7.5 or 15 m²? How to Plan Greenhouse Bubble Insulation
How much insulation does your greenhouse actually need? The key figure is not the floor area but the total surface area of the glazing you want to cover. A simple panel map helps you choose between the GREEN24 7.5 m² and 15 m² insulation sets without planning over doors, vents or fittings.
The set size refers to insulation area
A greenhouse with a six-square-metre footprint can have considerably more than six square metres of glazing: the side walls, roof panels and gable ends all count. The 7.5 and 15 m² figures therefore describe the area of bubble insulation supplied, not the greenhouse floor area.
Both GREEN24 sets contain three-layer PRO3 greenhouse bubble insulation, 150 cm wide, together with fixing clips and assembly adhesive. The 7.5 m² set includes 20 clips, while the 15 m² set includes 30. Before choosing, always check whether the contents and fixing method suit your particular greenhouse.
Step 1: divide the greenhouse into panels
Make a rough sketch of every side of the greenhouse. Divide the structure into simple shapes: rectangles for wall and roof panels, and triangles for gable ends. Give moving parts such as the door and roof vents their own sections. This makes it clear where the insulation needs to be cut separately.
- Fixed panes: measure width × height.
- Triangular gables: calculate base × height ÷ 2.
- Door and vents: record them separately so they remain fully operable.
- Handles, openers and hinges: mark them on the sketch and do not cover them.
Step 2: add the areas and plan the lengths
Add all the individual panel areas first. Then plan how the 150 cm-wide insulation can be divided into lengths. Offcuts depend on the shape, layout and junctions of your greenhouse, so a fixed waste percentage would be unreliable. Instead, measure critical panels twice and note a separate cut size for each one.
Rule of thumb: map the panels first, then choose the set. Floor measurements alone are not enough.
Step 3: plan for ventilation from the outset
Insulation is not a substitute for ventilation. Keep roof vents, doors, automatic openers and all airflow paths operational. Moist air can condense on cold glazing, so visible condensation is a reason to review ventilation, watering and plant spacing – not proof of a product fault.
Clean suitable glass and aluminium fixing surfaces before installation and allow the supplied adhesive to cure fully in accordance with the packaging instructions. The insulation is secured mechanically over the threaded tips of the clips; it is not glued directly to the glazing. Follow the instructions on the original packaging and adhesive, ventilate well while working, and avoid contact with eyes and skin.
Which set size should you choose?
If your carefully planned insulation area fits within 7.5 m² and the cutting layout works, the smaller set may be sufficient. For a larger area, the 15 m² version is the natural option. When the result is close, the decision depends not only on square metres but also on the cuts, number of panels and available fixing points.
View the 7.5 m² insulation set | View the 15 m² insulation set
After installation: the function check
- Open and close the door fully.
- Test every vent and opener.
- Check for loose insulation and contact with moving parts.
- Leave some space between plants and the insulation.
- Ventilate in mild weather and monitor condensation.
An unheated greenhouse can still fall below 0 °C despite an insulating layer. Tender plants therefore need an overwintering plan suited to the species; reliably maintaining frost-free conditions requires heating and temperature monitoring where necessary.
For the basic preparation – cleaning, repairs and keeping ventilation routes clear – also see “Not Yet: Getting Winter Protection Ready Without Wrapping Too Soon”.
