Basement window buying guide
Updated: 23 October 2026
You are about to order a basement window from amazon.co.uk, and the title is doing too many jobs at once. Slider, hopper, cellar, shed, and sometimes egress all appear on the same line, while the price in this set sits between £39.10 and £100. This basement window buying guide is the order of decisions before you pick a row. Products Compared editorial team compared seven listings on amazon.co.uk. We did not lab-test the glass, and none of the kept pages states a U-value. The seven rows are on the main [Basement window](/hub/diy-supplies/basement-window) comparison. A qualifying purchase through tag pcuk26-21 can earn a commission at no extra cost to you.
You are about to order a basement window from amazon.co.uk, and the title is doing too many jobs at once.
You are about to order a basement window from amazon.co.uk, and the title is doing too many jobs at once. Slider, hopper, cellar, shed, and sometimes egress all appear on the same line, while the price in this set sits between £39.10 and £100. This basement window buying guide is the order of decisions before you pick a row. Products Compared editorial team compared seven listings on amazon.co.uk. We did not lab-test the glass, and none of the kept pages states a U-value. The seven rows are on the main Basement window comparison. A qualifying purchase through tag pcuk26-21 can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Glass | Opening | Frame | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Kathfly Kathfly 16 x 8 inch recessed basement window | Tempered, clear | Sliding, recessed | Aluminium | 8.8 | about £39.10 | View offer |
 CroBlissful CroBlissful 16 x 8 inch clear vinyl window | Double-layer clear | Slider or hopper | Insulated vinyl | 8.8 | about £96.18 | View offer | |
| Alternative |  Croblissful Croblissful 16 x 8 inch frosted window | Double-layer frosted | Slider or hopper | Aluminium alloy | 8.0 | about £86.64 | View offer |
On this page
Two different purchases
The folder you are in is a small marketplace window, not a surveyed cellar window from a fabricator. Listings here run from about £39.10 to £100. Wider sliders were also seen on amazon.co.uk at £267.47 and £286.74. Those prices are not rows in this table, and they are still not a made-to-measure quote. Neuffer's UK cellar page describes aluminium-faced windows made to the opening. That is a different purchase.
Trade notes assume the brick opening was measured in three places. Take the smallest of three widths and three heights. That step belongs on how to fit a basement window. If nobody is sleeping in the room and the opening already exists, a stock unit can be the right class of product.
Clear opening before brand
A 16 by 8 inch frame is about 406 mm by 203 mm. Approved Document B, for dwellings in England, asks for an unobstructed opening of at least 0.33 m² and at least 450 mm by 450 mm when that window is the escape route. Both sides of a 16 by 8 inch frame are already under 450 mm. None of the seven listings prints the clear gap, and a horizontal slider opens less than the outer frame.
The word egress on a title is a claim, not a measurement. Two Sion's store rows use it. The frosted 16 by 8 inch listing says sliding in the title and hopper in the bullets. The full arithmetic stays on basement escape window size.
Frame, glass and what is not printed
Aluminium and vinyl are both in this set, and neither comes with a U-value. Double-layer on a bullet is a description of the pane, not a pass against Approved Document L. Where Table 4.2 applies to a window in an existing dwelling in England, the limit is 1.4 W/(m²·K) or Window Energy Rating band B. Every kept listing leaves that cell empty. A shed or a coop is a different case, and that limit should not be dragged into an unheated outbuilding.
Approved Document Q, for new dwellings in England, points at PAS 24. No kept listing states it. Planning Portal's basement guidance is about the project, not a star line. This set does not print a safety-glass class. One Italy review of the £93.40 vinyl slider even disputes that the panes are glass.
How this comparison is arranged
The main comparison holds seven rows. Star lines exist for four of them. Three have no star line, so a blank is not a hidden five-star rating. Written reviews are mostly from the United States, or in one case Italy, so a 4.4 is an amazon.co.uk count, not a British winter.
This page does not rank a winner. The best page says who the frosted row, the £39.10 row, and the thin-evidence rows are for. Read the room first, then the opening, then the paperwork this price band does not contain.
Common questions
What should I check before I buy a basement window?
Check who uses the room, then the clear opening, then whether the page states a U-value. No listing in this set prints a U-value or a clear opening. Measure the brick opening before you trust the title, and treat hopper, slider, and egress as words until the listing agrees with itself.
Is a £40 to £100 amazon.co.uk unit the same as a window-company cellar window?
No. These rows are stock sizes with short fixing notes. A made-to-measure cellar window, such as the aluminium-faced units Neuffer describes for UK openings, is surveyed and quoted above this band. That higher quote is not a national average. Wider amazon.co.uk sliders at £267.47 and £286.74 are still not that surveyed window. You are choosing a class of product, not a cheaper copy of the same specification.
Where do I decide hopper or slider?
Decide it on the listing you are about to pay for, because this set does not agree with itself. One 16 by 8 inch page says sliding in the title and hopper in the bullets. A review of that page describes an outward opening with no crank. Do not infer the action from the word basement.
Does double-layer mean it meets Part L?
No. Double-layer is a glass description. Approved Document L Table 4.2, where it applies to an existing dwelling in England, limits a window to 1.4 W/(m²·K) or Window Energy Rating band B. No kept listing states either figure. A coop or an unheated shed is not that dwelling test. You cannot promote a bullet into a whole-window energy rating.
Do I need planning permission to replace a cellar window?
Planning Portal treats a new or enlarged basement as a project with its own planning test. A like-for-like replacement is a different question, and a listed building is stricter again. This page cannot clear your address. The product pages do not mention planning, conservation areas, or listed status. Ask the local authority before you cut a new opening or change the appearance of a protected building.
When does PAS 24 matter?
Approved Document Q, for new dwellings in England, uses PAS 24 as the security reference for windows and doorsets. No listing in this comparison states PAS 24. It is the wrong demand for a garden-shed vent, and it is a fair demand when the window is part of a new home. A star line does not substitute for that certificate.
Related pages
Sources
Public UK sources and the amazon.co.uk listings compared on this page. Updated 22.10.2026.
- Approved Document B Volume 1, paragraphs 2.10 and 2.16 (retrieved 22.10.2026)
- Approved Document L Volume 1, Table 4.2 (retrieved 22.10.2026)
- Approved Document K, critical glazing locations (retrieved 22.10.2026)
- Approved Document F Volume 1, paragraphs 3.14 to 3.15 (retrieved 22.10.2026)
- FENSA: jobs you can register (retrieved 22.10.2026)
- Planning Portal: basements and building regulations (retrieved 22.10.2026)
- BS 8102:2022, protection of below-ground structures against water (retrieved 22.10.2026)
- Hampshire building control: replacement windows and doors (retrieved 22.10.2026)
- diy.com RISOR 90 by 40 cm tilt window, not in this set (retrieved 22.10.2026)