The Ultimate Beginner’s Guide to Loft Conversions

Loft conversions are some of the most popular ways to transform the functional appeal of your home.

These are actually quite common throughout the United Kingdom and as opposed to other types of renovations such as extensions, a typical loft conversion can be carried out with only a minimal level of disruption. However, there are still several variables that should be adequately addressed before beginning such a project.

This is particularly the case if you have never tackled this type of task in the past.

We have therefore taken the time to put together a comprehensive guide so that all major points are covered.

What is a Loft Conversion and Why Are They so Popular?

From a very general standpoint, a loft conversion is defined as transforming an existing attic or loft into a functional living space.

These conversions are often popular if you require a spare bedroom, office, bathroom, or living area.

We should also mention that loft conversions have been known to add up to 21 per cent onto the original value of your home (1).

This is great if you plan on selling the property sometime in the future.

Pro tip:

Loft conversions can add up to 21% to a home’s value but only the space is practical, ideally with an en-suite if possible.

Take a look at nearby roofs to see if any of your neighbours have converted their lofts. Check sold prices on Rightmove to see how much value the loft as added.

Loft Conversions Versus Changing Locations

Have you been looking to compare a loft conversion to a home relocation?

This is an important point to address, as each is associated with its own set of benefits and drawbacks.

For example, the main advantages of loft conversions include:

  • Contributing to the resale value of your home.
  • They can be completed in a relatively short amount of time.
  • They are less expensive when compared to larger renovation projects.
  • The space can be rented out; presenting an additional source of much-needed income.

Still, loft conversions can be complicated for the uninitiated and not all properties will meet the legal requirements.

Having said this, some potential benefits associated with changing homes could be:

  • The ability to live in a different neighbourhood.
  • Access to a property with better amenities.
  • A (potentially) larger living space.
  • Homes located close to important public services such as schools and transportation hubs.

The main pitfall associated with such a move is that it will require a large financial commitment. Also, moving has been known to cause a great deal of stress; particularly if you have a young family.

Pro tip:

Moving house is very expensive, just check this list of costs just to sell a property. Investing your cash by extending your home, rather than paying estate agent fees, taxes and legal duties etc makes sense financially.

What are the Different Types of Loft Conversions?

Let us now assume that you have weighed all of the variables and a loft conversion is the best option.

The next logical step is to understand the types of configurations that are available. While there are literally dozens to choose from, some common options include:

  • A loft room
  • A dormer
  • A hipped dormer (sometimes known as a “hipped-to-gable” dormer)
  • An L-shaped dormer
  • A mansard loft

A loft Room

These are arguably the most popular due to the fact that it will normally require the least amount of construction. As the name suggests, this type of conversion makes use of the existing space as opposed to creating an entirely new area. Loft rooms are generally employed when the interior dimensions allow for such an option.


Dormers are another great choice and they are often used when a sloping exterior roof is present. First, a vertical wall will be built on the slope. This wall is then adjoined to a horizontal roof that extends from the slope; essentially forming a 90-degree angle. The flat section is also able to provide the maximum amount of headroom; ideal if you are concerned about a limited amount of interior space.

Hipped to Gable Dormer

One variant of the standard dormer is known as a hipped-to-gable dormer. A “hipped” roof is defined as a roof with angled edges between the lower ridges and the eaves. In some locations, these are known as “colonial” designs. The main intention of a hipped-to-gable dormer is to modify the hipped side of the roof so that its gables are perpendicular to the ground. This method is often used when working with semi-detached homes or chalets. Please note that there may be times when planning permission will be required (this is covered in a later section).

An L-shaped dormer

L-shaped dormers are another option that could be considered if you have a Victorian-style home. Typically, this dormer actually consists of two separate structures which are joined to create a rough “L” shape. These dormers are often popular in older homes which have the kitchen and bathroom located in the rear of the property. As you might imagine, the construction process tends to be a bit more involved when compared to the alternatives mentioned above.

Mansard lofts

Mansards are a final option to keep in mind and they tend to offer the most accommodating dimensions. They are generally employed if you already have ample existing roof space. The loft is literally placed atop the roof while working together with the slope that is present. While considered by many to be aesthetically pleasing when used in conjunction with older homes, the chances are high that you will need to modify the existing structure of the roof. This will likely require planning permission ahead of time (as well as a good deal of preparation). Mansard lofts can also represent significant financial investments depending upon their size and any utilities that need to be included within their design.

Windows in loft converted space

A Look at Planning Permission and Building Regulations Approval

Building regulations and planning permissions were mentioned several times in the last section. Before we move on and discuss the mechanics involved with a loft conversion, it is critical to know when such certifications will be required.

One of the main reasons why loft conversions are very popular choices is that there are many instances when typical planning permissions will not be necessary.

However, you will still need to take into account the Building Regulations which cover how the conversion is built.

Check out our guide if you’re confused by the difference between Planning Permission and Building Regulations.

The first main concern is thermal efficiency. You will be obliged to minimise heat loss through ceilings, windows and walls. There are many types of modern insulation brands which should effectively reduce such instances. This insulation should remain constant between the walls and the roof of the loft. This helps to eliminate a loss of heat through a process known as “cold bridging”.

Your next concern involves the interior height of the loft. While regulations do not set forth any stipulations in regards to internal headroom in the main area, there are other figures that need to be mentioned.

In order to avoid accidental slips or falls, the minimum height found within stairways (including any escape routes) should be two metres. Although this can be reduced to 1.8 metres in the event that you are dealing with a sloped roof, the peak height still needs to rise at least two metres.

In terms of planning permission, any loft under 50 cubic metres in size can fall under the Permitted Development framework, so no additional permissions will be required if you adhere to the PD rules.

However, these dimensions fall to 40 square metres in reference to a terraced property.

You will still require planning permission if the structure is found within a Conversation Area or if it is considered to be a listed building.

Also, keep in mind that any loft conversion (such as a dormer) must not be higher than the highest portion of the existing roof, unless you get planning permission which is often refused for “raising the roof” conversions.

There are times when these regulations can be slightly confusing. This is why it could be a good idea to seek the help of a trained consultant in order to determine your personal and legal responsibilities before the actual construction process begins.

Pro tip:

The minimum head height at the loft staircase is a key problem for many small shallow lofts.

You must estimate the required floor reinforcement, floor boards, carpets and ceiling plasterboard when measuring up for the first time.

Fire Safety and Loft Conversions

According to governmental regulations, you will also need to address concerns related to personal safety and potential fire hazards. Current guidelines stipulate that mains-powered smoke alarms now need to be present within the loft as well as throughout any adjacent stairwells. These should also be included on every floor of the home.

The dimensions of the windows must be addressed, as they need to be large enough for an inhabitant to escape in the event of a fire. Current regulations state that they should be at least 450 millimetres wide and their height must be no more than 1.1 metres above the floor of the loft. A specific type of hinge that allows the window to swing fully open likewise needs to be present so that any occupants can escape in a timely fashion.

There are many times when a loft will be found at or above the second storey of a property. Assuming that this is the case, you will likely need to install fire doors in order to slow down the spread of fire and smoke in the event of an emergency (2). These are often referred to as “half-hour” fire doors due to the fact that they can resist flames for up to 30 minutes.

Please note that any lofts located on or above the third storey might require additional safeguards such as sprinkler systems or fire-retardant materials between the floors. These are often judged on a case-by-case basis, so it is wise to speak with a professional in order to gain more clarity and insight.

Pro tip:

The Planning Portal’s official fire safety documentation is the best place to find more in-depth information.

Loft Conversion Roof Structure Considerations

Although this may be slightly surprising, the structure and design of your existing roof could very well determine whether or not a loft conversion is affordable.

There are two categories to address here:

  • Houses built before 1965.
  • Structures erected from 1965 into the present.

Homes constructed prior to 1965 often employ what are known as <u>rafter-and-purlin roofs</u>. All joists, rafters and similar supporting structures were generally fashioned on site and subsequently fitted into place. As a result, it is much easier for these assemblies to be accessed and modified as may be required. They are also known for their superior levels of strength, so fewer reinforcements will be necessary. This is why the rafter-and-purlin design is generally considered to be the most suited for loft conversions.

Houses built after 1965 rely more heavily upon trusses that were made within factories. The main issue here is that while they were economically viable options, this generic framework also tended to be thinner. Thus, they are unable to support the additional weight associated with a loft. Their load-bearing capabilities are much lower and you might therefore need to add in additional features such as underlying steel beams. While this does not necessarily signify that a conversion is out of the question, the chances are high that it will be a much more involved project and the overall costs can be quite substantial.

Pro tip:

Check your roof’s design to see which type of timber construction method was used.

General Design Concerns

It is always wise to seek the advice of an architect or a knowledgeable construction firm in order to ultimately determine your conversion options.

There are nonetheless several factors which you can determine with a bit of research.

For the sake of simplicity, we have broken these areas down into a handful of easily digestible categories:

  • The available head height.
  • The type of roof present.
  • Concerns with the floor and rooms below.
  • The presence of utilities such as mains electricity, heating and water pipes.

Regulations state that you will require at least 2.2 metres of internal head height in order to legally perform a loft conversion. Note that the extra 0.2 metres are intended to accommodate for additions such as electrical cables, overhead lighting and drop ceilings.

One of the most common mistakes involves failing to take into account the structures found below the loft. Let’s imagine for a moment that you will need to add a staircase. Where will this access be located and how much space will it require? As the purpose of any conversion is to increase the functional appeal of your home, it makes no sense beginning a project only to subsequently realise that it has actually made life more difficult.

How easy will it be to include mains electricity and water within the loft?

Will you need to relocate any water tanks in the loft and where will they go?

Pro tip:

Consider how much space will be lost by adding a staircase and how this may affect the value and function of the home.

Consider the existing central heating system, whether it can cope with new radiators added to the loop. Other key points are the location of wasterwater pipes, theses should ideally line up vertically with the additonal waste pipework.

Loft Conversions: How Much Will Your Project Cost?

No two loft conversions are ever the same and every homeowner will have different requirements, especially when choosing finishing items.

One of the easiest ways to get a rough idea of the cost of converting your loft is to check out our research that we first published in 2017.

In a nutshell:

  • One room roof window (Velux) conversion – from £25,000
  • One room dormer conversion – from £30,000
  • One room dormer with ensuite conversion – from £35,000
  • Hip to gable conversions – from £40,000
  • Mansard loft conversion – from £50,000

Conversion Completion Times

Logistics should be anticipated as accurately as possible in advance, as any type of conversion will likely cause a certain level of disruption within your home.

The good news is that loft conversions are quicker and less disruptive than any other type of extension.

A typical schedule can be divided into a few stages (4).

  • The inspection and preparation phase (consultation with architects, examining the roof and obtaining any applicable permits).
  • The “rough” portion (the installation of joists and floorboards, the reinforcement of rafters and the construction of the dormer itself).
  • Finish work such as electrical components, heating systems, plumbing networks and the addition of windows.

Velux window type loft conversions are the simplest and can be completed in 2-3 weeks.

Dormer style loft conversions require 4-5 weeks.

Hip to gable conversions will need longer at around 5- 6 weeks.

Mansard lofts require even more time at 6- 8 weeks.

Pro tip:

Loft conversions are built from the outside with the workers gaining access from a scaffold for most of the project. This minimizes the disruption to the occupants.

The Bathroom

As previously suggested, an ensuite bathroom is practical and will maximise your investment.

The simple fact is; buyers love ensuite bathrooms and if you have the space to install one and it’s practical, you should consider it.

To keep your costs down and for practical reasons, try to locate the bathroom and any pipework vertically in line with the existing pipes. That usually means your ensuite is located directly above an existing bathroom.


Lofts can become very cold in the winter.

While insulation and double-glazed windows are great ideas, the fact of the matter is that they might not be enough. Most lofts are equipped with an additional form of heating such as a radiator or two.

You should check your existing central heating boiler and pump to see if they can cope with the extra radiators.

Also, consider underfloor heating if headroom isn’t an issue in your loft.

Choosing a Trusted Architect or Builder

Finally, it is absolutely crucial to select the right building firm for your upcoming project.

Not all professionals are created equal and if you encounter a builder associated with substandard work, the chances are high that you will endure rising costs during the project.

There are several ways in which you can find a worthwhile and reliable company. It is first wise to perform an adequate amount of online research.

Once you have selected a handful of organisations which serve your local area, ask questions such as:

  • How long have they been in operation?
  • Do they specialise in loft conversions or are they an “all-in-one” construction firm?
  • Do they provide no-obligation estimates?
  • How long will it take them to complete the project?
  • Will they offer ancillary services such as plumbing and electrical work?
  • Are they accredited with the appropriate bodies?

The team here at Job Prices can help you source prices from local, trusted and rated loft installers.

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