Cost of having your Loft Converted

All you need to know about having your loft converted including costs of materials, costs of labour and time frames.

loft conversion

What the job entails

There are several different types of loft conversion, but the three most popular types in the UK are: Roof windows but no dormer, roof windows with dormer, and dormers without roof windows. A roof window loft conversion with no dormer offers good lighting but compromises on size/space, they are however the cheapest and easiest conversion.

Roof windows and dormer conversions offer extra space and headroom, plus the extra light through roof windows. Whereas a dormer conversion but with no roof windows offers maximum usable space less light. Roof windows allow lots of extra natural light into the loft space, but dormers protrude from the roof and create additional space and headroom. The cost of a loft conversion with a dormer is considerably higher than a loft conversion with only roof windows, but you may have to install a dormer to meet building regulations for headroom, depending on the location of the staircase.

It makes sense to carry out other related jobs that may need doing at same time, such as installing a loft ladder and hatch, or a full staircase. Also don't forget about the existing roofing which should be in good order with no rot or missing/damaged roof tiles.

The most common reason for converting a loft is to provide an additional bedroom double bedroom, often with an en-suite bathroom. The work required would include all professional fees (architects, structural engineer, planning permission, building control etc), hire of scaffolding, all materials required (timber, steel joists, plasterboard, skirting etc), construction and roofing, staircase, fire escape, windows, electrics, heating, plumbing, insulation, flooring, decorating and skip hire.

As you can see it's a big list, involving a lot of work and materials, and therefore cost. If you are on a tight budget and want to maximize the potential added value on a loft conversion, then try and avoid dormers, bathrooms and shower units - these are the most expensive part of any loft conversion.

Using a reputable contractor and getting professional advice will greatly reduce the chances of any future problems with a loft conversion, however using a cowboy contractor that promises a good job done cheaply can end up costing an absolute fortune, in addition to being dangerous. When considering expensive structural alterations to your home, do not decide simply on price! There are some other factors which may increase the cost, for example if you have a water tank which will need to be moved along with the required plumbing work.

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Loft Conversion Cost

This is one of those jobs where the cost can vary considerably depending on the size of your loft, whether or not you want a dormer, what you want your loft to be (bedroom or bathroom), whether your house is terraced, semi or detached, whether your roof is gable, hip, mansard, trussed, traditional, etc, your location and the company you choose. Prices for loft conversions can range from £15,000 to £45,000.

Most loft conversion specialists charge around £300-£500 per day with 2-4 tradesmen working at the same time. You can expect the job to take anywhere from 4-8 weeks to complete depending upon the complexity.

Here are a few average costs for hiring a company to carry out a loft conversion. Please note that these are average prices. If you're house is around the London area, expect to add £10,000-£15,000 to the price.

Conversion Type Avg. Cost Duration
Bedroom with Velux Windows £12,500-£20,000 3-4 weeks
Bedroom with Ensuite & Velux Windows £17,500-£25,000 4-5 weeks
Bedroom with Dormer & Velux Windows £20,000-£25,000 5-6 weeks
Bedroom with Ensuite with Dormer & Velux Windows £25,000-£30,000 6-7 weeks

Cost Breakdown

Individual costs for hiring a loft conversion company to install a double bedroom with dormer and 2 velux windows - Total Cost: £25000


Materials & Waste






Almost any loft can be converted but to get planning permission/building approval for an additional living space, it is crucial is that there is enough headroom, a minimum of 2.3m from the existing ceiling joists to the apex of the loft is a decent starting point. Even without the building constraints, if you cannot achieve at least 2m of ceiling height then converting your loft simply isn't worth the cost!
Since 2008 loft conversions have normally been considered permitted development so do not require full planning permission subject to certain limits and conditions.
If you have a standard two story house, then you will need a fire door at the top or bottom of the new stairs from 1st floor into the loft, plus all doors off the 1st floor landing to bedrooms will need to be fire doors. Essentially to comply with Building regulations you need a safe corridor from the loft to the outside of the building, so all the existing doors on rooms on this escape route must be changed to fire doors.

To comply with Building Regulations electricians will also be required to fit hardwired smoke detectors in the landing at each level. These smoke alarms are mains hardwired plus have standby battery backup power supply. All loft conversions require a window through which a person could escape if the stairway does not provide a safe escape route. Building Regulations state that window openings must be 450mm or wider and should be supplied with non-locking fasteners for use in fire escape situations. Fire escape windows in the loft should be easy to access and close to the eaves level for rescue from the outside.
In most cases, yes, as long as the work is professionally done and complies with building regulations. However, it will depend a lot on where you live and what type of house you have. If you're already got plenty of bedrooms an extra one is unlikely to add much to the value of the property.
It is possible to carry out a loft conversion using a Building Notice but most professional loft conversion companies will carry out a full plans submission to the Local Authority before works to ensure that the Local Authority agree to all technical specifications of the loft conversion and can then simply carry out site inspections when the work is in progress to ensure every detail fully meets Building Regulations every step of the way.
Anyone can do a loft conversion if they have the required equipment, tools, skills and experience. But if they do not then the loft conversion project could cost you tens of thousands of pounds to put right at a later date! You should also consider the time involved, professional conversion companies can often take several weeks for a single loft conversion with 2-3 tradesman working full time - if you can only spare a few hours evenings and weekends, then be realistic about how long the job will take.
Every loft is of course different but a typical velux/roof window type conversion will take around 4 to 5 weeks, whereas a dormer conversion will take a week or two longer.