24 Feb 2014

View TV contractors with a grain of salt!


When I can, I like to catch some of the “reality” television programs featuring home construction and repair. Some of these programs feature a contractor coming in to help out a “do-it-yourself” homeowner finish or redo a project. There is at least one program that follows a contractor as he and his crew come in to help out a homeowner that has been “let down”, if not subjected to criminal negligence,  by a previous contractor.

I took interest in an episode recently that, amongst other issues, dealt with a seeping cement block basement and the mold that was probably caused as a result. A seeping concrete basement is not that uncommon, unfortunately, and that is not what caught my interest.  What I did notice was how much trouble and expense they went through to achieve, I believe, a repair that could let them down in the future.

In the repair that they chose, they at least understood and admitted that moisture/water was permeating the concrete block walls. They also decided that the best method to repair was from the inside of the basement. But from here on, well, they did it wrong!

They actually cut and removed at least a 1 foot wide section of “pour-in-place” concrete floor around the entire inside perimeter next to the basement wall! Next they dug out enough soil/fill/gravel to create a trench followed by the installation of “weeping tile”. The next, major, component that they added was a “dimpled” rubber like sheet. This sheeting was “nailed” to the inside surface of the concrete block wall.

They still have to over fill the weeping tile with aggregate and carry in concrete slurry to rebuild the cement floor!

So in review, their repair expects, and is not trying to stop, fluid from coming through the concrete; they are only trying to “re-direct” the permeation of water to the weeping tile.

Other than what this repair must have cost, I can see at least two future problems. Water that comes through the concrete will still be inside the basement “envelope”. This water may be in “evaporative” or humidity form, but I am sure it may still lead to mold.

Also, at least where I live, there are salts in solution in the ground water. When this “salt water” comes through the concrete wall, the water will evaporate at the surface of the concrete leaving the salt to crystallize within the concrete. This is what is referred to as efflorescence and will “tear up”, or spall the inside surface of the concrete wall; the same place the nails have been installed to hold the rubber sheeting. I am sure the nails used were galvanized, but galvanization is a surface coating; will hammering them into concrete scratch the coating away and lead to metal corrosion? Both the concrete spalling and the nail corrosion could lead to the collapse, and detachment, of the rubber sheeting.

Why take such a chance at failure, and at such an obvious expense? All you need to do is apply Seal-It Concrete Sealant to the inside concrete surfaces.