Underpinning Inspections in PhiladelphiaStrucTech Structural Engineers

Digging next to somebody else's building is the highest-risk thing most Philadelphia projects do. New foundations go deeper than the neighbor's, party walls sit on rubble stone with almost no footing, and the excavation removes the soil that has been holding everything in place for a century. Underpinning is how that gets handled, and it only works if the sequence is followed and the work is observed while it is open.

We start before excavation. A pre-construction survey documents the adjacent property with photographs and notes on existing cracks, settlement, and prior repairs. That record protects everyone. Without it, every crack in the neighbor's plaster becomes your crack. We review the underpinning design and the pin sequence with the contractor so nobody improvises in the field.

During the work we inspect each pit before it is poured. Bearing material gets checked, depth and width get verified against the design, the excavation gets confirmed as within the approved sequence, and dry-packing at the top of each pin gets observed. Skipped or over-wide pits are the common failure, and they are the reason walls move. We stop those on the spot rather than writing them up later.

Adjacent conditions get monitored as the job progresses. If movement shows up, you hear about it while there is still time to respond. At completion we issue a signed and sealed letter confirming the underpinning was installed and inspected in accordance with the approved drawings, which is what L&I, the adjacent owner, and your insurer all want to see.

Have an excavation coming up next to an occupied building? Call (267) 310-1172 or send the foundation plans through the contact form and we will get the pre-construction survey scheduled before the machine shows up.