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Soil FAQs

No, air admittance valves can not be fitted externally they must be fitted in an internal non-habitual space like a loft.

Yes, Brett Martin soil pipes are compatible with most other manufacturers' systems. It is best to contact our technical department for further information.

An 87½° Rest Bend (B4131) should be used at the base of a soil pipe.

An expansion gap of 10mm should be used on push fit soil stacks.

All soil pipes should be supported at every 2m vertically. In the horizontal position, 110mm soil pipes should be supported at every 1m and 160mm soil pipes at every 1.2m.

No.  According to The Building Regulations PVC-U pipe installed underground must be manufactured according to BS EN 1401 or BS EN 13476. Soil pipe is manufactured according to BS EN 1329.

Product manufactured to BS EN 1329 is compatible with product manufactured to EN1401, however where the soil pipe goes from above ground to below ground the pipe installed must change from BS EN 1329 to BS EN 1401.


Brett Martin manufactures a range of soil products, certified to EN 1329. As a result of Brexit, Brett Martin has consulted with BSI and confirmed that in the case of the Kitemark, there was no need to make any changes to certification. This Kitemark continues to be valid throughout the UK and Ireland. Additionally, BSI issued the following statement on this issue:

“Kitemark is a voluntary 3rd party certification scheme and is completely unaffected by Brexit or the recent introduction of UKCA marking.

The certification scheme remains valid across the globe and demonstrates quality, safety and performance related characteristics backed by independent testing and regular assessment of the quality management system at the point of manufacturer.

Our Kitemark schemes are accredited by the UK’s national accreditation body (UKAS) which remains a member of the European co-operation for Accreditation (EA), International Laboratory Accreditation Co-operation (ILAC) and International Accreditation Forum (IAF).”


All products are manufactured to existing British and/or European standards. 

Brett Martin’s Soil systems are covered by our Guarantee