Residential Sub-Surface Exploration
A GrayWolf Residential subscriber noticed an unusual separation developing between the baseboards and floor covering in their Master Bedroom. The current homeowners are a family of four and are not the original builders. The house is a mid-70's split level with the rear at grade and two steps up from grade at the front and sides (+11 inches). The house lies on an east/west axis and there is a finished basement on the eastern half. The Family Room is on a slab at grade, and the Library, Master Bedroom, Master Bathroom, Bathroom Closet, and Foyer are on a slab at +11. Upon investigation it was determined that the upper level concrete slab was sinking and had already moved a stunning 2.25" inches as measured at the baseboard. As the scope of this problem exceeds the services that GrayWolf Residential is able to provide we were asked to provide assistance. We developed and implemented a protocol with Thorson, Baker & Associates, Consulting Engineers, and Solar Testing Laboratories, Consulting Engineers and Testing Laboratories, to determine what was going on under the concrete slab and what to do about it.
Now, core drilling holes through concrete is no big deal if you have or can rent the equipment and subsurface geotechnical sampling is done somewhere every day, so what this case study is really about is our ability to get in and out of a fully occupied and functional residential dwelling in less than 10 hours and leaving it impossible to tell we were there other than it has been suggested (by the homeowner) that it may have been cleaner when we left then when we got there. We had to: Remove and relocate furnishings from the Master Bedroom, Bathroom Closet, Library, Family Room, and Foyer. Remove carpet and padding in the Master Bedroom and Bathroom Closet. Open up the Tongue and Groove hardwood floor in the Library and Foyer. Cover up and protect all furnishings, relocated and otherwise. Core Drill (8) 4" holes through the concrete slab for sampling; 2 holes in the Master Bedroom, 1 hole in the Bathroom Closet, 2 holes in the Library, 2 holes in the Foyer, and 1 hole (the control point) in the Family room. Samples had to be taken to a depth of 48 or more inches from each hole, and then everything had to be put back together again. All photos were taken by Melissa Mitchell, GrayWolf's liaison to the homeowner, and some activities are not shown (specifically the floor coverings coming out or going in) due to her own hands-on involvement with the homeowner during those processes. There will be a separate case study of the final resolution (if we are involved) once the laboratory and engineering reports are complete and the problem has been remediated