Wood frame with fire integrity query

[dgratton]

Hi, I'm wondering if anyone call help me. I'm fitting a borrowed light above my stairs - it is an internal window 1m x 1m. I'm aware that the glass has to have a minimum of 30 minute fire integrity - in better words it will hold out for 30 minutes in the event of a fire. I've already sourced the glass, however I'm now told that the means of supporting the glass also has to have 30 minute fire integrity (which I suppose is logical). The aperture for this window is made of 4''x2'' wood (that is to say the surround in which the glass will sit). Can anyone advise me of what spec I need to make the frame for the glass so as to satisfy the building inspector. My original thinking was to create a rebate for the glass to sit against and then use silicon to secure it and then beading to finish off. If this is a correct method what size wood/rebate/beading will I need?
Any help will be gratefully received.

 

[^woody^]

Who told you you need 30 minutes fire protection

If this is a single domestic property without a second storey, you don't

But it may need to be safety glass.

Otherwise, a 4x 2 frame is fine. You will need some thicker timber beads - 20mm or so

Why is the building inspector involved with an internal window?

 

[dgratton]

Thanks for your reply Woody. The property has had a loft conversion and this is why the building inspector is involved. The window in question is above the stairs which is deemed a fire route hence the palavar.
So do you think the existing 4''x2'' frame surround is ok to sit the glass on and then use 1'' hardwood beading to secure it? Is the beading used on either side of the glass and would you use silicon to secure to the beading or would you use something else.
Really appreciate your help.

Dave

 

[^woody^]

If you are using plant on beads both sides (ie flat timber), then they should give a minimum of 15mm cover to the glass and be a minimum 20mm long. But proper 20 or 25mm beads will do

If you are rebating the frame then the rebate should be a minimum 13mm

The beads will have to be securely nailed or screwed not siliconed, but you can use silicone to set the glass to stop it rattling.

I would confirm your proposals with your BCO first though