By Bennett's Concrete and Excavation, Norwich, NY. Updated October 2026.
The short answer
- Poured concrete (cast in removable forms): solid, common and economical. Insulation is added separately.
- Concrete block (masonry units and mortar): built unit by unit, with more joints. Insulation is added separately.
- ICF (insulated concrete forms): foam forms filled with reinforced concrete that stay in place as insulation on both faces.
A Portland Cement Association brief on basements noted that close to 100 percent of North American basements are built with concrete wall systems, so the choice is usually which kind of concrete wall, not whether to use concrete.
Poured concrete walls
Contractors set reusable forms, place steel and pour the wall in one go. The PCA brief describes cast-in-place walls as economical, with a hard, durable surface on both sides, and says insulation options depend on what you want. A Penn State Housing Research Center (PHRC) report on foundation walls says properly insulated and finished cast-in-place walls can perform more than adequately as basement walls.
The catch for a finished basement is that the insulation and framing come later, as a separate step.
Block walls
Concrete masonry units are laid in mortar, with steel and grout in cores where the design calls for it. The PCA brief notes block comes in many colors and textures and can be insulated. Block is easy to get and build in small batches, which can help on tight sites or small additions. It also has a mortar joint every course, which is something to keep in mind for water and air leakage, and like a poured wall it needs insulation added for a finished basement.
ICF walls
ICF blocks are hollow foam forms that interlock, get braced, filled with rebar and concrete, and stay in place. The PCA brief calls ICF a highly energy-efficient wall that's ready for drywall on the interior. Fox Blocks, an ICF maker, rates its wall at R-23.
The PHRC report notes two things to plan for: both faces have to be finished, and foam below grade has to be considered where termites are a concern. The residential code includes termite provisions for foam in areas with very heavy termite risk. Bennett's specializes in ICF foundations; our ICF guide walks through the build.
Side by side
| Poured | Block | ICF | |
|---|---|---|---|
| Insulation | Added later | Added later | Built in, both faces |
| Joints in the wall | Few | Mortar joint every course | Few |
| Interior finish | Frame and insulate, then drywall | Frame and insulate, then drywall | Drywall attaches to the form |
| Exterior above grade | Concrete surface | Block surface | Foam must be protected |
| Cost drivers | Forming crew, concrete | Masonry labor | Forms, bracing, concrete |
What every foundation needs anyway
The wall type doesn't change the basics. The PCA brief recommends waterproofing membranes over dampproofing, a drainage system at the base of the foundation, and a vapor retarder under the slab. Footings go to the depth your plans and code office require; engineering firm KHH notes most Central New York engineers use 4 feet. Backfill and grade so water runs away from the house; see grading away from your foundation.
Climate matters too. Chenango County is in climate zone 6A, among the colder zones in the energy code, so basement walls here need real insulation whichever system you pick.
How to choose
Ask what the basement will become. If it will be finished living space, ICF's built-in insulation and drywall-ready surface save steps. If it's storage or a mechanical room, a poured or block wall may do the job with less up front. Your designer or engineer sets the wall design and steel; your code office signs off. Bennett's builds ICF foundations and does the excavation and site prep that come before any foundation.
