We all know Gas prices are a joke which is why a massive amount of people are looking towards natural heating. The biggest being at the moment is the classic log burner. However the biggest problem we all have to contend with is how do we plaster a fireplace?
How do you keep your chimney breast protected from the heat and stop your walls from cracking? Sounds scary? Don’t worry because show you everything you need to know and give you the exact process on plastering your fireplace.
However I must warn you: theres a lot to it! You have to prepare the chimney breast for a extreme levels of heat which involves render using a specific mix. Heres the full break down:
- Scratch coat render
- Top coat render with added lime
- Plastered Finish using flexible plaster
This is the full process for plastering a fireplace surround. If your new to the game of plastering well Im afraid to say you have a lot to learn but luckily your in the right place. Lets do it!
Rendering Your Fireplace
The first thing you need to do is to render your fireplace. This will give your wall the strength it needs to deal with extreme levels of heat whilst having a stable background for finish.
However we have to make sure we use the right materials and products. The first thing we need to do is bead the edges of your fireplace. I recommend you use stainless steel render beads.
They will never rust, they are protected from standard water based paints and can withstand the heat and pressure from your log burners. I plant them using galvanised clout nails – just make sure you fix the beads plum on both sides.
It takes a bit more time but it is definitely worth it in later stages. Heres an article on how to fix corner beads from our website. Just take your time and make it right. It can be annoying but trust me its worth it later on.
The biggest thing we need to consider is the render mix we use because this is what gives the strength to our plastered fireplace.
Sand Cement Render Mix For Plastering A Fireplace
Everyone you meet gives different snippets of advice on rendering. Everyone has the perfect mix and the funny thing is everyone has different answers. The real answer is this:
There isn’t a perfect mix!
Everyone has successful results with there own methods. However we have a mix thats works a treat so you might as well copy us because it simply works. Why fix something that isn’t broken?
This is a time proven formula:
- 5 plastering sand
- 1 lime
- 1 cement
- 6 plastering sand
- 1 lime
- 1 cement
The biggest secret in this magic mix is the lime. This allows your walls to expand during extreme heat temperatures and makes your wall a fortress to be reckoned with!
All you need to do now is render the dam thing! Heres how you do it.
This is a scratch coat. The first coat of render which is roughly 7-10mm in thickness. This is the beginning of your wall and helps create a resistance against the log burner.
A scratch coat is a layer of render which is scratched (no s**t), to give the coat a mechanical key. This makes it easy for the next coat to grip allowing you to render for the top coat.
A picture of the top coat:
This is the top coat and as you can see, its been rendered to the thickness of the beads. This process is slightly different and requires a lot more skill and precision. With the scratch coat you can simply render your wall and scratch it a little later.
The top coat needs a lot more attention. You need to render, rule of using a straight edge and then float it using a tool called a devils float. This is basically a plastic (or wooden) float with nails hit through the tip. This is what you use to float and flatten your walls whilst giving a key.
A key is baiscially a form of creating traction for the next material, providing grip for adhesion. If you didn’t create a mechanical key then your next coats of render would simply slide to the floor.
Thats why the picture above has loads of lines going through because this provides a mechanical key for your finish coat. For more advice on internal rendering I’d watch this video series from plastering force. He’s a great plasterer and a good guy so go and have a look at his stuff!
When you’ve finished I would leave the render to dry for at least a week to allow the render to cure. The final step is to put the finish coat on:
Plastering Over Render
Ok so you have a few options here. You could PVA your rendered walls and finish your chimney breast with British Gypsums Multi Finish plaster. This has been done before and can give good results.
However there is a chance the plaster can crack due to the extreme temperatures which deems the job useless. The other option is to use Victus Heat Resistant plaster. This is a product that is designed solely for the use of fire places and heat exposed areas.