Log Burner wall spacing in garden office

[Joff-Turbo-Nova]

Hi all

Just need to pick the brains of the masses.

I have a Bosca Limit 350 log burner which I am installing in a garden office I am building at the moment.

The construction is mainly timber with a rosemary tiled roof.

I have sourced locally some 12mm slate tiles (approx 30 x 60cm) and plan making both the hearth and two wall covering with them (the burner will sit in the corner) .

The specs (see below) state that there should be a 300mm gap to combustible surfaces. With the hearth and surrounds being 12mm slate, would I still need to stick to 300mm or could I go to 150mm (or less) without issues?

Cheers

Jonathan

 

[Doggit]

As you're adding slate the the wooden walls, then you no longer have a combustable surface, but you'd need someone better than me to tell you how close you can go. How are you constructing the flue through the roof though.

 

[Joff-Turbo-Nova]

As you're adding slate the the wooden walls, then you no longer have a combustable surface, but you'd need someone better than me to tell you how close you can go. How are you constructing the flue through the roof though.

Yes straight up and twin wall before it gets to the roof with an appropriate flashing kit to keep it water tight.

Jonathan

 

[Doggit]

Sounds good, you could start a conversation with Firebrand or Burnerman to help you where I can't.

 

[Corgigrouch GTi]

Hello. Wooden sheds are always a pain in the bum, the correct rule to use is the same rule to use with flues. you can reduce the distance to the timber surface to 1.5 times the flue diameter (In your case 225mm) by means of providing a 12mm non combustible surface with a 12mm air gap behind it.. Unfortunately, this cannot be attached with screws within 450mm of the stove as they can transfer the heat to the timber.

 

[big-all]

i use old radiators cut to fit in the space to form a heat barrier at least 25mm from the wood
i use spacers and wood screws now off course the wood screws are only 25mm from the wood but the metal radiator acts as a heat sink
the radiators are around 75-100mm from the 4kw wood burner at the closest but never any problem but off course has to be set for the worst senario to allow for any dangers

 

[Burnerman]

For sure it is a difficult one, and the manufacturers always play safe - naturally enough. My own wood burners have vermiculite cheeks inside, which again helps prevent heat transfer to the surroundings. With this, I'm down to 150mm but the surround is brick anyway.
Is there any possibility of lining the timber with vermiculite sheets, and then fixing your slate to that?
John

 

[Joff-Turbo-Nova]

For sure it is a difficult one, and the manufacturers always play safe - naturally enough. My own wood burners have vermiculite cheeks inside, which again helps prevent heat transfer to the surroundings. With this, I'm down to 150mm but the surround is brick anyway.
Is there any possibility of lining the timber with vermiculite sheets, and then fixing your slate to that?
John

As the walls are not yet built I have free range to tweak the design to suite the requirements - I think some vermiculite sheets will now be on my additionals list !!

This burner has a steel jacket to aid convection of the heat upwards so this should help too !

Many thanks for the input !!

Jonathan