What Is a Lean-To Roof?

A lean-to roof (lean to roof diagram below) is a single-sloped roof that leans against another structure or wall. It’s one of the simplest and most cost-effective roofing solutions used in extensions, sheds, porches, and outbuildings. The slope allows water runoff and is typically supported on one end by a higher wall.

Key Features:Lean to roof diagram below

• Single Pitch: One continuous slope from high to low.

• Simple Structure: Often uses timber rafters or steel beams.

• Cost-Effective: Less material and labour required than gable or hip roofs.

• Common Uses: Conservatories, rear extensions, carports, sheds, and utility rooms.

Construction Overview:

• Structure: One side supported by the main wall, the other by posts or a lower wall.

• Pitch Range: Usually 15–30 degrees depending on material.

• Material Options: Felt, polycarbonate, metal sheets, tiles, or shingles.

• Drainage: Designed to allow efficient rainwater run-off.

Technical Drawing:

Below is a simple technical drawing of a typical lean-to roof setup:

(Uploaded as: “A technical line drawing depicts a lean-to roof structure with labeled parts, including rafters, support wall, flashing, slope angle, and guttering.”)

Pros and Cons: