How Are Foundation Connections Coordinated for a Light Steel Residence? | ESS En

Setting Out the Connection

The base detail is decided in the drawing set, not on site.

• Anchor bolt diameter, embedment, spacing and projection from the drawing
• Base track fixing method: cast-in bolts, chemical anchors or screw anchors
• Slab edge, plinth and damp-proof course detail under the track
• Position of hold-downs at braced wall ends and corners

Transferring Uplift and Shear

Overturning tension is the load that foundations most often miss.

• Hold-down brackets sized for the calculated uplift at each braced wall
• Continuous load path from roof diaphragm to anchor
• Shear transfer through base track fixings and slab friction only where allowed
• Reinforcement detailed to anchor the tension into the concrete

Tolerances and Site Inspection

Small setting-out errors become expensive once the frame is fabricated.

• Bolt position tolerance agreed and checked before pour
• Level and flatness of the bearing surface verified
• Inspection record and photo set signed before erection begins
• Procedure for a misplaced bolt, agreed in advance

Frequently Asked Questions

Can chemical anchors replace cast-in bolts?

Sometimes, where the design allows and the concrete is sound. Cast-in bolts are preferred where uplift is high, because they are more reliable.

Who designs the foundation?

Typically a local engineer using the reactions and bolt layout supplied by the frame designer, because soil and code are local.

What tolerance is realistic for anchor bolts?

The frame can absorb a small positional tolerance if the base plate holes allow it. The value must be stated on the drawing and checked on site.