Grand designs - the wood house

[Great_scot_selfbuild]

Anyone watching the GD episode tonight on the wood house?

 

how on earth is the fire protection achieved on an all-wood lined building (all CLT) - 3 story too (protected stairwell?)

[ProDave]

I wired a house that was built with the internal walls finished in OSB.  That had to be painted with some expensive clear fireproofing material.

 

My question about tonight's house is gosh the staircase looked narrow, how was that allowed?

 

And with the walls made of solid CLT panels, how do you route cables to sockets?

[Nickfromwales]

15 minutes ago, ProDave said:

I wired a house that was built with the internal walls finished in OSB.  That had to be painted with some expensive clear fireproofing material.

 

My question about tonight's house is gosh the staircase looked narrow, how was that allowed?

 

And with the walls made of solid CLT panels, how do you route cables to sockets?

The manufacturers of one system I saw pre-drilled service holes vertically, every 300mm iirc, and you ran cables in those. 
 

Personally, I could think of no worse a home to have spent my money on. Not watched it, as GD gets right up my nose tbh.

[Ed_]

1 hour ago, ProDave said:

And with the walls made of solid CLT panels, how do you route cables to sockets?

It looked to me like they were running electrics under the false floor. Or maybe just put sockets on the internal walls?

[DownSouth]

I wondered if that’s why the top room was presented as an office - because surely you’d need a fire door otherwise. I liked the cladding design, thought the overhang was clever. Loved that his grandparents got to see it built - no sad GD bits and little jeopardy, made a nice change!

[Great_scot_selfbuild]

8 hours ago, ProDave said:

My question about tonight's house is gosh the staircase looked narrow, how was that allowed?

Hadn’t thought about that - good point. 

[Mr Punter]

10 hours ago, ProDave said:

My question about tonight's house is gosh the staircase looked narrow, how was that allowed?

 

I vaguely remember that Building regs do not specify minimum stair widths.

[ProDave]

23 minutes ago, Mr Punter said:

 

I vaguely remember that Building regs do not specify minimum stair widths.

They do in Scotland.  I would have thought they did elsewhere?

[saveasteading]

I may watch that. My experience of wood wall lining is that it needs a LOT of intumescent varnish then a sealing coat. Very expensive and rather ugly.

 

But that most people don't  put nearly enough on (cost and ignorance) and the bco usually just wants a spec and certificate. I've never known one check the thickness. 

 

I've seen a film of a fire test on a timber wall. As fire heat rises up the wall from the source,  it preheats it then there is a flash of flame and smoke. Scary.

 

 

[SteamyTea]

45 minutes ago, saveasteading said:

I've seen a film of a fire test on a timber wall. As fire heat rises up the wall from the source,  it preheats it then there is a flash of flame and smoke

The question needs to be how long it takes until smoke becomes a problem and how long until structural integrity fails.

 

I suspect that most consumer products would fail a similar test.

 

The Grenville Tower Enquiry Report has just been sent to the Crown Prosecution Service, with both company and individuals named. Be interesting to see how fast the CPS act. Took the 18 months to prosecute me over some so minor that I was not even fined.

[saveasteading]

7 minutes ago, SteamyTea said:

how long it takes 

2 different scenarios.

The structural integrity won't be life threatening in small domestic circumstances but could in large buildings.

The smoke is a threat in any size but obv only with combustible materials.

In the test, the smoke filled a large sports hall sized shed in, from memory, 30 seconds following the flash-over.

Flame climbed up the wall, about 7m, at about half m/s until it hit a critical stage and flashed up and across the 20m ceiling in seconds. That would be deadly.

I don't think that test had any fireproofing, just ply or osb, but the principle applies.

 

I once bought about 10 tins of intumescent paint and the merchant gave me a fancy certificate which basically said I  had bought ten tins, plus lots of words. Nobody checked it was properly or fully applied.

Another time, I instructed painters who claimed to understand the subject,to apply each tin over x metres of wall, thinking that made it easy for them. 

They proudly told me it had gone much further and I'd lots of spare tins to take back for rebate.

From peering at exposed steel i have seen that the top seal coat often isn't applied  I'm confident it will be in grand projects, but not on smaller private ones.

 

For those who haven't used or seen the stuff, it usually requires multiple coats and is noticeably thick. It's expensive hence plasterboard is popular.

Without a seal coat it can absorb moisture and scuffs easily. When heated it expands as char which protects the substrate. After a fire it rubs off like cigarette ash.