Introduction
Many conservatories are now reaching the end of their natural
life or are costing substantially more to heat than previously.
Homeowners are looking for a cost effective way of retaining
existing floor space whilst improving the energy efficiency of
the structure. To meet this need homeowners are choosing to
replace obsolete translucent roofs with solid ones.
This guidance has been produced to advise and inform
suppliers, builders, architects and design consultants on
the Building Regulations that will apply to the replacement
of a translucent roof to a conservatory or porch with
a solid roof.
The preferred option for many homeowners is a lightweight
composite solid roof. Some roofs have a LABC Registered
Detail that provides an approved design, quality control and
accredited installation. Other options may simply underdraw
or overclad existing polycarbonate roofs. Or replace the
existing roof with a traditional tiled roof that may not have
taken into account the adequacy of the existing structure
to carry increased loading.
Definition of a conservatory
The Building Regulations in 2010 removed guidance on the
definition of a conservatory. Conservatories and porches
now share a common description with Regulation 9(1), 21(4)
stating to meet the exemption status in Schedule 2 Class 7;
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than 30m
2
.
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by walls, windows or doors which meet the energy
efficiency requirements, and
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the conservatory or porch.
A Department of Communities and Local Government
(DCLG) circular letter on 28 September 2010 stated that
“Building Control Bodies will want to note that the definition
of conservatory in terms of percentage translucent material
as set out in previous editions of the Approved Documents
no longer applies”.
To address the lack of a suitable definition for a conservatory
we produced a
Best Practice Guidance Note MG0010411 -
Application of Part L
to Conservatories attached to existing
dwellings
. This defined a conservatory and/or the type of
structure that could meet the exemption criteria. We based
this on what is generally considered to be key features of
a typical conservatory; a lightweight structure comprising
of predominantly glazed walls and roof that is thermally
separated from the dwelling it is attached to.
Our
Best Practice Guidance Note MG0010411 -
Application of Part L to Conservatories attached to existing
dwellings
has also been accepted by the Building Control
Alliance (BCA) and Association of Corporate Approved
Inspectors (ACAI).
The view of DCLG
While preparing this guidance we have taken into account
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issued on 29 July 2013. The letter confirms that to benefit
from exemption a conservatory or porch;
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glazed (no % given)
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into the conservatory or porch
The circular letter also stated if the amount of glazing to
the walls or roof was significantly reduced the conservatory
or porch could no longer be regarded as an exempt
conservatory or porch.
The circular letter did not offer
guidance as to what constitutes a conservatory but did
state it should have a significant proportion of the roof
and walls glazed.
Importantly, the circular letter highlights:
“Where the relevant building control body decides that
the extension is no longer an exempt conservatory
or porch, regulations 4(1) and 4(3) of the Building
Regulations would apply. This would mean that the
work itself would need to comply with the applicable
requirements of Schedule 1 (regulation 4(1)). It would
also mean that the conservatory or porch must be
no more unsatisfactory in relation tothe requirements
in Schedule 1 than before the workwas carried out
(regulation 4(3))”.
Our view
The recent DCLG letter indicated a conservatory must
have a significant proportion of the roof and walls glazed
to be considered exempt. This further validates the
definition of a conservatory as set out by us in our
Best Practice Guidance Note MG0010411
.
When work is carried out that significantly reduces
the proportion of glazing, or level of translucence to
the roof, the conservatory or porch can no longer be
considered exempt.
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