Holding Down Bolt Installation

Holding down bolts (HD bolts) anchor steel columns, base plates, and equipment to concrete foundations.
Bolt positions must be set to very tight tolerances, typically within 3mm, to align with the steelwork above.
Cast-in HD bolts are placed in the formwork before the concrete pour and set using a template.
Post-fixed HD bolts are drilled and chemically or mechanically anchored into hardened concrete.
Incorrectly positioned bolts mean the steelwork will not fit, causing costly delays and rework.
HD bolt groups projecting from foundations create serious impalement and trip hazards on site.
Protection caps or covers must be fitted to all exposed bolt groups until the steelwork is erected.
Bolt threads must be protected from damage during the concrete pour and subsequent construction work.
Grouting beneath base plates after steel erection transfers loads and requires careful quality control.
CDM 2015 requires that impalement hazards from projecting reinforcement and bolts are managed on site.

Prevent impalement	Projecting HD bolts cause impalement injuries when workers fall or trip onto unprotected bolt groups.
Tolerance critical	Even small positioning errors in HD bolts prevent steel erection, causing programme delays and expensive remedial work.
Structural integrity	Incorrectly installed, damaged, or under-grouted HD bolts compromise the structural connection and building safety.

Do

Don't

Use bolt setting templates to achieve the required positional tolerances.
Check bolt positions against the steelwork drawing before the concrete pour.
Protect all projecting bolt groups with impalement caps immediately after pouring.
Guard bolt threads against damage from concrete, plant, and foot traffic.
Survey bolt positions after the pour and record any deviations from design.
Report positional errors immediately so remedial action can be planned early.
Use approved chemical or mechanical anchors for post-fixed bolt installations.
Grout beneath base plates to the specification using non-shrink grout products.
Remove impalement caps only when the steelwork is ready to be erected.
Torque HD bolts to the design requirement and record the results.

DON'T leave projecting HD bolts unprotected at any time during construction.
DON'T skip checking bolt positions before the concrete pour is carried out.
DON'T allow concrete vibration to displace bolt groups from their set positions.
DON'T force steelwork onto misaligned bolts; report the error for assessment.
DON'T damage bolt threads by allowing concrete splatter or impact from plant.
DON'T drill post-fixed bolts without confirming reinforcement positions with a scanner.
DON'T grout base plates until the steelwork alignment has been approved.
DON'T use non-approved anchor systems for post-fixed HD bolt installations.
DON'T ignore bolt group trip hazards on foundations during general site access.
DON'T assume bolt positions are correct without surveyed verification after pouring.

See also: Steel Erection Safety | Rebar Impalement Prevention

Presenter		Project
Location		Date

Toolbox Talk Record