A guide to loft conversions

Loft conversions are a popular way to create additional space within the roof area. This information is intended to provide guidance on the requirements of the Building Regulations. Whether you intend to construct a dormer or build within the existing roof space, you will need to show how your proposals comply with the requirements. This usually means preparing drawings supported, where necessary, with structural calculations.

The requirements

Structural stability

• The conversion will usually require steel or timber beams to support the new floor and walls.
• The existing rafters, walls, lintels and foundations need to be verified as adequate to take new loads.
• You may need to seek advice of a competent person to justify the proposed structure.

Fire Safety

Where your house becomes three or more storey, you will need to comply with the following requirements (a reduced standard applies to bungalows).

• The new room must have a FD30S fire door to separate it from the rest of the house.
• The new stairway to the new room(s) is to be enclosed in 30 minute fire resisting construction.
• Unless the new room(s) has an escape window all doors enclosing the staircase (except to bathroom/wc) must be changed to FD20S and fitted with self-closing devised.
• Glazing in the stair enclosure must be 30 minutes fire resisting.
• The new floor is to achieve 30 minutes fire resistance.
• The ceilings below landings is to achieve 30 minutes fire insurance.
• Although not a requirement, a mains operated smoke detector to each floor is recommended and should be interconnected.

Escape Windows

• An ‘Escape Window' must be accessible via a ladder to assist rescue of the occupants from the new room(s).
• Whether incorporated within a dormer or a roof light, it must have a clear opening area of 0.33m2 with either the height or width being at least 450mm.
• The escape window should be within 1.7 metres of the eaves, measured along the roof slope.
• The height of the sill of the vertical window should be between 800mm and 1100mm above the floor, and for a roof window between 600mm and 1100mm above floor level.

Staircase to habitable rooms

• A retractable loft ladder is NOT acceptable.
• The new staircase should be either:
  • A standard staircase;
  • A spiral staircase:
  • An alternating tread staircase (see next note);
  • A fixed ladder (see next note).
• Alternating tread stairs and fixed ladders are only acceptable where there is not enough space for either a standard or spiral staircase.
• A 2.0m headroom is required to the new staircase. Slight reductions are allowed where the roof slope obstructs the headroom on one side of the staircase.
• Handrail and guarding is to be provided together with landings top and bottom.
• Two way lighting should be provided.

Lofts used as storage areas

• Some lofts are converted to provide storage areas assuming that no permission is required. If the storage area is capable of being used for living purposes or increases the loading on the roof, then Building Regulations consent may be required. In such cases, and before you carry out the work, please check with us.

General Advice

• Some lofts are already converted by previous occupants without the benefit of permission. Contact us for advice in such cases.
• Although there is no requirement to submit plans, you are advised to seek professional advice due to the complex nature of such conversions.
• At the start of the work we should be notified so that an early inspection be made of the work. We need to inspect the work and where problems are encountered offer advice.
• In some cases Planning Permission may be required, especially if a dormer window is to be constructed.

Do I need Planning Permission?

Please contact the planning enquiry desk if in doubt. Email planning@stevenage.gov.uk or telephone 01438 242838.