Flat
Continuous thickness of concrete.

Waffle
Concrete is thicker at some points than others.

Post and Beam
horizontal and vertical columns of concrete surrounded by foam insulation.

There are 3 basic types of Insulated Concrete Forms as shown to the right. ICF Direct generally recommends a Flat Wall System, but others can also perform well in certain applications with experienced crews and the correct engineering. The reasons why are:

Strength: A Flat Wall System offers a wider range of rebar placement options, allowing the ability to design the wall to a greater structural loading capacity and greater security against wall penetration due to natural or human damage.

Labor: Window and door placement is less labor intensive since the wall is the same thickness throughout.

Experience: Post and Beam systems are bridged by polystyrene, thermal mass is reduced which can cause higher air infiltration if not carefully installed.

Thermal Mass: The thermal mass of the concrete combined with the EPS insulation reduces temperature fluctuations inside. Even though waffle/post and beam systems have more EPS insulation, they reduce the thermal mass and strength.

There are advantages to Waffle/Post and Beam systems (such as using less concrete) and do perform better than Stick Frame houses. We are not trying to suggest that Systems other than a Flat Wall are inferior or should not be used. They do however have more limitations and you should consult your local ICF Direct Consultant. You should not blindly consider an 8" Post and Beam system a direct replacement for a 8" poured wall.