Installing Blanket Insulation in Basements

This blanket type insulation comes in rolls up to 70 feet in length.  Some specialty products may come in rolls up to 100 feet long.  Blanket type insulation is available in both vinyl-faced and unfaced, unfaced requiring an additional fire-resistant vapor barrier.  If you decide to use the unfaced insulation, you are required to cover it with a  fire-rated 4-mil polyethylene film (visqueen). 

Blankets are particularly useful in long runs between ceiling or floor joists and for areas requiring insulation longer than 96 inches.  Blankets are primarily used for insulating unfinished walls in basements.

How to Install Blanket Insulation in Basements

Unframed, exterior basement walls should be insulated with blanket insulation and it can be installed either 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 some special fasteners for driving into the concrete or cinder blocks.

To Install the Insulation Horizonally

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

Predrill an ample supply of 1"x 2" furring strips.

Measure the length of insulation you are going to need for the full wall and cut it on the unfaced side.

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 the ductwork, plumbing or electrical that may lie along the walls.  Otherwise, carefully cut and fit the blanket around these obstructions.

When you have covered the full wall, you will 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 and then staple the blanket flange to the furring strips.

If you have installed unfaced insulation, be sure to cover it with polyethylene film (as required).

To give faced insulation a finished look, tape over all joints, seams and stapled edges with 3" wide white vinyl patch tape.

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

To Install Insulation Vertically

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

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

Attach the blanket to the wall using furring strips or Hilti-type gun to drive fasteners into the concrete or cinder blocks.  Fit adjacent blankets tightly together.

Trim the bottom of the insulation flush with the floor.

If you have installed unfaced insulation, be sure to cover it with polyethylene film (as required).

To give the faced insulation a finished look, tape over all joints and with a 3" wide white vinyl patch tape.


Disclaimer:   The material on this website is to be used for informational purposes only and is not meant to substitute for any particular application due to geographic location and other unknown variances.  Links to other websites are included for the user's convenience only and do not constitute an endorsement of the material on those sites.