Q.When making structural changes that involve adding a point load to a house built on a post-tensioned concrete slab, is it necessary to add a footing for a structural post? I'm concerned that cutting through the slab to pour a pad footing could sever one of the cables, but I don't want to assume that the slab can support a point load anywhere.A.Brian Allred, S.E., of Seneca Structural Engineering in Laguna Hills, Calif., responds: A typical post-tensioned foundation is reinforced with high tensile-strength steel strands instead of conventional rebar or wire mesh. Once the slab is poured, the strands are...

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