Greenhouse Insulation

Why Use UV Stabilised Bubble Wrap?

Standard packaging bubble wrap degrades quickly when exposed to sunlight, often falling apart and turning brittle within a single season. UV stabilised greenhouse insulation is manufactured specifically for horticultural use, containing UV inhibitors that allow it to last for 3 to 5 years.

Thicker than standard wrap, horticultural insulation typically features large 25mm (approx 1 inch) bubbles or smaller 10mm bubbles. We generally recommend the large 25mm bubbles for the best balance of performance:

• Better Light Transmission: Larger bubbles allow more sunlight to enter the greenhouse—crucial during shorter winter days.
• Superior Insulation: The larger air pockets provide a more effective thermal barrier against frost.
• Cost Efficiency: Installing high-quality insulation can reduce your heating costs by up to 50%, making it a necessary investment if you use a greenhouse heater.

How to Fix Insulation to Your Greenhouse

Securing insulation properly prevents draughts and eliminates cold spots where frost can penetrate. The method depends on your greenhouse frame type.

Aluminium Greenhouses

We recommend using specific plastic clips that twist and lock into the glazing channels of your frame:

• Standard Alliplugs: These pin the bubble wrap directly flush against the frame and glass.
• Super Alliplugs: These feature a spacer that creates a 25mm air gap between the glass and the insulation. This 'double glazing' effect significantly improves thermal efficiency and helps reduce condensation on the glass.

Wooden Greenhouses

For timber frames, the process is straightforward. You can simply use drawing pins or a staple gun to attach the wrap directly to the wooden spars. Ensure you do not staple too tightly, which can pop the bubbles and reduce insulation value.

Managing Light and Condensation

While insulation keeps the cold out, it also reduces light transmission by approximately 10-15%. To counter this, clean your greenhouse glass thoroughly before fixing the insulation to maximise available light.

Condensation can build up between the plastic and the glass, which may lead to fungal diseases like Botrytis (grey mould). To prevent this:

• Ensure the insulation is sealed well at the seams using waterproof tape.
• Ventilate the greenhouse on mild, dry days to allow excess moisture to escape.
• Remove the insulation promptly in spring once the risk of frost has passed.

Calculating Your Requirements

To calculate how much insulation you need, measure the two sides, the two ends, and the roof area. As a general guide, a standard 6ft x 8ft greenhouse generally requires approximately 20-25 square metres of bubble wrap to cover all glass areas comfortably, including an overlap for sealing joints.

We always advise buying slightly more than your calculated area to allow for cutting around vents, louvres, and door handles.