Old buildings and fire

[Maris]

Hello,
I saw a story on the news this morning that contained the line '...and because the building was old, the fire spread quickly...'
The story was about a restuarant in St Ives. It didn't even look that old, and had nasty UPVC windows..
How does being old make fire spread faster? Was there any reasoning behind this statement or was it just one of those throwaway lines that insurers use to put their premiums up?
It really annoyed me, anyway, so I had to find somewhere to rant about it!

cheers,

Maris.

 

[biffvernon]

Was it this fire?

I guess the element of truth in such throwaway comments is that new builds have to conform to fire protecting Building Regulations Part B

 

[Penners]

Was there any reasoning behind this statement or was it just one of those throwaway lines that insurers use to put their premiums up?

I think that flammability depends much more on the building materials than it does on the age of the property. If the old building has got lots of wooden lath walls, a thatched roof and so on, then it is certainly going to burn more readily than a modern brick-built house. However, it's a bit of a fallacy that oak in an old timber-framed house is a fire risk. In a fire, oak tends to develop a charred surface and then not to burn any further.

Of course, a modern timber-framed house (ie: softwood) is going to burn like a good 'un!

 

[biffvernon]

Wooden lath walls tend to be buried behind plaster so don't catch fire any more easily than expanded polystyrene behind plaster. The smoke produced when they do burn is very different.

The surface charring of oak beams and subsequent slow burn mean that they perform much better than steel beams in a fire. Steel is about as much use as plasticene when it's hot.

Closed, smoke tight doors and escape routes are the things that save lives and are not dependant on the age of the building.

 

[Maris]

Good stuff.
Thank you for the link to the building regs. We've just had to make a few concessions regarding the new insulation/ U value regulations, since we're making substantial repairs to an old cob and stone cottage. Thankfully the building inspector is sympathetic towards old buildings, and has an interest in cob (low u-value apparently, but good at storing and releasing heat?) . We hadn't got as far as talking about fire safety issues. Thats next weeks meeting with the architect. Our plans to make the internal doors out of old floorboards might be out.

 

[MattJ]

I believe Bob Bennett of the Lime Centre did a fire resistance test comparing lath & lime plaster to plasterboard, after being challenged by Building Control over some situation (might have been the replastering of the powder magazines on Nelson's Victory?) and the lath and lime lasted longer than the plasterboard.

However I'm sure a few period cracks in lime on lath would reduce the fire resistance quite a bit.

Matt