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Closed cut valley 1
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Closed cut valley 3

3. Open Valley Shingle Installation

An open valley relies on an Armourvalley membrane or metal flashing for protection. Armouvalley and metal flashing are left exposed, so these materials stay visible on the roof. Some homeowners do not like the look of metal (flashings) in the valley. Therefore we offer the Armourvalley roll which is matching the color of the shingles. Open valleys with laminated shingles have many advantages. One of the advantages is better drifting of water to the gutters, reducing the risk of ice dams or blockages of debris. Especially low slope roofs (9,5°- 20°) are good candidates for open valleys because they are more likely to accumulate debris. Experience learns that if the shingles are installed properly, performing properly, the open valley system holds up better over the time.

Open valley shingle installation

Quick guide how to install an open valley:

  • Snap two chalk lines from the ridge to the eaves 8 cm apart increasing in width by 1 cm per meter towards the eaves.
  • Trim the shingles to these lines and cut a 5 cm triangle off the top corner to direct the water into the valley.
  • Nail the shingles 5 cm back from the chalk line.
  • Do not use a shingle trimmed to less than 25 cm in length to finish a course running into a valley.
  • If necessary, trim a part off the adjacent shingle in the course to allow a longer portion to be used.
  • Glue the valley end of each shingle with bituminous mastic.
  • There should be no exposed nails along the visible part of Armourvalley.
application open valley
application open valley

4. Our most favorite method:

It is the easiest, most money and time effective method!

IKO tip & trick for the Cambridge shingles:

One variant of the open valley is the “Californian valley”. In our community it is also called “Cambridge valley” because this valley is only possible to do with laminated or Cambridge shingles. For this method, the last shingles on both “cut” sides of an open valley are actually installed sideways, so they run up and down the valley parallel with chalk-lines.

This saves the time of cutting shingles and is the fastest way to shingle a roof valley.

Remember:

A properly installed valley is a critical component of any roof, ensuring the long-term protection of this vulnerable area. IKO’s recommendation is to install laminated shingles, or architectural shingles, using the open valley method, for best roof performance.

Application instructions:

Easy application (for professional roofers):

  1. Base is a wooden or concrete underdeck construction with a waterproof IKO underlayment.
  2. Apply roof shingles with IKO nails.
  3. You would need +/- 35 pc/m². Valley, hips and ridges are easy to install without purchasing a huge range of extra accessories.

Foresee solid insulation and also good ventilation for an optimal and long-lasting roof - improving heating and cooling costs.

Eaves, rakes, walls, chimneys, roof windows, etc. require metal flashings.