The extension can no longer be considered of a kind
described in Schedule 2 Class 7 and therefore has to
comply with the applicable requirements of Regulation 4(1).
In which case the following regulations will apply:
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alteration, but not a material change of use. To better
understand the intent it is suggested the work is classed
as a structural alteration to the roof, and as stated in
the DCLG letter it is for the “work itself” i.e. the roof to
comply with the regulations.
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so that it complies with the applicable parts of Schedule 1.
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has been completed the work shall comply with
the applicable requirements of Schedule 1 or where
it did not previously comply it shall be no more
unsatisfactory than before.
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or replacement of thermal elements
(1) Where the renovation of an individual thermal element—
(a) Constitutes a major renovation; or
(b) Amounts to the renovation of more than 50%
PG UIF FMFNFOU T TVSGBDF BSFB
the renovation must be carried out so as to ensure that the
whole of the element complies with paragraph L1(a)(i) of
Schedule 1, in so far as that is technically, functionally and
economically feasible.
(2) Where the whole or any part of an individual
thermal element is proposed to be replaced and
the replacement—
(a) Constitutes a major renovation; or
(b) (in the case of part replacement) amounts to the
replacement of more than 50% of the thermal
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the whole of the thermal element must be replaced so
as to ensure that it complies with paragraph L1(a)(i) of
Schedule 1, in so far as that is technically, functionally
and economically feasible.
The regulations are clear that when you carry out building
work to a roof, the roof must comply with the regulations
(subject to the caveats of 50% surface area). In other
words, the roof must comply with Part L.
What we would like to find on site
The existing roof will either be glazed or polycarbonate and
usually have uPVC window and doors. If the roof is glazed,
it is likely the vertical frames will have been designed to carry
the roof load. In the case of a polycarbonate roof, the vertical
frames may only have sufficient reinforcement to carry that
particular load. To assess the suitability of the supporting
framework it may be necessary to verify the type and extent
of reinforcement on site by either drilling pilot holes or testing
with a magnet to test for the incorporation of a steel core.
If there is no reinforcement new window frames may
be needed to support the weight of the roof, or additional
reinforcement installed abutting the existing frames.
The typical loading of an existing glazed conservatory
roof (not polycarbonate) is less than 10kN/m. A light-
weight composite solid roof is only likely to add an
additional 0.5kN/m.
The existing foundations should have trial holes
excavated to ensure they are adequate to support the
new loading. In most cases a 150mm thick concrete strip
foundation or reinforced concrete slab which bears onto
original ground will be adequate. Foundations passing
over drains, close to tree roots or on filled ground may
require further consideration.
What you are likely to be asked for by LABC
We assume that the building will remain thermally separated
from the house; the house heating system has not been
extended into the building; and suitable isolating valves and
controls are installed within the conservatory or porch as
described in our
Best Practice Guidance Note MG0010411
.
Your local authority building control team is likely to ensure
that the roof and supporting structure fully complies with
the Building Regulations. They are also likely to view the
remainder of the extension as being no worse than before
with regard to compliance with the Building Regulations.
The Building Regulations that are likely to apply are:
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of existing foundations by trial hole(s). If suitable vertical
supports are not present then either new windows are
required that comply with current Building Regulations,
or additional structural posts installed.
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roof, abutments and rainwater goods
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with current Building Regulations as a new thermal
element. The existing walls and floor should be
considered as being no worse than before (Reg. 4(3)).
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