Buildings Without Basements

Post/pier foundation systems are very environmentally-friendly.

Many buildings without basements are supported on cast-in-place crawlspace walls or frost walls that rest on continuous cast-in-place concrete footings. The construction time and concrete cost associated with these continuous concrete foundation walls and footings is significantly greater than that associated with a post-frame building that utilizes embedded posts or a post-on-concrete pier system (figure 4) as its foundation system.

The material and labor savings associated with post/pier foundation systems makes them the most environmentally-friendly foundation system in common use today. Additionally, embedded post and precast pier foundations can be easily removed and reused – a feature which adds to their status as a very environmentally-friendly foundation system.

Embedded post and precast pier foundations are very environmentally-friendly. Both can be easily removed and reused.
Embedded post and precast pier foundations are environmentally-friendly. Both can be removed and reused. 

Most buildings without basements feature concrete slab-on-grade floors. More frequently today, these slabs contain radiant heating systems. When post/pier foundation systems are used, the interior concrete slab can be placed after the building shell has been erected. This has two major advantages:

  • Concrete is much more protected during its placement from wind, precipitation in all forms, and temperature extremes. This can translate into fewer unexpected scheduling delays, less need for costly heat and moisture protection systems, and enhanced concrete surface finish, durability, and strength properties.
  • Less preplanning is required for below slab installation of HVAC, plumbing and electrical system components. In fact, no preplanning is required when the interior concrete slab is placed after HVAC; plumbing and electrical system installations have been completed. With respect to utilities, it is also important to realize that insulation must be placed under a slab that contains a radiant heating system, and placement of this insulation requires a very level, properly compacted base – something more easily achieved and maintained in a protected environment.

Some builders may opt to place posts on the thickened edge (i.e., grade beam) of a concrete slab. Such systems generally require more total concrete than systems with concrete pier foundations since the extra concrete required for the grade beams usually exceeds that required to fabricate the concrete piers. Additionally, the probability of a foundation failure is greater for floating slab foundations than for buildings completely supported on piers and other foundation systems that extend below the frost line.

Figure 4: Mechanically-laminated post attached to a precast concrete pier.

Figure 4: Mechanically-laminated post attached to a precast concrete pier.

Figure 5: Splice region of a glue-laminated post in which preservative-treated lumber has been finger-jointed to non-treated lumber.

Figure 4: Mechanically-laminated post attached to a precast concrete pier.