How To Measure A Fireplace

How To Measure A Fireplace

Guide – How To Measure A Fireplace

Choosing the right size fireplace for your room is often a more difficult decision than you’d image. You don’t want it too big or too small, you don’t want it to look lost in the room, you don’t want it to dominate the room. These are things we hear every day when discussing the right size fireplace for someone’s living room. There is no right or wrong answer; it’s very much a personal choice. However, there are a few points to take into consideration and a few tips we can give you to help you choose the right size fireplace for you.

Firstly, if you’re putting the fireplace on a chimney breast, then you need to make sure that the width of the fireplace or fire surround isn’t wider than the chimney breast. There’s not rule to say it can’t be wider, but it might look a bit odd. Some people like the mantel to go right up to the edge of the chimney breast while others like to have a reasonable sized space bordering the fireplace. If you fit the fireplace on a flat wall, then there’s nothing that will limit the width of the fireplace.

We often suggest that people draw or use tape to illustrate the size of the fireplace they’ll considering, this will give you a good visual idea of the size and how it’ll look in the room.

Once you’ve worked out what width mantel you want then the next choice you need to make is the height. Again, there’s very little to dictate right or wrong, draw or mark your wall with tape to work out the best size.

Rebate Sizes:

A very common question we get asked is “what does rebate mean”. The rebate is the space between the inside edge of a fireplace the wall. This space allows the back panel, slips or cast insert to fit behind the fireplace. All fireplaces have rebates, and they tend to be 25mm, 35mm 50mm or 75mm.

Hearth sizes:

There are a few standards sizes when it comes to fireplaces, these are dictated by building regulations. If you’re installing a solid fuel or gas fire, there are a few points with regards the size of the hearth to take into consideration.

For either an inset gas fire or solid fuel fire, the hearth needs to:

  • extend 12 inches (300mm) in front of the appliance
  • have at least 6 inches (150mm) either side
  • have a minimum thickness of 2 inches (48mm)

Most fireplaces come with a hearth of the correct depth that is normally roughly the same width as the mantel. This will give plenty of clearance either side of the fire.

If you want a wall-mounted gas fire or hole-in-the-wall gas fire and don’t want a hearth, you must install the fire at least 12” (300mm) off the floor.

If you’re installing an electric fire, then there’s no real concerns with regards to the sizes.

Fire Surrounds and Cast Inserts:

When it comes to choosing a fire surround and cast iron insert then there are a few measurements that need checking to make sure that the items you choose will work together. You need to make sure that the opening of the surround is big enough to take the cast insert that you choose. Below are some measurement examples:

Fire surround and cast iron insert line drawings

In fig.1, you can see the opening of the fire surround (measurements C and D). You need to make sure that the decorative band of the cast (fig. 2 measurement E and F) is less than this.

The other measurement you need to check when buying a cast insert is the insert sizes (how much room you’ll need inside the chimney). If it’s bigger than the insert you are looking at then it’s fine, as it’s fairly easy to reduce the size. If however it’s too small you might be able to remove a layer of bricks to increase the size, but please check with your fireplace fitter or builder before removing any fireplace structure.

You can telephone or e-mail us to discuss any questions that you may have. We try to be very helpful, and would be glad to answer your questions and offer advice.

You can note your measurements for us as seen below:

Existing Fire opening in the wall:

A – Width: __________ cm/inches.

B – Height: __________ cm/inches.

Existing fireplace size:

C – Width: __________ cm/inches.

D – Height: __________ cm/inches.

Chimney Breast:

G – Width: __________ cm/inches.

F – Height (approx) : __________ cm/inches.

What size is your existing Hearth:

(The Hearth is the piece of floor stone/marble that your fireplace sits on)

Width: __________ cm/inches.

Depth from wall:________ cm/inches.

If you would like to know more about our range of Fireplaces including Inserts, Combinations and Surrounds, or if you would like to know more about specific types of Fireplaces, please call us on 0161-444-0921 or email us at, we are very helpful and will be glad to answer your questions and offer advice.

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