DFB: 3 mins to escape from fire in a modern house vs 17 mins 40 years ago

0lddog

https://twitter.com/DubFireBrigade/status/1183444818208460801

DFB quote a source dated 2008

Would the escape time be similar for 2019 ?

Why ?

- Old houses frequently had rooms partitioned with blocks?
- Lower ceilings ?
- MHRV duct work ?
- Other stuff ?

Gumbo

Less electrical.
Less ‘stuff’ in general.
Carpets, toys, clothes and the shear amount of items plugged in.

I wouldn’t be surprised if the time was that low.
But it can be significantly increased by following some simple rules :
Make sure smoke alarms are working.
Place then in every room, if even only battery operated ones.

When you go to bed, close all doors to rooms not in use. This will delay fire spread while still activating smoke alarms.

Know your home, know how to get out and what way to go.

0lddog

Very true about the causes and avoidance, Kceire

My take on the DFB tweet was that it highlighted the time available to get out has decreased greatly in recent builds ( rather than the cause etc of fires ).

Seems to me that this means that modern houses are made of stuff that is significantly more combustible than 40 years ago and / or much more smoke is given off at an early stage of a fire. Given the increase in regulation WRT fire in modern houses I find this very perplexing

Metric Tensor

I think it's the furnishings more than the construction materials. I'd imagine that synthetic curtains burn faster than wool ones for example - especially considering the wool was probably damp! Also - cushions filled with synthetic fabrics rather than feathers, etc. etc.

Added to that is the vast number of additional causes - particularly phone chargers in every bedroom and especially the cheap knock off ones that seem to be ubiquitous.

A concrete block from 2019 is just as combustible as a concrete block from 1979!

sydthebeat

https://www.nist.gov/sites/default/files/documents/2017/04/28/NIST_TN_1455-1_Feb2008.pdf


Heres the report of anyone wants to read it.

Lumen

sydthebeat wrote: »

https://www.nist.gov/sites/default/files/documents/2017/04/28/NIST_TN_1455-1_Feb2008.pdf

Heres the report of anyone wants to read it.

I've skimmed it briefly and can't find anything about construction details, so as Metric Tensor says, it seems to be about what's in the property rather than how it is made.

Also, it's a US report and they have different construction methods depending on region.

I also can't find anything to support the conclusions posted in the tweet.

It's all very odd.

That said, I can see there being a concern with mechanical ventilation feeding oxygen to a fire, but at the same time it's not beyond the wit of man to have it shut off when there is a fire (intumescent sleeves?). And if that were to happen, an airtight construction with no external vents would presumably contribute towards slower fire spread.

0lddog

Do MVHR units have integrated smoke detectors ?

sydthebeat

0lddog wrote: »

Do MVHR units have integrated smoke detectors ?

Certainly not as standard.

Current regs require SD/FD in all habitable rooms anyway.

tabby aspreme

Metric Tensor wrote: »

A concrete block from 2019 is just as combustible as a concrete block from 1979!

House's in 1979 had concrete blocks in both internal and external walls, that's why fires are slow to spread, house's in 2019 may have blocks on the outer leaf of the external walls with studded partitions every where else.

0lddog

tabby aspreme wrote: »

House's in 1979 had concrete blocks in both internal and external walls, that's why fires are slow to spread, house's in 2019 may have blocks on the outer leaf of the external walls with studded partitions every where else.

Yup, thats what I should have said in the first post. Thanks.

Gumbo

0lddog wrote: »

Do MVHR units have integrated smoke detectors ?

No but the rooms they ventilate will have detection and depending on the house and it’s construction type, the rooms will have fire doors and fire collars on the vent grills in the ceiling (especially if open web timber joists).

Metric Tensor

tabby aspreme wrote: »

House's in 1979 had concrete blocks in both internal and external walls, that's why fires are slow to spread, house's in 2019 may have blocks on the outer leaf of the external walls with studded partitions every where else.

Not where I can help it!

Although, you are correct - there is more in the way of framed construction around. I'd be more concerned about transmission of smoke through the voids and burning of insulation within the voids than the actual studs themselves - solid timber is surprisingly robust in fire conditions provided it's thick enough to char. Having said that a block wall is obviously still better for a whole host of reasons.

lgk

tabby aspreme wrote: »

House's in 1979 had concrete blocks in both internal and external walls, that's why fires are slow to spread, house's in 2019 may have blocks on the outer leaf of the external walls with studded partitions every where else.

Timber framing was pretty popular in the late 70's in the US.

The paper says the difference in time is...

related to some combination of faster fire development times
for today's products that provide the main fuel sources for fires, such as upholstered furniture and mattresses, different criteria for time to untenable conditions, and improved understanding of the speed and range of threats to tenability.

So, especially with the changing criteria for what constituted untenable conditions, I'm not sure we can conclude too much from it.