Planning a Loft Conversion

Loft conversions

Although an empty loft can seem like an open invitation to extend your living area, loft conversions can be quite tricky. They usually involve dealing with an older, established structure and reorganising the loads it has to cope with. The change of usage in the top part of the building may nave unanticipated knock-on effects elsewhere if not properly thought out. Perhaps most importantly, you arc interfering with the main waterproofing of the house. If this goes wrong, it can nave serious, long-term implications for the fabric of the building.

Unless the building firm hires scaffolding or a crane, access for building materials to the work site is restricted to what can be carried through the house, and use of the space itself may be hampered by a number of factors. For example, as it is often prohibited for dormer windows to face the road, because this counts as a development `overlooking the public highway’, it is a common aspiration to insert bathroom facilities under the front eaves, and put the main rooms in the roomier, rear-facing dormer area. But drainage pipes and soil stacks are usually positioned at the side or the back of the house, and running a soil stack from one side of the house to the other is often impractical (especially at right angles to the joists) and not allowed. The Building Regulations allow the use of a pumped macerator unit and small-bore pipework if the siting of appliances makes running conventional soil and waste pipes difficult. Shredding and pumping units, such as Saniflo, originally designed for boats, don’t need a large-bore soil pipe and work more or less anywhere.

Assessing the feasibility of conversion

Whether you can actually convert your loft depends on the structure of the roof of your house. Until the 19605, pitched roofs were constructed on site from a framework of rafters (the sloping beams that support the roof’s covering), purlins (the horizontal beams that tie the rafters together) and struts (which brace the purlins against the first-floor ceiling joists and any internal load-bearing walls). Viewed from within the loft, such a roof structure may look like an awkward place in which to fit a new room, but it can generally be easily adapted by relocating the struts and other components within the roof’s space. However, this is a job that needs professional assessment in order to ensure that the alterations do not weaken the roof’s structure.

In more recently built houses, the roof is usually constructed with roof trusses. These are prefabricated, triangular, timber frames that span the walls of the main house, thereby removing the need for internal load-bearing walls. The way in which the trusses are erected and braced, however, means that removing any of their components will seriously weaken the roof’s structure, and therefore altering it to allow the creation of loft rooms will be difficult and expensive. Unless you are prepared to go to these lengths, all that you can realistically do is to provide improved access to, and lighting of, the roof space, and then use it for storage purposes.

Building Regulations

Loft conversions always need Building Regulations approval in order to make sure that the alterations satisfy the requirements concerning structural stability, safe access, thermal insulation, ventilation, fireproofing, waste disposal (if the conversion will contain sanitary facilities), and, above all, means of escape in the event of fire.

Fire regulations involving sprung door-closing devices, door-width specifications and the ‘no room off a room’ rule may appear to exist to thwart the feng shui of your plans, but save lives.

You must deposit full plans, not just a building notice, if you are converting a two-storey building.

Planning permission

This is mandatory in Scotland, but not normally necessary for a loft conversion in England and Wales unless:

• dormer windows or other alterations to the shape of the roof will face a highway

• the height of the roof will increase

• the volume of the building will be increased by more than 50 cu m, or 40 cu m for a terraced house. Note that this volume counts against your overall permitted development rights.

Permission may be required if the building is listed or in a Conservation Area.

Building Regulations

In most houses the loft space was not originally designed for occupancy, and the change of function involves far more work, and consequently regulation, than most people imagine. Structural stability, access, insulation, ventilation and drainage (if applicable) are all tightly controlled, but the most important — and potentially most restrictive — regulations are for fire.

The fire rating, which is the amount of time for which a material can resist the spread of fire, is specified on many materials used in converting a loft, such as doors, glass and insulation, and can also relate to the actual construction of partitions and floors. In a loft conversion it is often necessary to upgrade the fire resistance of existing floors and doors leading off the stairway. Having a ‘means of escape’ is vitally important. If there is no space in the downstairs hall to accommodate the staircase, this can sometimes completely scupper a loft-conversion plan. It is not possible to site a staircase within a room off the hall because this counts as a ‘room off a room’, which doesn’t provide a proper means of escape. If you nave to move a wall to accommodate the staircase, you will be entering a whole new world of regulation.

Letting in light

The two most common ways of creating windows in loft rooms are to install some in the plane of the roof’s slope, or to build projecting dormers. Roof windows are designed in sizes that match the standard rafter spacings; narrow models fit between adjacent pairs of rafters, while wider ones require the removal of a section of rafter. Dormer windows are built out from the roof’s slope, and have a conventional, vertical window fitted between the sides of the dormer under a flat, sloping or ridged dormer roof. So-called ‘bay’ dormers extend to the eaves, and help to create additional headroom within the loft. In theory, a dormer can also span the full width of the property, but this rarely looks attractive, and you may have trouble getting your local planning authority to agree to the scheme.

The most common problems

• Keeping the floor level down to maximise the ceiling height It is very rare to get permission to develop above the established roof line, and most houses in the UK have a fairly low roof ridge. Very careful consideration needs to be given to the thickness of the beams and joists strengthening the floor, because every inch could be critical. Loft specialists routinely use wider beams, which are less deep than conventional supports.

Positioning the staircase  – This affects now the room is used upstairs, and the floor space of the floor below. Be cautious if a general builder advises you to take out a wall specifically to site the staircase. This may not be necessary, and is probably not advisable if you are not planning to change the use of the downstairs rooms. There are several types of staircase available for use in loft conversions — including spiral staircases, box staircases and `space saver’ stairs (with alternate paddle-shaped treads) — all of which take up less room than a conventional staircase and should be considered if you have a problem. Specialist loft conversion suppliers (see below) have a good selection of these. A loft conversion must have a permanent staircase, not a loft ladder.

Strength of walls – Are the walls strong enough to cope with the increased pressure caused by the extra load? Roof spread, where the weight of the roof presses the walls outwards, can be an issue if the purlins, the cross supports within the roof, arc adapted to create more space. This creates new ‘vertical load paths’ which the walls need to he able to hear. If they cannot, then reinforcing them with ties can be costly and unsightly, and can reduce a prospective buyer’s confidence in the building.

The biggest problem: Building Regulations compliance

Planning-  There are tight Building Regulations governing means of escape in case of fire. Often this may mean upgrading the fire protection of existing floors, doors and walls rather than putting in an actual fire escape.

Neighbours – People living nearby, or perhaps even in the same building where the work is taking place, may have the inclination — and the right — to object to something which will inevitably inconvenience them. Most people are generally magnanimous, but there are people who can be difficult. People with a share of the freehold, for instance, may have a right of veto over the development of a loft, even if they live in separate flats, have no right of access and would not he affected by its development in any way.

The sequence of events

1. Creating the access This can initially mean a secured ladder during the works, but when it is time to install the staircase, loft converters recommend using a specialist firm for its manufacture and positioning. Making successful use of the space depends on where the staircase is sited.

2. Strengthening the structure Once access is in place, the beams or rolled steel joists (RSJs) which will strengthen the structure can be carried up. Although the ceiling joists inside the loft may look strong, they are usually designed to carry only the weight of the ceiling below, and will almost certainly require reinforcement if the extra weight of a new room is imposed. Roof support timbers are also repositioned at this stage.

3. Access is made for windows (dormer or roof window or both). The hole in the roof can seem a bit alarming in its raw state, but the transformation of the room brought about by the new rush of light more than makes up for it. Peering out of a gap in your own roof is heady stuff. When choosing your window, don’t forget to plan how you are going to clean it.

4. Insulation Money spent on the careful siting of good-quality products here will soon come back to you in lower heating bills. You may, in fact, have little choice over what you fit, as Building Regulations cover insulation in lofts in some detail.

5. The internal walls go in, if applicable — although the joy of a loft is often that there aren’t any internal walls and the light, airy space benefits from the whole of the building’s footprint as its floor area.

6. Wiring and plumbing Services can usually be extended from the existing supply, though the header and storage tanks will almost certainly need to be re-sited to the eaves.

7. Plastering, decorating, inhabiting.

Timescale: four to six months, from planning to completion.

The case for using a specialist

When you poke your head into your loft for the first time with an eye to conversion, it is easy to see it as a finished room. There is a floor, a roof, and usually a lot of unused space with the potential for developing a lot more. However, things are seldom as simple as they seem, and a general builder may soon get bogged down in the extensive Building Regulation requirements, and the logistical difficulties of working at the top of a house that people are living in. In addition you want the finished product to be sympathetic to the rest of the building, or it may end up looking like a shoddy add-on rather than the value-enhancing feature you intended. For these reasons, no matter how simple the job seems, a specialist is always infinitely preferable to a general builder.

In London, for instance, different boroughs can have diametrically opposed policies on issues such as whether dormers can face the road, and whether you are allowed to run them gable end to gable end or just have isolated windows. Boroughs which border each other may have completely opposite policies, so that one side of the road looks totally different from the other. One tried-and-tested means of blocking dormer window applications, and thus pouring cold water on the whole conversion, is to check old Ordnance Survey maps to see whether there might be a path, even an ancient one, long forgotten and overgrown, running along the bottom of your garden — which counts as overlooking the public highway A specialist will be able to advise on the local restrictions and regulations and work around the planners to ensure that as far as possible you get the desired result.

If the work involves a party wall, which it very often does, you need to notify the other people involved. A general builder might leave this to the Royal Institution of Chartered Surveyors (RICS)*. However, the party-wall notification document that the organisation sends out looks like a summons and requests a response within a certain time. It could alarm the recipient, and may spark a dispute. A big disagreement means employing party-wall surveyors on both sides, plus a third, independent expert observer, which can cause considerable expense. Specialists know that a personal letter letting your neighbours know your intentions can achieve results more effectively.

Finding a loft conversion specialist You could ask the Federation of Master Builders (FMB)* or another registration scheme for a list of members who specialise in loft conversions.

An inside insight

One specialist reckons it is surprising how little some planners know about loft conversions. ‘I took a group of planners from one London borough around some conversions that I’d done to show them the sort of thing that is achievable, and they were saying things such as: “Oh, is this a conversion, then?” It turned out that the man who set one council’s entire policy on loft conversions had never actually been in one.’

 

06. June 2017 by admin
Categories: DIY Projects, Extensions and Conversions, Featured Articles, Home Maintenance | Tags: , , , | Comments Off on Planning a Loft Conversion

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