Types of Building Foundations We Find in The Midwest

Block wall foundations are very popular in Minneapolis and Saint Paul, first a strip of concrete (the footing) is poured around the perimeter and then a block wall is built on top of it.  The hollow blocks are staggered and stacked up to the desired height of the basement.  

Block walls are relatively easy to install and not as costly as a poured foundation.  Any water that gets inside the blocks will flow to the bottom, if cracks or holes develop on the inside wall, your foundation will leak.  If an interior drain-tile system is installed, the bottom coarse of blocks is drilled through to the open cores allowing water to drain into the underfloor pipe system.  A sump basket will collect the water and a sump pump will pump it back outside.

Wood foundations are much rarer but we do run into them every few years.  The home is built with treated wood that can be buried below-grade.  Since our focus is Real Waterproofing, the main issue we've seen with wood foundations is that they just don't seem to be able to hold back the pressure of the surrounding ground when in contact with water.  The pressure of expanding-contracting soil pushes and moves the joints creating holes.  We've also seen rotted wood even though the wood is sold as rot-resistant.  Most of the homes and buildings we've inspected were built in the early 80's.

In this photo you can see a "dimple board" water drainage membrane attached directly to the wall.  With this type of drainage, the foundation may be in constant contact with water.  Personally I'd love to know how they keep the metal pins holding the membrane on the wall from rusting and creating small holes through the wall.  The water will also move through the seams between the panels with this set up, there should be a seal on all seams.

Poured wall foundations are also very common in the Midwest and over the last 28 years are the preferred method for planned subdivisions.  If your home was built in a subdivision, they tend to have solid poured walls, it's easier and more cost effective for the contractor to do multiple homes using this method.  

The walls are made by filling removable forms with concrete, when dry the forms are reused but they do need to leave sacrificial "tie-rods" in the concrete, metal pins used to hold the forms together.  Most forms are 3' wide, you can see a small vertical seem where the panels are attached. 

Rubble walls are mostly found in older homes and consist of flat rocks stacked on top of each other.  The rock is strong and long-lasting but the mortar joints turn to sand allowing water and dirt to move through the wall onto the basement floor.  Most of these homes have steep roofs and didn't have gutters installed for the first few decades, shedding water inches from the basement wall.

The effects of years of exterior water pressure are clear in this photo, the back wall, on the right side,has a concrete skim coating which still looks good, there's a porch off the back of the home protecting this area.  The wall to the left has been left to the elements and water has pushed through and also pushed off the concrete skim coating that used to cover the rocks, making the mess on the floor.

The skim coating can be redone but exterior waterproofing should be done beforehand to ensure the new concrete coating sticks for a long time, without exterior waterproofing the water pressure would continue to push any surface finish off.

Found on older homes, usually in farming areas, stone walls have rounded stones stacked up to make up the foundation.  These foundations can be really strong but the mortar joints are the weak point and holes will eventually develop allowing water to run right through the wall.  To effectively fix these walls, they need to be waterproofing on the exterior.  

Water pushing through the walls develops a lot of pressure and any interior fix will only be temporary since they tend to lose their bond with the surface.  When you run your hand across the surface you'll feel a sandy, grainy texture, most paints and concretes like a clean surface to bond to.