How to Insulate Windows with a Draft Snake

A draft snake (also called a draft stopper or draft excluder) is a simple, effective tool for blocking cold air that seeps in along the bottom of a window sill. It's one of the easiest and most affordable window insulation solutions available. Here's how to use one effectively.

What Is a Draft Snake?

A draft snake is a long, cylindrical tube filled with insulating material (sand, rice, foam, or batting) that sits along the bottom of a window or door to block cold air from coming in underneath. It's placed on the interior window sill or along the base of the window frame.

When Is a Draft Snake the Right Solution?

Cold air is coming in along the bottom of the window sill
The window has a large gap at the bottom that weatherstripping can't fully seal
You want a quick, no-installation solution
You're renting and can't make permanent modifications
As a supplement to other insulation methods

Using a Draft Snake on a Window

Place the draft snake along the interior window sill, pressing it firmly against the base of the window frame. For double-hung windows, place it along the bottom rail of the lower sash where it meets the sill. The snake should span the full width of the window.

Making Your Own Draft Snake

A DIY draft snake is simple to make:

Cut a piece of fabric (an old towel, fleece, or denim) to the width of your window plus 4"
Fold in half lengthwise and sew along the long edge and one short end
Fill with dry rice, sand, or polyester batting
Sew the open end closed

A rice-filled snake also acts as a heat pack — microwave it for 2 minutes and place it on the sill for extra warmth.

Combining with Other Methods for Maximum Effect

A draft snake alone addresses only the bottom gap. For complete window insulation, combine it with:

Shrink film over the glass for thermal insulation
Weatherstripping on the sash sides and top
Rope caulk for any remaining cracks

Frost King Indoor Shrink Window Kit 42"x62" 9-Pack — pair with a draft snake for complete window insulation: snake blocks bottom gap, film insulates the glass
XFasten Transparent Window Sealing Tape 2"x30yd — seal the sash perimeter while the draft snake handles the sill gap

Draft Snake vs. Weatherstripping

Draft snake: No installation, portable, works on any window, best for large bottom gaps
Weatherstripping: Permanent, more effective seal, requires installation, best for consistent gaps

Use a draft snake as a quick fix or supplement, and install weatherstripping for a permanent solution.

Effectiveness

A draft snake is most effective when cold air is coming in along the window sill — a common problem in older homes with single-pane windows and worn sill seals. It won't insulate the glass itself, but it can significantly reduce the cold air pooling at floor level near windows.

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