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.
Soil pipes should be supported at every 2m vertically and every 1m horizontally.
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.