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How to Render a Wall – The Simple DIY Guide

For the first time, novice DIY enthusiasts, rendering a wall might seem like a fairly complex task. However, rendering a wall follows a fairly similar process to plastering a wall, so if this is something you’ve done before, rendering should be no problem. 

The Guild of Master Craftsmen has created a simple, easy-to-follow guide on how to render a house wall, whether it’s external or internal. In our guide, we address a range of different types of render; such as cement, lime, and sand, and how to achieve the correct mix to create a durable and professional-looking rendered wall.

We will teach you how to:

  • Apply the first coat and the second 
  • How long to leave between coats
  • How to flatten and level them once dry
  • The importance of sponging the render and how to do this
  • How and why you may need to conform to Building Regulations 

Step 1: Preparing the Wall for Rendering 

First, take a look at the width of the wall you want to render. If it’s a particularly wide wall, you may want to install a flat, rectangular piece of wood (a batten) at about 900mm apart and ensure the screws, when drilled in, are flush to the wood (flat). The battens are usually around 15mm thick and help you divide up the wall into segments for easier lime, sand or cement rendering. It’s also strongly recommended you use battens if this is your first time rendering, as once you can treat the first segment as a tester to see how much render you need for the rest. You will also need to dampen the wall before you apply the render.

  • Top tip: Make sure that the screws are flush when drilled in. If they aren’t, you will run into trouble when it comes to rendering the wall (below).

Step 2: Applying the render

Now you can apply the render. To do this, you’ll need a plastering trowel to apply the render. Using your hand, scoop the render and firmly press the render to the damp wall. Make sure your first application is a thinned coat of render (approx 5mm) and that it sticks to the wall. Be sure to work up from the bottom.

It’s important to stick to around 5mm because the wall won’t be able to absorb, or “suck” the render into it if it’s too thick. If you apply too much render to the wall, it will just drop off due to gravity.

You should see your 5mm of render begin to stick almost instantly. You then want to scratch the surface of the first coat to help the second coat bond. You can do this using a professional; scratching tool, or make your own DIY one. For the latter, simply get an old piece of wood (about 10 inches long) and hammer four or five nails at it. The finished product should resemble an oversized comb.

  • Top tip: you don’t need to scratch down to the original wall, just a light combing should be enough for the second coat to stick. 

Step 3: Applying the Second Coat

The first coat will take around 30 minutes to dry before you can apply the second (this counts for both internal walls and external walls). Your second coat should be double the thickness of the first (10mm). This should bring the coat thickness level to match the battens, maybe even a little over the battens. This overspill won’t matter because you will be levelling it off using a straight edge. Again, be sure to work up from the bottom and move the straight edge from side to side as you move higher.

There will undoubtedly be some holes in your render as you glaze over it with the straight-edge. This is normal and can be fixed by grabbing a trowel and filling in any holes, then using the straight edge to smooth them over.

Once completed, leave on the wall for about an hour to dry. Once dry, carefully remove the battens and then fill in the holes left by them using a gauging trowel.

Step 4: Floating up the Render

After removing the battens and rendering the gaps, your house wall, garden wall (or any other brick wall) should be a level and fairly smooth finish. Your cement rendered wall should now be hard enough to withstand a float being pushed into it without the cement render bulging out from the brick wall.

Floating involves essentially closing the render, filling in any tiny air holes to ensure the brick wall becomes completely smooth and more waterproof. When using the float, be sure to be firm with it and move it in gentle, circular motion. You will need to cover the entire wall. Once finished, go back and do this again until your finishing coat looks smooth and without holes. 

  • Top tip: the technique for floating requires a bit of practice – you won’t be an expert on your first attempt! Take as many attempts as you like, it won’t negatively affect your internal or outside block wall. 

Step 5: Sponging Down the Rendered Wall

Whether you’re plastering or rendering an internal wall or an outside wall, you will need to sponge the wall after the last layer of render has dried. By gently sponging the entire wall, you will be smoothing out the surface and closing any final gaps you may have missed. This way, you close any gaps that may have otherwise encouraged water to leak through.

Once done, you should have a professional-looking rendered wall.

Want to Hand it Over to the Professionals?

If you would rather have a professional renderer undertake the task, that’s where we can help. With hundreds of highly skilled and qualified tradesmen featured on our website, we’re confident you’ll be able to find an affordable renderer to tend to your internal and external walls. Whether you’re looking for coloured rendering for a large garden wall or internal rendering for an indoor conversion or extension, you’ll find the right tradesmen with us.

Explore our range of hand-selected renders on our website; all of which have been chosen based on their experience and customer service across the UK.