However a closed system simply performs better.
Open or closed roof valley better.
The metal is usually pre painted to best complement the shingles color blend.
I m leaning towards an open metal valley but i ve had contractors disagree saying that the metal expands and contracts too much.
And while some homeowners may prefer the aesthetics of a closed valley the heavier and thicker the shingle the less likely it is to lie flat across a joint.
The reason that many roofers like an open valley is that they feel that tree leaves and needles will more easily slide down or wash down an open valley when it rains.
After covering the roof with underlayment they ll then install a pre bent metal valley.
It might cost a little more in materials around 150 500 on average depending on the home and material.
However it is said that provided the rest of the roofing shingles were properly installed and are performing properly open valleys will perform better over time than closed valleys.
Open valleys on the other hand leave the metal exposed which may be more pleasing to the eye especially if copper is used as the valley lining.
They ll then install the shingles onto the roof deck extending them through the valley.
It is important to remember that a closed valley conceals the valley lining and allows the planes of the roof to blend together.
Thus closed roof valleys extend the time between your roof repair projects.
For an open valley a sheet of metal usually steel sometimes copper is fastened to the roof deck.
The shingles will act as the valley lining and will protect the roof deck and underlayment against water run off.
The closed cut valleys are cheaper and commonly done in my area but they tend to wear out sooner due to the high volume of water in the valley washing away the protective grit on the shingles there before on the rest of the roof.
Open valleys may be susceptible to water backup if the cut off shingles are not properly trimmed potentially causing roof leaks.
Architects often prefer closed valleys to open valleys as they feel that it gives a home better architectural appeal.
I kind of prefer the look of the closed valley.
For this reason professional roofers proudly supports the closed system of valleys.
Closed roof valleys are also more affordable as installing a metal lining costs extra.
Although the open valley is recommended by the manufacturer closed valley is acceptable.
When installing a closed valley the roofer will cover the roof with underlayment.
The open valley looks like each plane of the roof was cut in separate and the eye is drawn to the separation.
It is always a good idea to check with the manufacturer or a certified installer of the product such as ourselves.
The only type of valley that is unacceptable is the woven valley.
