Fig 1. Examples of Where to Insulate
- In unfinished attic spaces, insulate between and over the floor joists to
seal off living spaces below.*
1A attic access door
- In finished attic rooms with or without dormer, insulate ...
the studs of "knee" walls;
2B between the studs and rafters of exterior
walls and roof;
2C ceilings with cold spaces above;
2D extend insulation
into joist space to reduce air flows.
- All exterior walls, including ...
3A walls between living spaces and
unheated garages, shed roofs, or storage areas;
3B foundation walls above
ground level; 3C foundation walls in heated basements, full wall either
interior or exterior.
- Floors above cold spaces, such as vented craw spaces and unheated garages.
Also insulate ...
4A any portion of the floor in a room that is
cantilevered beyond the exterior wall below;
4B slab floors built directly
on the ground;**
4C as an alternative to floor insulation,
foundation walls of unvented crawl spaces;
4D extend insulation into joist
space to reduce air flows.
- Band joists.
- Replacement or strom windows and caulk and seal around all windows and
*Well-insulated attics, crawl spaces, storage areas,
and other enclosed cavities should be ventilated to prevent excess moisture
**For new construction, slab on grade insulation should be
installed to the extent required by building codes, or greater.