What Is a Grade Beam vs. Strap Footing?

Grade beams

Grade beams span between deep foundation elements (pile caps, drilled piers) carrying the building's wall and column loads to them — the standard foundation for pile-supported structures. They also tie footings together for seismic (the code requires footing ties in higher seismic categories, and grade beams serve this function). Designed as beams for bending and shear under the wall loads plus the tie forces.

Strap footings

When an exterior footing sits at the property line, the column load is eccentric to the footing — it wants to rotate. The strap beam (a stiff concrete beam, designed to be rigid) connects it to the interior footing; the interior footing's dead weight counteracts the rotation. The strap is designed for the moment transfer, and the interior footing gets bigger to supply the counterweight. Used where combined footings will not fit.

Design notes

Grade beams: size for the wall/column loads plus seismic tie forces, detail the connections to the pile caps or footings for the full forces, and consider expansive-soil detailing (void forms beneath grade beams on expansive clay). Strap beams: the rigidity assumption is critical — a flexible 'strap' does not restrain rotation; the engineer sizes it stiff and checks the interior footing's stability under the added uplift.

The bottom line

Grade beams tie foundations together and carry wall loads between piles; strap beams balance property-line footings against interior footings. Both need rigidity and full-force connections.

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