A photograph of a completed loft conversion.


Loft conversions are an effective and popular way to maximise space within the home and add market value to a property. This article addresses essential questions concerning loft conversions and how to approach such a project as a homeowner and/ or property developer.

DIY loft conversion

It is important to understand that loft conversions are often complex projects and require expertise in design, planning, building regulations and construction. If you’re an experienced and competent ‘DIY’ enthusiast with the necessary skills, experience and knowledge, you might consider a simple loft conversion to create storage space. Larger conversions, such as those which involve the addition of dormers and habitable loft rooms will require reputable and experienced contractors.

Proceed with caution!

Properties advertisements often state a ‘loft room’ or ‘attic conversion’. There is, however, some important information missing, for example, the word ‘bedroom’. In order for the converted attic, or loft space to be a ‘habitable’ room, it must comply with building regulations. Adding an additional story to an existing property often increases the risk to the occupants. In our opinion the best approach is to prepare and submit a ‘Full Plans’ building regulations submission. Before starting work or engaging architects it is a good idea to research loft conversions, thoroughly.

Loft conversions can be some of the most challenging projects to design for homeowner clients. It is a risk to start construction work without a completed design and detailed design drawings. As a minimum we recommend approaching a contractor for a quotation with a completed design. As a minimum the loft conversion should have planning approval and building regulations ‘Full Plans’ approval.

It can be tempting to obtain a construction quotation before appointing an architect. We advise against accepting any such quotations, which are often prepared without drawings, a schedule of work or a bill of quantities. They are, in effect, a guestimate. A reputable contractor will always request drawings and specifications before preparing quotations. Be aware that an ‘estimate’ is not the same as a qualified, tender return.

To demonstrate a technical drawing for a building regulations submission.

Modelling projects in 3D helps our clients to visualise their projects in realtime

Preparing for a loft conversion

Not all lofts are suitable for conversion, and a preliminary assessment is crucial. Here are some key factors to consider:

Headroom: A minimum height of 2.2 meters is required in the completed space. Therefore, an existing maximum measurement of 2.2m is likely to require an increase in the height of the existing roof. This is because a typical roof build-up for a loft conversion with a flat roof is defined as a ‘warm roof’ and therefore thicker than the existing roof.

Roof Structure: The type of roof influences the feasibility of a loft conversion. Traditional pitched roofs are generally the most suitable candidates for conversion. Trussed roof designs can also be converted with the correct structural analysis and adaptations.

Access: Assess the current means of access to the loft. A safe and practical staircase will be required to access the converted loft space. This will form part of the ‘protected escape’ route required by the building regulations. Typically, staircases cannot exceed a maximum pitch stated in the Approved Documents. Loft conversion stairs can be extremely innovative with integrated storage where space is at a premium.

Ventilation: Often overlooked, ventilation is an important aspect of a compliant loft conversion. Avoid ‘cold roof’ construction, particularly above dormers. This approach is fraught with risk and rarely built to the correct standard. In the worst-case scenarios, dormers, less than a year old have suffered major, interstitial condensation problems, leading to black mould growth in concealed voids. We would not recommend this type of roof construction for any part of a loft conversion.

Building Regulations: Building regulations cover structural integrity, fire safety, acoustics, access, insulation and ventilation. Both the ‘Full Plans’ approval notice and the Final Inspection Certificate are required for building regulations approval. These documents are the gold standard for compliant loft conversions.

Loft Conversion Cost: Establish an initial construction estimate for the loft conversion. Speak to friends and family who have completed similar works. Always allocate funds as a contingency i.e. in additional to the construction budget. Contingency sums are typically between 10% and 15% of the construction budget. Use different methods to estimate the construction budget, for example try and calculate the total floor area of the loft conversion and multiply this by a base-build rate. It is easy to overlook aspects of the work, such as reconfiguration of plumbing, electrical, drainage etc.

A photograph of a completed loft conversion.

One of our completed loft conversions with charred timber cladding and full height glazed openings

Where do I begin with a loft conversion?

Embarking on a loft conversion project involves several key steps:

Ideas: Start by defining the purpose of the project. Will it be a bedroom, office, or recreational space? Sketch out a layout to imagine and visualise how the new space will work. The value of preliminary sketches cannot be over-stated. We love to see our clients’ getting involved and producing their own sketches!

Cost: Research loft conversion costs for different types of loft conversions. If you know people in the industry, ask for their advice. Do your research on reputable websites and look for references, particularly for cost rates and figures.

Finding An Architect: Reach out to Bloom via our contact form or telephone number. You’ll find the details on our contact page.

Planning Permission: Your Local Authority is unlikely to tell you whether or not your project will require a planning application. In our experience, they will direct potential applicants toward architects, instead. So, get in touch via our contact page. Be aware that some local authorities produce supplementary planning guidance which restricts the design and size of loft conversions. It can also be very difficult to achieve planning permission on designated land, such as conservation areas.

Building Regulations: Following receipt of planning permission all projects require building regulations approval. We would recommend a ‘Full Plans’ submission to the Local Authority or an Approved Inspector. Contractors will sometimes have a business/ working relationship with Approved Inspectors. You will need to appoint a chartered structural engineer at this stage, to work alongside us to prepare and coordinate the design.

Tender: Information, such as drawings and specifications necessary to obtain quotations for the work from reputable, competent and experienced contractors. Obtaining more than one quote is usually the best approach and allows for basic comparative analysis. Meet with your chosen contractors to discuss your project and ask for testimonials from previous clients.

Construction: Can begin when planning permission and building regulations approval are in place. We strongly recommend the use of a building contract and retaining our services throughout construction and to administer the contract. Clients benefit from our experience and have a point of contact throughout the build. We also love seeing our design work turn into built work!

Planning Permission and loft conversions

The simple answer is yes. Some loft conversions are classed as permitted development (planning permission is automatically granted for projects which follow strict guidance). This guidance includes specific constraints such as not extending beyond the plane of the existing roof slope, offsetting dormer walls to sit within the roof plane, not extending the ridge height, etc. Many of our clients wish to design beyond these constraints and so require us to prepare a full, householder planning application following completion of the design.

It can be difficult to elicit useful information from Local Planning Authorities, who in recent years, are more likely to refer prospective applicants to local architectural practices. This is one of the main reasons we have written this detailed guide. We are experienced architects and can help you to navigate any necessary permissions and optimise your loft conversion within the guidelines.

To demonstrate a technical drawing for a building regulations submission.

A detailed technical cross-section drawing demonstrating the proposed construction build-ups of the loft conversion for the Building Regulations 'Full Plans' submission

Building Regulations and loft conversions

Building regulations are a crucial aspect of any construction project and loft conversions are no exception. These regulations exist to ensure the safety, structural integrity, energy efficiency and comfort of buildings.

Structural design: A loft conversion often involves significant structural changes, such as installing new floor joists, modifying roof structures, or adding dormer windows. Such elements are designed by a qualified, chartered structural engineer. Architects work very closely with structural engineers.

Fire safety: Adequate fire safety measures are essential in any living space. Building regulations cover fire-resistant materials, escape routes, and the installation of smoke detectors. These measures are particularly important in loft conversions where access to ground-level exits may be limited.

Thermal efficiency and air tightness: Insulation needs to be of an appropriate thickness, type and specification. It should be installed tightly leaving no gaps. Gaps in construction allow warm, moist air to interact with cooler air, which in turn causes interstitial condensation to form on layers within construction build-ups. High levels of workmanship and competency mitigate these problems. Loft conversions usually involve timber structures, which require both a waterproof membrane and a vapour control layer. These layers protect the timber structure from absorbing excessive moisture, while allowing it to breathe.

Electrical and Plumbing Safety: Loft conversions often involve the installation of electrical systems and, in some cases, plumbing for bathrooms or other amenities. Competent installers (electricians and plumbers, or central heating engineers) ensure compliance with the building regulations. The works need to be certified by building control which means they will need proof that such installations meet the building regulations. Such evidence is provided by competent and qualified professionals in the form of certificates.

Accessibility: If you plan to use the loft conversion as a habitable space, access systems will need to meet building regulations. The staircase must meet the requisite standards in terms of its pitch, tread depth and riser height.

Energy Efficiency: Building regulations increasingly focus on energy efficiency. Loft conversions, like all projects must adhere to these standards, which include requirements for insulation, energy-efficient windows, and sustainable building practices. This not only benefits the environment but also reduces energy bills for homeowners.

In theory there are multiple ways to achieve compliance with the building regulations. The government produce guidance documents, called ‘Approved Documents’ which, if followed represent a route to compliance. In reality, the Approved Documents are the most common method to achieve building regulations approval. We encourage all clients, however, to consider exceeding these requirements. The more efficient the envelope of your property is (walls, floor slab, windows, doors, roof, etc), the less energy it will require to maintain a warm and comfortable environment.

A concept called ‘Fabric First’ dictates that the fabric of the property is the most important aspect of energy efficient dwellings. Increasing the efficiency of the building envelope (increasing the amount of insulation in the walls, floors, roof etc) will reduce the amount of energy required to heat the spaces within. It is both worrying and shocking to learn that the UK has the least energy-efficient homes in Europe. Let’s change that!

To demonstrate a technical drawing for a building regulations submission.

A detailed technical cross-section drawing demonstrating the proposed construction build-ups of the loft conversion for the Building Regulations 'Full Plans' submission


Converting a loft is an excellent way to add space and value to your home. In summary:

  1. Do your research. There is a wealth of information online, but be sure to interrogate your findings and fact-check!
  2. Use our guidance to assess the existing attic space (head room, access etc.).
  3. Start sketching! Try to imagine the space in plan and place rooms and furniture where you would like them to be. Work with what is already there.
  4. Contact us via our website or email.

While small loft conversions might be suitable for a competent ‘DIYer’, more complex projects, like dormer loft conversions, typically require professional expertise. Collaborating with an architect is a wise choice when embarking on a loft conversion project. Our expertise will ensure that your loft conversion is both beautifully designed and building regulations compliant.

Let’s Build Something

Please drop us a note about your project via our contact form.