Sliding window pile weatherstrip slides into a T-slot in the sash or frame. To replace it, measure the old strip's backing width and pile height, open or lift out the sash, pull the old strip out of the slot, slide the new one in from the end and crimp the slot ends so it can't creep out. The pile should brush the opposite surface lightly.
IllustrativeMeasure two numbers
| Measure | What it is | Note |
|---|---|---|
| Backing width | Width of the flat base that sits in the slot | e.g. 4.8 mm, 6.9 mm |
| Pile height | Height of the brush above the base | Choose to brush the facing surface |
| Fin | Plastic fin in the middle of the pile | Better wind and rain resistance |
Step by step
- Open the window and lift the sash out if the slot is hidden.
- Grip the old pile with pliers and pull it along the slot.
- Clean the slot.
- Slide the new pile in from one end; cut it 5 mm long and push the end in.
- Pinch the slot ends with pliers so the strip stays put.
Self-adhesive pile
If there is no slot, use self-adhesive pile on a clean frame. See pile height guide for sizing.
Quick questions
Why does my sliding window still whistle?
The pile is too short or worn flat, or there is no fin. Fit a taller finned pile.
Is wool pile real wool?
Usually not – most pile weatherstrip is polypropylene fibre on a plastic backing, siliconised to repel water.
Need a seal for this?
Send your section, gap size or a photo of the old seal – Dora replies usually within 2 hours. Brush & wool pile seals are available from 10 m.