3mm gap and related questions

[jkerr]

Hello

Thanks in advance for any help.

I need to fit intumescent strips and smoke seals to my doors.

1. My first question, regarding the max 3mm gap allowed around the sides and top of the door. Is this the gap between the door and frame not including any space that is closed by fitting seals/strip? Or, if, when the seal and strips are fitted, and they contact the frame, does this constitute the gap that needs to be closed (ie it would be <3mm)?

2. Depending on the answer above, how can i reduce the gap between the doors and frame? Can I build out the trims on the doors or add to the frame?

2. Before looking on the site, I had assumed that I would need to take the doors off and cut/machine grooves in the doors to install the intumescent strips and smoke seals. However, I see that the products here are adhesive. I assume this is the modern/normal accepted approach now?

Thanks

John

 

[Tom Sutton]

The 3mm +/- 1mm gap between the door and frame, around the sides and top of the door should be measured before the seal and strip is fitted. 

The gap can be reduced by increasing the lippings width, which should be 6mm to 13mm as required by many global assessments for fire doors, so dependent on the size of the existing lippings you may be able to reduce the gap by a small amount. 

You do need to router the door so the intumescent seal is level with the surface but the smoke seal should project above this to fill in the 3mm gap the self-adhesive holds the seal in the grove. 

Check out http://www.asdma.com/pdf/BPG.pdf  and  http://www.firesafe.org.uk/fire-doors/

[jkerr]

Brilliant this is so helpful.

I've started referencing these documents.

Just so i can be clear:

1. Lippings: refers to the border strip of wood around the perimeter of the door?

2. Routering the door to make sure the seal is level. Does this mean sanding the lipping so that it is an even/level distance with the the seal that's attached to the frame?

3. When you say the self adhesive holds the seal in the groove: what does this mean?

Thanks so much again.

John

[Tom Sutton]

On further consideration removing the lippings and replacing with wider lippings would be a major job but you could consider modifying the door frame which could be easier. Another consideration,depending if the gap on the hinge side if less than 4mm you could shim the hinges to reduce the gap on the other side.

Remember 3mm +/- 1mm.

[Guest John joiner]

Tom if you add a hardwood timber lipping do you lose the original fire door certified because you have modified the door?

[Neil Ashdown MAFDI]

If the perimeter gap is too large then a non-compliance exists. Removing the existing lipping and replacing like for like (but thicker) is one method of resolving the issue. There are others. Check with the door manufacturer with regard to retaining certification.

[Guest Bryan]

If the gap in an existing door is greater than 3mm can this be rectified by fitting a Raven RP78si Acoustic & Smoke Perimeter Door seal which is fixed to the door frame or door stops

[Neil Ashdown MAFDI]

Fitting that type of product will resolve the issue of restricted cold-smoke spread, but not the fire performance non-compliance caused by an excessive perimeter gap.  If you can identify the fire door to its manufacturer you may be able to find out permissible gap tolerances for fire performance. 

[Guest Bruce]

I have the same 3mm problem. Is there any possibility that the fire door has a built-in intumescent strip already in place? That could help to make a 3mm thick strip (asbestos?) fixed to the frame, a possibility??

Thanks,

Bruce.

[Neil ashdown]

BS 8214:2016  Timber based fire door assemblies- Code of practice.  Paragraph 9.5.2 deals with operating gaps  "A typical gap to achieve good fire performance is between 2mm and 4mm".

[Mike North]

You would need to interrogate the certificate for the construction of the door which will tell you what modification can be made to the door.