hairline cracks

[master]

hi there been plastering for around 20 years lately seem to have quite a few hairlines on outside render finish is top notch but hair lines spoil it . any ideas on prevnting this

first coat using soft wash sand travis perkins
4-1 or 5-1 depending on background with waterproofer .wet the sratch coat in and topcoat 6-1-1 any ideas appreaciated

 

[warriorupnorth]

try using plastering sand instead of soft sand, maybe some fibres in the mix, welcome to the forum by the way, have look and search , loads of advice on rendering mixes etc

 

[malc]

how can you render in soft sand?

 

[master]

sorry

travis perkins plastering sand what we have been using

 

[master]

used fibres in scratch coat and mesh where needed

 

[malc]

sorry

travis perkins plastering sand what we have been using

still to soft , we would use sharpe sand to scratchcoat with plastering sand mixed 50/50 with sharpe to top coat.

 

[master]

cheers ok will give it a go worth a try we do put sharp in the scratch just not the top coat

 

[nickelarse]

still to soft , we would use sharpe sand to scratchcoat with plastering sand mixed 50/50 with sharpe to top coat.

must be horrible to use tho??

 

[Arti]

still to soft , we would use sharpe sand to scratchcoat with plastering sand mixed 50/50 with sharpe to top coat.

what do u mean by too soft malc??.....we just use plastering normally

 

[ARBIS]

Fix fibre glass mesh into waterproofed adhesive,I would recommend Baumit duo contact,or weber you can also use flexible exterior tiling adhesive,make it levelled leave it 2hours and then one more coat until mesh is fully covered.After 24. Hours apply white Primer leave it dry and then choose coloured acrylic or silicone render.Whole system is just 3mm thick it is anticrack,anti mildew,waterproof,decorative and self washable (when rains).

 

[lucius]

Dont know where you are from master but in my area soft washed is plastering sand nothing like soft sand so you probably aint doing nothing wrong sand wise.

 

[lucius]

Fix fibre glass mesh into waterproofed adhesive,I would recommend Baumit duo contact,or weber you can also use flexible exterior tiling adhesive,make it levelled leave it 2hours and then one more coat until mesh is fully covered.After 24. Hours apply white Primer leave it dry and then choose coloured acrylic or silicone render.Whole system is just 3mm thick it is anticrack,anti mildew,waterproof,decorative and self washable (when rains).

Tiling adhesive

 

[malc]

must be horrible to use tho??

i know what you are thinking, it goes on well but you must let it cream up. the scratchcoat goes hard with the extra grit in it. the final coat finishes very well, when you float up ,the float does not dig in just skims the surface. we float up twice to get water into the render then finish with a sponge.

 

[malc]

what do u mean by too soft malc??.....we just use plastering normally

you need different sizes of grit in the mix to put strength into the render

 

[Arti]

you need different sizes of grit in the mix to put strength into the render

Roger ..........:RpS_thumbup:

 

[bubbles65]

No, Malc :rolleyes)

 

[mark ross]

you need different sizes of grit in the mix to put strength into the render

Not if you start adding polymers.

 

[DannyMac]

Not if you start adding polymers.

Which polymers apart from SBR do you use Mark?

 

[malc]

Not if you start adding polymers.

i agree but you are starting to eat in to the profit. cement and sand render is very basic and low cost. the thincoat render systems are far more supreme, but they are out of a lot of clients price range

 

[Rigsby]

These cracks might be because he has rendered it before the base coat has cured. A wall can look fine until it rains and then on drying out the cracks in the base shows up. For flat render I use loads of fibres in the base coat now and at least stress patches.

 

[Rigsby]

I have seen some of the so called plastering sand some merchants sell. Its washed building sand! Find a good sharp plastering sand.

 

[bubbles65]

Sent 3 lots back in the last month - "It's got a 'P' on the bag so it must be right" - fkin clowns:RpS_mad:

 

[essexandy]

try using plastering sand instead of soft sand, maybe some fibres in the mix, welcome to the forum by the way, have look and search , loads of advice on rendering mixes etc

how can you render in soft sand?

i know what you are thinking, it goes on well but you must let it cream up. the scratchcoat goes hard with the extra grit in it. the final coat finishes very well, when you float up ,the float does not dig in just skims the surface. we float up twice to get water into the render then finish with a sponge.

For what it's worth I use soft washed sand for a lot of my external work although I'll often throw a few shovelfuls of sharp into the scratch coat and always use fibres.
If not that I'll use the Travis plastering sand again with fibres.
Using a sand because it goes really hard isn't necessarily a good thing is it.