Fischer concrete screws FBS 4 and FBS 5: key installation notes for M&E engineers
Reviewed by Tom Sullivan

First reported on The Construction Index
30 Second Briefing
Fischer has launched FBS 4 and FBS 5 concrete screws for electrical and HVAC fixings in concrete and dense masonry, with fire resistance rated up to R120 and expansion-free undercut anchorage allowing small edge distances and close spacing. Serrated thread geometry cuts rapidly into the substrate for faster installation with cordless impact drivers, while two anchorage depths let installers adjust for differing load demands and to bridge plaster layers. The zinc-plated range spans five variants, including FBS 5 US with hex head and washer, FBS 5 M6 threaded stud, and a dedicated FBS 4 cable clip screw.
Technical Brief
- FBS 4 and FBS 5 are specified for concrete and dense masonry, including solid sand–lime brick.
- Fire resistance classification R120 allows use where 120‑minute structural or compartmentation performance is required.
- Screws can be installed with cordless screwdrivers, impact drivers or manually, aiding access‑constrained retrofit work.
- Positive mechanical interlock is achieved as thread flanks cut into the substrate during driving.
- Five head/connection variants cover panhead Torx (FBS 4/5 P), hex‑washer (FBS 5 US), countersunk Torx (FBS 5 SK), M6 stud (FBS 5 M6) and a dedicated FBS 4 cable‑clip screw.
- Typical fixings include cable clips, cable ducts, mounting rails, surface sockets, wall cabinets and light secondary items.
Our Take
Fischer’s launch of multiple FBS 4/5 variants with two anchorage depths signals a push to cover both light and heavier-duty fixings, which in practice can simplify approvals and stocking for UK contractors working across mixed concrete strengths.
The R120 fire-resistance assessment positions these concrete screws for use in UK applications where designers are trying to avoid post-installed anchors with separate fire collars or complex detailing, especially in services and secondary steelwork.
In our database, Fischer also appears in a June 2026 piece on autonomous drilling robots for ceiling fixings in Frankfurt, suggesting the company is aligning new screw lines with automated installation methods rather than just manual trades use.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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