Cost of a Loft Conversion Updated for 2020

By November 28, 2018 March 20th, 2020 Guides and Information

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If you are like many homeowners in the UK, you have a loft that isn’t used for much. That’s not necessarily a bad thing. Your loft space represents good, usable space if you’re willing to pay for a loft conversion. A lot of people are doing it these days. Indeed, they are choosing a loft conversion rather than moving into a larger home.

Pricing a loft conversion can be a challenge. It is not as simple as pricing out new windows or getting quotes for replacing kitchen appliances. Converting a loft is a process that consists of a lot of moving parts, so to speak. There are planning permissions, architectural drawings, and then the actual construction.

Before we begin talking costs, let’s discuss the different kinds of conversions commonly offered by UK builders:

  • Velux – A Velux conversion is the most affordable. It involves very few structural changes other than adding one or two roof lights to allow natural light in.
  • Dormer – If the Velux conversion is the most affordable, the dormer is probably the most desirable loft conversion right now. Small windows, also known as dormers, are built into the roof in a box shape that adds extra definition.
  • Gable – A gable conversion is one which portions of one or both sloping roof sections are replaced with a gable wall.
  • Mansard – This loft conversion involves removing one whole side of the roof, building a wall, and then closing the gap with a flat roof section. It is easily the costliest of the four loft conversions.

Budget is only one of the considerations when choosing your loft conversion style. You also have to consider the current design of the house, its structural stability, and any local regulations that may dictate aesthetic appearance. Obviously, planning permission will be required before you can build anything.

Average Costs for 2019

Below is a short list of average estimated costs for different kinds of loft conversions. Note that these prices only cover the cost of construction and materials. You will probably incur additional costs for planning permissions, architectural design, interior design, and odds and ends.

Based on a 4 x 4 floor size, you can expect to pay the following:

  • Velux with two roof lights – £21,000
  • Velux with four roof lights – £23,000
  • Dormer with one new dormer and one roof light – £27,000

For a 6 x 5 conversion, expect the following prices:

  • Velux with two roof lights – £27,000
  • Velux with four roof lights – £29,000
  • Dormer with one new dormer and one roof light – £40,000
  • Dormer with two dormers and two roof lights – £44,000

For a 12 x 8 conversion, expect to pay:

  • Velux with two roof lights – £41,000
  • Velux with four roof lights – £43,000
  • Dormer with one new dormer and one roof light – £58,000
  • Dormer with two dormers and two roof lights – £63,000

Again, all of these prices are average prices based on materials and labour only. You may pay less by choosing entry-level materials. You can pay considerably more by selecting more expensive materials.

Other Things to Consider

A contractor who comes in to do an estimate is likely going to account for every conceivable cost on that estimate. So in addition to the material and labour costs listed above, expect to see some additional costs. For example, your contractor may offer to handle getting all your permits for you. If so, permit fees will be included.

What you will not see on the estimate are services above and beyond the scope of the contractor’s business. One of the first such costs that come to mind are for architectural services. In order for you to get your loft conversion approved, you may have to submit architectural plans. You will definitely need plans if you are hoping to do a dormer, gable, or mansard conversion, as they all involve structural changes.

On the other hand, if your conversion consists of little more than putting in new flooring, a few roof lights, and a coat of paint, you may not need architectural drawings. Check with your local council for specifics.

Another cost that may not appear on your estimate relates to interior design. This will only matter if you want to finish the project with professional design services. Interior designers tend to charge by the hour, and they are likely to have you spending a little bit more on furniture and accessories. You can skip interior design if you don’t want to pay for it.

Phases of a Loft Conversion

The loft conversion project is composed of several stages and these are broken down below. Most builders do not provide separate costs for each individual component. However, if you are looking to have a loft conversion, then most often you can choose to pay your tradesmen after they have finished the job.
Loft Conversion Plans
Before you can start your loft conversion, you must get full plans drawn first by an architect. This will give you some ideas on the changes that will happen as well as its appearance when it’s finally done. This will include all the necessary structural changes that need to be done. Typically, it can cost you about £1,000 plus VAT.

Planning Permission

Most loft conversions do not actually need any planning permissions since the changes can already be considered as permitted developments. Nevertheless, there are some cases, depending on some factors wherein you need to apply for a planning permit. Presently, in England it costs £172.

Building Regulation

No matter what your planning status is, the building regulations department will have to inspect it just to make sure that everything is done according to the rules. For instance, did it comply with fire safety, floor-length, etc? Getting your loft conversion inspected will cost you between £400 and £800.
Most often, you may also be required to get a Party Wall Agreement in case your conversion can affect your neighboring properties. Be sure that your neighbours will agree to the construction. A bat survey that costs around £400 is another potential cost to consider.

Loft Construction

After your plan has been approved, then the construction will start. Generally, they will start working on the external portion, then create access into the loft from the inside. They will make sure that the floor will be strong enough.

Cost Overruns

The prices posted in this guide are average prices based on the most common options. The most important thing to remember here is that our prices are estimates only. Do not assume that any price you see here is concrete. Also do not assume that the price you are quoted by your contractor will ultimately be the price you pay.

Though it is unpleasant, cost overruns on a loft conversion are not abnormal. You can get a quote of £20,000 that easily turns into £25,000 once construction begins. How does that happen? More often than not, cost overruns are the result of extra work that wasn’t anticipated.

Let’s say you choose a dormer conversion that will entail creating a symmetrical look building two dormers on the front of your house. Your contractor will cut into the roof where the dormers will go. In so doing, workers may discover some structural deficiencies that have to be repaired before proceeding. That extra work will bump up your total cost.

Mansard conversions usually entail the most cost overruns for the simple reason that they are the most complex conversions. Do not be surprised if your contractor finds a lot of hidden problems during demolition, problems that will force your total price higher.

A loft conversion can add extra living space to your home at a fairly decent cost. But don’t expect to get away with a loft conversion cheaply. Loft conversions are second only to additions when it comes to pricing out home renovations.

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