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Best Draught Proofing for a House with Single Glazed Sash Windows
Single glazed sash windows leak heat in three places: the sliding gaps between sash and frame, the meeting rail where the two sashes close, and the thin glass itself. The five picks below cover all three, from a brush pile seal that keeps the sashes sliding to a shrink film kit that turns the whole pane into a trapped air pocket. It suits period-home owners, renters who cannot modify the frames, and anyone facing one more winter before a full window replacement. The overview table shows the short version; the reviews explain the fit.
The Picks at a Glance
| Product | Key Spec | Best Use | Price Tier |
|---|---|---|---|
| 16 Ft Sliding Sash Tape Pile Brush Seal | 5mm x 12mm brush pile, 16 ft roll | Sash channels and sliding gaps | Budget |
| XFasten Transparent Window Sealing Tape | 2 in x 30 yd clear film tape | Sealing glass edges and small cracks | Budget |
| Weather Stripping Door Window Seal Strip | 33 ft, 0.35 in wide x 0.35 in thick foam | Frames, stops and cabinet doors | Budget |
| Clear Silicone Weather Stripping Seal Strip | 35mm wide, 33 ft total, 2-pack | Wide frame gaps and glass edges | Mid-range |
| Duck Brand Window Insulation Kit | 62 in x 420 in shrink film, fits 10 windows | Whole-pane insulation for winter | Mid-range |
1. 16 Ft Sliding Sash Tape Pile Brush Seal
Type: Brush pile seal strip
Profile: 5mm x 12mm
Length: 16 ft (5m)
Color: Gray
Intended use: Sliding sash windows and doors
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Brush pile is the one seal designed for a window that has to keep moving. The flexible bristles fill the gap between the sash and the frame while letting the sash slide past, which is exactly what a rigid foam strip cannot do. The self-adhesive backing presses into the channel, and the gray color blends with most painted frames.
This is the pick for sash windows that still open and close and need the draught killed without being painted shut. It also works on sliding patio doors with the same channel profile.
Trade-off: The bristles flatten over a season or two of heavy use, so the strip needs replacing more often than a solid rubber seal.
2. XFasten Transparent Window Weather Sealing Tape
Type: Clear film sealing tape
Width: 2 in (50.8mm)
Length: 30 yd (27.43m)
Color: Transparent
Removal: No-residue claim
Intended use: Window draft isolation
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This is the blunt instrument of the set, and sometimes that is what a window needs. The clear tape bridges the seam where the two sashes meet and any crack around the glass, forming an airtight film over the gap. Because it is transparent, the window still looks normal from inside and out.
It suits renters and anyone sealing a window they will not open until spring. The no-residue claim matters here, since the tape sits directly on painted wood and glass.
Trade-off: Taped seams cannot be opened, so a taped window is out of action for the season and the adhesive can still lift paint on old, chalky frames.
3. Weather Stripping Door Window Seal Strip
Type: Self-adhesive foam seal strip
Length: 33 ft
Profile: 0.35 in wide x 0.35 in thick
Color: Gray
Intended use: Doors, windows, cabinet doors
Properties: Soundproofing, draft blocking, dustproofing
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A square foam profile like this is best used where the sash does not slide — the outer frame, the window stop, or the gap behind the staff bead. The 0.35 inch thickness compresses to fill an uneven gap and springs back, which handles the slight movement of an old frame better than a flat strip.
It is the cheap fix for the perimeter gaps around a window, and the same roll covers cabinet doors and internal doors that rattle.
Trade-off: Foam this thick will stop a sash from closing if it is pressed into the sliding channel, so it belongs on the fixed frame only.
4. Clear Silicone Weather Stripping Seal Strip
Type: Transparent silicone seal strip
Width: 35mm
Length: 10m / 33 ft total
Pack: 2-pack
Color: Clear
Intended use: Door and window frames, glass, gaps
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Silicone holds up better than foam to sun, paint and repeated compression, and the clear finish keeps it invisible against white frames and glass. The 35mm width covers a wider gap in one pass, so a single run can bridge the space between sash and frame where a narrow strip would need two.
This is the step up for anyone sealing a window they intend to keep for years rather than one season. The two-pack gives enough length to do a full bay without running short.
Trade-off: The wider profile is less forgiving on tight channels, and clear silicone shows dust and grime along its edges faster than a colored strip.
5. Duck Brand Window Insulation Kit
Type: Shrink film insulation kit
Film size: 62 in x 420 in
Coverage: Fits up to 10 windows
Included: Window tape
Color: Crystal clear
Installation: Indoor, cuts to size
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Shrink film does not seal a gap — it removes the glass from the equation. Taped to the frame and tightened with a hair dryer, the film traps a layer of still air against the single pane, which is the same principle as a second glazing pane at a fraction of the cost. The kit includes the tape, so nothing else is needed.
It suits the coldest room in the house and anyone who wants the biggest comfort gain per dollar. The 62 inch width covers a large sash window in one piece.
Trade-off: The film is a seasonal measure that has to come down in spring, and the tape can pull at old paint when removed.
Before You Buy
- Gap type: Sliding channels need brush pile; fixed frame gaps take foam or silicone; the glass itself takes shrink film.
- Sash movement: Any window that must still open needs a seal that slides with it — brush pile, not foam or tape.
- Frame condition: Chalky, flaking paint weakens every adhesive, so sand and prime loose areas first.
- Width and thickness: Measure the gap before choosing a profile; an oversized foam strip will jam a sash.
- Finish: Clear seals disappear on white frames, gray blends with painted wood, and film is visible as a sheen.
- Removal: Tapes and films are seasonal, so check the removal claim before applying to a heritage frame.
- Coverage: Add up total window perimeter and compare it with the roll length before ordering.
Frequently Asked Questions
-
What is the best draught proofing for single glazed sash windows?
Brush pile seal for the sliding gaps plus shrink film over the glass covers the two biggest losses. The brush keeps the sash working; the film handles the pane. -
Can sash windows be draught proofed without stopping them opening?
Yes. Brush pile strip is designed for that, because the bristles flex as the sash slides past. Foam and tape are for windows that stay shut. -
Does shrink film work on old wooden sash windows?
It does, provided the frame is clean and dry so the tape grips. The film attaches to the frame, not the glass, so uneven putty is not a problem. -
Is clear tape or brush seal better for the meeting rail?
Tape gives a tighter seal at the meeting rail but locks the window shut. Brush pile is the choice when the window still needs to open. -
How much seal strip is needed for a typical sash window?
Measure the full perimeter of the frame and the two vertical channels, then add a little spare. A 33 ft roll usually covers two or three windows. -
Can these products be used on rented property?
The tape and film are the safest choices for renters because they lift cleanly. Brush pile is also removable but leaves adhesive behind on some finishes.
Bottom Line
For most single glazed sash windows, the 16 Ft Sliding Sash Tape Pile Brush Seal is the right first buy — it seals the sliding gaps that cause most of the draught while keeping the window working. Pair it with the Duck Brand Window Insulation Kit for the glass, and the room will hold heat through the coldest months.
