Fire Resistant Windows - what are the regulations?

[LeanTwo]

I'm putting a double glazed window in an elevation of my new kitchen/diner extension that abuts a neighbour's property.  I have to comply with building regulations so as to provide thirty minute fire resistance.  Can anyone point me towards some more information on this such as a technical (but not too technical!) description of what is required, please?

[AliG]

Most window suppliers should be able to supply a window with a fire rated double glazing unit and frames. Fire resistant glass is very expensive approx £300 a square metre. The frame would also have to be fire rated as well as the glass. I think your window supplier is the first port of call.

 

You can get cheaper wired glass but I would presume you don't want that.

 

I didn't know that the regs required fire resistance if windows are close to the boundary but apparently they do having just looked it up in Part B of the Building Regs. You are allowed a certain amount of "unprotected area"(windows or doors) that rises as the distance from the boundary increases. If you exceed this area the exterior doors or windows have to be fire rated.

 

[Montipora]

If you are within 1m of boundary you are allowed max 1m2 unprotected area i.e. Window including frame. If your window is larger then it would need to have 30 mins protection 

[LeanTwo]

Thanks for the replies AliG and Montipora.   The window is right on the boundary.  It's a triangular fixed single sash measuring approximately 2.5m on the horizontal and 1.0m on the vertical, including the frame.  My (very poor) maths makes that approximately 1.25 sq. m., including the frame.  

 

It's at the top of the elevation on my lean-to so it's for letting light in and not for seeing through so wired glass would not be a problem, if I also made a good cost saving. Maybe a smaller window would save me a lot of money?

[AliG]

I think if it is actually on the boundary it will have to be fire rated. If it is 1m away then you could prob use a normal window if the size is less than 1sq m.

[LeanTwo]

Just to add to this one..

 

Speaking to my local District Council Building control officer, any window less than 1m sq (including frame and glass) in area does not need to be fire resistant, even if it's less than 1m away from the boundary.

 

The relevant building regs can be found at: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/485420/BR_PDF_AD_B1_2013.pdf and are:

 

Section 8  clause 8.3

Section 9  clause 9.7

Appendix A  Tables A 1 and A2

[Temp]

The window is right on the boundary.

 

Is the neighbour happy with that? Just in case you aren't aware... The neighbour could legally put up a fence or build something that obscures the window. They can also get you to remove anything that overhangs the boundary and that includes the window sill.

[LeanTwo]

Thanks for the reply Temp.  We've kept our neighbour up to date before the application and during it.  We've talked it through so they are aware, fully and have raised no issues with us. They have seen the full plans. We will continue to consult them as we go forward with the project as often the reality of things going ahead will cause concern.

 

The window is a triangular light above normal head height and so could not be used to look into the neighbour's garden, easily.  No concerns have been expressed from our neighbours.  The proposal has been granted full planning permission.

 

If our neighbour chose to obscure our window, then I would take the appropriate professional advice to determine what options were available to me.

 

Thanks for raising the issue.

[willbish]

On 03/02/2017 at 10:40, LeanTwo said:

Just to add to this one..

 

Speaking to my local District Council Building control officer, any window less than 1m sq (including frame and glass) in area does not need to be fire resistant, even if it's less than 1m away from the boundary.

 

The relevant building regs can be found at: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/485420/BR_PDF_AD_B1_2013.pdf and are:

 

Section 8  clause 8.3

 

Section 9  clause 9.7

 

Appendix A  Tables A 1 and A2

 

 

I've been looking into the fire rating of windows close to the boundary and since the above post the Part B building regs has been updated (from 84 pages to 180 ?)

 

The sections now relating to external walls, boundaries and unprotected areas are

 

Section B4 11.4 Boundaries

Section B4 11.16 Methods for calculating acceptable unprotected areas

 

Appendix B25 Table B3 External Walls

Appendix B25 Table B4 Dwellinghouses

 

From what I can see the numerical values haven't changed regarding 1m2 of small unprotected areas such as windows. Larger windows or other unprotected areas will most likely require 30' fire protection but depends on building size height and distance from boundary

 

Part B Building Regs 2019

 

 

[Moonshine]

On 16/01/2020 at 21:17, willbish said:

 

I've been looking into the fire rating of windows close to the boundary and since the above post the Part B building regs has been updated (from 84 pages to 180 ?)

 

The sections now relating to external walls, boundaries and unprotected areas are

 

Section B4 11.4 Boundaries

Section B4 11.16 Methods for calculating acceptable unprotected areas

 

Appendix B25 Table B3 External Walls

Appendix B25 Table B4 Dwellinghouses

 

From what I can see the numerical values haven't changed regarding 1m2 of small unprotected areas such as windows. Larger windows or other unprotected areas will most likely require 30' fire protection but depends on building size height and distance from boundary

 

Part B Building Regs 2019

 

 

 

I am coming to this issue, i have a façade on the boundary to the next door property, the actually building of the property is 1.5m away from the proposed facade, though there are three fixed obscure glazed windows in in the façade right on the boundary (W18, W19, W16), W17 is set further back

 

The BCO has highlighted the this as a potential issue for fire, and should be fitted with fire resistant glass.

 

 

The window proposed are aluminum 6.8mm Lam / 18mm Argon / 4mm Planitherm One.

 

Any idea if this will the requirements?

[Mr Punter]

12 hours ago, Moonshine said:

 

I am coming to this issue, i have a façade on the boundary to the next door property, the actually building of the property is 1.5m away from the proposed facade, though there are three fixed obscure glazed windows in in the façade right on the boundary (W18, W19, W16), W17 is set further back

 

The BCO has highlighted the this as a potential issue for fire, and should be fitted with fire resistant glass.

 

The window proposed are aluminum 6.8mm Lam / 18mm Argon / 4mm Planitherm One.

 

Any idea if this will the requirements?

 

If W18 and W19 are each less than 1m2 and at least 4m apart they will be acceptable.  If the floor above W16 is a compartment floor and less than 1m2 it will be OK.

 

If not, you may need special fire resistant glass (expensive).

[Moonshine]

43 minutes ago, Mr Punter said:

If W18 and W19 are each less than 1m2 and at least 4m apart they will be acceptable.  If the floor above W16 is a compartment floor and less than 1m2 it will be OK.

 

If not, you may need special fire resistant glass (expensive).

 

Thanks, W18 and W19 are both 750mm x 750mm so 0.56m² each, 1.12m² in total. They are 2m apart so not acceptable (Diagram 11.5 of Approved document B).

 

W16 is 600 x 600mm so 0.36m²

 

The floor above W16 is a standard timber floor but will have a minimum fire rating of 30 minutes (https://www.gyproc.ie/sites/default/files/C106029.pdf), so W16 is o.k.

 

The issue is going to meet the requirements of Diagram 11.5 of Approved document B for the two windows as they don't have the separation required. I think the most straight forward solution is to drop W18 or W19 as these aren't really critical.

 

 

Edit: spoke to the BCO all sorted.

Edited May 6, 2021 by Moonshine

[richardhomeowner]

i have just become a member, so hopefully its ok to jump on the end of an old post. 

 

i had an extension done 10yrs ago and seem to remember the architect saying something about maximum window size of 1 sq mtr. there used to be a bungalow next door, which has since had building work done to make into house.

 

so i have a detached house with a side wall 850mm from the boundary fence. nieghbour is also similiar distance from boundary.

 

on this side wall i have a dining room window downstairs and a bathroom window upstairs.

 

the room next to the bathroom is a bedroom with an ensuite, that doesnt have a window. ( their is a brick wall between the bathroom and bedroom ensuite

 

i want to create a new window opening 1200 x 600 for the ensuite ( less than 1m2 )

 

but looking at the building regs document diagram 20 space seperation, which shows distance between windows, im not sure if im allowed.

 

the old drawing BR 2013 used to have measurements between windows on the same level. the newer BR 2019 drawing doesnt

 

1) am i right in thinking that if the bathroom and bedroom/ensuite is divided by a brick wall, that is classed as a different compartment and their is no min distance between windows ?

2) i can have a window less than 1m2 obscured glass and it doesnt have to be a special fire rated window.

3) can the window have a small top opening window

4) do i need building regs officer to inspect this, if i do it myself or get a registered dbl glazing company to install ?

 

many thanks for any help