BASC Search | Building America Solution Center

Right – After installing the insulated concrete foundation wall panels, the builder installed underslab rigid foam, which was topped by 4 inches of crushed rock then the poured slab.

Image

Exterior fiberglass insulation on this new home was (incorrectly) cut to terminate below-grade after backfill, which will expose the above-grade portions of the foundation wall to cold temperatures

Image

ICF foundation walls wrap the floor slab in R-22 of insulation while the entire space under the slab is covered with 4.3 inches of closed-cell spray foam.

Image

Right – Two inches of rigid foam was installed on the ground before pouring the basement floor slab while precast, pre-insulated concrete panels comprise the basement walls.

Image

For homes built on an open foundation, provide a continuous air barrier by sealing all joints between the rigid insulation, floor support beams, rim joist, and bottom wall plate

Image

Brick veneer is supported by a concrete stem wall thermally separated from the slab-on-grade foundation with turn-down footing which is also insulated on top; anchorage for seismic resistance is also shown

Image

Right - Permeable rigid mineral wool insulation and appropriate water-management flashing details are integrated with new rigid foam siding to keep water away from the sill beam above the foundation wall

Image

Assembly can be used in IECC CZ 3 and above to thermally isolate garages in multifamily row houses with slab foundations. For unheated garages, it is unnecessary to insulate wall between garage and exterior of slab or slab underneath garage.

Image

Pest protection measures include a termite shield under the rim joist and extending out on either side of the stem wall, insect screening under the furring air gap, and brick veneer to protect slab-edge insulation.

Image

Right – Insulated concrete form (ICF) blocks are stacked like bricks, then rebar is set horizontally and vertically in the plastic spacers, then concrete is poured; the rigid foam and spacers stay in place to add support and thermal resistance to the wall

Image

Right – The raised slab foundation has a 3-ft stem wall of filled concrete block, then is back-filled with compacted dirt and crushed rock, then insulated with 1” rigid foam covered with taped vapor barrier, under a floor slab.

Image

Insulate a post-tensioned monolithic concrete slab: A) Install rigid foam in form before pouring concrete for slab, B) After concrete cures, install a second layer of rigid foam and protection board on the exterior perimeter of the wall

Image

This raised-slab poured concrete foundation includes flood-resistant features such as a sloped grade, capillary break under the slab (gravel or sand), vapor retarder under the slab (rigid insulation), and capillary break at the top of the foundation wall

Image

How to Insulate a Basement

Video

Video describing how to warm up a chilly concrete wall with This Old House general contractor Tom Silva.

Air Sealed, Insulated Basements

Guide

Guide describing how to insulate a basement to improve the overall thermal performance of the building and provide more dry, usable conditioned space for home occupants and HVAC equipment.

Spray foam on concrete foundation wall with framed interior wall

CAD File

Right – This wall is constructed with the sill plate overhanging the top of the foundation wall so that when rigid foam is installed on the exterior of the foundation wall, its surface will align with the surface of the wall sheathing.

Image

Termite-Resistant Foundations and Walls

Guide

Guide describing techniques and measures for increasing the termite resistance of a home's foundations.

IECC Climate Zone 3A: SIP Roof, SIP Wall, Stem Wall, Slab on Grade

Image

IECC Climate Zone 3B: SIP Roof, SIP Wall, Stem Wall, Slab on Grade

Image

IECC Climate Zone 4A: SIP Roof, SIP Wall, Stem Wall, Slab on Grade

Image

No Vapor Retarders on Interior Side of Air-Permeable Foundation Insulation

Guide

Vapor retarder plastic should not be installed over fibrous insulation on basement or crawlspace walls; rigid foam or spray foam should be installed directly against the concrete, behind the blanket insulation.