A hearth is not just a functional component of your fireplace; it's a statement piece that can enhance the overall aesthetic of your living space. Whether you plan to cozy up by a warm fire or you're simply looking for a decorative addition, a well-crafted concrete hearth can be the perfect solution. In this article, we'll explore the ins and outs of making a concrete hearth for your fireplace, taking into account key considerations such as regulations, thickness, finishing, and style.

First Things First: Regulations

Before diving into the creative process of crafting your concrete hearth, it's essential to consider safety and compliance with hearth regulations, especially if you intend to have a fire on it.

Log Burner Hearth Regulations

As per building regulations (Part J), any stove must be placed on a non-combustible material such as granite, slate, steel, glass or concrete.

In most existing homes of a certain age with a fireplace you will have what is called a “constructional hearth”. This is typically made of concrete and is at least 250mm thick they normally outwards into the room and are wider than the fireplace recess.

Image Courtesy of Phillips Heating & Stoves Ltd

Image Courtesy of Phillips Heating & Stoves Ltd

For free-standing stoves, the hearth should extend at least 300mm to the front and 150mm to either side, be at least 12mm thick, made from non-combustible materials, and cover a minimum area of 840 x 840mm.

If your stove's heat doesn't raise the hearth's temperature above 100°C, or if it hasn't been tested, the required thickness increases to 250mm.

Hearth Regulations for Stoves in Fireplace Recesses

If you're placing your stove into a fireplace recess, you'll need a 'constructional hearth,' as mentioned above. It should project at least 500mm outwards into your room and be wider than the recess by a minimum of 150mm. You would place your concrete hearth on top of this.

Once you're certain that your hearth will comply with these regulations, you can proceed to the fun part: making your concrete hearth.

Crafting Your Concrete Hearth

Assuming that your hearth will meet the regulations, there are two primary methods for crafting it: cast insitu and prefabrication.

Prefabricated Hearth

A prefabricated hearth is made elsewhere, in a mould, and then lifted into position. Thickness should be sufficient to avoid cracking but not overly heavy. A thickness of 40mm is the sweet spot for this.

Making a hearth in this manner is very similar to making a concrete worktop using the method in this article.

Cast Insitu Hearth

This method involves building a timber shutter around the outer perimeter of where you want your hearth to sit and then mixing and pouring your Cast-In-Place Concrete Mix into this shuttered area. If your hearth is going to have a fire on it, it should be at least 40mm thick to ensure it won't crack under the heat.

This is probably the simpler of the two methods because everything is done in one place. It will rely of your trowel skills to get a smooth finish as the concrete begins to cure but most of the work is done by the mix itself because it will level itself out.

Colour & Finish Considerations

Colour considerations: Mid and dark grey are traditional choices, while lighter colours are more contemporary. Sealing the concrete is crucial for lighter colours to prevent stains.

Prefabricated hearths can be highly polished due to the smooth mould materials, whereas cast insitu hearths have a more rustic look, typically requiring trowel smoothing.

Sealing the Concrete

Soot can stain bare concrete, so it's advisable to seal the surface. However, if some stains don't bother you, a simple wax and buff can suffice.

Styling Your Hearth

Consider making your hearth large enough to hold a log pile or log basket, along with fire tools. The style of your hearth can range from rustic to contemporary, depending on your design preferences.

Creating a concrete hearth for your fireplace is an exciting DIY project that can transform your living space. Just remember to start by understanding the regulations and safety requirements, then let your creativity and personal style shine as you craft the perfect hearth for your home. 

Renovating Your Existing Hearth

Of course you may have a hearth already and have a little green eye when the thought turns to a lovely new concrete hearth. Well never fear! Our microcement is the perfect partner for this. Microcement can be applied over most substrates and is very suitable for existing hearths. We've tested it on marble and granite so we know it adheres 100%. We've also tested our microcement next to log-burners to ensure that it isn't effected by heat. AND of course it is a fire-proof material.

So in the next few articles we will cover how to make a hearth using the two techniques briefly described above and also renovating an existing hearth using microcement so you don't miss out on the beauty of concrete next to your already wonderful log burner! 


By Toby Hurst


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