UPDATE
ON REQUIREMENTS FOR APPROVED DOCUMENT L Part 1 B:
(U-VALUE REQUIREMENTS).
Approved
document L1B came into force in April 2006. The requirements
set out within it aim to improve the energy efficiency of
existing homes when any alterations are carried out to walls
and roofs. This effectively means that Building Regulation
approval is now required for the replacement of more than
one quarter of a roof. Unfortunately, the regulations were
framed without consultation with thatchers, or, evidently,
English Heritage.
On
9th July 2008, representatives of the NSMT met with the
Minister for Planning and Local Government, Iain Wright.
The purpose of the meeting was to raise the issues which
affect the practical and economic survival of historic thatch
as a roofing material and to present suggestions for modifying
the application of existing laws and local council policies
in order to make the current system both workable and sustainable.
Sir George Young, who had also raised the subject on behalf
of his constituents in an adjournment debate, said that
the meeting was very constructive. “The Minister explained
that there would be legislation on heritage matters in the
next session of Parliament, which could give Parliament
the opportunity to revisit the rules about thatched cottages.
He also said that the relevant PPG’s were in the process
of being revised. After the meeting, Sir George asked the
NSMT to produce revised guidance on thatching for the new
PPG, which he would send to the Minister.” The piece
in italics below is part of the submission made to the Minister,
to illustrate the problems of blind enforcement of some
new legislation.
"The
introduction in April 2006 of the Approved Document “Conservation
Of Fuel And Power In Existing Dwellings” L1B, caused
surprise and consternation in its application to listed
buildings and in particular those with thatch. English Heritage
has issued interim guidance which states that RdSAP conventions
are unworkable for thatch.
For
the thatching industry it is important to have a National
response in the enforcement of the current regulations from
Building Control Officers; yet, in the past six months the
response from some is to ignore the legislation, or work
with thatchers to find a sensible compromise, or the extreme
a recent experience where work on the re-thatching of one
side of a listed thatched house was suspended for three
days. The local offices of English Heritage were unable
to help as they could not decide which area office had responsibility
for Bedford, the thatcher lost three days work, which is
a serious situation for a single thatcher business. Honour
was only satisfied and work re-started after payment of
a “fine”.
It
should be relatively simple to have a national code for
nationally applicable laws. This is essential when the introduction
of new legislation does not contain sufficient flexibility
to deal with exceptions, such as thatch."
However,
until changes are made through the appropriate channels
the NSMT, as a responsible trade body, has to advise its
members to abide by current rules, however inappropriate
they might be.
The
information below contains the relevant part of the law
regarding work on roofs; a demonstration calculation to
determine the “U” values for the different types
of thatch and English Heritage’s response to the law
in regard to work on listed buildings. For thatchers working
in the Bedford area, please note the attitude
to thatch by the local Building Control. They are inflexible,
but within the letter of the law have right on their side.
East Dorset Building Control has the most
knowledge and experience of thatch construction and will
work with thatchers to achieve the best outcome for the
building. Please let the office know of any successes or
difficulties in working with the new legislation. Any information
useful to others can be added to this page.
Document
L1B was not framed in relation to thatch. However, the result
of the legislation is that re-thatching of one side of a
roof could be considered to require the submission of an
application for building regulation approval. To put this
into context, the regulations require that when work such
as replacement of external render or tile hanging to a wall,
extensive re-plastering internally or having new roof tiles
or slates, extra insulation may need to be added at the
same time. The requirement is that when the work is completed,
the insulation value of the roof as a whole shall exceed
a U-value of 0.16 W/m2.k. However, a rethatch will improve
the insulation value of the roof and some authorities are
not requiring submissions, whilst others, such as Bedford,
require a submission to be made before work is started and
will enforce a stoppage to any work that has not been authorised.
We
have had calls from thatchers unaware of these regulations,
who have been visited on site by officers from Building
Control. In some cases, officious inspectors have harassed
thatchers and, while ignorance of the law is not an excuse,
it is incumbent on those who formulate and enforce rules
to do so constructively. For instance, as a lead body in
thatching, the Society has not been informed officially
of the new requirements. Unfortunately, those in authority
do not appear to fully understand the rules themselves.
Some, who have been giving thatchers a hard time, seem to
be unaware of Regulation 9 paragraph 5a of the document
which states that buildings that are
where
compliance with the energy efficiency requirements would
unacceptably alter their character or appearance are exempt
from the requirements. However, the local Building Control
department will need to be informed that work is to be carried
out.
Buildings
that are not listed or are not in a conservation area will
require Building Control approval for the work and an application
must be submitted. Document L can be downloaded from:
http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1B_2006.pdf
The
website for the local authority where you are working will
probably have the necessary links to download the appropriate
form for the householder to complete with respect to building
control requirements. For instance, there is guidance on
the Dorset website:
http://www.dorset-technical-committee.org.uk/reports/fuel-change.asp
We
will keep a close watch on developments and update the Society's
website with relevant information as it becomes available.
Thatch was peripheral to the framing of this legislation
and problems may arise where buildings are not listed. Most
unlisted thatches should be relatively newly built and may
already comply with the requirements but a single layer
of any thatch is not going to meet the requirements of the
Act (see below).
Home
information packs (HIPS), “U” Values and Energy
Performance
In 2007
the introduction of the new energy performance measurements
in the for all properties requires a calculation of the
insulation performance of the roof. This includes any property
offered for sale and requiring a Home Information Pack (HIP)
or when major work is carried out to the roof, including
repair of the thatch. For major repairs and refurbishment
it is a legal requirement to complete the necessary forms
and agree the work with the local building control officer,
before any work is undertaken.
English Heritage has issued interim guidance relating to
home information packs and on advice for domestic energy
assessments. English Heritage has concerns that some “improvements”
may be inappropriate, harmful and sometimes even illegal
if applied to traditional and historic homes. “Historic
and traditional buildings make up about 25% of the housing
stock. While they are not exempt from Energy Performance
Certificates (EPC) they do require more careful consideration
since they are built very differently to modern housing
and because listed buildings and buildings in conservation
areas subject to statutory protection.”
Loft insulation and the current RdSAP (Reduced data standard
assessment procedure) conventions are unworkable for thatch.
The rule is to measure half of the thickness of the thatch
and add it to the insulation at the joists, with the exception
of new buildings and single thickness, coat roofs this is
impossible.
Building insulation is measured by the “U” value
of the walls, floors and roof. The measure represents how
much heat passes out of a building. The lower the value
the more heat is kept in by the part of the structure being
measured. The “U” value is actually a measure
of the overall ability of a roof to prevent heat loss and
is measured in watts per square metre per degree Celsius
(Kelvin) (W/m2.k.). A pitched roof will lose more heat than
a flat roof even if they have the same thickness of insulating
material BRE (2005). A water reed thatched roof, 300mm (12ins)
thick at a pitch angle of 45 degrees has a “U”
value of 0.35 W/m2.k. This is because thatch structure is
cellular and the direction and movement of confected warm
air is always back into the loft cavity West (1985). Deeper
thatch will of course deliver a lower “U” value.
The Dorset Building Control Technical Committee website:
www.dorset-technical-committee.org.uk
provides
figures regarding “U” values for thatch taken
from CIBSE Guide A3:
