Non-combustible timber?

[Donkmeister]

I know this topic has sometimes caused disagreements... I've no dog in that fight, I'm just trying to make sure if I sell my house I don't have a ball-ache on my hands proving my shed isn't non-compliant.

I am planning out my new shed/workshop. It's going to be a timber-frame building on a concrete slab, right by the boundary and within permitted development. Ideally I want to build it 20m2, but then I'll need to meet the rule on "constructed substantially of non-combustible materials". My fallback solution is to build a 15m2 timber-framed shed, as my bricklaying abilities would not make for a good result.

So, to meet the non-combustible rule for a timber-framed shed, do I need to build the frame with timber that has been treated with a fire retardant? I've looked for BS476 "non-combustible" or EN13501 "A1" timber but had no luck - I realise I could be looking for the wrong thing but I remember seeing a Kiwi carpenter on YouTube using a pink-dyed fire-retardant timber.

Or can I address this through using a cement-board or similar for the cladding?

Or... am I just on to a bad idea with trying to build a timber-framed shed that is "constructed substantially of non-combustible materials"?

 

[mrrusty]

Build it out of block and clad it in either cement board or coated steel panels (which are inexpensive). Laying blocks is pretty easy as long as you set up some string lines to work to. After the first couple of courses you'll get the hang of it. You might get away with cement board over timber frame - ask your BC.

 

[big-all]

make sure its the internal floor area you are measuring and not the overall size
and keep it below 2.5m height from ground level

 

[^woody^]

You can build it as a timber frame as long as it is suitably clad and detailed to prevent both internal and external fire spread. 1 hour fire resistance

And whilst everyone tends to quote the "substantially of non combustible materials" bit and interpret this as building the walls in masonry, they tend to forget about the roof, and the section of roof within 1m of the boundary. And the eaves for that matter, fire getting in or out of the eaves.

Ignore your fire proof timber idea, that's pointless and a red herring.