Bespoke Hearths cut to size

Over the past 24 years, here at Manthorpe Slate we have made thousands of slate, granite and stone hearths cut to size for wood burners, solid fuel stoves and open fires.  The information below is designed to help ensure you get the right material and size hearth for your needs.  Should you have any questions, please do not hesitate to contact us or come and visit our small showroom in Manthorpe – we would love to meet you!

The Supplied Hearth

All  our  cut to size hearths are supplied finished on their exposed edges,  normally with a 3-4mm chamfer.  The corners are also chamfered to remove their sharpness.  With porous materials like limestone, we use a non-colour enhancing sealant to reduce the porosity of the stone.  With slate and granite however,  we use a colour enhancing clear fluid which quickly dries to a mat finish. We do not use a sealant on the polished granite as this comes pre-sealed from the quarry.

Maintenance of your slate hearth

There is very little maintenance required to keep our hearth looking stunning! With granite, an occasional wipe over with a damp cloth is all that is required. With honed granite and riven ( natural) slate, oiling with WD40 instantly restores a it to to its former glory if it has been covered with dirt and ash from continual use.  I know it sounds odd but oiling slate hearths is a traditional remedy and  WD40 is the best oil out there, evaporating quickly and leaving no sticky residue unlike linseed oil etc.

The size of your bespoke hearth – (Building Regulations Document J, pages  37-42 )

This should be a minimum of 840 x 840mm for a freestanding stove.  There should be a minimum of 300mm in front of your stove if  it can run with the door open, or 225mm if it can only run with the door closed.  However, 225mm in front of your stove it is very narrow and whilst your stove might comply, every time you open the door it will probably deposit ash outside of the hearth. Therefore, I personally would leave 300mm in front of your stove, or better still, the width of the arc the door travels through.  You should allow 125mm either side of your stove and it is good practice to have 100mm to the back wall but please check with the stove fitter or manual as this distance does vary .

Thickness of your hearth  (Building Regulations Document J pages 37-42 )

If your stove does not exceed 100 degrees C  hearth temperature, building regulations say a minimum of 12mm of non- combustible material should be under the stove (slate, granite, or limestone decorative hearth).  In reality, with a heavy stove on top of your hearth, many natural materials would fail through bending if poorly bedded.   For instance, a wooden floor where you can get a lot of movement might leave the hearth poorly supported with seasonal movement of the floor. We would always recommend bedding onto a concrete subbase as a “belt and braces ” approach but understand there are instances where bedding onto a concrete sub base is not practical and we are happy to advise what would be the best approach and material in these cases.

If the stove exceeds 100 degrees C hearth temperature, building regulations say you need 125mm of  non-combustible material under the stove.  This can comprise of a 20mm decorative hearth and 105mm of concrete sub base. A huge stepped change from the 12mm requirement!  It is now rare to find a stove which emits so much heat downwards but it is always good to read the stove’s fitting instructions and the hearth will need to be sectioned, irrespective of material, to prevent thermal cracking .

To get a quote, please use our Manthorpe Slate & Stone Contact Us page, stating your requirements including material, dimensions and thickness.

When choosing a material for your bespoke hearth, there are some other key points to consider:

Open fires:

High levels of wear and tear on hearth.

Creates localised heat stress and depending on the size, the hearth may require sectioning.

Size requirements – 300mm in front of fire and 150mm either side.

Wood burning and Solid fuel stoves:

Medium level of wear and tear on hearth.

Most stoves are certified not to exceed 100 degrees celcius, so sectioning is not usually required. However, you will need to check your stove’s specific specification beforehand.

Size requirements – stoves fitted into a recess require 300mm in front and 150mm either side.

Gas and electric fires:

Highly decorative, so minimal wear and tear on hearth.

Low heat stress so no sectioning required.

Gas fires require a minimum hearth height of 50mm (this can be a 20mm hearth with a 30mm plinth).

Our cut to size hearth materials are detailed below. Please use our Manthorpe Slate & Stone Contact Us form or email your requirements including material choice, size and application (for example, stove, open fire or gas/electric) to find out about suitability, pricing and current lead times.

Tel 01778 77 20 45 or 07751 674021

We are always here to help.


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