Building Regulations - Information
If you are thinking of converting
your unused attic space to extend your home you need to be
aware that building work needs to be constructed to
a good level of health and safety standards.
The building controls ensure that alterations are
carried out correctly so they do not cause problems at a
later stage. For example, there could be problems in
selling your home when changes are noted by a surveyor
or a structural problem results from use of inadequate
materials.
As professional builders, we must consider:
1. Structural Stability
If the space is for use other than
light storage then a new floor will have to be provided.
The existing ceiling joists are not designed for
heavy loads.
Any alterations to the roof structure such as
skylights or dormers require careful consideration so
they do not adversely affect the overall stability of
your roof. This includes assessing load baring walls -
their construction and foundations.
Any structural members, e.g. beams, beam bearings,
posts, trimmers and connection details must be justified
by calculations.
2. Fire Resistance
UK Building regulations require loft
floors and certain walls and doors to resist fire for a
specified period (usually half an hour).
The correct form of construction will protect
occupants in the conversion for this period.
Staircases need to be enclosed by construction (doors
and walls or partitions) with 30 minutes fire
resistance, or, existing doors retained, if not glazed
and self-closing.
En Suite bathroom or toilet doors need not be fire
resistant. The condition of existing doors and
doorframes are assessed.
The installation is to comply with BS5446: Part 1:
1990 or BS5939: Part 6: 1995 with regards mains powered
smoke detectors.
The dormer roofs need to be capable of resisting
external fire spread for at least 30 minutes.
3. Access and Means of Escape
Access to the converted loft is via a
flight of stairs and you need to consider the type of
stair you require.
Traditional stairs will give safe and easy access,
however other types are available and will gain approval
only where space is restricted.
Stairs also provide a safe escape route for occupants
in the event of a fire.
For two storey houses, Building Regulations give
specific advice on the loft conversions in these
situations.
Particularly, the route must discharge to an external
door - the staircase must discharge close to a door
leading to an external safe place and not in a room.
Escape windows such as the VELUX®
escape/access skylights need to be large enough to
escape through and positioned for easy rescue by ladder.
4. Weather Resistance and Energy Conservation
The loft walls and roof must keep out
the elements and retain heat.
The materials we use in construction are designed to
reduce heat loss. This will conserve energy and cut your
fuel bills.
External loft walls are constructed to achieve a
U-value of not more than 0.35W/m2oK, and roof areas to
achieve a U-value of not more than 0.30W/m2oK.
5. Ventilation
Building regulations give guidance on
ventilation so a health living environment is created.
Ventilation provides clean air to the living
environment and vents moist or stale air, which would
cause condensation.
Ventilation is also required under the roof tiles,
again to prevent condensation that would not be seen or
detected before it caused serious problems.
Ridge vents to a continuous 5mm gap and eaves vents
to a continuous 25mm gap are built in front and rear -
unless a vapour permeable sarking layer (breather felt)
is used.
Dormer are built with a warm deck roof, ridge vents
to a continuous 25mm gap.
Ridge vents are positioned to ventilate the roof
space above ceiling level.
To reduce risk of condensation, a vapour check layer
is added at ceiling level to restrict water vapour from
rooms into the roof space.
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