Warranty Position Regulatory Position and Guidance Exemptions Does B4 still apply?
Green indicates we consider our position best practice and not in dispute Grey items cover the December 2018 Amendments, Approved Documents and MHCLG's own FAQs and advice notes Green indicates that the item IS exempt from Regulation 7(2), in accordance with Regulation 7(3) Green indicates that B4 still applies, and refers to relevant parts
Yellow indicates our position has the potential to be subjective   Red indicates that the item is NOT exempt. Refer to Regulation 7(3) Red shows that B4 no longer applies


Warranty Position

Definition: Membranes, used at junctions and interfaces, e.g. to seal around windows or installed across movement joints and around penetrations etc.

Membranes are exempt from the regulations.

**Noting that Approved Document B is guidance: In this instance, if the width of the membrane strip is kept small, it is unlikely that B4-(1) could be shown to have not been met by using a Membrane that was not class B.

Noting that the membrane would require both heat and air to combust: If the membrane is trapped between a non-combustible insulation and a non-combustible sheathing board air will not be readily available.

Requirement: If a membrane (max 250mm wide) that is not class B is proposed for these locations, then an Assessment confirming compliance with B4-(1) will potentially be required.

Is the position indisputable? This may not be the view of all organisations.

December 2018 Amendment

Section 2 Reference: None.

Reference titles: None.

Approved Document

Reference title(s): 10.15(a).

References: Membranes used as part of the external wall construction above ground level should achieve a minimum of class B-s3, d0.

MHCLG FAQS / Advice Notes

Reference: Section 4.

Reference title(s): Approved Document B volume 2 paragraph 12.14 a. provides further guidance on membranes and provides that they should achieve at least Class B- s3, d0.


Is the item exempt from Regulation 7(2), in accordance with Regulation 7(3)?: Yes.

References: 7(3)(g) and 7(3)(h).

Statement: Membranes. Seals, gaskets, fixings, sealants and backer rods;

If exempt, are there any restrictions on the use of the system, component or material given in the guidance in ADB vol 2: Approved Document B clause 10.15(a) states "Membranes used as part of the external wall construction above ground level should achieve a minimum of class B-s3, d0."

Does B4 still apply?

Yes: Reference: B4-(1)

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Disclaimer: The information in this document is believed to be correct in light of information currently available and at the time of publication but is not guaranteed. Neither LABC Warranty nor its agents can accept responsibility in respect of the contents or any events arising from the use of the information contained within this site. The guidance provided does not replace the reader’s professional judgement and any construction project should comply with the relevant Building Regulations or applicable technical standards. For the most up to date LABC Warranty technical guidance please refer to your Risk Management Surveyor and the latest version of the LABC Warranty Technical Manual.