Deta is pleased to confirm that it has successfully completed fire resistance testing in cooperation with several leading engineered joist manufacturers to demonstrate its fire rated downlights satisfy the new guidelines issued by the NHBC.

Following successful fire resistance testing with several leading engineered joist manufacturers and acceptance by the NHBC, Deta’s current (L1680/2 and L1690/2) and new (L1701) fire rated downlights can be installed in 30 minute floors constructed without noggins and without the need for fire hoods in the following floor constructions:

  • James Jones I-Joist
  • Metsa Wood I-Joist
  • Staircraft I-Joist
  • Steico I-Joist
  • Solid Timber Joist
  • Concrete

Note that NHBC acceptance is subject to the floor construction installed being equivalent to the floor construction tested. For further details, please contact Deta’s Technical Support Team on 01582 544 548 who will be happy to assist.

Deta has further fire resistance tests booked over the coming weeks with other leading engineered joist manufacturers, and are working very closely in partnership with them to accelerate testing and secure approval from the NHBC for Deta’s downlights to be installed in their floors without the need for fire hoods to be fitted.


The new guidelines included within the NHBC’s Technical Extra (Issue 25) publication state that where fire rated downlighters are installed in engineered joist floors, they will only be acceptable if test evidence supports their use in a similarly engineered joist floor build-up. 

The NHBC have further advised that they will require supporting evidence confirming that the manufacturer’s downlight has been fire resistance tested in an equivalent floor construction to that installed.  Note however that on the basis that each manufacturer’s floor joist specification differs, the floor construction and joist manufacturer tested must match with the floor construction installed.

Fire Hoods

Where test evidence in an engineered joist floor construction cannot be provided by the downlight manufacturer, the NHBC has advised that approved fire hoods must be fitted before building control sign off can be issued.

Tenmat fire hoods accepted by the NHBC are available to order from Deta.




                 Fire Rated Downlights IP20 IP65                  Fire Rated Downlights IP65                   Fire Hoods Brackenheath


                Fire-Rated Downlights (L1680/2 and L1690/2)                         Fire-Rated Downlights (L1701)                                            Fire Hoods Product Sheet