ST4 In-Rack Sprinkler Protection.

Since 2014 when TB234 was first issued. All in-rack protection pertaining to ‘ST4 Pallet Racking’ was changed. It now requires horizontal sprinkler locations at every transverse flue, at a vertical spacing of 3.5 metres or every second tier level (whichever is lesser).

Prior to the issue of TB234, in-rack protection for ‘ST4 Pallet Racking’ had always been split into 2 designations. This allowed for greater horizontal sprinkler spacing, only requiring protection at every other transverse flue for Category I & II goods.

Since the issue of TB234 there is no differentiation between the Categories.

Pre TB234. –

 Prior to TB234 the below diagrams were used for ST4 Pallet Racking. These show the split.  ‘Category I & II’ goods (to the left) can have a sprinkler every other transverse flue, but then this increases for ‘Category III & IV’ (to the right), to every Transverse Flue.

Diagram 1- Sprinkler Layout

Pre TB234

Diagram 2 - Sprinkler Layout

Pre TB234










Post TB234. –

Since the Release of TB234, the diagram below is used. This shows that for all ST4 Pallet Racking regardless of Category, a sprinkler is required in every Transverse Flue.


Diagram 3 - Sprinkler Layout

Post TB234

What impact will this have?

Should an In-Rack Sprinkler System that is designed to suit Category 1 or 2 groups require extending. It would be necessary to engage the views of the client’s insurance company. This would be to ascertain the suitability of designing any additional in-rack protection to the current requirements. It may also be possible to gain a dispensation from them to continue with the system original sprinkler spacing.

Furthermore, due consideration needs to be given as to the suitability of the existing pumped water supply should additional In-Rack protection be required to the correct standard.

If you require any further information please contact a member of our highly experienced team at or alternatively see our Contact Us page for further contact details.

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