Do you need a scratch coat when rendering?

You always have 2 coats of render. The scratch coat is the foundation of the render and the base to the whole product. This provides strength to the wall but also has the most amount of waterproofing. This is what keeps your building water tight and stops any moisture from getting through into your house.

What do you use to scratch render?

For scratch render you’ll need a Plasterer’s Scarifier to scratch the scratch coat. After applying the second coating, you’ll need a TGauge to scratch back at the render before finishing it all off using a Scratch Nail. You’ll also need an edge trimmer to trim the wall’s edge for a better finish.

What ratio is the scratch coat for render?

For the scratch coat as we call it the trade , the mix should be 4:1 , the best way to achieve this is gauge the sand in 12 litre bucket brought from any mechant ( builders bucket).

Can you paint scratch render?

Silicone Paint is the perfect solution for allowing your render system to continue to offer optimum performance.

Should I use PVA before rendering?

Paint the surface with a coat of PVA before application of the mortar. It can be applied undiluted for maximum sealing and/or adhesion, or diluted as above. The mortar or render is best applied when the PVA is slightly tacky.

Do you put lime in scratch coat render?

Lime is used to increase the elasticity of the mix, and prevent it from cracking once it dries. The most appropriate kind of lime to be used for rendering is hydrated lime. Other things could also be added to the rendering mix, such as colour-altering pigments, or additives that aid bonding and drying.

How thick should a scratch coat be?

The strength of the second coat should always be less than the first, but the thickness will vary according to the overall desired thickness, usually between 10-15mm.

Can you render over old scratch coat?

YES. There are many products on the market, one of which is SBR mixed with OPC cement. This creates a slurry which is applied using a brush. I then allow 24 hours for it to dry and then i apply a second coat but follow it straight up with a sand cement scratch coat whilst the slurry is tacky.

How long does Krend last?

Rather than having to repaint your house every 3-5 years, K-rend is designed to last for 30. You also have a really wide range of options with colours and styles, so you won’t feel the need to further decorate the outside of your house once the K-rend is applied. Cleaning K-rend is also easy to do.

Why is my render falling off?

The rendering is falling off because it is dead and no longer adheres to the surface of the wall. poolthetool is spot on. If you wait then water will get in behind it and more and more will fall off. Go all over it and knock off the loose stuff.

Do you wet the wall before rendering?

Only wet the walls down if they are porous – do a suction test by putting a small amount of render on the wall – if it starts to firm up in a few minutes then you may need to damp down, but it will stick without this if they are not too porous.

Can I use plasticiser instead of lime in render?

A lot of renderers don’t use it and prefer to use plasticiser which puts lots of bubbles into the mix which is a good thing but the lime is better as we demonstrate in this video. Roger also discusses the best weather for rendering.

Is plasticiser the same as lime?

Plasticiser can be used instead of lime to improve the workability and durability of mortar mixes. Lime tends to delay the drying time of mortar, whereas plasticisers don’t, still allowing ample time for adjustments. Ideal for use in bricklaying, pointing, rendering and back coatings.

What sand do you use for scratch coat render?

The sand must be plastering sand or rendering sand, not building sand – do not use building sand for rendering because it shrinks and cracks. Sometimes you can add some building sand to the mix for the base coat but it shouldn’t be your primary sand.

Can you smooth render over rough 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.

Can you skim over render?

A question we are often asked is, can you skim over external render? The answer is yes, providing the surface is sound and clean. To prevent your external render cracking, an alkali-resistant fibre glass mesh can be embedded into your scratch coat. This will stop new external render cracking.

Is K Rend worth it?

We use K Rend and we find it to be a more superior product to sand and cement render. The main benefit of using it is that it is maintenance free once done. I done my house 9 years ago with it and it still looks as good as new.

Is K render the same as Monocouche?

Product Description. K Mono is a monocouche render, designed for use with render spray machines. It acts as a one coat / one pass finish over most moderate to low strength brick and block work, providing a labour-saving and cost-effective solution due to reduced application times.

Do I need to PVA before rendering?

Sand, Cement and PVA Mix Paint the surface with a coat of PVA before application of the mortar. It can be applied undiluted for maximum sealing and/or adhesion, or diluted as above. The mortar or render is best applied when the PVA is slightly tacky.

Are cracks in render serious?

If neglected, serious flaws can develop. 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.

What is scratch render?

Scratch Render is through coloured with the finish displaying an attractive open texture after being scratched back when almost set. A smoother texture can also be achieved by the use of a wooden float, plastic trowel or sponge.

What is permarock scratch render?

PermaRock Scratch Render is for single or multiple coat applications to brick or blockwork masonry and onto surfaces treated with a PermaRock or PermaRend reinforced base coat. Incorporates lightweight reinforcement for additional system durability

Can you scratch Wetherby scratch render?

Wetherby Scratch Render lends itself perfectly to being scratched / scraped to provide an open textured surface. Wetherby Scratch Render is a traditional through coloured render which offers a cost effective and very popular textured finish.

How long does it take for render to dry before painting?

Most traditional renders are applied in two coats; a base coat and a topcoat. The first coat is known as the scratch coat, and is applied in a thin layer and left to cure. This can take from between 24 hours up to two days, depending on humidity, temperature, and airflow around the building.