It’s renewable, strong as steel, astonishingly fireproof – yet it’s easy and quiet to build with. Could timber construction be the future? We step inside the revolutionary new London workplace that everyone wants to touch
So, we have vast inquiries into how aluminium caught fire – and we’re to build in timber instead?
I’m assured that modern engineered timber is suitably fire resistant. After all, it is used across the Nordics – in both residential and commercial buildings – without great swathes of Helsinki burning down. Wood certainly makes for a more comfortable environment than glass and steel.
Planners in the UK don’t like it however, mainly due to similar fears to those expressed above.
I thought it was the low melting point, highly inflammable plastic inside the aluminium that burnt Grenfell Tower?
@MC
What’s the humidity like in the Nordics?
The problem here is the humidity, wood warps
And then it rots.
We could always coat it in plastic to seal the beam, but plastic baaaaad.
I sure I read/ saw somewhere that the English moved from timber to brick construction because of the Great Fire of London?
Little known fact. Wood is more fire resistant than steel.
Wood burns from the outside. So will retain its structural strength long into the burning process because the core continues to have structural strength.
Steel derives its structural strength from the profile of the rolled sections. It doesn’t take much heating for differential expansion to warp the steel & vastly decrease the structural strength.
So a heavy wood beam may classify as having a fire resistance measured in hours whereas the equivalent steel beam an unprotected resistance of a mere 30 mins.
@Chernyy Drakon
It’s usually a ventilation problem. Wood’s liable to rot above a certain humidity point. So keep the wood ventilated & it won’t. Most rot problems are due to enclosing the wood so there’s little ventilation.
Why those Vicky/Edwardian terraces people so prize are full of dry rot. It was common to design in timber load bearing members that were then encased in brickwork & plaster. Lintels above window & door apertures. They connect directly with the timber joists, so the rot spreads from them into the fabric of the house.
It’s why I regard them as jerrybuilt shit would be better pulled down. They didn’t have the skilled bricklayers could turn a structural arch. The arches you do see are mostly decorative. And reinforced concrete wasn’t then state of the art. Ordinary poured concrete isn’t structural load bearing. It needs vibrating to increase its density. So like most of the things in those places, the builders took the cheap dirty route. They weren’t bothered. As long as it stayed up long enough for them to get paid, down the road & round the corner it was good enough.
Bloke: It’s also why you often see better-built old properties in small towns, or where I grew up, land society properties. You were building a house for your neighbour, or a member of your self-improvement club, so if it fell down everybody knew who you were.
Termites?
These are marching steadfastly up from the South through France due to everybody’s favourite, global warming/climate change.
Switching from wood to coal, iron & steel, concrete and plastics is what stopped deforestation.
It’s so fireproof that Boy Scouts actually get a merit badge for starting a fire successfully, lol.
To change the structural strength of steel you need to get it up to red hot or better (460C), by which time timber is just a memory.
Sorry Southerner, but you just do not understand steel. Any steel structure depends on the geometry of its components & how they’re put together. Basically, the route loads are transmitted down to the ground. Steel has a high coefficient of thermal expansion & conductivity. Even quite low temperatures can change that geometry, alter the routes & stress the structure. Why everything in a steel structure has to be clad in concrete or some other fire retardant material to protect it. Look at building regs. Even concrete isn’t particularly resistant to fire. Differential thermal expansion. Couple hundred degrees will strip concrete straight off of a steel beam.
Wood in comparison is low thermal expansion & conductivity. Charring actually provides a lower conductivity protective sheath to the unburned wood underneath.
Sure a steel structure containing no inflammable material is pretty fire safe. Providing one’s allowed in its design for normal, every day, thermal expansion & contraction. But, in practise, most buildings – as used – get stuffed full of it. And that’s what burns.
As with other things (Vinyl v CD, Men v Women), we have two different things, both with inherent advantages and disadvantages. Why don’t we use the most appropriate medium for each requirement?
I seem to recall Grenfell was clad using material selected by the Tenant led building refurbishment team. Did the material meet the regulations set by HMG (actually, EU standards – Remainers please take note)? If not, have any of them been asked to answer questions? If so, have any people involved in setting the standards been questioned as to how they determined this stuff was safe? Were the manufacturers ‘economical with the actualite’ of the tests they had carried out? (PfizerBioNtech / Moderna we’re looking at you).
What has occured to deal with the ‘fridge spontaneously combusting’ problem? Have they all been recalled? Where is the bloke who had his suitcases packed, on the landing outside the flat where the fire started, prior to Fireman Sam turning up?
What happened to all the fire doors in Grenfell (and other tower blocks in the area)?
Did the LFB extinguish the fire initially but fail to notice the fire was still present in the cladding?
@Addolff
From what I’ve seen of the Grenfell reports, it was the voids that were the problem. Once the fire got in behind the cladding it could freely travel up the front of the building. And in that situation, the cladding’s going to act like a chimney. You’ll get an updraft in it, facilitates the fire.
I’ve been involved in fire checking on all sorts of buildings. Compartmentalisation’s the name of the game. Compartmentalisation within flats. You have an escape route to the exit of the flat & all apertures onto the escape route need fire resistant, self closing doors. There’s fire resistance required between adjoining flats & those below & above. Then you do the same with the escape route from the building. All from the flats to the common passages must have self closing fire check doors. Again, the access from the passages to the stair well, at each level, self closing firecheck. Regular inspections to ensure fire check doors are not propped open or the self closers defaulted. That includes inspections within the flats.
If you look at it, as I would, the cladding to each individual flat should be regarded as contiguous with the flat. Because the external windows aren’t firecheck. So there should have been a fire check between each level of the cladding & across between cladded flats.
Now Grenfell wouldn’t have been built to these standards. But the normal practise when I’ve been involved in this sort of thing, is you change the building or use of the building, you have to upgrade to current specs. Single dwelling is far less stringent than multiple occupancy, for instance. Cladding changed the building.
Manufacturers’ test specs on the materials used would depend on the application. They might be fine for one application, not for another. Were they consulted on the application?
My take on the whole thing, there multiple breaches of all sorts of best practise.Compartmentalisation on the cladding for a start. Then escape routes had doors propped open or closers defeated. Inflammable items left on escape routes. Inspections not carried out or breaches not remedied.
If you want to apportion blame, the architects specified & designed the cladding & also the during & post fit inspection regimes. Contractors if they intentionally breached specs or let sub-contractors do so. Building management for not inspecting or not remedying results of inspections. There have been reports of gas cylinders being in some of the flats. Normally, in multiple occupancy buildings, the tenancy agreement would particularly ban them. Every one I’ve seen has. And building management should pick them up on the residence inspection. Like they should have picked up propped open doors & defeated closers. But I doubt if they ever did residence inspections. None of building managements ever do. And of course there’s the fire certificates on the building to ensure it complies with all of the above.. Don’t know who did them. When I was doing this stuff, Westminster it was the Fire Brigade, outer London boroughs the LA.
Lie I say, if you want to find someone to blame, there’s a big list. All of who will be trying to pass the buck
Give you some idea. We used to do conversions of building into flats. I had a stack of files about 3 inches thick. Building regs & local authority specs. Specs & applications on all sorts of materials & applications. Intumescent door seals & paints for escape routes. Fire resistant sheeting & applications. Ditto wall coatings. Ducting through firecheck partitions & firechecking of. Including self initiating fireseals around pipes & conduits. Take a month to read it all.
Anyway back to subject of Tim’s post. There’s no reason a timber built structure shouldn’t be fire safe. It is always about compartmentalisation. Keeping any fire safely isolated until it can be extinguished. We certainly know how to do that. There’s any number of ways to do it. It’s just a matter of designing them in.
Now that old-growth forests are mostly cut down, large structural timbers are hard to find and very expensive compared to steel and concrete.
https://en.wikipedia.org/wiki/Glued_laminated_timber
And they did build Mosquitoes out of it.
There was a variant of this I used for a structural member in a building. Basically, a box section incorporating a pretensioned steel cable to provide tensile strength. Light enough, two labourers could pick it up, carry it to where it was required & position it. It was the alternative to over half a ton of steel & all the problems of getting that up through a five storey building & in position. Took a bit of charm to get it approved by building control, but they bought it. Worked fine. Now supports one end of a floor.
“And they did build Mosquitoes out of it”
Which (as I remember) was faster than many WW2 fighters, despite being primarily designed as a bomber. And I think it could carry the same bomb load as the far heavier and slower American B17…
Many people still build light aircraft from wood, and the French Robin DR 400 has significantly better performance than all metal equivalents with the same power. The main downside in these applications is the need to hangar them, whereas metal planes can normally be left parked outside.