ClassicBond EPDM 68mm Internal Drain Kit for Flat Roofs

Internal drains are one of the highest-risk areas on a flat roof. If water backs up around the outlet, it can:

• Track back under the membrane
• Saturate insulation
• Cause leaks inside the building
• Lead to long-term roof failure
• This is why anti-back-up protection matters.

The ClassicBond internal drain is designed specifically to stop water backing up between the outlet and the pipe, protecting the roof build-up below.

This internal drain kit is intended for:

• Flat roofs with internal drainage
• Roofs connecting to standard 68mm domestic downpipes
• Domestic and commercial EPDM roofs
• Warm and cold roof constructions

It is suitable for use with ClassicBond, ClassicBond Pro and other EPDM membranes

The ClassicBond Anti-Back Up Drain features:

• A smooth 285mm × 285mm flange for excellent EPDM bonding
• A 185mm outlet stem that pushes deep into the pipe
• Multiple compression ribs on the stem that form a tight seal inside the pipe
• A pressure-fit design that prevents water or vapour travelling back into the roof

Once installed, this design eliminates backing up of water, even during heavy rainfall.

This is not just a drain outlet - it’s a complete kit for a compliant, secure, drain installation.

Buying the kit ensures you have:

• The correct drain
• The correct uncured flashing tape
• The correct primer
• The correct leaf grate

Everything is designed to work together, removing guesswork and reducing installation errors.

Each ClassicBond 68mm Internal Drain Kit contains:

• 1 × ClassicBond Anti-Back Up Internal Drain (68mm)
• 1 × 300mm length of 9″ Uncured EPDM Flashing Tape
• 1 × 250ml ClassicBond EPDM Primer
• 1 × Leaf guard

This is everything required to form a watertight internal drain detail on an EPDM roof.

1. Cut the drain flange back to leave a 50–75mm bonding area
2. Mechanically fix drain flange into the roof deck
3. Install EPDM membrane over the roof (do not apply deck adhesive to the drain flange)
4. Cut out the membrane using the flange as a guide
5. Prime the flange and surrounding membrane (50mm overlap onto EPDM)
6. Install the uncured EPDM flashing with a minimum 50mm overlap
7. Cut the centre hole and press flashing tape down inside the outlet
8. Fit the leaf guard
9. This method ensures a secure seal both on the surface and inside the pipe

• Product: ClassicBond 68mm Internal Drain Kit
• Drain type: Anti-Back Up Internal Roof Drain
• Material: Synthetic rubber (IGOM CE)
• Colour: Black
• Flange size: 285mm × 285mm
• Outlet length: 185mm
• Outlet internal size: Approx. 62mm
• Downpipe size: 68mm (UK standard)

Internal drains are where flat roofs often fail - not because of the membrane, but because of poor outlet detailing.

Using an anti-back-up drain with uncured EPDM flashing tape resolves that problem. The outlet seals inside the pipe, the flashing tape seals to the membrane, and water has nowhere to go except down the drain.

It’s the most reliable way to detail an internal outlet on an EPDM roof.