Roof Dry Valley Construction

Installing a close cut grp valley with redland 49 tiles.

Roof dry valley construction.

The pitch of the roof here is 35 degrees the untiled main slope of the roof is 45 degrees. Valleys are typically found where gable dormer roofs meet the main roof or when a house has angled wings or additions where two roof sections in different planes meet. In many ways the roof construction for a pre formed grp valley is the same as that for a lead lined valley. The dry valley mitred at the ridge and awaiting the final tile course.

The valley area of a roof the straight lines formed when two different planes of the roof meet is a critical area that handles a tremendous amount of water run off. Some grp valleys are sufficiently robust to enable them to be laid directly over the rafters rather than being supported on valley boards. For an open valley a sheet of metal usually steel sometimes copper is fastened to the roof deck. No one but you can decide which kind of valley you want for your roof.

Redland dry valleys are suitable for both traditional cold roof and warm roof construction. Your choice of valley installation method is critical because when improperly installed valleys are risks for serious leaks. Alternatively a tile and a half may be used to avoid small cuts of tile. While making a decision about that do consider factors like cost then entire look and of course the functionality.

In this situation the bridge piece is placed in position to support the smaller cut tile section. Essentially there are three main ways to shingle a roof valley. It is therefore worth asking the valley manufacturer for guidance on this. Dry fix valley troughs are mortar free providing hidden water gulleys at the roof valleys.

Water collects in a valley to flow off the roof. Additional eaves closure pieces and counter battens are not required and they create a close cut appearance. The metal is usually pre painted to best complement the shingles color blend. Also keep in mind that at times open valleys are prone to storing water and thus causing roof leakages.

Open valley troughs have been designed as an alternative to traditional lead troughs a safe and efficient way to collect rainwater run off. Woven closed cut and open. Roofing shingles are installed then cut and sealed where they overlap the metal channel. Cut tile and a half tiles neatly and fix to form a gap minimum 125mm wide centred on valley.

Many of these warm constructions include a requirement for counterbattens below the slating or tiling battens. Either lay tiles dry or bed on mortar onto fibre cement undercloaks laid loose on each side of valley ensuring a minimum 25mm gap between mortar and the tilt fillet.