How should windows and doors be stored on a job site?

Windows and doors should be stored upright, indoors, on a level surface, and kept dry with protective wrapping intact, according to the Fenestration Self-Assessment Scheme (FENSA, 2026). Incorrect storage is a leading cause of frame warping, seal failure and voided warranties on job sites.

The key variable is whether the products are glazed or unglazed. Glazed units are heavier and more prone to glass breakage, so they demand extra care. Unglazed frames are lighter but still vulnerable to twisting if stored on uneven ground. The rules apply to all new installations, including replacement windows, patio doors and composite entrance doors. Storage conditions matter most when the job site is exposed to rain, direct sunlight or temperature swings, which accelerate damage to timber, uPVC and aluminium profiles.

Store upright on a level dry surface

Every window and door unit must be stored vertically, never flat. Laying a frame flat places weight on the glass and can cause the pane to crack or the frame to bow. The British Research Establishment advises storing units on a clean, level surface, preferably on timber battens to lift them off damp ground (BRE, 2026). The surface should be indoors or under a waterproof cover. If stored outside, raise the units at least 100 mm off the ground and tilt them slightly to allow water runoff without pooling on the sill.

Keep protective wrapping and spacers in place

Manufacturers supply protective film, corner protectors and glazing spacers for a reason. The Energy Saving Trust notes that removing these before installation exposes the frame to UV damage, scratches and moisture ingress (Energy Saving Trust, 2026). Leave all packaging intact until the unit is ready to be fitted. Spacers between stacked frames prevent glass-to-glass contact, which can cause micro-cracks that later lead to seal failure. Only remove the film immediately before installing, and avoid leaving it on for more than three months as it can bond to the frame in sunlight.

Secure against wind and accidental impact

A job site is a busy environment. The Health and Safety Executive requires that stored materials do not create a trip or crush hazard (HSE, 2026). Windows and doors must be restrained with straps or chocks to prevent them from toppling in wind or if bumped. Store them away from vehicle routes and pedestrian walkways. Never lean units against walls without securing them at the base. For large doors or heavy triple-glazed units, use purpose-made storage racks that hold each unit in a vertical slot. This reduces the risk of glass breakage, which can cost upwards of £200 per pane to replace.

A worked example

Glazing is standard-rated for VAT at 20%. The zero rate for energy-saving materials covers insulation, heat pumps and solar panels; HMRC names secondary and double glazing as excluded (VAT Notice 708/6). The homeowner stores the units upright on timber battens inside the garage for two weeks before installation, keeping all protective wrapping and glazing spacers intact. This follows the Energy Saving Trust guidance on preventing frame warping and seal failure. By avoiding flat storage or leaning units against a damp wall, the homeowner protects the warranty and prevents a costly replacement of a cracked pane or twisted frame.

What homeowners often get wrong

The most common mistake on job sites is storing windows and doors flat on the ground rather than upright. This misconception leads to three frequent errors that can void warranties and waste money.

1. Storing units flat on the ground Many people think laying a window flat protects it from falling over. The reality is that this places the full weight of the glass on the frame edges, which can crack the pane or bow the frame beyond repair. One cracked double-glazed unit costs £200 to £400 to replace.
2. Leaving protective wrapping on for weeks in sunlight Some assume wrapping keeps the frame clean until installation. In direct sunlight the plastic can bond to uPVC or timber surfaces, leaving a permanent discolouration or sticky residue. Removing this residue requires specialist solvents and can cost up to £150 in labour.
3. Storing units outside without raising them off the ground A common belief is that a waterproof tarpaulin is enough. Without a 100mm air gap underneath, moisture wicks up into the frame and causes rot in timber or corrosion in aluminium. This voided warranty means the homeowner pays full price for a replacement frame, typically £800 to £1,200.

Quick reference

• Store all window and door units upright on a level surface to prevent frame warping and glass breakage.
• Keep protective wrapping and glazing spacers in place until the moment of installation to avoid scratches and seal damage.
• Units stored outdoors must be raised at least 100mm off the ground on timber battens to prevent moisture damage.
• Never store units flat as this places the full weight on the glass and frame edges, risking a cracked pane costing £200 to £400.
• Remove protective wrapping within a few days of delivery if the units are in direct sunlight to prevent plastic bonding to the frame surface.