Building regs for loft

[Reeci]

Can anyone help me to understand the requirements below for part B . If you use  a non fire rated door why does it have  to be tradition timber and at least 32 thick within a protected corridor ?

[Marvin]

Hi @Reeci

 

I think that the requirements are so the doors still give a good fire resistance, i.e. look you want a fancy door so fine as long as it resists fire. Here's what it needs to be: .........

 

You want glass in it? Fine, here's what it needs to be......

[Temp]

In a regular two storey house you can also jump from a 1st floor window. Can't really do that from 2nd floor.

 

In theory we all shut the living room and kitchen door at night so when there is a fire in there we still have a semi fire proof corridor from the loft/2nd floor to the garden. If your doors are made of cardboard they perform much worse than a solid wood door even the door doesnt have seals and an official fire rating.

 

 

[kandgmitchell]

Ditto Temp, there is no self help escape from a second floor room. First floor you can lower and drop.

 

The Approved Document to Part B actually says this:

 

Dwellinghouses with one storey more than 4.5m above ground level
2.5 See Diagram 2.1c. The dwellinghouse should have either of the following.
a. Protected stairway – a stair separated by fire resisting construction (minimum REI 30) at all
storeys, that complies with one of the following.
i. Extends to a final exit (Diagram 2.2a).
ii. Gives access to a minimum of two ground level final exits that are separated from each
other by fire resisting construction (minimum REI 30) and fire doorsets (minimum E 20)
(Diagram 2.2b).
Cavity barriers or a fire resisting ceiling (minimum EI 30) should be provided above a protected
stairway enclosure (Diagram 2.3).
b. Alternative escape route – a top storey separated from lower storeys by fire resisting
construction (minimum REI 30) and with an alternative escape route leading to its own final exit.

 

The diagrams referred to above show doors opening onto the protected stairway as being E20 (or FD20) fire doors. If your BCO is co-operative then he may accept good quality existing doors. Trouble is that following the Building Safety Act there is a move towards specific liability for decisions of this nature. If you were a BCO why would you open yourself to that sort of responsiblity? The simple answer would be - prove your doors are equivalent to the standard or change them for ones that are.  

[DevilDamo]

20 hours ago, Temp said:

 

In a regular two storey house you can also jump from a 1st floor window. Can't really do that from 2nd floor.

 

It’s more for the fire brigade to access the window as opposed to an occupant hanging and/or jumping out.

[DevilDamo]

On 03/05/2023 at 22:25, Reeci said:

Can anyone help me to understand the requirements below for part B . If you use  a non fire rated door why does it have  to be tradition timber and at least 32 thick within a protected corridor ?

Are you adding an additional storey to provide a 3-storey dwelling?

[Temp]

15 hours ago, DevilDamo said:

Are you adding an additional storey to provide a 3-storey dwelling?

That's what a loft conversion does.

[kandgmitchell]

Not in a bungalow...............

[davejura]

Just jumping on to here rather than starting a new topic! We have attic trusses in our new build with the intention of converting a few years down the track. Our builder is saying we should put fire doors in now. But, our house is on a sloping site so we have an entrance on the first floor and ground floor. This means you would only be 1 storey away from an exit door if you are in the attic. Just trying to find out if we still need fire doors? Or maybe just on the first floor (which is the living area). We are in Scotland if that makes any difference.

[kandgmitchell]

Well in England the height of the top storey is measured from the lowest ground level, so if that meant it was more than 4.5m high, then the rules applicable to floors over 4.5m apply, even if there is an "upper" ground level (although there may be some flexibility depending on layout). I'm afraid Scotland is a different world..................

[DevilDamo]

On 05/05/2023 at 14:29, Temp said:

That's what a loft conversion does.

As a member mentioned below, not if it’s a bungalow. Could also already be a 3-storey town house. The OP doesn’t state what the existing house is yet.

[DevonKim]

I'd like to also jump in on this thread; 

 

I have attic trusses, so technically have a 3 storey house.  Where does the fire door have to go? 

 

My kitchen is at the rear of the property, my staircase at the front.  Does the fire door go on the exit from the kitchen, hence protecting the stairs?  Or does the door go on the staircase itself, between the first and second floors?  

 

 

[Temp]

I think what you need to provide is a "protected escape route" from the loft to an outside door. So all the walls and doors that lead off that escape route need to meet the 30min Fire/FD30. Normally this is your main staircase so every door off the stairs and hall needs to comply. 

 

Also need linked smoke alarms..

 

https://labcfrontdoor.co.uk/projects/loft-conversions/what-are-the-fire-regulations-for-a-loft-conversion

Edited May 12, 2023 by Temp

[ETC]

The amount of protection you need will depend on how high above ground level the final storey is. You will more than likely be asked to provide a protected stairwell where all doors to habitable rooms will need to be fire doors. Check out the. Approved Document for your scenario.

[Gus Potter]

On 03/05/2023 at 22:25, Reeci said:

Can anyone help me to understand the requirements below for part B . If you use  a non fire rated door why does it have  to be tradition timber and at least 32 thick within a protected corridor ?

This is a difficult subject to get your head round to say the least. Hope these general comments help shed some light.

 

You want to do a loft conversion that turns you house from a two storey into a three and you have non rated doors, say traditional 6 panel timber doors with fielded panels.

 

Timber and in particular hardwood doors (the timber is denser) can resist fire quite (talking 30 minutes here) well as the timber chars on the fire side and the charring provides an insulating layer which keeps the remaining timber cooler and thus intact. But you need a sufficient thickness of timber so you can get enough char to do the job. 32mm thick look a bit thin to me, if all other factors work in your favour then the Institution of Fire Engineers mention a figure of 35mm thick if the door has that thickness all over.. in other words a solid door. For me I would look at this as a possible practical / cost effective option for a non period house if the doors were 45mm thick or more and solid.

 

A fielded panel is much thinner, that is a problem. Now it gets more complicated.. you can protect the fielded panels but you need to understand how the panels are rebated into the styles, rails and muntins. Next you need to examine each door for distortion, splitting and so on.

 

Next we need to look at how we are going to install cold smoke seals and heat (intumescent heat) seals... do we fit them to the doors or the frame?

 

Onto the door frame now. Do we have enough meat in the timber to fit hinges and closers in accordance with the manufacturer's instruction? How thick is the door frame, is there a gap behind it and how thick are the door facings protecting the masonry frame interface?

 

The above covers some things we need to think about. In the old days we used to fit hardwood stops screwed and glued to the existing frame, maybe upgrade the fielded panels a bit and pretty much go to the pub. Changed days now as this sort of stuff is well scrutinsed, rightly so. To get this over the line with BC you need to do your research, develop the upgrade strategy, make the case, make sure your case will stand up to test by say the Institute of Fire Engineers and then hope that BC will agree. Anyone doing this type of design / upgrade carries the can liability wise so the days of doing ten minutes work and scooping up are over.

 

Now the above can be challenging and exciting.. but it comes at a cost.

 

3 hours ago, DevonKim said:

I have attic trusses, so technically have a 3 storey house.  Where does the fire door have to go? 

The objective is to provide a passage way (protected route) to allow people on the ground and first floor (if not too high above the ground to jump out a window, it's the height to ground level) to escape. On the third floor they escape by way of the stair case. Thus for now assume you need fire doors on all the rooms (sometimes not all rooms but that is for another day) connecting to the staircase so that if a fire starts in one room the smoke and heat can't get into the stair well.

 

Another thing we need to think about is this. When we create a third storey in the attic the attic floor becomes a structural floor.. that needs a 30 min fire resistance from below. If the ceiling joists are thin then sometimes you can't show that 12.5mm plasterboard directly fixed to say prefabricated truss bottom chords (89 x 38) gives the 30 min fire protection. But if your house was built with future proofed attic trusses the bottom chords may be 195 x 45 which usually gives you 30 min fire protection. It's not just the plasterboard alone that gives the 30 min it's also what it is fixed to and whether the plasterboard is skim coated or not.

 

You can get round this by beefing up the ceiling joists if they are thin.. but you need to check the strengthening nailing pattern etc. If you have lath and plaster ceilings that BC query there is a fairly cheep fire emulsion paint that you can apply to upgrade a lath and plaster ceiling to 30 min or more.

 

The above all sounds a bit doom and gloom.. but here a few ideas. Often when doing a loft conversion folk also want to make things open plan on the ground floor.. in new build you may have open plan ground floor also... both play havoc with the protected stair concept.

 

But now we have misting fire sprinklers! The price has dropped a lot and they don't need huge tanks in the loft or a "special" water supply. Yes they do need maintained so there is a cost there.

 

Hope this helps a bit.

 

 

 

 

 

 

 

 

 

[DevonKim]

Thank you very much @Gus Potter 

 

Lots to think about there 

[saveasteading]

9 hours ago, Gus Potter said:

Hope this helps a bit.

A Gus special that should be filed for reuse.

If you really want to design this yourself, then it is essential to understand the guidance. 

The principles are all good. Making sure everyone can escape.

 

I suggest printing the regs and marking up ( highlight pen) the relevant clauses to suit your own situation. It then becomes less of a muddle of ifs and buts.

Also accept that it can cost quite a lot, and may result in a door that you would rather not have.

Other, less well behaved and moderated, advice sites may suggest taking a door off after the bco is finished. Don't dream of it as lives are genuinely at stake and it wouldn't be a good way to go.