Building control comment back - encasing steel for fire

[Moonshine]

I submitted my building control drawings and have had 3 comments back.

 

One of these was "Gypsum fireline board should be used for fireproofing steels rather than wallboard". He indicated on the phone that 12.5mm fireline would be o.k.

 

The details of the steel encasements are below

 

The first one is in a garage and i think that the can be done easily, the second one i am not sure of as it has joists attached to it.

 

in fact its going to have a board attached to the steel (box steel rather than I-beam shown) for the joist hanger to go onto, so am i going to have to box in the box steel and bolt through the fire board to secure the wood to the steel?

 

Third one maybe easier to have a later of the ceiling as fireline? would that be enough?

 

 

[Conor]

Intumescant paint is normally sufficient. I got a 2.5l tin and wil easily do all the steels in our house. £60.

[markc]

Intumescent paint can often be used in place of fire board, however many SE`s are wary as application greatly affects its performance.

UB and UC sections require different paint to Flat sided Hollow sections and steel preparation and primer application are critical to effectiveness against fire.

Paint (film) thickness requirement must be determined and the dry film thickness measured to ensure compliance.

Fire board may seem fiddly but its pretty foolproof and easily seen for sign off purposes

[Moonshine]

32 minutes ago, markc said:

Fire board may seem fiddly but its pretty foolproof and easily seen for sign off purposes

 

 

yeh i think that i would prefer FB than painting on stuff.

[Temp]

1 hour ago, Moonshine said:

I submitted my building control drawings and have had 3 comments back.

 

One of these was "Gypsum fireline board should be used for fireproofing steels rather than wallboard". He indicated on the phone that 12.5mm fireline would be o.k.

 

The details of the steel encasements are below

 

The first one is in a garage and i think that the can be done easily, the second one i am not sure of as it has joists attached to it.

 

in fact its going to have a board attached to the steel (box steel rather than I-beam shown) for the joist hanger to go onto, so am i going to have to box in the box steel and bolt through the fire board to secure the wood to the steel?

 

Third one maybe easier to have a later of the ceiling as fireline? would that be enough?

 

 

 

Is he saying your encasement is inadequate or just that you need to substitute plasterboard for fire board in the existing proposal?

 

 

 

 

[nod]

I do a lot of this as part of my business 

Forget the diy paint It’s rubbish As already pointed out SE won’t specify it The fire retardant paint that’s used on most commercial sites is roughly three time the cost of boarding with 15 mil fire line 

Yours are difficult to get at 

I would suggest double boarding the ceiling with two layer of fire line All integral garages are done this way 

[Dan F]

Two layers of soundbloc achieves the necesary fire rating too.   We've followed a robust ceiling detail that uses 2xsoundbloc on resilient bars below steels and joists and this is satisfactory.  From what our building control guys said, it's the ceiling that needs the protection rather than the steels needing to be encased.

Edited April 21, 2021 by Dan F

[Mr Punter]

This seems an area of confusion.  I have an architect who insisted that the steels were painted, even though they were protected by the ceiling.  They then went on to say that unless we accepted the intumescent paint we would need to prove that the steels were protected from fire including from above.

 

There is basic ignorance abounding with this, among architects and building control.  I can see just why Grenfell happened.

 

In reality if you try to apply intumescent pain on site the steel will go rusty and you will not achieve the correct thickness.  It also needs a clearance all round to expand.

[saveasteading]

Intumescent paint is tricky. There is a calculation to tell you how thick it has to be, and it likely requires several coats on these steels. Then it gets a seal coat on top.

£60 does not do it. The building inspector should ask to see the calculations, and also check the thickness applied.

So for this little job it is not worth the hassle.

 

Plasterboard is easy and fool proof. In most cases you can use one layer of the pink fireboard or 2 layers of normal plasterboard.

The latter is handy because any tricky/ untidy cuts in the first layer get covered by the second.

It can all be calculated, but the BI is likely to accept either PB suggestion, and rightly so. If the  BI does not know this, perhaps just do what he expects and use pink.

There is very little chance of fire melting the steel from above,  but you might as well do what is expected and box the steels.

You can make a support of timber on or within the steel, to which the board is screwed, as that is automatically protected too.