Drain Hole Covers

Replacement uPVC drainage caps (weep hole covers) for double-glazed windows and doors. Made from UV-stable ASA plastic in 8 colours to match every major UK frame colour.

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Anthracite Drain Hole Covers White Drain Hole Covers

What are drainage caps?

Drainage caps (weep hole covers) are small plastic caps that clip over the drain slots in uPVC window and door frames. They prevent insects, dust and debris from entering the frame while still allowing rainwater to drain out. Made from UV-stable ASA plastic that won't yellow, crack or fade — unlike cheap ABS alternatives. Available in 8 colours to match every major UK frame: White, Black, Anthracite, Chartwell Green, Oak, Light Oak, Mahogany and Vanilla.

How to choose the right colour

Match the cap colour to the external foil colour of your frame, not the internal white finish. White for standard white uPVC. Anthracite for RAL 7016 grey frames (the fastest-growing colour in UK windows). Oak and Light Oak for golden oak woodgrain foil. Chartwell Green for heritage and conservation areas. Mahogany for dark rosewood-effect foiled frames. Vanilla for cream/ivory frames. Our ASA caps are push-fit for all standard UK uPVC frames — no tools or adhesive needed.
Trade Tip

Check all weep holes during annual maintenance — a blocked cap causes water to pool inside the frame cavity, leading to damp and mould.

Frequently Asked Questions

What are weep hole covers for windows?

Weep hole covers (drainage caps) clip over the drain slots in uPVC window and door frames. They prevent insects and debris entering while allowing rainwater to drain out. Every uPVC window has at least two weep holes on the bottom rail.

What is the difference between ASA and ABS drainage caps?

ASA plastic is UV-stabilised — it resists yellowing, cracking and fading in sunlight. ABS degrades faster in UV, causing caps to yellow and become brittle within 2-3 years. All GSD drainage caps are ASA for long-term durability.

How many drainage caps do I need per window?

Each window sash typically has 2 weep holes on the bottom rail. A standard casement window needs 2 caps. French windows and patio doors typically have 4-6 weep holes. Count the slots on your frame and order accordingly.

Can I paint drainage caps to match my frame?

We recommend choosing the correct colour cap rather than painting. Paint does not adhere well to ASA plastic long-term and will flake. With 8 colours available, there is a match for every standard UK uPVC frame colour.