Planning Permission

Many loft conversions can be undertaken without planning permission by utilising your Permitted Development rights, which allow you to increase the size of your roof space by a certain volume.
You can add 40 cubic metres to volume of a terraced house roof and 50 cubic metres to the roof of any other house type.
The existing loft space does not need to be included in this calculation - just the additional volume created by dormers and roof extensions.
If you wish to create a dormer or
otherwise alter the roof shape at the front of your house you will need Planning
Permission.
Please note you will also require planning permission if your house is in a
Conservation Area or an area subject to an Article IV Direction. If your property is Listed you will require specific advice.

Design Considerations

Loft extensions represent a substantial investment in your house and it is
important that the full implications of the alterations are properly considered.
Types of dormers, size and location
A large flat roofed dormer is often installed on the rear roof slope. These are never
particularly attractive but are sometimes the only solution which provides adequate space where the existing loft is very small.
Over-prominent pitched roof dormers on the side elevation of houses can be very detrimental to the appearance of the
property. Converting the hipped roof to a gable end may be visually more attractive.
Where possible, dormer size and position should be chosen for visual balance to the scale of the roof pitch.
Affect of the new stair on the hall
Access to the loft must rise from within the existing hall to meet the fire escape
requirements. Consideration needs to be given at an early stage to assess where the stair can be located.
Sometimes the only stair location available has a detrimental affect on room sizes or makes the hall too small.

Loft conversions are a very popular way of increasing the size of your
existing house.

Converting the loft requires some or all of the following approvals:

Planning Permission
Building Regulations Approval
Party Wall Agreements

See the boxes opposite for more details.

It may seem that converting the loft should be relatively straightforward - after all, you are altering what is already a weatherproof space.
However, to meet the Building Regulations requirements, the fabric of your roof space must be adapted in several ways:

A. The roof must be re-supported on a perimeter timber frame so that the current struts, props and bracing timbers can be cut away safely.
B. The joists supporting the ceiling but are not large enough to take domestic
loadings. New deeper joists must be
inserted between the ceiling joists and these, in turn, must be supported on new steel beams to transfer the additional loads to the external walls.
C. A new staircase is required, rising from the first floor hall. The staircase must be surrounded in fire proof partitioning. A
protected fire escape route must be achieved from the loft down to the front door. This normally entails renewing or upgrading all the room doors off the hall at first and ground floor levels (except doors to bathrooms).
D. New windows are required for daylight and ventilation under the Building
Regulations and can be either Velux type roof windows or dormer windows.
E. Very high levels of insulation are required and it is normally necessary to batten out the existing roof joists to provide the necessary depth for the thickness of insulation needed. Where headroom is at a premium, modern multi-layer foil
insulation can normally be used to reduce the overall insulation thickness.
F. New and existing services: Plumbing, power and lighting must be run up from existing services and existing water storage tanks, etc., in the loft relocated as
required.

Affect on ground and first floor rooms
All loft conversions must be provided with a safe fire escape route to an external door. This usually means existing ground and first floor room doors need to be
upgraded to provide 20 minute fire
resistance, so any glazed doors will have to be changed. First floor ceilings may need to be overboarded and replastered to achieve the required fire resistance to the new second floor.
Balancing living and bedroom areas.
To maintain maximum property value there needs to be a balance between
living and bedroom accommodation.
Consideration should be given to also
extending the ground floor living areas where a roof conversion will add two or more bedrooms to the house.
‘Space saver’ stairs
Sometimes loft access can only be achieved with a compact alternating tread stair. This type of stair usually has a
detrimental affect on the usefulness of the loft accommodation and can downgrade the property value associated with the loft conversion.

Party Wall Matters

If you have a terraced or semi-detached
house, you must speak to your adjoining
neighbours before proceeding with
construction and obtain their approval In
writing to any works that affect the party
walls.
Your neighbours cannot stop you from
proceeding but they can insist you involve
a surveyor to inspect the walls and
prepare an Award document.
This process is covered by the Party Wall
Etc., Act 1996 and an explanatory booklet
can be viewed online by following the link
below: