5n blocks. 5:1 sand and cement scratch, never had a problem. I have in recent years though got to be crack conscious so I either mesh stress points or chuck some 12mm fibres in that area.

I just assumed that with those crappy soft celcons at 4 newton and not being recommended for exterior walls, that all concrete would be much stronger.

The softest ones we have rendered have been 7+ I'm pretty sure.

Look at this link. This particular manufacterer recommends their 7 newton block as a minimum on exteriors.


concrete blocks, concrete building blocks Masterlite Pro
 
Yep they recommend it, but do builders follow that?

Do they **** they just look at the blocks and get the cheaper, thinking they are much harder then celcons. Then they get all upset when you say your gonna have to charge extra for mesh for them to get a warranty!

At this point they tend to get some other monkey in who doesnt know what they are doing and they mess it all up.

Oh how we laugh!
 
Yep they recommend it, but do builders follow that?

Do they **** they just look at the blocks and get the cheaper, thinking they are much harder then celcons. Then they get all upset when you say your gonna have to charge extra for mesh for them to get a warranty!

At this point they tend to get some other monkey in who doesnt know what they are doing and they mess it all up.

Oh how we laugh!
I was trying to avoid been the monkey...
 
So 5 to 1 scratch /6 to 1 float with lime 6/1/1 then. would you put fibres throughout the render? meshing stress points? not meaning s/s mesh I take it or movement beads?

Hi John

stress patching is when you cut the reinforcing mesh into 300 x 500 strips, apply the fist coat over corners of windows of doors (fairly thin) then embed the mesh strips. Then cover the whole area with first coat (and mesh the whole lot as Currier said)

Good luck mate!
 
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