Fire Door Threshold Gap

Thresholds are rarely mandated by the codes and standards for fire doors or smoke doors but when they are used in these applications thresholds must be listed to ul 10c or nfpa 252.

Fire door threshold gap.

Ask your fire door manufacturer for their recommended threshold gap. Gap solution for excessive fire door bottom undercut clearance 90 minute ngp edge intumescent door shoe. Underneath the fire door a gap of 8mm is traditionally acceptable although for fire doors that are required to limit spread of cold smoke only 3 mm is permissible with a threshold seal to be fitted if the gap is bigger. Bs9999 2008 recommends for fire doors with cold smoke control that the threshold gap should be either less than 3mm in height or should be fitted with a threshold seal.

If you have a requirement for cold smoke control eg fd30s your threshold gap should be less than 3mm or you should fit a threshold smoke seal. Mind the gap fire door seals fire doors play a crucial role in restricting the spread of fire and smoke. In general the gap should not exceed 3mm along the 2 long edges and across top of the door leaf to facilitate checking of the gap on site a bwf fire door alliance scheme gap tester is available on request here. Doorgap gauge fdtb 1 2.

The gap between the door and the frame is extremely important and must be suitable for the intumescent seal fitted. If a door is to work effectively in its normal role the door leaf must be free to move within the frame and in order to achieve this there must be a gap around the perimeter. Fire door thru bolts. The gap between door and frame at the top and sides should be 2 4 mm and the threshold gap as per manufacturers instructions typically around 8 10 mm the certificate will include details of this.

Nothing must be cut at the top at all and the certification label must remain intact. If this information is not available it seems reasonable to permit a gap of up to 8mm for general fire doors eg fd30. If the surveyor sees light through the door gap he she determines that the gap. There is negative pressure at the threshold during test conditions and so cool air is drawn in underneath the door.

It is through extensive testing of fire rated doorsets together with knowledge of the pressure regime within a fire test that a larger gap is permitted at the threshold of the door. Fire door thru bolts. When is a threshold or door bottom required for a fire door or a smoke door.