Historical Building Repair – PUR Injection

This well over a century old historical apartment building had persistent water intrusion through the masonry rock foundation into the below grade parking garage.

A SealBoss Technician was asked to come out and consult with a local installer in St. Louis, Missouri, to find solutions for the water ingress problem. The majority of the exterior walls where the sill plate sits at or just below grade had shows signs equivalent to years of water intrusion.

The century old stone wall, and the grout holding the natural rocks in place, had become compromised. Water would seep from the soil through the wall causing further decay, unsightly stains and in some areas growth of unsightly algae.

Previous non-permanent and haphazard repairs included cleaning the wall and opening up the face with a grinder then applying a cementitious grout over the whole face of the wall. This attempt of a repair would fail within a year of application.

The approach to a permanent historical building repair was to inject any visible cracks first. One of the areas with heavy water intrusion was a doorway that lead from the parking garage to the stairs leading to the domicile. Here there was a water bearing crack with an active leak overhead as well as a cold joint between the floor and stub wall.

The overhead crack was addressed using  5/8” Plastic Injection Ports as the grout lines would crack and flake when a mechanical packer was tried initially. A zerk tip was added to the injection port and the crack was primed by injecting water through the packer till positive refusal was seen from the crack.

SealBoss 1510 Chemical Injection Grout was then injected under pressure to displace any water in the crack and began to cure and seal the area.

To address the cold joint on the floor in the stairwell, ½” packers were installed on the floor roughly one foot apart and six inches from the wall. It was confirmed that behind the stub wall in the stairwell was substrate and upon install of the Packers, it was found that the floor had only been about a two inch pour.

With the thin floor slab, it was advised to inject through the slab creating a “blanket” of 1510 below the slab since the slab thickness would not allow for the standard 1, 2, 3, 45 Degree Injection Packer Placement Method.

A weep hole was also drilled in the slab to allow for a controlled point where the water and off gas could be directed. Positive refusal of the foam was visible from the cold joint, and once the joint had been sealed, packers were removed and a hydraulic cement patch was installed.

Once all cracks have been addressed, wet areas can be addressed by curtain / bladder injection, where chemical grout is injected behind the wall to create a waterproofing barrier between the soil and the wall on the positive side of the structure.

More on curtain injection grouting method – details and pictures.