External rendering and mesh

Sam85

New Member
Hi all

I'm having the exterior walls of my whole house rendered. The existing render has been removed down to the brickwork (which is in bad shape). The new loft gable wall has the thermalite blocks and the new ground floor extension has the dense concrete blocks.

My builder will be doing a scratch coat (sand and cement) first and then will do the second coat of sand and cement with a pebble dash finish.

I want to insert a fibre-glass mesh into the middle of the scratch coat to stop cracks appearing in the future and was planning on using the pink BOND IT RENDER MESH from selco.

Can I use this mesh for sand and cement?
Or is there a better one that someone can recommend?
Also does a waterproofer need to be added to the mix?

Thanks
 
i would not render sand and cement on thermalise blocks.
you will need a waterproof additive in the base coat to control the suction to receive the dash.
you can use scrim/ mesh. if preped correctly.
 
As Malc has said do not use sand and cement on Thermalite blocks. You will need something like Everbuild Rendagrip or Plastprime x as a barrier between the block and s&c. The usual mesh is 4mm, which is too small for sand and cement. there is 8 & 10mm on the market. If you can find Parex merchant they will sell you TV10 mesh that is 10mm.

rendagrip all of the wall. Rven drying out.
 
So to confirm if i use evergrip rendergrip on the thermalite blocks first then I can use a s&c render on the blocks?

Do you have to let the rendergrip dry out before s&c or do you put the s&c on while the rendergrip is wet?

Should I rendergrip the old bricks and the concrete blocks aswell? The bricks are in a bad state so they have a big keys.
 
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