Key Facts

Different types of loft conversions (e.g., dormer, mansard, hip-to-gable, roof light) have varying costs associated with their construction and complexity.

The size of the loft space being converted directly affects the overall cost, with larger spaces typically requiring more materials and labor. So the costs can jump… you get what you pay for.

Hiring an architect or designer to create plans and drawings for the conversion is an upfront cost. If you then good builder they can take on this responsibility for you, it can work out cheaper. A design and Build service can often reduce the loft Conversion cost

Reinforcing the loft's structure, including adding steel beams or additional support, may be necessary, especially for certain types of conversions. Some buildings/loft conversions require more work than others depending on site factors and this can change the cost of your loft conversion

If required, fees for planning permission and compliance with building regulations should be considered. These can range between £140 - £900

Sometimes are legal requirement under the Partywall act and this can add costs, from £0 - £5,000 on average. Your builder or architect can advise, but it MUST be factored in to the budget for a loft conversion

Costs for building materials, such as timber, insulation, roofing materials, and windows, can vary based on quality and quantity. Always opt for the builder to supply themselves the main materials, they will have trade discounts and understand qtys. For the finishing details, you can do these bits yourself, but ask the builder if they they have trade discounts for things you order…. tiles, paint, bathroom supplies etc…

The cost of skilled tradespeople, including builders, carpenters, electricians, plumbers, and decorators, is a significant part of the budget. - Best to opt for a total package rather than break down labour or labour and materials. All in one is always cheaper

If the conversion includes windows, skylights, or dormer windows, the type and quality of glazing can affect the cost and budget. Ensure you have an idea of what you want and that it goes into the specification

Repairing or replacing the roof can be a substantial expense, depending on its condition and materials. Have the builder give a review of the current condition and if needed cost for repair. The rear roof is often included in most types of loft conversions.

Consideration should be given to heating and ventilation systems to ensure comfort and compliance with regulations. Is your boiler up to scratch and do you want to consider AC in the new rooms?

Costs for interior finishes such as flooring, wall finishes, doors, and fixtures should be factored in.

If the loft conversion includes a bathroom or kitchen, the cost of fixtures, fittings, and appliances needs to be included. These are often excluded in quotations, so it needs to be in your budget

The creation of storage spaces, wardrobes, or cupboards should be budgeted for. It can be sizable additional expense.

If a new staircase is required to access the loft, the design and construction of this element should be considered. It is nearly always in a builders quote, but pay attention to the type of stairs…. Closed string Vs Cut string, or Softwood Vs ply and MDF….. do the spindles match the existing etc…. They do vary in cost and its a good way for a builder to hide costs by providing the cheaper option

Budgeting for furniture, furnishings, and decor to complete the converted space is often necessary. Both are common exclusions in a quotation, but you do need to factor it in. Furnshing cost is based on taste but decoration, which differs from “simply painting” for newly plastered walls , can cost between £2000-£5,000

Beyond architectural fees, costs for structural engineers, surveyors, and building control inspections should be accounted for. Some of these are included in Quotes, Particularly Design and Build services. But Building control, council fees and Partywall fees are often excluded and need to be factored in.

If you hire a project manager or contractor to oversee the conversion, their fees should be included. Our recommendation is to find a builder that offers this service as standard. Make sure you get a PM and not a on-site team leader, make sure you meet them before contracting so that your comfortable with the choice and check how many projects they run at any one time. Any more than 10 at once is too many for these types of works and the ideal would be 5 per manager.

The cost of cleaning the site and disposing of construction waste should be considered. This also includes licenses for skips, permits, porta loos and parking. Again this is a great cost center that adds up quickly if not included in the quote of factored into your budget.

Legal fees for contracts and insurance coverage for the project may be necessary. If you are a shared freeholder or leasholder or need to have the loft space demised to your holdings, this can add £0,000s to your costs. A good builder and architect will be able to support you in this for budgeting and walk you through the factors to consider.

Depending on your location and circumstances, you may need to account for Value Added Tax (VAT) or other taxes. Many builders quote without it +Vat.
In addition if the property has been vacant for a period of time or you run a business and intend to use part of the space as an office, then you may be entitled to various VAT reductions.

Again a good builder and accountant will be aware of this and able to assist you.

It's advisable to allocate a contingency budget for unforeseen expenses or changes during the project. We recommend finding a builder who provides a Fixed price Quote and Locked in Prices. But you still need some spare capital in case you add additional works and therefore additional costs.