It is sometimes possible to replace a flat garage roof with a pitched roof, but the work involves more than fitting new timbers and a roof covering. The existing garage must first be assessed to confirm that its walls, base and foundations can safely support the proposed structure.
A pitched roof may improve the appearance of a garage, change how rainwater is managed and provide additional internal height. However, it is not automatically the right solution for every leaking or damaged roof.
Can a Flat Garage Roof Be Converted?
The answer depends on the garage’s construction, condition and dimensions. A survey should consider:
- The condition of the concrete panels, brickwork or timber frame
- Whether the walls can support the new roof loads
- The garage span and proposed roof pitch
- The condition of the base and foundations
- Wind, snow and drainage requirements
- Whether the garage is attached to another building
Roof timbers, trusses and supports must be designed for the individual building. Generic rafter dimensions or spacing should not be used without appropriate calculations.
Does a Flat Roof Always Need Replacing?
A sound, properly installed flat roof can provide reliable protection. Leaks are often caused by localised faults such as damaged coverings, failed joints, blocked outlets, defective flashing or standing water.
Before committing to a pitched-roof conversion, arrange an inspection to identify the source of the problem. In some cases, a professional garage roof repair or replacement may be a more practical and affordable solution.
Check for Asbestos Before Work Begins
Some older garages have asbestos cement roof sheets. Their appearance alone may not be enough to confirm whether asbestos is present, so an appropriate survey may be needed before work begins.
Do not drill, cut, sand or break a roof that may contain asbestos. Work that could disturb the material should be assessed and completed by people with the necessary training, equipment and waste arrangements.
Planning Permission and Building Regulations
Changing a flat roof to a pitched roof can alter the garage’s height and external appearance. Whether planning permission is required will depend on factors including the garage’s position, its new height, the property type and any local restrictions.
The work may also require Building Regulations approval because it affects the structure of the roof. This is separate from planning permission. Contact your local planning authority and building control team before starting work, or read Dencroft’s garage planning permission guide for an introduction to the rules in England.
Choosing the Roof Design and Covering
An apex roof has two slopes meeting at a central ridge. It can provide more internal height and a traditional appearance, although the additional height and weight must be considered during the design process.
The roof covering must be suitable for the proposed pitch and supporting structure. Its weight, weather resistance and fire performance should all be considered, together with suitable flashing, ventilation, fascias, gutters and downpipes.
How the Conversion Is Normally Planned
A professional pitched-roof conversion will generally involve:
- Inspecting the garage, roof, walls and base
- Checking for asbestos and other hazardous materials
- Preparing a roof design and any necessary structural calculations
- Obtaining the required planning or Building Regulations approvals
- Removing the existing covering using appropriate safety measures
- Installing the designed supports, roof structure and covering
- Completing the flashing, ventilation and rainwater drainage
- Inspecting the finished roof for structural and weatherproofing issues
This is not generally suitable as an unsupported DIY project. Removing or altering roof components without understanding how the building is braced can cause movement, cracking or collapse.
Should You Repair, Convert or Replace the Garage?
If the walls, panels and base remain sound, repairing or replacing the existing roof may be sufficient. A pitched-roof conversion may be worth considering when the structure can support it and the change offers a clear practical or visual benefit.
Where the garage has widespread structural damage, or the desired roof cannot be supported safely, replacing the building with a purpose-designed apex roof garage may make more sense.
Discuss Your Garage Roof With Dencroft
If your garage roof is leaking, damaged or nearing the end of its useful life, Dencroft can help you consider the available repair, re-roofing and replacement options. Contact the team to arrange advice and discuss the condition of your existing garage.