What Is An Internal Render?

If you’re in the process of home renovations or building a new home, you’ve likely heard the term “internal render.” It’s thrown around a lot in renovation discussions as of late, but what exactly does it mean? What is a render in general? These are all good questions that we’ll be answering shortly, so stay tuned!

An internal render is the process of adding a cement mixture to walls for a smooth or textured wall.

There’s a bit of ground to cover here, so let’s just get right into it, shall we?

Internal Render: What and Why?

Let’s start with why one would even render a wall in the first place. This is generally done on external walls, but can be done to internal walls for the same effect. It uses pretty much the same basic components as plaster: cement, sand, lime gypsum, and water.

The purpose of rendering is to make it more durable by making the wall water-repellant, and the lime in the mixture allows the wall to let moisture escape rather than just sit. It’s great in heavily moist environments, as it helps prevent walls and floors from collecting condensation, and by extension, mould.

For external walls, people often add a layer of fibreglass mesh (similar to plaster) to allow the wall to be a bit more flexible, with the added benefit of being more resistant to fire and heat.

Another nice benefit to rendering is that you can blend pigments with the mixture as a way to “paint” the wall, even adding another topcoat to truly get the look you want. It’s especially nice on exterior walls if you’re renovating multiple buildings at once. This is because a new render over the whole thing can give the impression that both the old and new buildings were completed at once.

Why an Internal Render?

Long story very short, internal renders are a cheap way to create a smooth surface on masonry. It allows you to make a drastic improvement on old, outdated walls. It’s also nice for walls in rooms that see more moisture like entryways, bathrooms, and kitchens. Alongside its naturally water-resistant properties, a concrete render just looks nice!

If you want to create a feature wall, for example, textured concrete internal renders are great. You can add pigment for a more rich, deep colour compared to paint. Of course, you can always just paint the wall, but that requires a smooth finish, which kind of removes the charm, right?

While I have other looks that I like as well, I do like an internal render’s ability to bring new life to old masonry that’s looking tired. It’s especially good at tying a room with multiple looks (like bare wood, masonry, and basic drywall) because you can vary its overall look to fit.

And of course, you’ve got the added benefit of the fact that it’s concrete. That means you’ll have walls that are about as sturdy as it gets – fewer scratches, and no holes or dents. Add in concrete’s ability to dampen sound, and it’s looking better by the minute.

What Do I Need For an Internal Render?

You need a few things to do your own internal render with concrete. The masonry you’re putting it on needs to be as clean as possible, and you’ll need somewhere to mix it. Add in the mixing tools (wheelbarrow and shovel), a rendering hawk, trowel and flat wood, and a sponge trowel for good measure. But what do you need these for?

  • Wheelbarrow & Shovel – These are used to (respectively) hold and carry your mix, and to mix everything up.
  • Rendering HawkRendering hawks are what you use to actually smooth over the final product.
  • Trowel and Wood – These are used to apply and level your render. The trowel puts it on, the flat piece of wood will keep everything even and flat.
  • Sponge TrowelThis is used to remove any leftover or excess render in gentle, circular motions – just like using a normal sponge.

There are more things that go into a professional internal or external render than this, but if you’re looking to do it at home, these are the basics. I personally recommend that you hire a professional, as there’s a good bit of knowledge that they’ll have to help. They’ll know what to mix in and why (which we’ll briefly cover below), but more importantly, they’ll do it right.

What Goes in Render and Why?

Like we’ve briefly discussed above, there are only four components to concrete render – cement, sand, lime, and water. It’s okay to use general-purpose cement, but the sand needs to be fine and clean. You’ll use more coarse sand for the first coats, but fine sand ensures an even and smooth coat that you won’t get with more gritty sand.

You can use lime mortar (where the cement is replaced entirely with lime) to render older buildings. Lime renders were used in a lot of older buildings, so it’ll fit right in. It’s generally quite flexible and breathable, making it less likely to crash or sustain moisture damage. Its only real downside is that it can’t dry very quickly.

Premixed acrylic render is also an option, boasting strong water resistance and strength with a more broad application. Their main advantage, though, is dry time. A traditional render can take as much as a month to dry, while acrylic typically dries within two days.

Most modern render mixtures made by professionals generally add silicone that’s more breathable (like a lime mortar) than an acrylic render.

Final Thoughts

An internal render is a great option to upgrade old and tired masonry. Whether you want to modernise the look of your home, or you just want a different look, it has a massive spread of options. You can always paint it, but you can also dye or texture it to fit whatever you want! And my personal favourite part about it is that it’s near indestructible. Whether you have kids, pets, or are just plain clumsy, you don’t have to worry about denting or scratching concrete renders.

While it is entirely possible to do this yourself, I personally recommend that you hire a professional to put up a concrete render. Not only will they do it quicker and better than you likely can, but you can rest easy and end up with a new wall.

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About the Author Harry Thompson

Involved in home renovations throughout his life, Harry is an expert in everything to do with home and garden DIY. In his spare time, he enjoys cooking and tending to his garden.