Fire protection of steels

[Nickfromwales]

  On 04/04/2025 at 13:13, Post and beam said:

Nick they are load bearing. 

 

I am glad you say nothing needs doing to them.  is that because they will have plasterboard below them and are not on show?

 

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In that case, not to stir the pot any more than I usually like to do, those timbers should be boarded and skimmed too then? Has that been specified?

[Mr Punter]

  On 04/04/2025 at 14:01, saveasteading said:

BTW I have worked with severely fire damaged buildings and the steel structure was always intact.

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Yes I do wonder why there is such a focus on steel and fire protection.  I could understand if it is a large complex steel framed building, but a dwelling or a small block of flats?  I would be interested to see if there has ever been a case in this country that a small domestic building has collapsed or partly collapsed due to failure of structural steel in a fire.  I very much doubt it.

[Nickfromwales]

  On 04/04/2025 at 13:15, Post and beam said:

Standard plasterboard provides the 30 minutes protection though doesn't it? 

 

The timber posts and beams are a structural element and the steels sit on them. Nobody has mentioned a thing about providing additional 30 minutes protection of those. Curious.

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Sorry. Missed this.

 

My thoughts exactly which means the world’s gone mad! And your BCO lady is out of a job.

 

Protect a steel that’s already protected, but leave the wood exposed that’s holding the fecking steel up.   🤷‍♂️🤦‍♂️

 

  On 04/04/2025 at 13:13, Post and beam said:

is that because they will have plasterboard below them and are not on show?

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Yes. If an open flame in the room / space interior cannot ‘lick’ the steel (because it’s behind a continuous layer of board and skim) then it doesn’t need to be considered at all.

[ETC]

  On 04/04/2025 at 07:44, nod said:

I do fireproofing as part of my business

We are never asked for any protection for two story homes But once that extra floor is added You will need an hour protection Some insist on the beams being wrapped Then boarded Others are happy to treat them like an integral garage Two layers of fire line board It should really be on the drawing 

 

Our last two builds are full of steels supporting the floors No protection needed 

 

This is our current build 

Note no mention of unnecessary fire protection from the SE 

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Your BCO should be asking for all structural steel in a two and three storey dwelling to be fire protected to achieve 1/2HRF - simplest way is to paint with intumescent paint. Boarding requires a tested detail from British Gypsum to be followed. Sticking two layers of fire line board might do the trick but I doubt BG would sanction the construction.

[Gus Potter]

  On 03/04/2025 at 16:43, Post and beam said:

I have 2 steel joists running across the living room. They will not be visible once the plasterboard ceiling is installed. 10 inch posi joists carry the rest of the ceiling/s. Building control have asked for fire protection of these steels.    Is it acceptable to just use 15mm fire  rated plasterboard across the entire living room ceiling. Or do they need to be encased? 

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Hi all.

 

This fire protection thing crops up often on BH.

 

I'm going to pick out some of the folk that often chip in on fire design. Now you could be a designer, a contractor or just someone that has done a lot of self builds. What you see is a lot of is folk saying we did this and that. But if you are a newcomer to the self build or internal alteration / extension market then unless you all then go onto say why you did what you did / or do then it gets even more confusing?

 

  On 04/04/2025 at 14:35, Nickfromwales said:

My thoughts exactly which means the world’s gone mad! And your BCO lady is out of a job.

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  On 04/04/2025 at 21:11, ETC said:

Your BCO should be asking for all structural steel in a two and three storey dwelling to be fire protected to achieve 1/2HRF - simplest way is to paint with intumescent paint.

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I've just copied a bit of an extract from posts. There is nothing wrong in the above or right. It's a best guess on limited info on a building forum. @nod you do this stuff as a day job.. time to step up to the plate design / theory wise?

 

Now there are a lot of folk here commenting as above. What would possibly be more helpful is to say.. we had to do this because of this type of design.

 

I use my own name. I write stuff., over time I've been a member I've said some daft stuff, BH members and the MODS have cut me a lot of slack. yes this is a place where as an SE you can shoot the breeze if off duty.  BH is also a place where you can make mistakes and folk will forgive. So in that context folk surely you can go the extra mile and say.. here is why we think we did what we did. in terms of fire protection.

 

In summary, folks who comment on fire protection often. We should be stepping up to the plate and saying.. this might work and here is why. We kind of owe that to new members?

 

 

 

 

 

 

[ETC]

There are a hundred and one ways to skin a cat but only one set of Regulations - often open to interpretation - as long as you comply with the Regulations youare home in a boat.

[Thorfun]

  On 05/04/2025 at 06:45, ETC said:

as long as you comply with the Regulations youare home in a boat.

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As a minimum!! If we only had to comply we’d all have leaky poorly insulated houses. 🤣

[saveasteading]

I have learned from this discussion.

I didn't know this...or maybe I used to and have forgotten.

It is the minimum weight of plasterboard that determines which boards suffice for sound insulation in a ceiling.

See the bottom bit about the weight of pb from different brands.

Combine this with the fire properties and it becomes apparent why a 15mm fireboard is thought to be the norm.

[Gus Potter]

  On 05/04/2025 at 06:45, ETC said:

There are a hundred and one ways to skin a cat but only one set of Regulations - often open to interpretation - as long as you comply with the Regulations youare home in a boat.

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Hi @ETC there use to be a bloke called @the_r_sole who was a right down to earth Architect and massively experienced that gave up his time to contribute to BH. He really knew his stuff.. a bit like you. You can find his posts in two ways.. on google and with a BH search.. hard to find. Try and look them out. His writing style probably is similar to yours, no nonsence. I have my own informal style of writing / shite spelling ( story for another day).. it's ok to be different and give Clients a different offer. 

 

@ETC I'm chatty on BH,  (just sharing my knowledge) when I pitch for a design brief.. I seem to win briefs.. but when I deal with industrial or hard nosed folk I can play that game too.  I do now and again Claims work.. my head does not zip up the back. My style then is a different animal... but I'm confident in my ability... my style sets me apart from the competition. Even when I do claims and just day to day jobs. Over the years I've learnt my design craft.. but also try and improve the way I can communicate what are often complex design issues into simple concepts that a lay person can get their head around while enabling them to make informed  financial descisions. @ETC that in my view thatv  is the mark of a good professioal.

 

I think the mods on BH are ok and if you get a bit of business, it's ok provided you don't take the pish. Now and again someone from BH engages me, often these are folk that are really stuck, bad builder. and so on. About two years ago I commented on a post about bad blocks from Ireland.. got a email  couple of days ago.. can you help. That is the thing I love about the BH community folk will come back to you for help. My basic qualification is in Civil Enginnering and that key word is Civil.. we work for the public. For all I'm proud of that and will never forget my civic duty. @saveasteading has expanded on this civic duty. It's like being a doctor.. we have a duty not to harm, you as Client are lower down the list even thought you are paying the bill!

 

The sole put his heart into BH but basically got hounded off BH as there were too many twats that thought they knew better, they thought all Architects were arseholes. So going back a bit and not picking anyone out in particular..I'm just saying remember when the sole was doing his best. 

@nod @MikeSharp01 and the rest of the mods.

 

On the other hand @ETC what about using your own name like I do? I would like to see you tighten up many of you comments, you can't have your cake an eat it? For me I read what you write and think.. mmm here is a smart arse.. It would be good if you went on to reason out your comments so the lay person on BH can undestand.. that is what I try and do.. give it a go!

 

 

 

 

 

 

 

 

 

 

 

 

Edited Monday at 23:47 by Gus Potter

[Super_Paulie]

For what it's worth, my BC said I can just fly over my beam with standard plasterboard because it's within the ceiling void. Nothing else required for him to give it the old ok.

[nod]

  On 07/04/2025 at 23:41, Gus Potter said:

 

Hi @ETC there use to be a bloke called @the_r_sole who was a right down to earth Architect and massively experienced that gave up his time to contribute to BH. He really knew his stuff.. a bit like you. You can find his posts in two ways.. on google and with a BH search.. hard to find. Try and look them out. His writing style probably is similar to yours, no nonsence. I have my own informal style of writing / shite spelling ( story for another day).. it's ok to be different and give Clients a different offer. 

 

@ETC I'm chatty on BH,  (just sharing my knowledge) when I pitch for a design brief.. I seem to win briefs.. but when I deal with industrial or hard nosed folk I can play that game too.  I do now and again Claims work.. my head does not zip up the back. My style then is a different animal... but I'm confident in my ability... my style sets me apart from the competition. Even when I do claims and just day to day jobs. Over the years I've learnt my design craft.. but also try and improve the way I can communicate what are often complex design issues into simple concepts that a lay person can get their head around while enabling them to make informed  financial descisions. @ETC that in my view thatv  is the mark of a good professioal.

 

I think the mods on BH are ok and if you get a bit of business, it's ok provided you don't take the pish. Now and again someone from BH engages me, often these are folk that are really stuck, bad builder. and so on. About two years ago I commented on a post about bad blocks from Ireland.. got a email  couple of days ago.. can you help. That is the thing I love about the BH community folk will come back to you for help. My basic qualification is in Civil Enginnering and that key word is Civil.. we work for the public. For all I'm proud of that and will never forget my civic duty. @saveasteading has expanded on this civic duty. It's like being a doctor.. we have a duty not to harm, you as Client are lower down the list even thought you are paying the bill!

 

The sole put his heart into BH but basically got hounded off BH as there were too many twats that thought they knew better, they thought all Architects were arseholes. So going back a bit and not picking anyone out in particular..I'm just saying remember when the sole was doing his best. 

@nod @MikeSharp01 and the rest of the mods.

 

On the other hand @ETC what about using your own name like I do? I would like to see you tighten up many of you comments, you can't have your cake an eat it? For me I read what you write and think.. mmm here is a smart arse.. It would be good if you went on to reason out your comments so the lay person on BH can undestand.. that is what I try and do.. give it a go!

 

 

 

 

 

 

 

 

 

 

 

 

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👏 

[nod]

  On 08/04/2025 at 00:05, Super_Paulie said:

For what it's worth, my BC said I can just fly over my beam with standard plasterboard because it's within the ceiling void. Nothing else required for him to give it the old ok.

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A rule of thumb for PB weight and thickness is 400 centres 12.5 boards 

600 15 mil boards 

MF 1200 grid = single layer PB

800 grid = 2 layers of anything 

Not a Google technical answer 

But a rough guide 

  On 05/04/2025 at 18:35, saveasteading said:

I have learned from this discussion.

I didn't know this...or maybe I used to and have forgotten.

It is the minimum weight of plasterboard that determines which boards suffice for sound insulation in a ceiling.

See the bottom bit about the weight of pb from different brands.

Combine this with the fire properties and it becomes apparent why a 15mm fireboard is thought to be the norm.

Expand  

 

[saveasteading]

  On 07/04/2025 at 23:41, Gus Potter said:

It's like being a doctor.. we have a duty not to harm, you as Client are lower down the list even thought you are paying the bill!

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Not a lot of people know that.

 

As a Chartered Civil Engineer we are sworn to do what is right for the world first, and the client comes second.

A Chartered Surveyor once said to me that this only applies to Civil Engineers, Doctors and nurses.....and he wasn't so sure about nurses.

He showed me the surveyors' ethos....hmmmm: nothing about fairness.

 

It probably hinders our earnings potential but helps our consciences. 

 

BTW "Civil" comes from " not military" rather than politeness.

[Post and beam]

  On 08/04/2025 at 00:05, Super_Paulie said:

For what it's worth, my BC said I can just fly over my beam with standard plasterboard because it's within the ceiling void. Nothing else required for him to give it the old ok.

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Is this 2 x steels with some PIR between?  and is the timber either side part of the construction or part of some fireproofing subsequent.

[Post and beam]

  On 08/04/2025 at 05:26, nod said:

MF 1200 grid = single layer PB

800 grid = 2 layers of anything 

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 I understand the 15mm for 600 centres bit but i do not understand the MF part i copied in. please elaborate

[Thorfun]

  On 08/04/2025 at 12:28, Post and beam said:

 I understand the 15mm for 600 centres bit but i do not understand the MF part i copied in. please elaborate

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I believe it’s the weight bearing capacity of the MF ceiling. A standard 1200mm grid as per BG design will take a single sheet of PB but if you want thicker or soundbloc or double boarded then you need to make the grid smaller to take the extra weight. 
 

the BG docs do state this. 

[Thorfun]

  On 08/04/2025 at 12:28, Post and beam said:

 I understand the 15mm for 600 centres bit but i do not understand the MF part i copied in. please elaborate

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And you can use (afaik) 12.5mm at 600mm centres for ceilings but you need noggins for the board ends. 
 

although happy to be corrected if this isn’t the case but it is my understanding 

[nod]

  On 08/04/2025 at 14:55, Thorfun said:

And you can use (afaik) 12.5mm at 600mm centres for ceilings but you need noggins for the board ends. 
 

although happy to be corrected if this isn’t the case but it is my understanding 

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Yes 

But why go to the trouble of nogging all the edges Just use a 15 mil board 

[Thorfun]

  On 08/04/2025 at 15:31, nod said:

Yes 

But why go to the trouble of nogging all the edges Just use a 15 mil board 

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I agree and is what we did. Just giving options. 😉

[ETC]

  On 08/04/2025 at 00:05, Super_Paulie said:

For what it's worth, my BC said I can just fly over my beam with standard plasterboard because it's within the ceiling void. Nothing else required for him to give it the old ok.

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I presume there is a roof not a floor above this?

[Super_Paulie]

  On 08/04/2025 at 12:26, Post and beam said:

Is this 2 x steels with some PIR between?  and is the timber either side part of the construction or part of some fireproofing subsequent.

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It's a twinned steel which I insulated between with PIR. The timber is joists on the inside and I guess a wall plate on the outer.

 

  On 08/04/2025 at 19:36, ETC said:

I presume there is a roof not a floor above this?

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Steels support the cavity wall above, pitched roof to the front, room to the rear.

[haythorn_1]

  On 08/04/2025 at 22:44, Super_Paulie said:

Steels support the cavity wall above, pitched roof to the front, room to the rear.

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interesting, I have a similar setup. It’s not a great thermal bridge! What is your cavity filled with?

 

mine is with mineral wool and at the moment you can see it between the steels.  I don’t see what the benefit of adding PIR is here

Edited Wednesday at 07:10 by haythorn_1

[ETC]

  On 08/04/2025 at 22:44, Super_Paulie said:

It's a twinned steel which I insulated between with PIR. The timber is joists on the inside and I guess a wall plate on the outer.

 

 

Steels support the cavity wall above, pitched roof to the front, room to the rear.

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I do believe that the steelwork should be fire protected within a domestic floor where it supports an element of structure above - in this case a cavity wall. I don't think your BCO is correct if he/she is saying that simply enclosing the beams in the floor will give the fire protection.

[Mr Punter]

  On 09/04/2025 at 08:28, ETC said:

I do believe that the steelwork should be fire protected within a domestic floor where it supports an element of structure above - in this case a cavity wall. I don't think your BCO is correct if he/she is saying that simply enclosing the beams in the floor will give the fire protection.

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I have heard this from some people where although the floor may be rated for 30 or 60 mins, the steelwork within the void is treated differently, but I have never heard a coherent reason why.

[Super_Paulie]

  On 09/04/2025 at 07:09, haythorn_1 said:

interesting, I have a similar setup. It’s not a great thermal bridge! What is your cavity filled with?

mine is with mineral wool and at the moment you can see it between the steels.  I don’t see what the benefit of adding PIR is here

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yeah its wool in the cavity. I could have filled between the steels with wool but i had PIR so just used that and with wool on top/around it and foamed it in. I think i used a 15mm PIR underneath the beam to bring it flush to the bottom of the joists.

 

 

  On 09/04/2025 at 08:28, ETC said:

I do believe that the steelwork should be fire protected within a domestic floor where it supports an element of structure above - in this case a cavity wall. I don't think your BCO is correct if he/she is saying that simply enclosing the beams in the floor will give the fire protection.

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You may be right. I was just following the guidance of my BCO, see below extract. Im in the North East of England if that has any bearing:

Afternoon Paul,

Given that the subject beam will be set above the ceiling level, without any down stands, I can confirm that a standard single 12.5mm plaster board would be deemed satisfactory in terms of providing the required fire protection.  As such, you can use either approach of an additional strip of plaster board or placement of insulation.

Regards.

Edited Wednesday at 08:59 by Super_Paulie