Redland's mix of Victorian and Georgian properties means flat roof sections, whether over a rear extension, a dormer, or a lower-level addition, very often sit right up against an existing slate or tile pitched roof. Getting the junction between the two materials right is one of the more technically important parts of any EPDM installation on a property like this, since it is exactly the kind of detail where leaks tend to start if it is not done properly.
The general principle behind joining EPDM to a slate or tile roof is that the flat membrane needs to be dressed up and under the edge of the pitched covering, rather than simply butting against it or being tucked in from below. This allows water running down the slates or tiles to pass over the top of the EPDM upstand rather than finding a gap and getting behind it, which is the direction water always needs to be encouraged to flow at any junction between two different roofing materials.
In practice, this usually involves carefully lifting a course of slates or tiles at the junction, running the EPDM membrane up behind them to an appropriate height, and then securing it before the slates or tiles are relaid or reinstated over the top. Done properly, the junction becomes almost invisible, with the pitched roof appearing to continue naturally and the flat roof simply tucking underneath it.
This is a detail that genuinely benefits from experience, since slate and tile roofs on older Redland properties do not always follow a perfectly uniform pattern, particularly if there have been past repairs or alterations. An installer needs to work carefully with the existing roof rather than forcing a standard detail onto a non-standard situation, and lifting and relaying roof coverings without damaging them takes a level of care that not every flat roofing specialist is set up to provide.
Where the existing slate or tile roof shows signs of its own deterioration near the junction, such as slipped or cracked tiles, or deteriorating pointing around a chimney the flat roof abuts, it is worth addressing those issues at the same time as the EPDM installation rather than working around them. A perfectly detailed EPDM upstand will not help much if water is getting in a few inches away through a damaged tile that was left unaddressed.
Flashing details, whether in lead or another suitable material, often play a supporting role alongside the EPDM at these junctions too, particularly around chimneys or where the roofline steps in an unusual way. The membrane and the flashing need to work together as a single, continuous weatherproofing system rather than as two separate details that happen to sit near each other.
For Redland homeowners with a flat roof meeting an existing slate or tile roof, it is worth asking specifically how that junction will be handled before work begins, since it is one of the details that most affects whether the finished roof performs reliably for years to come.
If you have a flat roof in Redland that needs to tie into an existing slate or tile roof, Brunel Roofing Bristol can assess the junction and detail it properly as part of a full EPDM installation.
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