Summary: Advice for creating a loft, discussing how roof designs influence loft conversions, planning the loft conversion and planning for power and heating when converting a loft.
The loft makes up a large proportion of a property’s internal space: space that more often than not is under utilised. This space has enormous potential and with careful planning a loft conversion can greatly enhance the overall living experience, in addition to increasing the property’s value.
It is generally accepted that a loft conversion can increase the habitable floor space of a two-storey property by as much as 30%. And with loft conversions usually being less expensive than building an extension onto the property, it is no surprise that converting the loft has become so popular.
A loft conversion of any kind involves a great deal of work, so detailed planning is essential. Although there is an almost endless variety of loft sizes and shapes, all loft conversions should be approached in a similar way. In this article we intend to look at the points that need to be considered to enable you to realise the full potential of your loft.
How roof designs influence loft conversions
The age of the property can be a significant factor in how suitable the loft is for conversion. Before the 1970’s roof frames were constructed on site using the traditional rafter and purlin method which left a void in the roof space ideal for loft conversions.
More modern houses have roofs with A-frame structures that are manufactured off-site. The rafters in A-frame roof structures are supported by a number of trusses or struts throughout the roof space, causing an obstruction and major obstacle in a planned conversion. This problem is not insurmountable but will involve installing supports for the rafters to replace the obstructing trusses. Cutting and removing trusses can affect the structural stability of the roof and must never be undertaken without professional advice.
The popularity of loft conversions has resulted in some house builders substituting A-frames with attic trusses. Made from larger timber sections, attic trusses are designed to support the roof and floor loads while leaving a clear area in the roof space for any future conversion.
You will also have to decide which of the three types of loft conversion is most suitable for the roof of the property.
Roof light – this is the most popular type of loft conversion and involves installing windows into the roof that run flush with the roof’s pitch or slope.
Dormer – a dormer conversion is recognisable by a structure projecting from the pitch of the roof which accommodates the window. The roof of the structure can be pitched or flat and ties into the existing roof. Constructing a dormer window in an existing roof is highly difficult, requiring professional advice and assistance.
Mansard – the least common, a mansard loft conversion is generally used on properties with roofs that have a very shallow pitch. Properties with a London roof – named after a style of roof commonplace in the capital – a mansard loft conversion is the only option. This is because a London roof will comprise of two planes that rise from a low central gully to higher eaves at their edge.
Planning the conversion
So what type of room can the loft be transformed into? Well practically anything is the easy answer, although some conversions will be more difficult than others.
The most popular conversions are:
- Additional bedroom
- Additional bedroom with en suite bathroom
- Home office or study
- Children’s play room
The first stage of any loft conversion is a close inspection of the loft space to find out its exact dimensions and whether conversion is feasible.
On entering the loft you need to establish there is adequate room under the ridge of the roof. A measurement of 2.3 metres is required to allow enough headroom and there must be at least 2 metres clearance above the position of the access stairs.
The roof should be checked for any signs that rainwater is entering the roof space. The appearance of dark stains on the roof rafters is a strong indication that this problem exists. Repairs to the roof must be carried out before starting on converting the loft.
The roof joists need looking at too, as they may not be strong enough to support a floor. Standard roof joists are made from 100mm x 50mm timber beams and floor joists for a loft conversion should be 150mm x 50mm or even 200mm x 50mm. With all structural matters involved in converting a loft, it is best to consult a structural engineer or surveyor for advice.
Then you must decide on whether the loft is to consist of one open space or whether to divide it with a stud partition to create two rooms. This design feature will undoubtedly be part of the plan where the loft is being converted into a bedroom with en suite bathroom.
On inspecting the loft you may discover that the water tank is in the way. There are two possible solutions to this problem: relocate the water tank above the ceiling of your loft conversion or behind a kneeling wall – the low walls fitted between the rafters and the floor. But in both cases the water tank must be placed on a sturdy base.
Power and heating
With the major structural design work decided upon, it is now time to plan where the power points, light fittings and switches are to go. This will allow you to plan the circuit route. How the loft is to be supplied with power will depend on the age of the existing wiring, but it may be possible to extend an existing circuit. Otherwise a new circuit will have to be installed.
More people are working from home, so transforming the loft into an office is another conversion idea that has grown in popularity. But with so much to think about in relation to the structural work and the installation of electric circuits and heating, the position of junction boxes for telephones and Internet access can be overlooked. So if your loft is to provide you with a place to work, keep this mind
How to heat the loft is another decision that needs to be made. Some loft conversions rely solely on convection, in other words warmth is provided by centrally heated air rising from the rooms below. Extending your central heating system into the loft is another option but this does have disadvantages.
- Radiators can take up valuable loft space.
- The heat is controlled by a thermostat situated some distance away
- The boiler may need upgrading
An alternative to central heating is under floor heating. Laid on top of the floor insulation and beneath the floorboards, the heating cables or mats work differently to conventional heating. A central heating system first warms the air before warming the occupants. Underfloor heating produces a radiant heat made up of heat waves that warm the objects and the occupants in the room before it warms the air. This heating system has several advantages over central heating.
- Heat is only supplied to the loft
- Lower energy costs
- Thermostatic control inside the loft
- Produces a comfortable heat
- Reduces dust circulation
- Reduce condensation
- Totally silent in operation
- Concealed under the floor – no s loft pace is wasted
- Warms up quickly even from cold
- Suitable for most floor coverings
For a loft conversion to be deemed a habitable space, permanent stairs must be installed. Any conversion that can only be accessed by a loft ladder is not deemed a habitable space. To meet Building Regulations the stairs must enter the main stairwell on the second floor and be fitted with a handrail to aid evacuation in the event of a fire.
Loft stairs can be constructed on site or manufactured to your specifications but in both cases accurate measurements are crucial as the stairs usually fit into tight spaces. Furthermore, the pitch of the stairs must not exceed 42°.
Where there is no room to install a proper stairway, most local authority building control officers will consider other types of stirs, but only if the loft conversion creates a single room.
To resolve access problems that a confined space can cause, a space saver staircase could provide the solution. This is a staircase that has alternating treads allowing you to get up a flight of stairs in approximately half the “going” distance – the horizontal distance between the face of the first and last risers – of a normal flight of stairs.
A spiral staircase may seem to be the solution to limited space, but this could result in difficulties when trying to move furniture into the loft, so give the design of the stairs plenty of thought. Stair lighting should also be considered when designing the stairs.
The position of the windows is another major consideration. Not only is it important to have enough windows fitted to ensure adequate daylight, their position and size are critical in providing a means of escape in the event of fire. At least one window should allow access to the roof and have a minimum height and width of 450mm. The window sill must be between 600mm to 1100mm above the loft floor and not more than 1.7 metres above the eaves of the roof. Once again it is a good idea to seek professional help on where to position the loft windows.
Windows also provide ventilation to a loft conversion and whether you have rooflights or dormer windows fitted they should have trickle vents. Not only do trickle vents remove stale and humid air, they prevent the build up of excessive condensation in the roof void above a converted loft, which can cause timber decay.
Insulation and ventilation
Loft insulation is an important aspect of any loft conversion and should be carried out according to Building Regulations. The three important areas are:
- Ceiling and walls
- Party wall
For underfloor insulation mineral wool insulation is a good choice of material. Laid between the floor joists at a depth of 250mm, not only does it provide excellent thermal and acoustic insulation, its flame retardant properties will resist fire for at least 30 minutes. This will be an important factor in complying with the Building Regulations.
To prevent losing heat through the ceiling and walls thermal-check plasterboard can be fixed to the rafters and stud framework of your loft conversion. This type of insulation consists of a sheet of plasterboard with a layer of insulating foam on the back.
Party walls are usually built of brick and need to be insulated to reduce heat loss and improve soundproofing. This is achieved by building a timber stud frame in front of the party wall, leaving a gap of 25mm between the back of the timber frame and the wall. Acoustic-check plasterboard is then cut to size and fitted to the frame. If the roof void behind the party is a cold space, mineral wool insulation should be fitted between the stud uprights before fixing the plasterboard.
Building Regulations in relation to ventilating the converted loft space state that the total open window area should be equivalent to 5% of the total floor area.
Condensation forms when warm air meets cold air. This necessitates adequate ventilation of cold spaces behind all new walls and ceilings forming the loft conversion. In most conversions ventilation at the eaves and the ridge of the roof will be sufficient to prevent condensation and the problems of damp and decay it can cause.
The most stringent part of the Building Regulations relating to loft conversions is fire prevention, particularly for a loft above a second storey. We have seen how using mineral wool for the loft floor insulation can create a flame retardant barrier for at least half an hour, and how the stairs and windows should be positioned to facilitate escape should there be a serious fire.
Additionally, any new doors fitted as part of the conversion should be self-closing fire doors that will prevent fire spreading for at least 30 minutes. And all internal doors leading to the stairwell on the ground and first floors should also be self-closing.
Last but not least, an interlinked system of mains powered, smoke and fire detectors must be fitted on all floors including the loft and on the stairs that lead to it.
A loft conversion is a major undertaking and seeking professional assistance from a structural surveyor and an architect is recommended. Even if you engage a professional builder to carry out a shell conversion – the major structural work – much work will still need to be done, requiring many different DIY skills, before the project is completed.
It must be stated: a loft conversion is not a suitable project for the inexperienced. But for those who believe they have acquired the requisite skills, turning a redundant roof space into a modern and pleasant living or work area will find this project very rewarding.
Loft conversion regulations
The most frequently asked question in relation to loft conversions concerns whether planning permission is needed. In England and Wales planning permission is not required for a loft conversion unless dormer windows are being fitted in a pitched roof facing the road. In Scotland planning permission has to be obtained if the conversion involves installing dormer windows in any part of the roof. Planning permission will definitely be needed if the loft conversion extends above the existing roof line.
If you have already extended your property, even with a conservatory, planning permission may be required if the loft conversion exceeds the volume limits set for your property. Further information about volume limits can be obtained by visiting www.planningportal.gov.uk or by contacting your local authority.
Listed buildings and properties situated in conservation areas will definitely need planning permission regardless of where you live in the UK.
These are general guidelines and you are strongly advised to check with your local authority before commencing work.
Although planning permission may not be needed, all the work carried must meet the Building Regulations. The local authority Building Control Office must be notified of your intention of carrying out a loft conversion. This is to ensure that the work carried out meets the required standard and will involve a building control officer visiting your property to inspect the conversion. Along with the quality of the construction work the inspection will cover:
- Structural stability
- Electrical wiring
- Safe access
- Plumbing and waste disposal (bathrooms)
- An adequate escape route in the event of a fire.
Under the Party Wall Act 1996, if you live in a terraced or semi-detached house you will need to get a party wall agreement from your neighbours. A letter of formal notification detailing the work you intend to carry out, the date when the work is due to commence and how the work will effect them, should be sent to your neighbours at least two months prior to the beginning.
Neighbours must reply in writing stating that they are happy for the work to begin. If consent is not forthcoming, the dispute must be resolved by an “Agreed Surveyor”, and involves engaging the services of a professional surveyor who meets with the approval of both parties. The Agreed Surveyor will set out what work can be carried out, when and how it is to be carried out, and supply a report on the condition of the adjoining property to be used in the event of a later dispute following the completion of the work.
Do not be discouraged by the legal obligations that converting your loft entail, as they have been put in place to protect both your property and peace of mind.
- How to board a loft
- Fitting a loft ladder
- Fitting a loft hatch
- Insulating a loft
- Insulating the rafters
- The party wall etc. act 1996