How Much Is A Loft Conversion?

How Much Is A Loft Conversion

Remember the Hidden Costs When Planning Your Conversion

A loft conversion is a great way to add space and value to your home. But be sure to work out all the cost implications in advance.


A loft conversion is among the most common and popular of home upgrades. Conceptually, it makes a whole lot of sense. There is typically enough room to make a good-sized bedroom, study or playroom for the kids, and in most cases, it is space that is being under-utilised for storage, or not used at all.

Like any home improvement project, the key to success is in the planning. That doesn’t just mean in the design and construction, but also in having a firm handle on the costs. As well as labour and material, keep in mind that you might also have to pay for a party wall agreement, building regs approval and other costs that might not immediately spring to mind.

Materials and Labour

Naturally, the most significant cost will be around the materials and labour. These vary depending on the type of conversion you are contemplating and the construction of your roof. If you have an older property with a framed roof, this will certainly keep the cost down, as it will reduce the need for additional supports in the form of steel RSJs.

Another factor to keep in mind here is the type of windows. Velux-style skylights are the simplest and most cost-effective. If you are considering adding a dormer, this will put an additional £3,000 to £5,000 onto the overall cost.

The construction of the roof itself is also a consideration. Slate roofs are fiddlier, and therefore more expensive, to work with than a conventional tiled roof.

Party Wall Agreement

If you live in a detached property, this is not an issue, but for a terrace or semi, you will almost certainly need a party wall agreement. Drawing up the notice and serving it on your neighbours doesn’t cost anything, and if they agree, all is well. However, if they either dissent or fail to respond, you will need to appoint an independent surveyor, who will produce a party wall award. This is essentially a final and binding decision on what is, and is not, allowed to take place in relation to the party wall.

Surveyor costs vary, but budget on somewhere around £150 per hour, and the cost of the award is approximately £1,000.

Planning permission

In around three quarters of cases, planning permission is not required for a loft conversion. However, there are exceptions, for example if your proposed conversion is outside the permitted development limits or if you live in a conservation area. Costs vary, so speak to your local planning office to check what, if anything, is needed.

Building regulations

Even if you don’t need planning permission, your conversion still has to meet building regulations to make sure it is structurally sound and meets the requirements for fire safety, insulation and various other factors. This will require that you submit plans and have at least one visit from a building inspector. If only one inspection is necessary, the total cost will be about £400.