System Designs:

Also visit my What To Expect page.

A quick overview of active sub-slab suction:

There are two ways to install the systems, internal or external.  Both require penetrating the slab, digging a pit under the slab and installing a  vent pipe and a fan.  I use a diamond coring tool and only cut a whole large enough to put the pipe in.  There is a minimal amount of water that I vacuum up as I bore, which prevents dust coming from the coring tool.   I use 3" or 4" PVC pipe for the vent going from the suction pit to the fan. 

If I am installing an external system, I route the pipe outside to the fan.  On an external system, I put a condensation bypass system around the fan and vent the pipe up the side of the house.  I can use rain downspouts to continue from the fan to the roof, creating a more aesthetic look.  The pipe needs to extend beyond the edge of the roof by at least 12 inches.

For an internal system, the fan must be located in an unconditioned living space and above any living spaces.  The fan can be installed above the garage, in an attic or behind an unconditioned knee wall.   If I install an internal system I route the pipe from the basement to the attic using closets or chase ways.  Keep in mind that if you have a multiple storey home that it is necessary to have your closets match on each floor.  Once the pipe enters the unconditioned space, a fan is installed and then an exhaust pipe is vented through the roof.  I sometimes use Kozy Kollars so that I do not have to access the roof from the outside.  If the exhaust pipe is near a deck or other frequently used outside area, a muffler can be installed.  The muffler changes the pitch of the air flow and has a minimal performance impact.

Example images of systems and cores.

Example System Photos