Rebuilding a Church on a Higher Plane

New Piers

1 of 5

The Trinity Episcopal Church in Pass Christian, Miss., once stoo… Read More The Trinity Episcopal Church in Pass Christian, Miss., once stood on piers about 4 feet above grade and 14 feet above sea level. In August 2005, Hurricane Katrina's 26-foot storm surge washed away the walls but left the church's laminated-arch frame virtually intact. During reconstruction the church was raised another 10 feet to assure it would withstand future storms.

The shoring crew first disconnected the floor framing from the f… Read More The shoring crew first disconnected the floor framing from the foundation by cutting the steel bolts embedded in the short concrete piers.

The crew installed cribbing and hydraulic jacks for lifting the … Read More The crew installed cribbing and hydraulic jacks for lifting the building.

Each jack was connected to a hydraulic manifold powered by a die… Read More Each jack was connected to a hydraulic manifold powered by a diesel engine.

The jacks were able to lift the 3,000-square-foot structure more… Read More The jacks were able to lift the 3,000-square-foot structure more than 10 feet with less than 3/8-inch difference in elevation between any of the 10 lifting points.

While the lift was quick, we had to wait two months for the foundation contractor to complete the iron and concrete work needed to build the new pier foundation. Needless to say, I was anxious to get the building bolted down before the next storm season started. The shoring company reinforced the existing piers with grade beams and extended them with new rebar dowelled and epoxied into the old concrete (see slideshow). The crew also built new concrete piers for the two transept additions to the main building.

Steel work. To anchor the building to the piers, workers embedded 1/2-inch-thick steel plates into the concrete at the top of each pier during the pour. Each plate had four 3/4-inch by 12-inch J-bolts welded to it to strengthen the connection between the concrete and the steel.

We also bored holes through the forms and inserted short lengths of conduit so that later we could through-bolt steel brackets to the piers. These brackets accommodate 1-1/8-inch-diameter diagonal steel rods and steel tubing that reinforce the tall piers (see drawing “Pier Connection Details” on page 4 of the PDF).

Around the perimeter of the building, ironsmith Craig Campbell welded 1/2-inch-thick steel plates to the steel framing brackets that the shoring company had cut loose from the old piers. These new plates extend out over the tops of the piers 5 inches from the original wall plane, and help support the 5-inch by 15-inch glulams that hold up the SIP walls.

A few days after the pour, we measured the strength of the new concrete. It registered at over 3,000 psi, which meant the building could finally be lowered onto the piers. Campbell then spent a couple more days welding all of the metal plates together, using shims as necessary. He also cut bolt holes in the plates, and we sprayed the steelwork with Rust-Oleum’s Cold Galvanizing Compound (800/323-3584, rusto leum.com) to protect against corrosion.

Then we bolted the big perimeter glulams to the steel plates with 1-inch all-thread rod and to the framework of the church with 3/4-inch bolts 16 inches on-center. To account for the thickness of the panels’ inner OSB skins, we shimmed the glulams out from the framing with 5/8-inch plywood shims.