fire behaviour of corrugated steel/wriggly tin

[lingmoor]

Hi all

has anyone got any info on the fire behaviour of wriggly tin sheets

cheers

[col10]

Insulated?

[lingmoor]

no Colin, just single skin

[Mike Buckley]

I am not sure about wriggly tin, however if it is steel expect to act like steel and start to loose its structural strength when it reaches about 500 C. Another thing to look out for is the surface to volume ratio, the rate the material will heat up will depend to great extent on the surface area exposed to the heat. As the wriggly stuff is fairly thin it has a greater surface area to a given volume of steel and will therefore absorb the more heat than a solid lump of the same mass. It is just like the cooling effects of a water spray v a water jet.

[John Webb]

Other factors to consider are orientation (vertical/horizontal/sloping) and if it has any form of coating. Particularly in the vertical mode as external cladding, distortion at overlaps can occur if the fire is external to the building, and may allow fire into the building as well as the heat transmitted through the sheet.

[Fishy]

Reaction-to-fire performance (RTF):  If it's only galvanised then it won't contribute to a fire.  If coated, then RTF performance will depend entirely upon the coating(s);

Fire resistance:  will depend entirely upon the construction.  Joint and fixing detail would be important, as would the supporting frame.  Non-insulated panelling will get very hot and potentially ignite combustible materials due to radiant heat even if it stays in place and intact.  If the construction has no evidence of fire resistance performance, safer to assume that it has none.

[lingmoor]

Thanks for your replies it is appreciated.

Just been scouring the ADB.

Building Control are only interested in the roof as if it didn't have one then it wouldn't require BC approval

Table 16 of ADB says that for a roof less than 6m from a boudary then the roof covering of AA, AB or AC is acceptable (bear with me )

Page 124 (on-line version)  says that if a structure for storage is not more than 5 metres high and not sprinklered then it has to be 60 min FR

now.... Page 128 states that AA designation can be pitched roofs, covered with with a self supporting sheet without underlay, with a timber, steel or concrete supporting structure.... the roof can be single skinned galvanised steel, alluminium etc

and it gives a list for pitched or flat roofs of various metals that are acceptable with fully supported materials

So it appears to say that a single skinned galvanised metal construction with the above criteria gives 60 mins of fire resistance (AA)

I'm sure that the radiated heat would me a concern though
for all those with an intimate knowledge of the Building Regs can you tell me if this is right or utter cock...ta

[wee brian]

60 mins FR applies to elements of structure.

For a single story shed, with no boundary issues, there are no elements of structure.

only issue will be the AA etc ratings - wriggly tin is going to be AA unless you paint it with something funny.