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Loft Conversion – A Beginners Guide

A Beginner’s Guide to Loft Conversions

A Loft conversion seems simple at first glance but there are lots of options and planning factors to consider. Get the jargon-free beginner’s guide to loft conversions below and settle all your questions before you take the next step.

Can my loft be converted

Many homes can have their loft space converted but sometimes it’s not possible due to planning application, Permitted Development (PD) rules and your Local Planning Authority. The first thing to do when you’re thinking of a loft conversion is to see if your home has any restrictions in place or if it has any existing approved applications. Permitted Development is a set of rights that are given to homeowners to allow them to carry out certain building works without needing any further permissions. These apply to different types of properties in different ways and each set of building works has a criteria that yours must meet to be considered ‘approved’.

Refer to Planning authorities’ guidelines on permitted development:

The most common cause of not meeting the criteria for Permitted Development is that the roof height needs to be increased. It must be 2.2m minimum to meet the requirements and if it isn’t then the roof will need to be raised or the ceiling of the room below lowered. These types of works require planning permission. If there are other homes in your street or in your area with the loft conversion that you want then it could be worth speaking to them to ask if they had planning permission. If they did you could ask for a copy and then approval is very likely. Your conversion will follow the precedent of the area and hit the other criteria you may not know about.

If you live in a conservation area, on any form of designated land, or you live in a listed building, then PD rights are removed, and a planning application will be required to carry out any building work relating to a loft conversion.

Is planning permission required?

From referring to the councils permitted development rights, you should be able to ascertain if an application is required, alternatively speak with your chosen designer who should be able to advise. This can normally be done over the phone or if not certainly at your initial consultation with your designer.

As previously mentioned, Permitted Development lays out criteria that must be met so that homeowners don’t have to get explicit planning permission for a loft conversion.

If you do have to submit planning permission though the most common reasons for this are:

  • Requirement for a balcony/Juliet doors.
  • Volume exceeds allowances (40 m³ for a terrace house, 50m³ for a semi-detached or detached property).
  • Materials that are not similar to the existing property.

It’s always important to take a quick look around the surrounding roads/streets to see if any of your neighbours had done a similar loft conversion, or even take a quick look on good Google maps https://www.google.com/maps/ . If other properties have done a similar loft conversion then that tells you that its feasible, if there are not similar extensions carried out nearby on similar properties you may ask yourself why? Is there sufficient head room available? Are there any specific planning rules in place that prevent such conversions.

It may be the case that neighbours have submitted similar plans for a loft conversion but have been unsuccessful, check your local councils planning portal, where you can see all planning applications that have been made. Just because a planning application has been made and wasn’t successful, doesn’t necessary mean that yours would be, a refusal could be based on many reasons.

If it was rejected for not being in-keeping with the local area for example, you can choose materials more fitting or a style that suits the period of the area.

Will a loft conversion add value to my property?

If a loft conversion is carried out properly by professionals and it’s completed to a high standard and the space provided is well designed, then there’s no reason why a loft conversion wouldn’t add value to a property.

It has been reported by the Nationwide Building Society that on average, homeowners could expect 20% of their property value to be added after a well thought out and designed loft conversion has been completed. Whilst that report has been based on past information, you could safely assume this figure is the same or even higher now depending upon location of said property.

In nearly all cases, adding that extra bedroom, normally with an en-suite within the loft adds that magic number of an additional bedroom, whether it 2 beds to 3, 3 beds to 4 or 4 beds to 5, that extra bedroom number is often key to adding real value.

Depending on what you are creating a loft conversion for, its often the case of striking that balance between providing that extra space for a growing family and making the use of the space as a family, and the reassurance that added value is created.

If it’s a pure value adding exercise to incorporate a loft conversion, it’s wise to check out other projects in your area and get a feel for what value has been added to those properties. You will need to be fully aware of what the ceiling price for properties in your area is with loft conversions, there’s little point in spending excess amounts of money and out pricing your property when you come to sell it.

What options are there for loft conversion?


Option 1- Roof light loft conversion

Loft conversion

Loft conversion


A roof-light conversion, is an easy type of loft conversion to create additional living space, providing there is sufficient head space within the existing loft it can be converted into a usable space.

The conversion consists of applying a new staircase leading up to the loft normally from the first floor (in accordance with current building regulations) applying new floor joists, a single or set of roof light’s via a VELUX roof window, or similar approved, roof insulation and internal plaster board, and ventilation, and works carried out in accordance with current fire safety regulations,  once this has been completed the room is habitable.

This is the least expensive type of loft conversion which often suits period properties since there’s so much space in the loft. In most circumstance planning will not be required for this type of conversion, however a building regulations application will need to be submitted.

Option 2- Dormer loft conversion

Dormer conversions are the most popular loft conversion type in the UK. They involve adding what’s essentially a ‘box’ to the outside of the roof to create enough space for a full room. This maximises the head height and provides a fantastic usable space.

Dormers can have just one ‘box’ protruding from the roof, or they can consist of multiple. These loft conversions are more costly than a simple roof-light conversion, however the add real value to a property by providing the maximum internal usable space.

When considering a full dormer conversion, its important to discuss with your designer the options available, whilst creating a pitched dormer is perhaps more ascetically pleasing, it does partially restrict the internal usable space. A box type dormer maximises the internal space and head height, be mindful of the external treatment to both options, with some careful design and planning the dormer cheeks can marry nicely into the roof tiles and be coherent with the roof design, which not only aids the planning process but gives you a more aesthetically pleasing dormer extension – see below CGI showing before and after a dormer extension.

Option 3- Hip to gable loft conversion

A hip-to-gable conversion is a common conversion often applied to semi-detached properties. By removing the existing hip and replacing it with a full height gable wall it maximises the internal usable space, it is often the case that the existing stairs from ground to first floor sit on this wall line and by applying a hip to gable extension, it allows for the existing stairs to follow this same route up into the loft conversion.

This in turn allows for a full width rear dormer extension, which makes the best use out of the newly created loft space, and often allows for the incorporation of a master bedroom accompanied by an en-suite and perhaps walk-in wardrobe.

is like a dormer conversion except the protrusion from the building is a rectangle that runs along the full side of the roof. This gives an incredible amount of space and more often than not will be used as two rooms, or something like a master bedroom with an en-suite. A hip-to-gable conversion can also include a balcony or veranda too, if planning permission is requested and approved.

Loft Conversion


How long does it take to build a loft conversion?

Every project is unique when it comes to loft conversions. Especially as unforeseen circumstances like old floorboards not being up to the job adds in more time. With a dormer conversion, the most popular type in the UK, you’re looking at up to 6 weeks from start to finish. This figure really varies on the size of the roof and how much work needs to be done to the existing structure.

Inevitably, weather can play a big factor, whilst it goes without saying the best time to construct a loft conversion is through the summer months, unpredictable weather can take its toll!

Hip-to-gable loft conversion projects will take longer than 6 weeks as they’re essentially building an extension on your roof and consideration needs to be given to tying into your existing roof structure. An allowance of 8 to 10 weeks is a reasonable time frame.

Finding the most suitable contractor for your project is paramount, refer to our blog ‘how to find the right builder’ for more information.

Straightforward roof-light conversions require a new staircase added, new floor joists, insulating the usable space to current standards, plaster finish and the incorporation of roof lights, as such these projects are more simplistic and can normally be completed within a 4 week window.

Building regulations!

Whilst various types of oft conversions may not require planning permission, this should not be mistaken for building regulations and the need for compliance. Any works carried out that effect the structure of an existing property or effect thermal properties of existing and new materials, need to be carried out in full compliance with the current building regulations. A formal building regulations application should be made to either your local building control authority or to an independent building control inspector prior to any works being carried out on site. Your designer/Architect and contractor should be able to provide you with all the information you need to know and in most circumstances your designer/architect will make the application on your behalf.

How much does a loft conversion cost?

The figures below are an indication of potential costs, these can vary depending on location and full scope of works plus the condition of your existing property.

Type of conversion              Cost

Rooflight conversion                  upto £15,000

Dormer conversion                     £15,000 to £35,000

Hip to gable conversion             £35,000 to £65,000


At PJH Architectural Services, we have an extensive knowledge and strong reputation for well-designed and throughout loft conversions, ranging from smaller rooflight conversions through to full dormer conversions on both detached and semi-detached properties as well as full bungalow conversions. If you have project that you would like some advice on, please feel free to get in touch we would be happy to assist you.

For more useful blogs please feel free to have a look at the following:

Finding the right builder for you project
An essential guide to keeping your builder
Velux Windows – Why Bother?


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