Fire safety for structures - timber frame?

[Mr Punter]

https://www.bbc.co.uk/news/uk-england-bristol-49028337

 

This shows a Premier Inn ablaze and a large part of it collapsed. I suspect it is timber frame as lots of their newer builds are. Quite why the fire spread through the building and caused such destruction I do not know, but it does raise some concerns.

[Carrerahill]

1 hour ago, Mr Punter said:

https://www.bbc.co.uk/news/uk-england-bristol-49028337

 

This shows a Premier Inn ablaze and a large part of it collapsed. I suspect it is timber frame as lots of their newer builds are. Quite why the fire spread through the building and caused such destruction I do not know, but it does raise some concerns.

As I see it a timber frame is going to burn, the way we just completed ours, to latest BS, I cannot see what will stop it burning down to be honest - that is obviouslt dependent on the location of the outbreak. The "fire-stops", as per our approved BC drawings, are 50x50mm treated timber - timber - give that a month or two and that will be bone dry.

 

It depends where the fire breaks out to be honest - if it's in the plasterboard shell of the room then the PB offers 30mins (according the Gyprocc) now that doesn't really take into consideration things like penetrations that may not always be very well "fire sealed". If the fire breaks out in a socket (why I always use metal pattress boxes for that little extra protection) then flame could easily lick up the stud and ignite - heck knows what the 100mm of PIR will do.

 

If a fire were to break out in our roof void I think the roof would be in flames fairly quickly, the fire would rage and quickly burn down through the timber fire stops at the top of the walls then the fire would then travel down the frame. Unless it was caught fairly quickly, and that time depends on where the fire breaks out, I think it would be a gonner. If the fire was stopped in its tracks, yet had managed to weaken timbers the building is still going to need to be torn apart and rebuilt anyway - so all these are about life protection.

 

Ideas and thoughts - Build in block, concrete floor and concrete first floor - a false PB ceiling with 100-150mm void for lighting, ducts etc. then a twin sheeted Fireroc ceiling to protect timber above at roof level. I think that would be a good idea - then for other common sources -  electrical, pattress boxes could be bigger metal boxes fastened between studs with fire rated glands then a smaller section which actually takes the socket - space for proper termination and not a crowd of wires, when correctly installed into a wall against PB any ignition sources are contained and the socket and cable ought not to self extinguish anyway. Just ideas and thoughts here but stop the fires in the first place is my thought.

 

I watch a YouTube channel of a young Canadian framer called "The crazy framer" - he basically builds complete timber houses by himself - I note they use a product called DensGlass on walls adjacent to other buildings - it is a fiberglass/gypsum product used for, but possibly not limited to, external sheathing like we use OSB for here. They use it due to the fire-rating it can provide - I don't know how long it gives you but if say it gives you 15minutes before the fire breaks through the sheathing either way it will help protect. He also uses a lot of PB between lintels and where main floor supports meet etc. this is all to reduce fire spread and I like it. I think it is a good idea. The idea of using PB on an open timber frame might not work too well here in the wet but I have line rafters and under the loft floor in plasterboard around most of my downlights. I know you can buy hoods but I think my idea is better as I made a big box, sealed the wire penetration into the PB bulkhead I formed and that lets me pull the light in the future and pull out the tail to the junction box and I think A, it stops draughts via the light which causes that bad dusty mess on them over time and B if that GU10 LED lamp was to go pop and even blow hot material about it is not going to land on anything flammable - that is the theory. I keep meaning to do a test - i.e. get two pieces of 2x8 and make the PB bulkhead then set fire to it. I might do that when I have PB left over from the lining stage.

 

When I do my electrical on my extension I am going to form fire-stops with PB in the wall - I will post it up at the time. My belief is that arresting the source of the fire is better than pointless stops - their inclusion is futile.

 

 

 

 

Edited July 18, 2019 by Carrerahill

[Mr Punter]

5 minutes ago, Carrerahill said:

If a fire were to break out in our roof void I think the roof would be in flames fairly quickly, the fire would rage and quickly burn down through the timber fire stops at the top - the fire would then travel down the frame. Unless it was caught fairly quickly, and that time depends on where the fire breaks out, I think it would be a gonner. 

 

I doubt this would happen as fire will normally travel up, not down, so if a fire breaks out on an upper storey, the storeys below are normally OK.

 

7 minutes ago, Carrerahill said:

they use a product called DensGlass on walls adjacent to other buildings - it is a fiberglass/gypsum product used for, but possibly not limited to, external sheathing like we use OSB for here. They use it due to the fire-rating it can provide - I don't know how long it gives you but if say it gives you 15minutes before the fire breaks through the sheathing either way it will help protect.

 

We have used Fermacell as sheathing to external walls close to other buildings and also on some party walls to compartmentalise. This is supposedly to reduce the fire risk during construction but I guess it would help after completion too.

 

We have smoke detectors and sprinklers in every room and corridor. It is still the case that if a fire breaks out in a cavity they will not be much help.

 

I am just intrigued why the Premier Inn did not seem to have sprinklers or passive fire protection that worked.

[nod]

The are 

Im just waiting to start plaster the one At Blackpool 

Most of the student accommodation are TF 

It would be difficult to keep to the tight deadlines on traditional built 

Once they catch they don’t half burn 

All that dry timber 

 

The upside is Ten years before the smoking ban 

ALL TF buildings where strictly no smoking  No second hand smoke to breath in 

It seems mad now 

[Carrerahill]

2 hours ago, Mr Punter said:

 

I doubt this would happen as fire will normally travel up, not down, so if a fire breaks out on an upper storey, the storeys below are normally OK.

 

Yes totally, I agree and that comment may have appeared daft, but, in my case a roof fire at the sides could sit on these firestops and burn them through then burning debris would fall to the bottom, quickly melt the membrane and start to ignite the OSB.