21.5mm Pond Glass Window

Raised brick pond, depth in the 300s, width well under 1,400mm. That is the build this pond glass window is made for. Two layers of 10mm toughened glass bonded with a 1.5mm EVA interlayer. The EVA, ethylene vinyl acetate, is what holds the two glass layers together if the outer face breaks and what stops the panel separating under water pressure, which is the actual failure mode worth thinking about.

Each pond glass window is heat-soaked after toughening. The process runs the glass through several hours at elevated temperature, which causes any nickel sulphide inclusions in the glass to expand and fracture the panel in the oven rather than in your pond wall. It does not remove the risk. It moves it to a controlled environment during manufacture rather than leaving it to resolve itself in the field. For a full breakdown of what type of glass is used for pond windows and why toughened, laminated, and heat-soaked construction matters, see our dedicated guide.

People order the 25.5mm for ponds like this and call it the cautious choice. It is not cautious. It is heavier on the install and more expensive, and the pond is not asking for it. If your depth sits right at 400mm or your measurement is not certain, the 25.5mm is the right call. Comfortably under 400mm and under 1,400mm wide? This is the correct pond glass window.

Key Features

• Two layers of 10mm clear toughened glass with 1.5mm EVA interlayer
• Heat-soaked for additional strength and reduced breakage risk
• All edges polished to a professional finish
• Made to your exact dimensions
• Production tolerance ±3mm
• Average lead time 12 to 14 working days
• Free mainland UK delivery (exclusions apply)

Pond Glass Window Thickness Guide

The 21.5mm is where the range starts. Step up to the 25.5mm (two layers of 12mm, up to 550mm deep and 1,600mm wide) once depth or width exceeds these limits. The 33mm moves to three layers of 10mm with two EVA interlayers for ponds up to 900mm deep and 2,000mm wide. Above that, the 39mm handles up to 1,000mm deep and 3,000mm wide using three layers of 12mm glass. At the top of the range, the 44.5mm covers ponds up to 1,200mm deep and 3,500mm wide with four layers of 10mm glass and three EVA interlayers. For a full explanation of how depth and width interact with structural requirements, read our pond glass thickness guide.

Ordering

Every pond glass window is cut to your exact dimensions and made to order. You have 24 hours from the point of purchase to change your dimensions or cancel. After that the glass is likely already in production and changes or cancellations may carry an additional charge. For a full breakdown of how pond glass is priced, see our guide to pond glass window cost in the UK.

Delivery and Handling

We deliver by pallet or specialist glass-carrying van, curbside. The driver gets it to your property line. Moving the glass from there is your responsibility, so have help on hand. For guidance on receiving, handling, and fitting your panel correctly, see our pond glass window installation guide. Delivery is free to most mainland UK addresses. The following postcodes fall outside the free delivery zone: AB, BT, CT, DD, DG, EH, FK, G, IV, KA, KW, KY, ML, PA, PH, PL, TD, TN23-30, TR.