• Loft Conversion Bedroom

    Loft Extensions

    Do you need extra space for an extra bedroom? A loft conversion could be the solution!

Loft Conversions - Your Questions Answered

The information below will explain all you need to know with regards to planning your project. Don't move out, move up!

Subject to the roof structure and planning constraints, a loft conversion is one of the most straightforward and effective ways of increasing the space within your home. Most homes can benefit from the extension with a small amount of basic planning.

Is My Loft Suitable For A Conversion?

Loft Conversion Assessment: The features that will decide the suitability of the roof space for conversion are the available head height, the pitch and the type of structure. Obstructions such as water tanks or chimney stacks would also be taken into account. A free no obligation survey can be carried out by Extra Room Limited which would reveal the roof space structure and physical dimensions.

Head Height: A measurement is taken from the bottom of the ridge timber to the top of the ceiling joist; the useable area of the roof must be greater than 2.2m.

Pitch Angle: The greater the pitch angle, the greater the central head is likely to be and should dormers be used or the roof is redesigned, the floor area can be increased.

Type of Structure: Two key structures are used for roof construction, the traditional framed type and truss section type. The traditional framed type is normally found in pre-1960s houses where the rafters and ceiling joists, together with supporting timbers, are cut to size and assembled. This style of structure has more structural input so is frequently the most appropriate type for conversion. The area can be simply opened up by strengthening the rafters and adding supports, all at a reasonable cost. Since the 1960s the most common form of construction was factory made truss roof sections. These utilise thinner, cheaper timbers but have structural reliability with the additional braced diagonal timbers. These allow a house roof to be erected and felted in a day, which is a huge benefit. Nevertheless, this type of truss suggests that there are no load bearing structures below and opening up the area demands greater added structural input. This generally involves the insertion of steel beams between load bearing walls for the new floor joists to hang on and to support the rafter section, together with a steel beam at the ridge. This additional structural input requires skill, knowledge and equipment which can all be provided by Extra Room Limited.

Low Head Height

Should the initial roof space inspection reveal a head height of less than 2.2m, there are two possible options.

Option 1: Raise the Roof: This would include completely or partly removing the existing roof and reconstructing it to provide the required height and structure. This is structurally viable but the main difficulties are the high cost and gaining planning approval. Should the complete roof area require removal, a covered scaffold structure would be required to protect your home from adverse weather condition whilst the works are being carried out.

Option 2: Lower the Ceiling in the Room Below: The ceiling height within some rooms of older properties may be 3m or more so if the roof space is limited, it might be wise to consider lowering the ceilings below, providing it still allows at least 2.4m. This requires all the existing ceilings in question to be removed, causing a great deal of mess. This method requires a plate to be secured to the wall using shield anchors or raw bolts for the new floor joists to be hung from. There would also be a requirement for a suitable tie between the roof structure and the dwarf wall formed, to avoid the roof spreading.

New Joists

The existing joists are unlikely to be adequate to carry a conversion floor and further new joists would be needed to comply with Building Regulations. The Structural Engineer would specify the size and grade who would take into account the span and separation distance for a given loading. The new joists span between load-bearing walls and are usually raised slightly above the existing ceiling plasterwork by utilising spacers underneath the joist ends. Thicker timbers are used above window and door openings to bridge the opening so that stress is not put on the existing opening lintel. RSJs are specified to distribute the load and in some installations are utilised to carry the ends of the new joists. Should head height be limited, thicker joists, more closely spaced can be specified.

Loft Bathroom


A Building Control Inspector will state exactly what you require. The roof structure can be insulated in two main techniques. The simplest way is to use a “cold roof” method, this entails filling the area between the rafters with 70mm-thick slab foam insulation such as Celotex but this is ensuring that there is 50mm spacing between the roofing felt and the insulation (for ventilation via the roof and soffit vents). In addition, 30mm slab insulation is attached to the inside of the rafters, giving a total of 100mm of insulation. The rafter thickness is often less than 120mm, so a batten may possibly be required along each rafter to allow the 50mm spacing and the 70mm insulation. The roof area requires 300mm of mineral wool insulation (i.e. Rockwool), or 150mm of slab foam insulation such as Celotex.

The alternative main technique is “warm roof”, this method utilises 100mm Celotex insulation or similar over the rafters and a covering capping, followed by the tile battens and tiles. This option would only be a feasible option if the roof coverings have been stripped off. It could possible used with a dormer, in particular if it has a flat roof. Continuity of insulation between walls and roof is necessary to prevent any cold bridging. The dormer walls can be insulated with 100mm Celotex between the studwork. The internal partition walls and utilise a 100mm quilt that will provide sound insulation. Plasterboard is attached to one side of the wall then the quilt inserted, followed by plasterboard on the other side. Insulation is also positioned between the floor joists and this is usually 100mm thick Rockwool fibre or similar, mainly for its sound reduction properties.


The height minimum is 900mm above the pitch line and spindles must have a separation distance that a 100mm sphere cannot pass through.

The Staircase

The ideal location for a staircase to be situated in line with the roof ridge, this will make the best use of the available height above the staircase. The minimum height requirement above the pitch line is 2m but this could be reduced to 1.9m in the centre and 1.8m to the side of a stair. In practice, the actual position will depend upon the layout of the floor below and where necessary the available height can be achieved utilising a dormer or adding a roof light above the staircase or, if appropriate, converting a hip roof end to a gable.

Maximum Number of Steps: Regulations state that the maximum number of steps in a straight line is 16. This is not usually a problem, as a typical insulation usually only requires 13 steps.

Step Size: The maximum step rise is 220mm, while the step depth is a minimum of 220mm, these measurements are taken from the pitch point. The step usually has a nose that projects 16-20mm in front of the pitch line but the ratio of size should not exceed the maximum angle of pitch requirement of 42˚. Any winders must have a minimum of 50mm at the narrowest point. There are not regulations for the width of the steps but in practice the winders are likely to limit the reduction in width.

Windows & Dormers

A loft conversion requires means of getting natural light and ventilation and the simplest method is to use roof lights that follow the pitch line of the roof. This type is fitted by removing the tiles and battens in the position that the roof light will be fitted. Rafters are cut to make way for the roof light after correctly reinforcing the remaining rafters. The roof light frame is then fitted within the new opening and flashing added prior to making good the surrounding tiling. This type of window is the most economic and more likely to be allowed without planning permission under your PD (Permitted Development) rights. Conservation roof lights which are slightly more flush to the roof line and are made of metal, can also be specified.

Dormers not only give natural light but can also add space to a loft conversion and can be positioned at the ends or sides. They are particularly effective where the pitch angle is high as the useful floor space can be increased. The mansard type will give maximum conversion roof space because it projects the maximum head height, giving a greater usable floor area; a hip to gable conversion has a similar effect.

Dormers and other similar conversions are normally installed by opening up the roof and cutting the required specified timbers to size on site. Care needs to be taken with the roof and side coverings to obtain a good weatherproof structure.

Dormers can have gabled or hip roofs and with carefully design, can enhance your roof line. A mixture of the available types can result in the maximum light and space and provide a fire exit.

Fire Safety

Installing plasterboard ceilings in the upper rooms will impede the spread of fire to the roof area in an unconverted house. When an opening is introduced for the staircase, the risk is shared with the conversion therefore safeguards must be in place to lower the risk.

All habitable rooms in the upper storeys served by a single staircase should have an escape window with an obstructed open able area of at least 0.33m², a minimum 450mm high x 450mm wide and not more than 1.1m above the floor level.

Loft Bathroom

Why Choose Extra Room?

Our Staff

This is exactly what it means; our staff are the only people who are involved in your project. Extra Room Ltd does not sub-contract your project out to other contractors.

All operatives are employed by Extra Room Ltd we are always contactable by phone and email to deal with any queries or questions that may arise. All of our operatives have an Extra Room Ltd uniform and identification badge so that they are instantly recognisable.

Site Rules

We have very strict guide lines for all projects, all staff must wear the Extra Room Ltd uniform and personal protection whilst at work i.e. boots, high visibility jackets and safety helmets where necessary.

There is a no smoking policy at work and where possible we will provide a discrete portable toilet facility so that your home stays your home with no intrusion. No radios are to be played on your project. We understand that whilst your project is being completed this should not intrude upon your neighbours who are already being submitted to the noise of building works.


Extra Room Ltd provides a full time Project Manager who will be involved from the very start of the project until completion, he will provide all certificates and completion certificates which will then be held in a project file and presented to you at the end. They will also ensure that all site rules are followed and report directly to the Director of the company.

Unrivalled Guarantee

All structural works come with a 10 year no quibble guarantee, of which upon completion of your project you will receive a certificate of guarantee. All other works i.e. plumbing and electrics will come with a standard 2 year guarantee.

No Hidden Costs

Once we have surveyed your project, a quotation with a complete breakdown of costs will be presented to you. This break down will be individually priced so that you can clearly see where your budget will be spent and if at any time you would like to remove an item you will instantly know what the saving will be.

In the event that you decide that you would like to add additional works, these additions will be separately quoted and an instruction sheet issued that yourself and the Project Manager will both sign so that there is no hidden costs and you are in control of your budget at all times.

Peace of Mind

Before any works commence, Extra Room Ltd will provide you with a break down sheet of all the works to be completed within your project. This includes an empty box at the end of the description, yourself and the Project Manager will go through this sheet and check that you are completely satisfied with the completed works and then tick the box together. At this point you will only have ever paid for works that are fully completed and you will not be asked to pay any monies upfront or before the works are complete.

Further Information for Loft Conversions

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