Hair cracks in render

J

Jimmyatko

New Member
Hi all, ive just started internal render/plaster on my house, after about 5 days im still having to rub over cracks, admitedly, its a coat over wood fibre insulation, the coat also does have hair in. Its the first time ive ever done lime plastering so im hoping for some constructive advice/critisism, is it a norm to still have to deal with cracking this long after first applied?? Cheers
 
You may want to add vapour barrier such as OSB board and and plasterboard over it.
Wood fibre insulation itself may move/contract causing cracking in plastering layer over it.
 
Jimmyatko said:
Hi all, ive just started internal render/plaster on my house, after about 5 days im still having to rub over cracks, admitedly, its a coat over wood fibre insulation, the coat also does have hair in. Its the first time ive ever done lime plastering so im hoping for some constructive advice/critisism, is it a norm to still have to deal with cracking this long after first applied?? Cheers
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don't know the material your covering but possible to much suction in it. to heavy a coat on same day can cause it' a slow build up may help over time maybe 2 to3 coats you cant rush lime work
 
we are carrying out the same type of work at the moment. our first coat is euro cork with a full mesh. no problems what so ever.
 
Theres no name on the boarding, i gave the board a misting but it looked like the water was rolling off another issue is i cant build up layers as i have approx 55mm from wall to door frames, 40 mm insulation rest render Im not after a smooth finish on my walls, i used a mix of 3:1 being 2 grit sand-1building sand-1 lime, i didnt use any mesh as i assumed the mesh would be too fine for the grit sand. I will however find some thing to put on next time!!! Should i of put insulation on the wall and then spent a couple of days wetting it up before putting render on to it?
 
If you still have cracks, you could fix them with jointing compound (it has some glue in it).
You can always later add mesh, with premixed cement based render, it makes thin layer, so you will not have problem with clearance.
 
If you are using wood wool boards like I think you are describing, you do not need to dampen them.
I do 3 sand to 1 lime putty mix. (Add fly ash or brick dust in winter to speed up the set)
Mesh embedded in scratch coat and no need for fibres then.
When scratch is sufficiently hard dampen down and put on the second or final coat of the same mix depending on the finish you want.
Lime tends to do what it wants.
Keep it hydrated don’t make your mixes too wet.
If you are doing limework there by no means should any cement or gypsum be included.
 
Hi there you said you used (a mix of 3:1 being 2 grit sand-1building sand-1 lime)
What time of lime? Hydraulic lime /hydrated lime/Non-hydraulic lime or even a lime putty?
 
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