Sprinkler system modifications in a food takeaway in the City of London

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Ceiling with sprinkler Flexi-drops hanging loose during refurbishment

I was asked to give advice on the possible utilisation of an existing sprinkler system in the ground storey of the six-storey building in prestigious Leadenhall Street in the City of London being refurbished as a fast food takeaway. The refurbishment contractor (my client) had removed a suspended ceiling which was previously used to locate the sprinkler system spray heads. The heads were connected to the distribution pipework by flexible helical steel pipe connections called Flexi-drops and on the day of my inspection the heads were dangling in an arbitrary manner.

I advised that it was possible that a sprinkler system might not be needed if the shop had at least one hour fire resisting boundaries as seemed likely from the reinforced concrete construction, but this option was not pursued. I pointed out that If there had been a change of use in the premises the hazard category may have changed i.e. it might have been LH and may now be more onerously categorized OH. This had implications for pipe sizing, flow pressures and duration of water supply etc.

I refreshed my memory on the code requirements (BS EN 12845) and drew up a list of relevant factors which a specialist sprinkler contractor would need to consider e.g. height of sprinkler head below soffit (which surprisingly could be up to 0.45m for small areas), sprinkler spacing, possible sidewall sprinkler for certain areas, and record drawings and test regime. I saw no good reason why the Flexi-drops should not be retained provided they were adequately supported horizontally and vertically by non combustible construction e.g. steel sections fixed back to the concrete soffit above or to the distribution/range pipework.

My client obtained tenders from two sprinkler contractors and I reviewed and commented on the proposals. I also suggested a fire safety strategy was needed but this was not within the remit of my client.

Client: Fit-out contractor.