And they're *still* using lead !?!?!?!

[Bill Wright]

Does lead have molecules in it?

Bill

[Jethro_uk]

If it's synthetic, surely it could be coloured ?

[alan_m]

And perhaps overrides on the controls to stop the lift stopping on a floor which may be on fire.

[alan_m]

Or is that just the supplied length of the rolls. The rolls can be very heavy.

When my roof was replaced the roofer did a nice job of joining the lengths of flashing with a kind of folded under tuck and a small tab in the opposite direction to secure the the join.

[soup]

There's a fancy way of saying a sheet with handles that can be lowered over the worst of the bumps but generally the non-ped gets slid about on.

[Andrew Gabriel]

Lifts can be designed for use in fires - there were two in the office I worked in for a few years, one at each end of the building. They were next the the floor refuges where people who can't make it down the stairs wait for recovery in a long stay fireproof room.

I don't know all the special things that are done for those lifts, but they did have a triple power feed - one from each of the building's two mains feeds, and a third from the building's UPS/generator set. Having a lift do an unplanned stop in a building on fire would be a very bad thing.

However, most lifts do not have any such protection, or any protection against taking you into the fire, or stopping on a floor with a fire. Many decades ago, a type of rectangular touch sensitive call button got very popular on high-end lifts. These used infrared from your hand. It also meant they got called to all the floors with raging fires, and after a disaster in a US office block where people tried using lifts to escape and the lifts stopped at all the floors with raging fires, they were all ripped out.

Nowadays, lifts are usually linked to the fire alarm in a modern installation, which prevents them being used except under manual (fireman) key control.

[harry]

ISTR there is a plastic substitute.

[harry]

[Dave Plowman (News)]

That might need a localised repair - but not total replacement. Lead is very easy to repair if you have the skills. Only reason to replace the lots is if it had been eroded away. That does happen with zinc - but even that should last 100 years or so.

[Dave Plowman (News)]

I'd guess it's one they have total control over via a key?

[Dave Plowman (News)]

No - it's because lead expands in the heat far more than things like slates. So you need to provide a means of allowing for that expansion. And being a dark colour absorbs heat from the sun readily.

Which is what that allows.

[Roger Hayter]

You probably have to stretch the definition of molecule to include monatomic ones. My chemistry teacher thought you could, and he actually had a PhD in chemistry. Not sure why he was teaching kids in Leeds, probably some sort of penance.

[Andrew]

By telling people to stay in their flats behind their

60 minute entrance firedoor, while the firebrigade deal with the flat on fire.

There should be fire and smoke doors to protect the stairwell, but something went horribly wrong at Grenfell.

That alway was the standard advice.

[Andrew]

The church that was raided down in Hampshire had a very ornate structure on its roof, possibly bell tower, that was covered with lead.

[Andrew]

The local rook family are quite partial to pecking at the lead strips that are used to hold slipped slates in place.

[Andrew Gabriel]

The story as I've heard it is the insurance company won't insure a lead roof once it's been stolen and insists on repair using an alternative product. OTOH, English Heritige won't allow the use of alternative products until the lead has been stolen twice.

[newshound]

DU is used in trim weights on large airliners. Positioned in the tail.

One solution to discouraging lead theft might be to spike lead flashing with a radioisotope, given that (I believe) many scrap yards now have detectors to spot stolen medical sources, etc. There isn't an obvious lead isotope, but there must be something suitable.

[alan_m]

Probably very easy to alarm a lead roof so that if a panel were lifted a circuit would be broken.

[alan_m]

Don't they have to be very careful when opening lead coffins as it may contain more than just the body? Smallpox or the Black Death may be additional reward for the lead theives.

[tabbypurr]

Cables that are mostly al with a thin layer of cu lack the ductility for long term reliability. But a cable that's mostly cu with a thin strand of al in the centre should not suffer - it will however have much lower scrap value as it's mixed metals.

Thieves aren't that thick

a) I'm not suggesting using something unreliable b) to stop cable thefts

NT