Product Guide: Fireplace Size

Fireplace Measuring Services

For all Home Survey and Installation orders we will take measurements and check details for you to ensure that your chosen Fire and Fireplace is compatible in your room.

Please use the below information to help order the right product based on your requirements but it is also possible to change or cancel your order if the Home Survey advises that your original specification is not possible.

For all Delivery Only orders, we do not carry out a Home Survey and therefore it is your responsibility to ensure that your chosen Fire and Fireplace is compatible. You can search for a Fireplace Installer by visiting HETAS / Gas Safe

For more information on Fireplace Installation, see also Product Guide – Installation Service

Recommended Fireplace Sizes

Choosing the right Fireplace size is important to get the desired look based on the proportions of your room and wall.  Ultimately it is down to your own style preferences, however, we recommend trying to follow these simple rules:

Fireplace Width for Rooms with Chimney Breast: Ensure the width of the fireplace is not wider than the width of the Chimney Breast. If the Mantel (typically the widest part of the Fireplace) overhangs the width of the Chimney Breast this will not only look strange, but exposed edges may present a hazard for getting damaged.

Fireplace Width for Rooms with Flat Wall: There is no recommended width restriction for rooms with Flat Walls.

All our Fireplaces have dimensions included on the individual product pages; we recommend using the dimensions provided to draw or mark on the wall the exact proportions.

J. Rotherham can manufacture all our fireplaces in bespoke dimensions. As we manufacture all our Fireplaces to order, there is typically no additional lead time, however, there is a slight increase in price to reflect the additional work involved.

If you have any questions regarding a recommended Fireplace size, or would like further information and prices on modifying the sizes of one of our Fireplaces, please contact our Fireplace Sales Team to discuss your requirements.

Rooms with Chimney Breast and Builders Opening

What is the Builders Opening?

The Builders Opening is the opening in the chimney breast that allows the fire to be situated within its recess. For Fires requiring a flue system, this typically allows a connection to the fire whilst remaining hidden within the chimney breast.

The type of fire you can have will depend on the size of this opening (as well as your flue type)

The Builders Opening size is relevant to the type of Fire you can install. The width, height and depth of the Fire appliance recess section will need to be smaller than the width, height and depth of the Builders Opening.

For Fire appliance sizes, please refer to the technical drawings available on individual appliance product pages.

What if I want a Fire appliance that is larger than my Builders Opening?

There may be the possibility that you can increase the size of the Builders Opening by cutting / removing bricks or wall material. In order to do this you need to discuss with your professional Fireplace Installer during a Home Survey.

Rooms with Flat Walls (no Chimney Breast / Builders Opening)

It is possible to install a Fire and Fireplace on a flat wall where there is no chimney breast and builders opening. Typically this will be an Electric Fire and Fireplace combination.

There are also methods for installing Gas / Solid Fuel Freestanding Fires and Stoves, however, due to complexities we do not sell these fires online, and recommend you call us to discuss your requirements.

Rebate Sizes

What is a Rebate?

A Rebate is the difference between the external depth of the Fireplace jamb (where the jamb meets the wall) and the internal depth of the Fireplace jamb (where the jamb meets the Fire). The internal depth of the jamb will be rebated (i.e. shorter) to allow for the slips, back panel or cast to fit in between the fireplace jambs and the wall, providing a neat and tidy finish.

Do I need to work out the size of the rebate I need to go with my Fire?

If you are ordering your entire Fireplace package (Fireplace and Fire) from J. Rotherham then no, you do not need to worry about working this dimension out. Our Fireplace Configurator is designed to ensure that this is all taken care of.

If you are ordering a J. Rotherham Fireplace surround only, and you want to re-use your own Fire then we may need to know what size rebate is required. We recommend contacting us to discuss this requirement.

Hearth Sizes

Fireplace Hearth sizes are dictated by two main elements; proportions that work with the chosen Fireplace surround and Building Regulations.

Depending upon your chosen Fire, J. Rotherham Fireplaces come with a specified Hearth that will ensure it both fits the proportions (approximately lining up with the width of the Mantel) and meets the minimum Building Regulation requirements.

What if you have a specific Hearth size and specification that you would like us to manufacture?

This is no problem at all, please contact us with your requirements and as long as it fits the Building Regulations we can make to order any size or style of Hearth. For clarification on Building Regulation requirements:

Electric Fires:

No minimum requirements

Gas or Solid Fuel Fires / Stoves:

Extend >300mm (12 inches) in front of the appliance

Extend >150mm (6 inches) either side of the of the appliance

Have a minimum thickness of 48mm (2 inches)

Wall Mounted / Hole-in-the-Wall Gas Fires without Hearth:

Extend >300mm (12 inches) above the floor

Wall and Floor Type

There can be restrictions for installing Stone Fireplaces when it comes to certain wall and floor types. Most homes will not have any issues, however, please check the below table and if you have a wall or floor types that is not recommended it may be necessary for the Fireplace Installer to check the structural integrity before allowing installation to take place.


Brick, Block and Sufficiently Strengthened Stud Walls will be acceptable.

Lightweight Metal Stud Walls will not be acceptable.


The floor must provide a good foundation to support the entire weight of the Fireplace. The weight of the Fireplace is provided in the Technical Details section for each Fireplace.

For all Home Survey and Installation orders we will check these details for you to ensure that your chosen fire and fireplace is compatible

For all Delivery Only orders, it is your responsibility to ensure that your chosen fire and fireplace is compatible

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