Homeowners looking to do loft conversions have been warned failing to secure planning permission could land them with a £50,000 fine. Approval from a local authority isn't always required, but it might be necessary if the work exceeds permitted development rights. Having a loft conversion done is a tempting possibility for some as it could add up to £100,000 to the value of a home if 24sqm of new space is opened up, according to extension experts at Resi. The value a loft conversion adds will differ depending where your property is though. 

In some cases, you may need planning permission. This includes if your loft conversion stretches beyond your property's roofline or uses materials which don't match the existing building. Owners who fail to secure permission can face fines of up to £20,000 for not abiding by the rules. Severe cases can lead to enforcement notices being issued. These require the owner to return the building to its original state. If such a notice is ignored, it can lead to a fine up to £50,000.

The cost of a planning permission application in England in 2025 varies based on the type and size of the development.

It starts at £258, but full planning applications for houses used as dwellings range from £588 to £635 per property.

Sally McClean from loft conversion company Rooftop Rooms said: "Loft conversions can be a great way to add value to your home, but homeowners need to be cautious when making changes.

"Many don't realise that even small alterations can lead to significant penalties if they fail to follow proper regulations, or even the need to undo the work."

She added it can take about eight weeks for a local council to make a decision on a loft conversion and possibly longer in more complex cases, such as if your home is a listed building or in a conservation area.

Ms McClean said: "It's important to be proactive and seek planning permission before starting your loft conversion.

"While it might take about eight weeks for the local authority to decide on less complex applications, understanding the requirements upfront will save both time and money, while making sure your project is legally compliant."

The expert said hiring a professional to guide you through the planning permission process can be a valuable investment.

She told the Mirror that a clear understanding of the regulations will save time and money in the long run.

It will also ensure your loft conversion is legally compliant and successful, according to Ms McClean.