ASA
Helps to Clarify Misleading Claims over Part L
Claims that a Dupont product obviates the need to ventilate roofs in order
to pass Part L were weakened by the Advertising Standards Authority (ASA)
in a recent judgement Building Products Design and Hambleside Danelaw
had both objected to an advertorial and a trade press ad for a roofing
manufacturer and also a mailing and a leaflet.
a.
The advertorial was headlined 'Roof Ventilation will not help Part L'.
It stated that new regulations introduced by the government, as part of
its commitment to saving energy and reducing greenhouse gases and global
warming, would mean that air-tight construction would be obligatory and
traditional ways of ventilating roofs would no longer be appropriate.
The advertorial stated '... The most straightforward solution to this
problem is the adoption of a non-ventilated roof system. This type
of system prevents condensation by the use of breather roof underlay,
negating the need for traditional roof ventilation. Systems such as the
DuPont Tyvek Supro non-ventilated roof system have no vents and require
no ventilation at all (no eaves vents, ridge vents, tile vents, soffit
vents and in-line vents) ...'. It featured a diagram that demonstrated
that no vents were needed when using the advertisers' product.
b. The trade press ad was headlined 'Surely you don't still believe you
have to ventilate the roof?' It stated 'With DuPont Tyvek breather membranes
there's NO NEED TO VENTILATE THE ROOF!' The ad listed several features
of the product, including '... fully BBA approved for NON-VENTILATED PITCHED
ROOFS ... fulfils ALL relevant building requirements & helps to comply
with BS5250:2002 ... up to 25% energy savings when compared to traditional
roof ventilation ... air leakage cut by 74% ... air tightness [sic] dramatically
improved ... domestic heating CO2 emissions cut by 11 tons per dwelling'.
c. The outside of the mailing stated 'Roof ventilation is totally redundant'.
The inside of the mailing repeated the claim and added 'Please watch the
video'; it contained a CD ROM. The inside of the mailing continued '...
latest research has clearly proven that roof batten space ventilation
is wholly un-necessary [sic] ... As we all know, Building Regulations
do not require roof ventilation. Technical guidance is provided in BS5250:2002
which recommends batten spaces to [sic] be open to the atmosphere ...'.
d. The leaflet was headlined 'WHAT ? No need to ventilate roofs ? NO!
Not any longer with the DuPont Tyveck non-ventilated pitched roof system
...'. It featured the diagram shown in advertorial (a) and listed the
same product features as the trade press ad (b).
Both complainants objected that:
1. the claims in ad (a) that no ventilation was needed when using the
advertisers' product were misleading;
2. the claim 'fully BBA approved for non-ventilated pitched roofs' in
ad (b) was misleading, because the BBA approval applied to roofing for
dwellings only and
3. the claim 'fulfills all relevant building requirements & helps
to comply with BS 5250:2002', in ad (b), in conjunction with the claim
'no roof space ventilation required at all', was misleading because BS5250:2002
recommended positive ventilation of the batten space if a vapour permeable
underlay, such as the advertisers', was used as an alternative to conventional
ventilation.
Hambleside Danelaw challenged the claims:
4. 'Roof ventilation is totally redundant ... latest research has clearly
proven that roof batten space ventilation is wholly unnecessary', in ad
(c), because they believed the advertisers' research was flawed;
5. 'As we all know, Building Regulations do not require roof ventilation'
and 'Comply with Building regulations', in ad (c), because they believed
the new building regulations made clear that ventilation was required;
6. 'BRE tests show whole house energy consumption reduced by 25%', in
ad (b), because they believed that figure was not attainable if the advertisers'
product was used as a simple alternative to 1F felt;
7. 'domestic heating CO2 emissions cut by 11 tons per dwelling', in ad
(d) and
8. 'improves air tightness dramatically' in ad (d).
Adjudication:
Dupont explained that Tyvek was a flexible sheet material that was waterproof
and highly water resistant and at the same time offered an extremely low
resistance to the passage of water vapour. They said, when applied as
an underlay beneath pitched roofs, Tyvek kept the wind and rain out of
the building but at the same time, allowed water vapour generated within
the building to escape safely into the atmosphere without the need to
ventilate. They sent evidence of studies and tests conducted on Tyvek
Universal Underlays (TUUs) from the British Board of Agreement (BBA),
Building Research Establishment (BRE) and University of Leuven.
Complaints 1 and 4 not upheld
Dupont said the Tyvek Non-Ventilated Roof System had independent third
party accreditation by the BBA, which was recognised and licensed by the
government to issue technical approvals for construction. They sent a
copy of their certificate 04/4101 for TUUs in energy efficient non-ventilated
pitched roof systems, which was a replacement of BBA certificate 99/3635.
They pointed out that their BBA certificate stated 'The Secretary of State
has agreed with the British Board of Agreement the aspects of performance
to be used by the BBA in assessing the compliance of roof tile underlay
with the Building Regulations. In the opinion of the BBA, Tyvek Universal
Underlays in Energy Efficient Non-Ventilated Pitched Roof Systems, if
used in accordance with the provisions of this Certificate will meet or
contribute to meeting the relevant requirements'. They pointed out that
the certificate stated the risk of condensation was equivalent to or less
than a conventionally ventilated cold roof system. They pointed out that
BBA certificate 04/4101 did not require ventilation of batten spaces.
Dupont argued that positive ventilation of the batten space was not necessary
because the vast majority of pitched roofs were naturally ventilated because
water vapour could readily escape through gaps between tiles and slates.
Dupont said a BRE research program under Partners in Innovation (Pil)
showed that, even for old roofs with moss and lichen on tiles and slates,
air containing water vapour could escape through the gaps between those
tiles and slates. They said that proved that batten spaces were self-vented
and positive ventilation of the batten space was not needed. They sent
an extract from the technical summary of the Pil project; the conclusions
included the statement 'Most roof coverings can be assumed to be sufficiently
air open so that no extra ventilators need to be installed in the batten
space, if an LR underlay is used without provision for loft ventilation'.
The ASA understood that ventilation in a roof system provided a means
of controlling condensation. We understood that the relevant building
regulation at the time the ad appeared was Approved Document F; Part F2
stated 'Adequate provision shall be made to prevent excessive condensation
a) in a roof, or b) in a roof void above an insulated ceiling' and gave
the alternatives of providing specified ventilation openings for the roof
void or following the guidance in BS 5250:1989 (which essentially amounted
to providing ventilation openings). We noted The Approved Documents for
the Building Regulations contained the prefatory remark 'There is no obligation
to adopt any particular solution contained in an Approved Document if
you prefer to meet the relevant requirement in some other way ... It will
then be up to you to demonstrate by other means that you have satisfied
the requirement'. We understood from the BRE that an example of a solution
would be to follow the specifications given in a certificate issued by
a certifying body such as BBA.
We noted BBA certificate 04/4101 stated that TUUs were satisfactory for
use in non-ventilated roofs as roof tile underlays in tiled or slated
pitched roofs in the UK. We contacted the BBA who said that their assessment
of the TUUs had been based on a complex computer simulation of condensation
risk based on the calculation of vapour movement in roofs, which took
into account all mechanisms of vapour movement and dispersal. That included
vapour diffusion through the 'breathable' roof tiles and between laps
in the roof tile underlay. BBA said evidence, since their initial assessment
in 1999, of condensation problems with the product had been extremely
limited; they were aware of four complaints and the two they had received
information and were able to investigate did not undermine the principle
of not ventilating.
We also obtained expert advice from the BRE. They considered that in terms
of the BBA certificate, explicit ventilation by the provision of vents
was not required and, in that respect, the ads were acceptable. They pointed
out that there needed to be a means of allowing water vapour to disperse
from the batten space but that it was now generally accepted that specific
provision for ventilation of the batten space was not needed because there
was sufficient fortuitous ventilation in a slated or tiled roof. They
said they had not been aware of condensation problems with the use of
the TUU.
We noted the ads were targeted at professionals with technical experience
in specifying insulated roof constructions. We considered that a form
of ventilation occurred within the roof construction with TUUs because
they relied on fortuitous ventilation through tiles and slates to disperse
water vapour. We considered, however, that readers would understand from
the ads that Dupont were highlighting that users of TUUs did not need
to positively ventilate the loft or the batten space. Because the advertisers
held a BBA certificate, which stated that TUUs were satisfactory for use
in non-ventilated roofs as roof tile underlays in tiled or slated pitched
roofs, we considered that the ads were unlikely to mislead.
On this point, we investigated the ads under CAP Code clauses 3.1(Substantiation)
and 7.1 (Truthfulness) but did not find them in breach.
2. Complaint upheld
Dupont pointed out that, following a previous ASA adjudication, they had
changed the claim from ' fully BBA approved for ALL TYPES OF PITCHED ROOFS
(any plan, shape, type, anywhere) ' to ' fully BBA approved for NON-VENTILATED
PITCHED ROOFS '. They said BBA Certificate 04/4101 was for 'Tyvek UNIVERSAL
underlays in energy-efficient non-ventilated pitched roof systems'. They
pointed out that BBA Certificate 04/4101 was awarded for 'non-ventilated
roofs', not dwellings. They said that, with the exception of high risk
buildings such as swimming pools and commercial laundries, the vapour
loading imposed upon a dwelling was higher than other buildings such as
offices.
We noted BBA Certificate 04/4101 stated that TUUs were satisfactory for
use in dwellings with non-ventilated tiled or slated roofs. We understood
that 'dwellings' defined in Building Regulations included flats, maisonettes
and houses, not commercial buildings. We considered that the claim implied
TUUs were BBA-approved for all roofs on all types of buildings whereas
it was approved for dwellings with tiled or slated roofs only. Because
Dupont had not demonstrated that TUUs were BBA approved for all roofs
on all types of buildings, we concluded that the claim was misleading
and told the advertisers to amend it.
On this point, the ad breached CAP Code clauses 7.1 (Truthfulness).
3. Complaints upheld
Dupont pointed out that, following a previous ASA adjudication, they had
changed the claim from ' meets BS 5250:2002' to 'helps to comply with
BS 5250:2002'. They believed BS 5250:2002 was advisory, not mandatory.
They said the objective of BS 5250 was implicit in the title of the document
'The Code of Practice for the Control of Condensation in buildings'. They
pointed out that the document did not state that ventilation should be
considered the sole means of controlling condensation. They referred to
Section 7 headed 'Controlling interstitial condensation', which stated
'To minimise interstitial condensation, it is necessary to do one or more
of the following ...'. The Code then listed five points, one of which
stated 'use material of low vapour resistance, or provide ventilated cavities,
near the colder side of the construction'. The note at the end of the
five points stated 'Any one particular procedure taken in isolation might
not necessarily minimise the risk of condensation'. Dupont believed the
note, taking into account the complex inter-relationship between many
different factors, clearly acknowledged that more than one means to control
condensation effectively existed; the Code recognised that the designer
must take a holistic approach. The release of moisture from a roof void
could be achieved either by ventilating the roof void to atmosphere or
by allowing the moisture to escape by diffusion through a Low Resistance
underlay, like TUU.
They stated that the Code also said that if a risk assessment, in accordance
with Appendix D of BS5250, showed that there was no plane of interstitial
condensation the construction could proceed, as far as condensation control
was concerned. They said Dupont and the BBA were licensed operators of
computer software that replicated the Condensation Risk Analysis and that,
using the formula and vapour resistance figures in BS 5250:2002, they
could demonstrate by calculation that there was no moisture build up at
any plane throughout a system. They sent two worked examples to demonstrate
the principle of the Risk Analysis procedure.
We obtained independent expert advice. The expert said that, at the time
the ad appeared, the version of BS5250 in force was BS5250:2002. This
had recently been amended and the new version 'BS5250:2002 with amendment1',
was published in December 2005. He said the new version was significantly
different in the sections covering roofs. He pointed out that his comments
referred only to the original version in place at the time the ad appeared.
He said section 7 of BS 5250:2002 included a reference to the use of low
vapour resistance materials and that it was reasonable to say that a vapour
permeable underlay such as Dupont's helped meet the requirements of BS
5250:2002. He pointed out, however, that the list under section 7 referred
to both low vapour resistance materials and ventilated cavities and the
Note pointed out that more than one procedure may be necessary. He believed
section 7 did not give blanket approval to the use of vapour permeable
underlays alone. He pointed out that BS 5250:2002 8.4.2.2 stated 'If a
vapour permeable underlay is used without continuous boarding, it is not
necessary to ventilate the attic space below the underlay. However, in
these circumstances, a ventilated counterbatten space should be formed
with the use of 25 mm counter battens and provision of ventilation at
low and high level.
Fortuitous ventilation through the tile/slate joints should not be relied
on to ventilate this space adequately.' The expert said the calculation
procedure that Dupont had used to assess the roof performance excluded
structures in which there was a significant air flow. He therefore believed
the calculations did not comply with BS 5250:2002. The expert considered
that positive ventilation of the batten space was required by BS 5250:2002
and that the claim 'helps to comply with BS 5250:2000' in conjunction
with the claim 'no roof ventilation required at all' was misleading.
We noted the expert's advice and that TUUs relied on fortuitous ventilation
through tiles and slates to help control condensation. We concluded that
the claim 'helps to comply with BS 5250:2002' in conjunction with 'no
roof space ventilation is required at all' was misleading and told the
advertisers to remove it.
On this point, the ad breached CAP Code clauses 3.1 (Substantiation) and
7.1 (Truthfulness).
5. Complaint not upheld
Dupont said BBA Certificate 04/4101 certified that TUUs in a non-ventilated
pitched roof system fulfilled all building regulations and that the risk
of condensation was equivalent to, or less than, that attending conventionally-ventilated
roof systems. They said building regulations did not require roof ventilation
but the control of condensation; Part F2 stated 'Adequate provision shall
be made to prevent excessive condensation a) in a roof, or b) in a roof
void above an insulated ceiling'.
We noted the claims were about the loft space and not the batten space.
We noted BBA certificate 04/4101 stated that '... in the opinion of the
BBA, TYVEK Universal Underlays in Energy-Efficient Non-ventilated Pitched
Roof Systems, if used in accordance with the provisions of this Certificate
will meet or contribute to meeting the relevant requirements.' The BRE
considered that, subject to adherence to all the requirements in the BBA
certificate, it was reasonable for the ad to claim that roof ventilation
was not required. We noted the ad was targeted at professionals with technical
experience in specifying insulated roof constructions and that they were
likely to be aware that the BBA certificate contained conditions that
they would need to comply with. We concluded that the claims were unlikely
to mislead.
On this point, we investigated the ad under CAP Code clauses 3.1(Substantiation)
and 7.1 (Truthfulness) but found that it was not in breach.
6. Complaint upheld
Dupont said BBA Certificate 04/4101 stated '... In conventionally-ventilated
roof constructions, energy loss by ventilation can account for up to 25%
of the total heat loss through the roof. The Tyvek non-ventilated system
will substantially reduce this mechanism of heat loss ...'. They said
testing by BRE & VTT, as part of BRE PiI Projects, showed that when
the roof was totally sealed, as described in BBA Certificate 99/3635 Detail
Sheet 2, air leakage was very low and energy savings amounted to 25% compared
to a conventionally-ventilation roof. Dupont said most air leakage was
lost through convection, which was prevented with TUUs because they did
not require positive ventilation of the roof space and the roof space
was sealed. They accepted that the figures had been extrapolated wrongly
and that the impression that whole-house energy consumption was reduced
by 25% was misleading. They apologised for the error and said they had
not used the claim since the ad under investigation had appeared and would
ensure that future claims were accurate.
We noted BBA Certificate 04/4101 stated that TUUs could substantially
reduce energy loss compared to conventionally-ventilated roofs. We considered
that the testing referred to by Dupont showed that energy consumption
was reduced by 25% through the roof construction only and not the whole
house. We understood from BRE that testing was conducted on one house
during a short period of time and results showed energy saving from the
whole house was at best 9.5%, achieved after remedial measures were taken
to seal the roof, which would not be in place in all dwellings. We concluded
that the claim was misleading and welcomed Dupont's assurance that it
was no longer appearing.
On this point, the ad breached CAP Code clauses 3.1 (Substantiation) and
7.1 (Truthfulness).
7. Complaint upheld
Dupont referred to testing by BRE and VTT, as part of BRE PiI Projects.
They said the figure of 11 tons per dwelling was established by multiplying
COİsavings made over one year in TUU's roof systems, compared with conventionally-ventilated
roof systems, by the average life of a dwelling, 60 years, taken from
the National Building Housing Council. They said the claim was no longer
appearing and that they would not use it again.
We noted the report showed a reduction of 179 kg COİemissions over the
period of a year and that figure was extrapolated over 60 years. We understood
that that figure was the result of one test only and that the figure of
11 tons per dwelling was based on an estimation of the lifetime of a house.
We considered that that was not sufficient to substantiate the claim,
which implied that the vast majority of dwellings would have COİemissions
cut by 11 tons. We concluded that the claim was misleading and welcomed
Dupont's assurance that it would not be used again.
On this point, the ad breached CAP Code clauses 3.1 (Substantiation) and
7.1 (Truthfulness).
8. Complaint upheld
Dupont said air tightness dramatically improved because air leakage was
reduced with non-ventilated roof systems, such as TUUs. They said the
claim was no longer appearing and would not be used again.
We considered that air tightness improved with TUUs if the advice in the
BBA Certificate 04/4101 was followed because the roof system was sealed
with no positive ventilation. We considered that the large percentage
reduction in air leakage referred to in the ad was from the roof space
to outside and not from the whole dwelling and that was not made clear.
We concluded that the claim was misleading and welcomed Dupont's assurance
that it would not be used again.
On this point, the ad breached CAP Code clauses 3.1 (Substantiation) and
7.1 (Truthfulness)