Secure Foundation Fixing for Steelwork & Equipment

Getting a foundation connection right starts well before the steelwork arrives. Bremick Hold Down Bolts provide purpose-made fastening options for anchoring compatible steelwork, base plates, fabricated structures & equipment to concrete foundations where bolt position, length, grade & projection all matter.

Often referred to as foundation bolts, concrete hold down bolts, cast-in bolts or foundation anchor bolts, these fasteners are designed around applications where part of the bolt is anchored within the foundation while sufficient threaded length remains available for the connection above.

Working across a broader structural fastening requirement? Browse Structural Fasteners & Bolts. For other anchoring hardware, explore Anchor Bolts.

Before ordering, check the engineering drawing, footing detail or specified bolt schedule. Diameter, overall length, grade, finish, embedment, thread projection & bolt position can all affect whether a hold down bolt is suitable for the connection.

What Are Hold Down Bolts?

Hold down bolts are long threaded fasteners used to anchor specified steelwork, base plates, frames, fabricated structures or equipment connections to concrete foundations.

Depending on the project or trade terminology, you may hear them described as:

► Hold down bolts
► Foundation bolts
► Concrete hold down bolts
► Cast-in bolts
► Cast-in anchor bolts
► Foundation anchor bolts
► Structural anchor bolts
► Metric hold down bolts
► Galvanised hold down bolts
► Grade 4.6 hold down bolts
► Grade 8.8 hold down bolts

These terms can overlap in everyday use, but not every concrete anchoring product performs the same job.

A cast-in foundation bolt is different from a post-installed mechanical anchor or chemical anchor. The fixing method specified for the project should determine which system is used.

For related concrete fixing systems installed after the concrete has cured, browse Anchors & Wall Plugs.

Why Choose Bremick Hold Down Bolts?

Get the Foundation Connection Right Before the Pour

Unlike a general workshop bolt, a hold down bolt can become part of the foundation before the steel column, frame or equipment base arrives.

That changes the way it needs to be selected.

Before installation, confirm:

► Bolt diameter
► Overall length
► Property class
► Finish
► Required embedment
► Thread projection
► Bolt centres
► Base plate arrangement
► Nut & washer requirements

Finding an incorrect projection or bolt pattern after the concrete has cured is a considerably harder problem than checking the specification beforehand.

Match the Bolt to the Specified Connection

Bremick offers different hold down bolt specifications for different requirements, including metric Grade 8.8 zinc options.

The bolt class should follow the specified connection.

Don't assume that moving to a higher property class is automatically an improvement. A stronger bolt can still be the wrong bolt if the connection was designed around a different specification.

Length Matters as Much as Diameter

Foundation bolts can be substantially longer than conventional hex bolts.

That extra length isn't arbitrary.

Depending on the design, it can contribute to the required embedment, projection & overall foundation connection.

An M20 hold down bolt isn't fully identified until its length & other specifications are known.

Common Applications

Steel Column Base Plates

One of the most familiar applications for foundation bolts is securing steel column base plates to concrete.

Accurate positioning matters because the plate holes need to align with the installed bolt pattern.

Before concrete placement, check:

► Bolt centres
► Bolt spacing
► Required projection
► Vertical alignment
► Base plate dimensions
► Finished concrete level

A small positioning error at footing stage can become a significant installation problem later.

Structural Steel Frames

Steel frames can rely on hold down bolts to connect columns or fabricated assemblies to their foundations.

These connections can involve requirements beyond simply finding a bolt that fits through the base plate.

Where engineering documentation specifies the bolt, nut, washer, position or installation arrangement, maintain those requirements.

Sheds & Industrial Buildings

Portal frames, workshops, sheds & industrial structures can use foundation anchor bolts around column bases.

Don't assume every footing on the project uses identical hardware.

Different column positions, loads or footing details may call for different bolt arrangements.

Equipment & Machinery Bases

Machinery, fabricated skids & industrial equipment can also require anchoring to concrete.

Before selecting hold down bolts for equipment installation, establish the required fixing method.

Some installations may use cast-in foundation bolts while others require post-installed mechanical or chemical anchoring systems.

Fabricated Structures

Fabricators preparing base plates, frames & support structures need the steelwork bolt pattern to agree with the foundation detail.

Checking the fabrication drawing against the footing plan before either component reaches site can prevent expensive modifications later.

Product Selection Guide

Start With the Engineering Detail

What should you check first?

Not the spanner size.

Not the base plate hole in isolation.

Start with the specified foundation connection.

A useful hold down bolt specification can include:

► Metric thread diameter
► Overall bolt length
► Property class
► Finish
► Required embedment
► Required projection
► Nut specification
► Washer arrangement
► Bolt pattern

That gives you a much clearer basis for selecting the correct foundation fastener.

Grade 4.6 or Grade 8.8?

Hold down bolts can be manufactured in different metric property classes.

Bremick currently lists Grade 8.8 zinc metric hold down bolts, including M12, M16, M20, M24 & M30 sizes.

Property class is only one part of the specification.

If a project calls for a different grade or coating, don't substitute based solely on diameter or availability.

Bremick Grade 8.8 Zinc Hold Down Bolts

Bremick currently lists its Grade 8.8 zinc hold down bolt family in these combinations:

This illustrates why ordering simply by diameter isn't enough.

An M12 x 175 mm foundation bolt & an M30 x 600 mm foundation bolt serve very different dimensional requirements even though they belong to the same product family.

Choosing the Correct Diameter

Common metric hold down bolt diameters can include:

► M12 hold down bolts
► M16 hold down bolts
► M20 hold down bolts
► M24 hold down bolts
► M30 hold down bolts

Use the nominated diameter from the drawing or specification.

Don't select the bolt purely from the clearance hole in the base plate.

Overall Length Matters

Two foundation bolts with the same thread diameter can have very different overall lengths.

Length can affect:

► Embedment
► Thread projection
► Base plate installation
► Nut engagement
► Levelling arrangements
► Connection geometry

Don't shorten, extend or substitute a hold down bolt without checking the requirements of the connection.

Check Thread Projection Before Concrete Placement

How much usable thread needs to remain above the finished concrete?

Answer that before the pour.

The exposed threaded section may need to accommodate:

► Levelling components
► Base plate thickness
► Washers
► Nuts
► Required thread engagement

Too little projection can leave insufficient usable thread.

Too much projection can interfere with equipment, covers or subsequent construction.

Hold Down Bolts vs Post-Installed Anchors

These are different fixing approaches.

Cast-in hold down bolts are positioned as part of the concrete construction process.

Post-installed anchors are fitted after the concrete has hardened.

Post-installed systems can include mechanical anchors, concrete screws or chemical anchoring systems.

If the engineering detail specifies one system, don't swap to another simply because it appears easier to install.

Hold Down Bolts vs Standard Hex Bolts

A standard hex bolt generally passes through components & engages a nut or threaded feature.

A foundation hold down bolt serves an anchoring role & can have a substantially longer body suited to installation within the foundation.

Sharing the same metric diameter doesn't make the two products interchangeable.

Zinc vs Galvanised Fasteners

Zinc & galvanised finishes are different coating systems.

Bremick's current Grade 8.8 hold down bolt range is listed with a zinc finish.

When another finish is specified for a project, consider the complete requirement rather than treating coatings as cosmetic alternatives.

Relevant factors can include:

► Exposure conditions
► Connected materials
► Mating hardware
► Property class
► Project specification
► Service environment

Match the Nut Correctly

Once the bolt is positioned, the nut still needs to suit the thread & connection requirements.

Confirm:

► Metric diameter
► Thread pitch
► Required nut class
► Finish
► Thread engagement
► Connection specification

For associated fastening hardware, browse Hex Nut.

Check the Washer Arrangement

Base plate connections can rely on washers as part of the specified assembly.

Don't select a washer simply because it slides over the thread.

Check:

► Internal diameter
► Outside dimensions
► Thickness
► Material
► Finish
► Required configuration

For conventional washer requirements, browse Flat Washer.

Positioning Before the Concrete Goes In

A hold down bolt can have the correct diameter, length, class & finish yet still cause problems if it's installed in the wrong position.

Before placement, verify:

► Bolt centres
► Bolt spacing
► Vertical alignment
► Required projection
► Orientation
► Template dimensions
► Finished concrete level

Measure while adjustment is still possible.

Use a Bolt Template Where Required

When several foundation bolts need to align with one base plate, a suitable positioning template can help maintain the specified bolt pattern during concrete placement.

The template itself needs to agree with the approved dimensions.

A neat bolt pattern is no advantage if it reproduces the wrong centres.

Protect Exposed Threads

The threaded portion left above the concrete still has work to do.

During construction, protect it from:

► Concrete contamination
► Impact damage
► Paint build-up
► Dirt & debris
► Damaged thread starts

Cleaning a lightly contaminated thread is one thing. Repairing badly damaged foundation hardware after the concrete has cured is another.

Don't Modify Misaligned Bolts Without Approval

Steelwork doesn't fit the installed bolt pattern?

Treat that as a connection issue before treating it as a fabrication inconvenience.

Bending, heating, cutting or otherwise modifying installed foundation bolts can affect the intended arrangement.

Where site conditions differ from the design, refer the issue to the appropriate project authority before modifying the fastening system.

Expert Tips

Check the bolt schedule before ordering. Diameter alone doesn't identify a foundation bolt.

Confirm projection before concrete placement. Once the footing cures, correcting an unsuitable exposed length becomes much harder.

Keep different bolt classes clearly identified. Similar-looking metric fasteners can have different mechanical properties.

Include the finish in the specification. “M20 x 375” still doesn't describe the complete fastener.

Verify bolt centres against the actual base plate detail. Don't rely on memory or an old template.

Protect exposed threads during construction. Concrete residue & impact damage can make later nut installation difficult.

Don't force a nut over damaged threads. Inspect the exposed thread before assembly.

Keep nuts & washers allocated to the correct connection. Foundation hardware is easier to control when the components remain organised together.

Check finished concrete level against the required projection. A correctly positioned bolt can still create problems if finished levels change.

Investigate unexpected misalignment before modifying anything. Establish why the steelwork & anchor pattern disagree first.

For an overview of bolts, anchors & related fastening hardware, read Fastener Guide Bolts Screws Anchors.

Foundation hardware can be inexpensive compared with the structure relying on it. Why Good Fasteners Matter More Than the Tool You Drive Them With looks at why the fastening component itself deserves attention.

Preparing equipment & fastening stock before busy construction periods can also reduce avoidable delays. Read Spring Jobsite Prep Getting Your Gear Ready.