Lean To Greenhouses

The "Elbow Room" Guide: Which Width Do You Need? 📏

Unlike freestanding greenhouses, your working space in a lean-to is dictated by the wall. Choosing the wrong width is the most common reason for returns. Use this guide to select the right frame depth:

Installation: The "Uneven Wall" Problem 🧱

A lean-to greenhouse relies on your house wall to act as the fourth side of the structure. The aluminium wall plate (the bar that bolts to your house) must be perfectly straight to hold the glass safely.

The Fix:

• Screw a pressure-treated timber batten (approx. 2" x 1") to your wall first.
• Use exterior-grade mastic sealant between the timber and the brickwork to create a watertight bond.
• Screw the aluminium greenhouse frame into this flat timber face.

Not confident doing this yourself? Our Installation Service teams handle timber packing daily.

Ventilation & The "Chimney Effect" 🌡️

Lean-to greenhouses typically run hotter than freestanding models. Your house bricks act as a storage heater, absorbing solar radiation during the day and releasing it at night.

While this is excellent for keeping frost away in March, it can cook your tomato plants in July. Heat rises and gets trapped at the highest point (the ridge against your wall).

Frequently Asked Questions ❓

• Are wall fixings included?

  Yes, all our models (including Elite, Vitavia & Janssens) are supplied with standard wall-mounting bolts and frame fixings suitable for typical brickwork.

• How safe are lean-to greenhouses in the wind?

  Lean-tos are naturally more wind-resistant than freestanding models because they are anchored directly to solid brickwork, which provides significant structural rigidity.

• Do they feature high eaves?

  Most of our 4ft wide models and larger feature high eaves (typically 5ft+). This is crucial as it ensures the door can open outwards without hitting the guttering, and provides ample headroom for taller crops.

• Do I need flashing for a lean-to greenhouse?

  Yes, for a complete seal. While silicone sealant works for the sides, we recommend using a roll of lead flashing or self-adhesive flashing tape along the top ridge. This directs rainwater from your house wall over the greenhouse roof, rather than letting it run behind the frame.

• Does a lean-to need a concrete base?

  For smaller models (4x2, 4x4), a level patio or paved area is sufficient – see our guide on building a paving slab base. However, for 6ft wide models or larger, the wind loads are significant. We recommend a concrete perimeter footing or a solid slab to ensure the structure is anchored securely against British winter storms. Read our DIY concrete base guide for full details.

• Can I put a lean-to against a wooden fence?

  We do not recommend this. Garden fence panels move in the wind and rot over time. A greenhouse requires a rigid, static fixing point. If you must use a fence line, you should concrete 4x4 fence posts into the ground to create an independent frame to bolt the greenhouse to, rather than relying on the fence panels themselves.