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LABC Technical Guidance Note

Subject : Use of Multi-foil insulation products

Compliance with Regulation 7 and Requirement L1

Date : August 2006

Purpose

LABC technical Guidance notes are provided to LABC members to inform, promote
good practice and encourage consistency of interpretation for the benefit of our clients.
They are advisory in nature, and in all cases the responsibility for determining
compliance with the Building Regulations remains with the Local Authority concerned.
Please note that this guidance note is based upon information available at the time of
issue, and may be subject to change.

Introduction

For most Building Control Surveyors in the UK, our first experience of multi-foil
insulations systems came in the mid 1990s with the introduction of products from
ACTIS. The claims made for such products were almost universally greeted with
scepticism, and would probably have found it difficult to find acceptance were it not for
the fact that the product was “certified” by TRADA. Given the very high level of trust that
the Building Control profession place in TRADA, many Building Control surveyors began
to accept multi foil insulation products, particularly for loft conversions.

Over the last few years, the basis of the testing on which the original certificate was
granted by TRADA has become the subject of considerable doubt throughout the
industry. For example, a recent adjudication by the Advertising Standards Authority did
not consider that the details of the testing substantiated the claims made for the product.

There are now several competing multi foil insulation products on the market, most of
which have used a similar basis for testing as that used by ACTIS, but which are
“certified” by organisations other than TRADA. In addition, the requirements of Part L of
the Building Regulations have changed significantly from April 2006,

Given the current climate of confusion, the Technical Group have been asked to
examine the information available, and to provide updated advice to Local Authorities on
the continued use of Multi foil products.

Review

Why is there a problem ?
The key issue of concern relates to the way the insulating properties of multi foil
products have been tested. For many years, the appropriate method for determining
insulation performance has involved the use of “Hot Box” testing in accordance with
National and European standards. There is no reason why multi-foil insulation systems
cannot be tested using this method, indeed one manufacturer has already done so
(Web Dynamics), and markets its product on the basis of these test results.

Several other manufacturers however feel that the “Hot Box” test does not fully reflect
the special characteristics of their products and hence that a test to current BS EN
standards will understate the actual insulation performance that can be achieved in real
installations. They have therefore sought to develop new test methods which involve
comparisons (using test rigs or actual buildings) between their own product and another
insulating product (usually mineral wool).

Ref No : 06/001
Revision : b
 
Such tests set out to demonstrate that the actual energy consumption of buildings using
multi-foil insulation will be equivalent to (or better than) an identical building using
mineral wool insulation, and having done so, claim the same “R” value for the multi-foil
product as would be accepted for the test thickness of mineral wool.

Unfortunately there are no currently accepted National or European standards for
performing tests in this way, and it is therefore not possible to be sure that the results of
such tests give a fair comparison of performance between competing multi-foil products,
or indeed between multi-foils and existing insulation products which have been tested to
established standards.

Is there a big difference in claimed performance ?
Tests carried out by the National Physical Laboratory (who have UKAS accreditation)
using test methods in accordance with BS EN ISO 8990 have indicated an “R” value for
multi-foil products in a range of 1.69 to 1.71 m2K/W. Those manufacturers who use
comparative testing are however, claiming “R” values for their products which range
from 5 to 6 m2K/W. In other words, multi-foil manufacturers who have used the
comparative testing route are claiming the insulating properties of their product to be
approximately three times better than can be verified using existing National or
European test standards.

In July 2005, the BRE also carried out an investigation into the performance of multi-foil
insulations by carrying out in-situ tests of buildings where multi-foil insulation had been
used. The results indicated that the “U” values of the constructions examined were close
to those which could be calculated using the BS EN ISO 8990 test values and
considerably less than would be calculated using the manufacturers claimed values
obtained as a result of comparative testing.

Do Multi-foils comply with regulation 7?
Regulation 7 (Materials and workmanship) is a generic Regulation which establishes
baseline performance standards applicable to all building materials. Section 1 of the
Approved Document to support Regulation 7 then goes on to give advice to Building
Control Bodies as to how the fitness of materials can be demonstrated.

A key point here however is that other requirements of the Building Regulations may
impose more demanding or specific requirements on particular materials, and Part L is a
good example of this. It is not enough for example to know that a particular type of
insulation product is “fit for purpose” (the regulation 7 requirement), it is also necessary
to know that it will achieve a particular standard of insulation (the Part L requirement)
which may vary according to the circumstances in which it is used.

Do things change as a result of the 2006 changes to part L ?
There are several key changes which result from the revisions to part L which have a
significant impact on the acceptance of multi-foil insulation products –

1. The withdrawal of the dispensation in the 2002 version of AD L1, which allowed the
sloping part of roofs exposed within loft conversions to have a “U” value of
0.3 W/m2.K (0.2 W/m2.K is now the appropriate standard).

2. Paragraph 11 of AD L1B now clearly states that “U” values must be calculated using
the methods and conventions set out in the 2006 version of BR 443. This is
significant because the 2006 version of BR 443 makes specific reference to multi-
foil insulation products whereas the previous version did not.
 
3. Paragraph 3.10.2 of BR 443 (2006 version ) now clearly states that “U” value
calculations for multi-foil insulation products must be calculated using performance
data “measured by a Notified Body accredited for thermal testing by an EU national
accreditation service” and the tests themselves must be carried out to appropriate
BS EN standards.

4. The circular letter which accompanied the April 2006 changes to the Building
Regulations contained several paragraphs (25-27) concerning the use of Multi-foil
insulation products. In particular, it raised the possibility that the Confederation of
Multi-foil Manufacturers hoped to obtain a European Technical Approval (ETA) for
their products by 31st December 2006. The letter makes it clear that once an ETA is
in place, values for thermal resistance obtained using the procedures outlined in the
approval can be used as an alternative to the test methods set out in BR 443. By
inference therefore, it implies that the test methods of BR 443 should be used until
such time as the ETA is in place, and it now appears that the target of the 31st
December may have been optimistic.

Recommendations

The LABC technical working group feel that the 2006 changes made to Part L of the
Building Regulations are sufficient to warrant a re-evaluation of the acceptability of multi-
foil insulation products. On the basis of information currently available, our advice is
therefore as follows –

1. For all applications where the work on site will be required to comply with the
Regulations in force prior to April 2006, the use of multi-foil insulation products
should continue to be accepted in accordance with previous guidance.

2. Where the works on-site will be required to comply with the revised Regulations
brought into force in April 2006, Multi-foil insulation should only be used on the
basis of test values obtained in accordance with paragraph 3.10.2 of BR 443 (see
note 1 below).

3. As a transitional measure (pending the anticipated introduction of a new
European Technical Standard) it is considered acceptable to continue using
products that have been subject to comparative testing, provided an “R” value of
1.7 m2K/W (or less) is used for the product in “U” value calculations. This may
mean that additional insulation is needed to meet the required “U” value targets.

Notes

1. On the basis of current information, “Thinsulex” (Web Dynamics) is the only multi-
foil product of which the technical group is aware that has been tested in
accordance with the requirements of BR 443, and whose technical literature is
based on the “R” value determined by the “Hot Box” test results.

2. The Product Type Approval given by LABC to “SuperQuilt” (YBS Insulation)
remains valid to demonstrate compliance with Part L 2002 only. Until the Type
Approval has been updated to comply with the 2006 revisions to Part L,
“SuperQuilt” should be treated according to recommendations (2) and (3) above.

3. The technical group have considered the basis of the test method endorsed by
TRADA and feel that the principle on which it is based has considerable merit.
LABC strongly supports the proposal by the Confederation of Multi-foil
Manufacturers to obtain European Technical Approval, and hope that this can be
achieved as quickly as practicable.