Installing a valley on a metal roof is a relatively simple process that can be completed in just a few hours. Valley flashing is important for directing water runoff from the roof and preventing leaks. When installing valley flashing, be sure to use a corrosion-resistant metal such as aluminum or stainless steel. Also, be sure to overlap the valley flashing by at least 2 inches on each side.

In order to install valley flashing on a metal roof, you will need to first measure and cut the necessary pieces of metal to fit the roof valley. Once the pieces are cut, you will need to secure them to the roof with screws or nails. Be sure to use a sealant around the edges of the valley flashing to prevent leaks.

How do you install a metal roof on a valley?

Using your carpenter’s pencil, begin outlining where the valley intersects with the eave end of the roof. Be sure to make your mark on the top side of the valley so that you can easily see it when you’re ready to install the valley flashing.

The first course of shingles should be installed along the eve and up over the valley. The last shingle in the course should extend a minimum of 3″ beyond the valley centerline. This will ensure that the valley is properly covered and protected.

How do you cut metal for valleys

When cutting the left side of a seam, be sure to do so at a 45 degree angle. This will help ensure a tight fit. You may need to trim the fabric as needed to get a perfect fit.

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We’re ready to start installing the cut, so we want to align it to the bottom where we need it.

Do roof valleys need mortar?

A common misconception is that the mortar bedding is there to prevent water access. However, in reality, a valley should work correctly even without mortar. Think of double lap plain tile valleys and slate valleys; these do not use mortar. In Scotland, single lap tile valleys are commonly installed without mortar.

It is important to put screws into the flat part of the roof when metal roofing, as this offers a more secure seal. This is according to most US metal roofing to install valley on metal roof_1

Do roof valleys need metal flashing?

Additional underlayment is always a good idea in a valley, regardless of whether or not there is metal flashing. This will help to protect the roof from water damage.

The most common open width for a traditional valley is 125mm. However, there are exceptions, such as low roof pitches and/or long rafter lengths, where a different width may be more suitable. Further guidance is available in the Lead Sheet Training Academy (LSTA) manual219.

How do you seal a metal roof valley

Metal roofs are subject to different types of degradation depending on their location. Metals located near sources of acid rain or other corrosive agents will corrode more quickly. Valley areas of roofs are also more prone to leaking since they are the lowest point on the roof. In order to prevent leaking, it is best practice to seal the valley area with a tape sealant. The sealant should be applied between the valley trim and the panel to create a waterproof barrier. The seal should then be compression fit to the structure using fasteners. This will ensure that there is no gap for water to seep through.

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The closed roof valley is the most aesthetically pleasing of the two types of valleys (closed and open). Many homeowners prefer the seamless look of the closed roof valley over the metal-lined open valley. The closed roof valley is also less expensive to install.

How do you cut roof valleys?

And then once you found it mark the 40 mil Yeah and you’re going to want it pretty tight Yeah then you can just bring that whole section down And then you can do the other side

Open metal roof valleys are a great option for sheds and other structures where you want to shed snow and avoid debris build-up. They don’t require as much nailing, so they’re easier to install and maintain.

How wide should metal valley flashing be

Metal valley flashings are an important part of preventing water damage to your home. They should be at least 24 inches wide, and extend at least 4 inches out under the roofing material at the eaves. This will help to keep water from seeping into your home and causing damage.

With a clean valley, you can lay down some peel and stick roofing membrane. Fold the top over the roof ridge and cut the bottom along the drip edge metal. Install synthetic roofing underlayment or felt paper according to manufacturer specifications and then install the first piece of valley flashing.

What’s the minimum flashing for valley gutter?

Valley flashings are an important part of any roofing system. They help to protect the roof from water damage by channeling water away from the roof and into the gutters. Valley flashings should be a minimum of 300mm wide in order to be effective.

Roofing mortar should be 1:3 cement:sand with plasticiser. The mix should be based on sharp sand with soft sand added to achieve workability. The proportion of sharp sand should not be less than ⅓ of the total sand to install valley on metal roof_2

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What causes roof valleys to leak

Leaks are one of the most common problems with roofs, and they can be caused by a number of different things. One of the most common causes of leaks is improperly installed or nonexistent flashing at the valley area. This sloppy work is usually done by inexperienced roofers or general contractors. The best way to avoid leaks all together is to hire a professional roofing contractor.

If you have lead valleys on your roof, the proper and sure way to fix them is to strip the tiles out on either side and relead them. This will ensure a long-lasting and secure repair.


1. Valley installation on a metal roof begins by determining the width of the valley. The width should be at least two inches wider than the largest roof panel being used.

2. After the width is determined, the next step is to Install the first course of valley flashing at the centerline of the valley.

3. Secure the valley flashing by driving nails every two feet along the length of the valley.

4. Install the second course of valley flashing, overlapping the first course by six inches.

5. Secure the second course of flashing by driving nails every two feet along the length of the valley.

6. Repeat steps four and five until the valley is completely covered with flashing.

Valley installation is a critical part of preventing water infiltration and ensuring the longevity of your metal roof. While the installation process may vary slightly depending on the type of metal roof you have, the general principles are the same. With a few tools and some basic instructions, you can easily install a valley on your metal roof and rest assured that your home is protected from the elements.