Roof Valley Troughs

In all cases and with all inclined roof valleys, valley troughs and valley lining materials, including membranes should be supported by valley boards or sark boards. Valley boards may be inset or continuous over the rafter.  The width of the board should be sufficient for the valley

Many years ago when these products became popular, the issues with lead were less understood and the wide range of flexible lead replacement products that we now have were not available. While still permissible, it is now considered to be slower and more costly to

Conventional ‘open cut’ tile or mortarless valley troughs are limited to 15°. The Danelaw dry fix valley trough can be used with a roof pitch differential of up to 20°.

Generally, valleys are not recommended below a 17.5° rafter pitch, and rarely used in rafter pitches above 60°. GRP valley troughs can accommodate this range, subject to roof area, valley length and pitch differential considerations. The Danelaw design of dry fix valley trough can accommodate a greater

We always recommend that the valley trough is installed with the central upstand pinched together. This minimises the visible opening which can easily be filled with a good quality external grade grey sealant such as ‘Leadmate’.

No – these additional components are not required with the Danelaw design.

Yes. The design, function and operation of valley trough remains the same. The height of the central upstand should be at least as high as the highest point of the lapping slates or tiles, but for aesthetic reasons, the profile should be chosen to best

No, unless the recommended minimum overlap cannot be achieved (see previous answer).

The requirement for all unsealed laps in roofing is generally 150mm when measured vertically, and this rule is applied to all Danelaw strip flashing products such as slate and tile valley troughs, Bonding Gutters, Conti-soakers etc. For a roof pitch below 22.5°, the overlap should generally be 350mm. This

Lead has traditionally always been used as a versatile flashing product to form a saddle detail. This is still an option, but with the increasing concerns over health, environment and theft, there are now many lead-free flashing options available – some better than others and

It is now recognised that the use of a good quality lead replacement product is no less reliable, and both quicker and more cost effective.