Installation Guide

Insulating Basements:

How to Install Basement Insulation on Unframed Walls: Horizontal Installation

How to Install Basement Insulation on Unframed Walls: Vertical Installation

How to Install Insulation in a Finished Basement

Basement walls and walls in unvented crawl spaces should be insulated to help prevent substantial heat loss. (A crawl space is

an unﬁnished, accessible area below the ﬁrst ﬂoor of a building. An unvented crawl space is part of the basement while a vented

crawl space opens to the outside.) Unframed, exterior basement walls should be insulated with blanket insulation, which can be

installed horizontally or vertically. Typically, the blanket is held against the sill plate at the top of the basement wall with furring

strips. In addition to the furring strips, you will need patch tape, and depending on the installation method you choose, possibly a

Hilti-type gun and special fasteners for driving into concrete or cinder blocks.

Finished basements are insulated like any other room in your house.

1. Seal around all penetrations in band joists. Any walls that leak water must be repaired

before insulating.

2. Pre-drill an ample supply of 1x2 furring strips.

3. Measure the length of insulation you’ll need for the full wall and cut it on the unfaced side.

4. Grip the insulation by the ﬂange, and with the faced side toward you, position it against the sill

plate at the top of the basement wall. Then position a furring strip and nail through the furring and

the ﬂange to the sill plate to secure the insulation. Whenever possible, pull the insulation behind

any ductwork, plumbing, or electrical that may lie along the walls. Otherwise, carefully cut and ﬁt

the blanket around obstructions.

1. Seal around all penetrations in band joists. Any walls that

leak water must be repaired before insulating.

2. Cut lengths of insulation a few inches longer than the height

of the walls.

3. Attach the blanket to the wall using furring strips or a

Hilti-type gun to drive fasteners into the concrete or cinder

blocks. Fit adjacent blankets tightly together.

4. Trim the bottom of the insulation ﬂush with the ﬂoor.

5. To give the insulation a ﬁnished look, tape over all joints and

with 3"-wide, white vinyl patch tape.

WALLS

5. When you cover the full wall, you’ll need to attach a second length of the blanket to the lower edge of the ﬁrst one. If you have

cut a piece to ﬁt and there is no ﬂange, create one by pulling back the insulation. Overlap the ﬂanges of the top and bottom

pieces so that the insulation butts together tightly. Then, staple through the ﬂange to hold the pieces together. An alternate

method is to attach furring strips to the wall at the mid-point and bottom of the wall. Then staple the blanket ﬂange to the

furring strips.

6. To give the insulation a ﬁnished look, tape over all joints, seams and stapled edges with 3-inch wide, white vinyl patch tape.

7. Cut small pieces of batt insulation to ﬁt against the header joists and push them into place between each ﬂoor joist.