Great Value Glazing Packers Trusted by The Trade

Colour-coded flat plastic glazing packers for precise levelling of windows, doors and frames. Available in 24mm, 28mm, 30mm and 32mm widths with thicknesses from 1–6mm. Made in the UK from 100% recyclable material. Dispatched within 48 hours.

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What are glazing packers (window packers)?

Glazing packers — also called window packers — are flat plastic shims placed between a sealed glass unit and the window or door frame. They level the glass, distribute its weight evenly, prevent the unit from sitting directly on the frame sill, and allow water to drain through the rebate channel. Every window and door installation in the UK uses glazing packers. Glazing Supplies Direct stocks UK-made window packers in the full range of trade sizes — colour-coded by thickness (1mm green, 2mm black, 3mm white, 4mm grey, 5mm blue, 6mm red) for instant identification on site. All packers are made from 100% recyclable material.

How to choose the right glazing packer

Selecting the correct glazing packer depends on three factors. First, rebate width — measure the channel in your frame where the sealed unit sits and choose a packer width (24mm, 28mm, 30mm or 32mm) that fits inside the rebate without protruding. Second, gap size — measure the gap between the glass unit and the frame and choose a thickness (1–6mm) that fills the gap snugly. Use multiple thin packers stacked together for non-standard gaps. Third, weight of the unit — heavier sealed units (triple glazing, large panes, composite doors) need thicker packers on the bottom edge to distribute weight. For standard double glazing, 28mm width and 2mm thickness is the most commonly used combination. For bulk jobs, our mixed packs and bulk box deals offer the best value per unit.
Trade Tip

Always use at least two packers on the sill — one at each end — before checking level. Adjust the sill first, then pack the jambs to plumb.

Frequently Asked Questions

What size glazing packers do I need?

You need two measurements: the width (match your frame's rebate depth — 28mm is the most common for standard double glazing) and the thickness (match the gap between glass and frame — 2mm is the most frequently used). For triple glazing or composite doors, use 32mm width and 4–6mm thickness.

What is the colour coding for glazing packers?

Our glazing packers are colour-coded by thickness: 1mm green, 2mm black, 3mm white, 4mm grey, 5mm blue and 6mm red. This lets installers identify thickness at a glance without measuring. Note that our U packers (horseshoe shims) use a separate code — 2mm yellow, 3mm red and 5mm green.

How many glazing packers do I need per window?

A standard single casement window typically needs 6–8 packers: 3 on the bottom edge (two corners plus centre) and 2–3 on the sides for toe-and-heel packing. A box of 1,000 mixed packers covers approximately 125–170 standard windows.

What is the difference between glazing packers and setting blocks?

Setting blocks (bridge packers) are thicker, bridge-shaped plastic supports placed at the bottom of the glass unit to carry its weight. Glazing packers are thinner, flat shims used around all edges to level and lock the unit in position. Most installations use both.

Can I stack glazing packers?

Yes. Stacking is standard practice — for example, a 2mm + 1mm stack gives 3mm with a tighter fit than a single 3mm packer. Stack no more than three packers together; beyond that, use a single thicker packer for stability.

Are your glazing packers recyclable?

Yes — all GSD glazing packers are made from 100% recyclable material (HIPS or polypropylene) and manufactured in the UK. They meet site waste management requirements.