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Render It™ Multisurface can be applied in a thickness ranging from 2mm to 10mm in a single application. If subsequent coats of render are to be applied, the surface should be raked or scratched within 30 minutes of application to provide a rough surface to aid the adhesion of any subsequent coat.
How thick can you apply render?
How thick can render be? They should have a thickness between a minimum of 10 mm and a maximum of 15 mm. Once the render is firm it should be raked or scratched to provide a key for the next coat. final coats Final coats are normally applied by trowel with a maximum thickness of 10 mm over the undercoat.
How thick should a scratch coat be?
The normal thickness is between 3 and 5 mm. On soft or weak background use 1:2 or 2:5. Successive coats must be weaker than this coat.
How do you tell if render is blown?
Look out for cracking or bulging render — both indicate trouble. Blown areas will sound hollow when tapped, while chunks of render may have even fallen off, exposing bare patches of wall behind.
How long to leave render before rubbing?
Wait for 10 minutes and try again. If you are applying a second coat, wait at least 24 hours between coats. There are a wide variety of finishes that can be achieved. Rub different types of floats and materials over the surface to achieve the desired finish.
Do you put Waterproofer in both coats of render?
We have always put waterproofer in both scratch and top. In the scratch in enables greater working time for larger areas. The mix depends on the stength of substrate being rendered.
Can you render with just one coat?
One coat renders are principally used to protect external surfaces from water penetration but their use internally is not excluded. They are normally applied in one coat, sometimes in two passes depending on the required thickness and type of background.
Will re rendering stop damp?
Render. This penetrating damp (as opposed to rising damp, which can be much harder to treat), rendering your external walls can be a great fix – as long as you dry the wall out first.
Can you render on top of render?
Additional coats of render can only be applied safely when the existing work is sound and has satisfactory adhesion over the whole area involved. Further rendering coats should not be applied over soft, friable material, or where the existing render is greater than 15mm thickness.
Is one coat of render enough?
You cant render with one coat and its doesn’t matter what type of finish you want. You need a scratch coat and a top coat so if you only have a top coat it wont adhere like it should .
Why is my new render cracking?
Using the wrong render product for the substrate can cause the water to dry out too fast, due to suction from the substrate, so causing cracking. Delamination occurs if the render product does not adhere – either by chemical key or by suction. Again, this is down to the choice of product for the substrate.
What if it rains after rendering?
Working while it’s raining, as well as rain falling on newly applied render can cause problems with the colour and texture consistency of the finish. As well as this aesthetic issue, excessive amounts of water can affect the bond/adhesion between coats, and could lead to more serious issues.
Do you PVA between render coats?
Instead, you need to use a mix of cement and plastering sand. As with internal walls, external walls will benefit from a few coats of diluted PVA. This is the optimum thickness so that the render can sink into the wall. As always, make sure that you scratch the render before you apply the second coat.
Do you need a scratch coat when rendering?
The first coat of render should be a very thin coat of about 5mm thick. There is no need to scratch right down to the original wall surface, just deep enough to provide a key for the second coat.
What mix is best for rendering?
A common mix ratio used for rendering is 6 parts sand, 1 part cement and 1 part lime. Any general purpose cement can be used, although the sand should be fine and clean of impurities. Coarser sand is usually used as the base layer and slightly finer sand for the top layer.
Does rendering a wall make it waterproof?
Along with protecting brick and strengthening the structure, the render covering the walls of a building acts as a sort of raincoat helping to prevent any water from penetrating the surface.
Do I need two coats of render?
external rendering should never be done with one coat, it will blow off or crack then blow off. The scratch coat is not only for building up or getting a surface flat.
How long do you have to wait after scratch coat?
Scratch coat drying times can vary but typically will require around one to two days of dry time. If you decide to “moist cure” your coat, it can take between three to five days of time. Having a well-done mortar scratch coat that’s given time to cure is important for any decent masonry project.
Can you K Rend over sand and cement scratch coat?
Private Member. Yes you can silicone ft. Let the scratch coat cure for 1 week.
What happens if you use too much plasticiser?
Excessive use of plasticisers can have an adverse effect on the mortar. Lime added to mortars is well known for giving them a soft, putty-like consistency which can make them easier to work and retard their setting.
Should I use Waterproofer In render?
If your render is so low that water gets up behind it, applying waterproofer to the mix would bave made no difference. This is a construction problem you need to fix. It is usual to stop the render about 2 courses of brick above ground level, and certainly no lower than any dpc.
