Is planning permission needed for prefab lean to garage?

Normally you would need a building permit.

Whether planning permission is needed for a prefab lean-to garage depends on several factors, including local regulations and the specific characteristics of your project. In general, you should consider the following points:

1. Size and Height: Many local authorities have limits on the size and height of structures that can be built without planning permission. If your lean-to garage exceeds these limits, you will likely need permission.
2. Proximity to Boundaries: If the garage is within a certain distance from your property boundary, you may need planning permission.
3. Purpose: If the garage is being used for purposes other than domestic storage, such as running a business, you may need planning permission.
4. Previous Extensions: If your property has already been extended, it may affect whether you can add further extensions without planning permission.
5. Listed Buildings and Conservation Areas: If your property is a listed building or within a conservation area, stricter rules typically apply, and planning permission is more likely to be required.
6. Local Regulations: Regulations can vary significantly by location, so it’s essential to check with your local planning authority.

To ensure compliance, it’s recommended to contact your local planning authority or consult a professional surveyor or architect familiar with local regulations. They can provide specific guidance based on your situation.

Depending on where in the garden you are putting it and don’t believe you need planning as it’s a prefab and not fixed onto a pad or the ground

Garages are usually considered as outbuildings and don't need planning permission. Of course, there are exceptions to this rule. If you want to avoid needing planning permission, ensure your garage: Has a floor space of below 15m2 if freestanding or 30m2 if attached to your home.

in the UK, you typically don’t need planning permission for a 24ft by 10ft lean-to prefab garage if it meets permitted development criteria. These include being no higher than 4m (3m for a flat roof) and not extending beyond the principal elevation of your house. Additionally, the garage must be for domestic use, and the total ground area of all outbuildings (including the garage) must not exceed 50% of the land surrounding the house. However, if the property is in a conservation area, a listed building, or an area with specific restrictions, planning permission may be required. Always check with your local council to confirm specific requirements before proceeding.

Depends on a couple of factors. First, has your house ever been extended and second does it cover more than half of the existing/original sqm of ground floor.
So for instance, yes it’s been extended but both the garage and the original extension don’t cover half the sqm then you can crack on without permission

as long as your lean-to is on your property and doesn't cover half the area of your land, you usually don't need planning permission for a lean-to.Sectional garages, workshops, sheds and other garden buildings are considered permitted development. They do not require planning permission as long as they are within the following guidelines:

No outbuildings are allowed forward of the walls that form the principal elevation.

Garages and Outbuildings must be single-storey with a 2.5 metres maximum eaves height and a 4m maximum overall height for dual pitched roofs or 3m for any other type of roof.

2.5m maximum height for enclosures, containers or buildings within 2m of a house or dwelling's curtilage.

No raised platforms, balconies or verandas.

Anything under 50% of the original house's surrounding land area is allowed to be covered by additions or other buildings.