Putting a chimney or flue pipe through a Sedum green roof

What is a Sedum roof?

A Sedum roof is a type of green roof. The roof is designed to be able to take the extra weight of plants, growing medium and water and the plants grow on top of the roof requiring relatively little maintained. There are about 400 species of Sedums found in the Northern hemisphere. Sedums are a good alternative to grass when making a green roof for a variety of reasons. The plants are often hardier than grass and can survive with less growing medium - so the roof weighs less when wet. They are hardy and suited to the harsh conditions on a roof where there is little growing medium, low water, hot sunshine. A Sedum roof can look very nice indeed and is relatively easy to install.

Putting a flue pipe or chimney through a Sedum roof

Sedum roof are becoming ever more popular and many customers have come to us wanting to put a twin wall insulated flue pipe through their Sedum roof so that they can install a stove. This is relatively easily done.

For Bauder Blanket System Sedum Roof

We offer custom Sedum Roof Flashings fabricated to order from 316 grade stainless steel. Please inform us early on in the project as these do take some time to make. These sedum roof flashings are specially designed to work with Bauder Sedum Blanket Systems, but are no doubt suitable for other sedum roofing systems. Our Sedum roof flashing maintains the 50mm gap to combustibles necessary for Selkirk twin wall flue pipe. Other makes of flue may need a larger 75mm gap. The penetration detail which we have designed does not create a cold bridge at the roof penetration and maintains air tightness.

Sedum roof flashing for 150mm Selkirk twin wall flue £149 inc VAT.
Sedum roof flashing for 200mm Selkirk twin wall flue £174 inc VAT.

Please specify the roof pitch when ordering

Generic twin wall flue penetration method for a Sedum roof

Generally we specify a Dektite square based flashing, the largest possible, which is then installed on the diamond, i.e. with one of its corners pointing directly up the roof slope. This stops water pooling against the edge of the flashing. The roofing materials need a 50mm gap from the twin wall flue so this dictates the size of the hole to cut.

If you use this method and you have not yet installed your roofing system then it also makes sense to have an upstand under the flashing to further raise the whole flashing and roof penetration, again to minimise the risk of water penetration.

For further technical advice, chimney and flue design and consultancy please contact us on 0845 226 5754

If you would like us to design your flue system then please go to the flue design service section of this site.