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Chimney & Fireplace

Constructional hearth extending in front slightly too short. (NOT 500mm)

Anonymous user 23/02/2024 - 3.24 PM

Hello everyone. I live in an Edwardian terraced property and my fireplace constructional hearth extends out at approx 430mm from the fireplace jambs. Not 500mm as building regulations state. There is however the correct 150mm clearance each side of the jambs. Would it be possible to lay a superimposed hearth with the correct dimensions over the top of the slighty short constructional hearth. My wood burning stove will be placed slightly forward from the recess to allow enough room at the back to accomodate a rear flue adapter. I'm also allowing here the 300mm clearance in front of the appliance. This means that approx 150mm of the superimposed hearth would need to extend out onto the floorboards. Another builder on here said that would be ok if the appliance doesn't heat the hearth to over 100 degrees and that I can then use a 12mm hearth over the floorboards. But although my wood burner is free standing it will be installed into an ingle nook/builders opening type fireplace. Not the free standing stove for the middle of a room/or against a normal wall. I will want to lay a granite hearth 40-50mm thick. I hope this all makes sense. Thank you.

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3 Answers

Ironworks

Rating: 5 out of 5

Shrewsbury

If the stove doesn't generate more than 100 degrees downward ( the manufacturer will tell you if that is the case ) then you only need to use a hearth with a nominal thickness of 12mm. In which case the size of the constructional hearth becomes irrelevant as you are not using it to dissipate heat. The distance required in front of an appliance that is designed to operate with the doors closed is 9" of non combustible material. However the 100 degree rule dictates what is below that and the size. If your stove doesn't meet the 100 degree rule then you need to modify the constructional hearth. You cant just overlap the decorative top onto your floor surface and meet building regulations.

Answered3 June 2019

Blazing Burners Limited

Rating: 5 out of 5

Penryn

Hi Mr G, The manufacturer of the stove will dictate the hearth(s). If they state that you need a constructional hearth, you need it to project at least 500mm forward (and 150mm to the side) from the jams. As "Ironworks" has stated if the manufacturer states you don't need a constructional hearth then the fact that your constructional hearth only projects 430mm forward is irrelevant. If you do need a constructional hearth, then you need to extend your existing constructional hearth by another 70mm (at 125mm thickness). "Toasty Stoves" point is a good rule of thumb. Regarding the "superficial/superimposed" hearth, check what the manufacturer requests. The minimum amount required by building regs (ADJ 2010) is 225mm in front of the stove (and 12mm thick). However, if the manufacturer requests 300mm or 350mm or whatever else, you have to meet that (unless it is under 225mm, in which case it has to be 225mm as building regs overrule). Worse than rugby rules eh! Your granite hearth of 40-50mm is over and above the superficial requirements of 12mm (but it looks better - right!). Your stove is classified as freestanding no matter where it is situated - fireplace or in the middle of the room. It is still "free-standing". The other alternative is a cassette/inset type, that fits inside an enclosed space. In a nutshell, open up the stove manual and see what they state. All the best, Damian

Answered20 June 2019

Toasty Stoves

Rating: 4.9 out of 5

Bristol

Simperly put if stove has legs you can use a 12mm heath..

Answered11 June 2019