Technical notes
Short, practical answers to the questions that come up on site. Always check the manufacturer's instructions and the current regulations for your job.
Fire doors8 October 2026
Intumescent strips for FD30 and FD60 doors: which size?
Most 30 minute doors take a single 15 x 4mm strip and most 60 minute doors take 20 x 4mm or two 10mm strips. The door's own test evidence always decides.
4 minute read
Electrical24 September 2026
Bathroom zones: what goes where under BS 7671
Zones 0, 1 and 2 explained, why shaver sockets are allowed and 13A sockets are not, and the IP ratings to look for in each zone.
5 minute read
Detection10 September 2026
LD1, LD2 or LD3: alarm coverage for HMOs
What each category of BS 5839-6 actually covers, which rooms need heat rather than smoke detection, and where radio interlinking saves days on site.
4 minute read
Hospitality27 August 2026
Hotel key card switches: what to put on them and what to keep off
A key card switch saves energy only if it controls the right circuits. Minibars, alarms and extract fans belong on supplies the card never touches.
3 minute read