Firewall for stoves.

[verra]

Hi, I'm wondering if anyone has built a firewall with lightweight concrete, is there anything special to consider? I have chipboard in the walls and have not checked if there is any other type of firewall material, anyone here who might know.
Thanks in advance// Verrra

 

[Pasi]

Built a firewall of lightweight concrete behind a Keddy Minette. I used blocks 100x200x600, used regular tile adhesive as grout. Drilled holes and countersunk a screw in every other block (screwed into OSB). Very easy to work with and if you do it "carefully" you can paint directly after drying. The chimney sweep was a bit hesitant when I asked if lightweight concrete was approved in a firewall, but I got the green light before I built it. A tip is to check with your chimney sweep.

 

[kinglace]

Firewall is usually available as an accessory for the stove. I personally built one using 3 standing 45mm metal studs and a masterboard (fire-resistant board). The board was painted with textured paint to make it look plastered.

 

[verra]

Thanks for your answers. I was also thinking of checking with the chimney sweep; he should have some experience with firewalls, etc. I also thought about painting with textured paint.
Take care// verra

 

[PeterF]

A general question... if I frame with regular wood and then cover with double 13 mm gypsum. How is it classified? EI ?

 

[zankan]

Just a general question.. if I frame with regular wood and then cover with two layers of 13 mm gypsum board. How is that classified? EI ?

Double gypsum on one side and wood studs EI 15 I think it can also be EI 30... Also REI15 if that's the case but the construction shouldn't be load-bearing...

 

[PeterF]

Thank you, will try to research further

 

[dymlingen]

There are special stones that are "hollow on the backside" for building firewall. These do not build as much as other approved firewalls. Otherwise, it's generally considered that a row of bricks is required against combustible material. That's typically how it's built in old kitchens between the wood stove and the kitchen cabinet. My mother-in-law installed a wood stove in her kitchen and only used 50mm ytong/lightweight concrete, which resulted in the kitchen cabinet almost catching fire. There was smoke development and the wood had turned completely black. When it comes to a wall behind a stove, there is usually quite a bit of air between the stove and the wall, so it doesn't get as hot, so 50mm leca would probably suffice. But build according to the existing regulations, and you will be on the safe side if something happens. I borrowed a book from the library when I installed my fireplace. It listed all the approved dimensions and materials. Among other things, it stated that it is not enough to place a sheet of metal on a wooden floor in front of the fireplace. There should also be a thin sheet of non-combustible material between the metal and the wood. There are special pressed mineral wool boards (about 3mm) available for purchase where stoves are sold. I also believe that gypsum would be approved. When I laid new metal at home, I ignored this insulation and the chimney sweep hasn't mentioned anything about it.

 

[Tomtebo]

Anyone know where to find current regulations?

 

[DragonLady]

How far from the wall must a flue coming up from the floor below be? Must this wall be fire-rated or does this only apply behind the stove on the ground floor?