How to Seal Roof Valleys?

Most roofing contractors agree that roof valleys are one of the most common places where leaks can occur on your roof. They are often susceptible to the effects of wind, rain, and snow which can all lead to leaky roofs.

What is a roof valley?

A roof valley is a small depression in the middle of a roof that allows water to run off the roof. It’s usually caused by an accumulation of ice or snow on top of the shingles. When it melts, this water runs down into the roof valley, making its way to the eaves where it can drip through the soffit onto the wall below causing a roof leak.

How To Fix A Roof Valley Leak

1. Remove any loose debris from around the leaky area. This could include leaves, twigs, or even pieces of insulation. If you see any nails sticking up out of the roof decking, remove them as well.
2. Check for damaged shingles or missing shingles near the leak. If there are any missing shingles, repair them before continuing with the rest of the project.
3. Clean the area thoroughly using a soft brush and soap or detergent. Make sure to scrub the entire area including the edges of the roof decking.
4. Use a waterproof membrane such as EPDM to cover the roof decking. You may need to use two layers depending on the size of the leak.
5. Apply a layer of roof cement over the waterproof membrane. The roofing cement will help prevent moisture from getting under the membrane.
6. Install flashing along the edge of the roof decking to divert water away from the roof. Flashing should be installed at least 12 inches above the highest point on the roof.
7. Seal the roof decking with an asphalt-based roof coating.
8. Cover the roof with tar paper. Tar paper acts as a barrier between the roof decking and the weather.
9. Apply new shingles to the roof.
10. Waterproof the roof decking again.

If fixing roofs is not your thing, we recommend that you get in touch with an experienced roofing professional.

Types of Roof Valley Systems

There are two types of roof valley systems:

Open valley roof

An open valley system has no covering material placed on top of the roof decking; instead, the roof decking is exposed to the elements. Open valley roofs are typically used when the roof is not expected to get very wet.

Closed valley roof

A closed valley system has some type of covering material placed on top of the roof decking. Closed valley roofs are typically used if the roof is expected to get wet. They are quite popular among homeowners. However, they do not last as long as the open valley roof.

Reasons for Roof Valley Leak

There are many reasons why roof valleys leak. Roof slopes, roofing material, roof shingles are some of the parts that contribute to leaks. Some of the other reasons include:

• Poorly designed roof vents
• Ice dams
• Rust
• Wind-driven rain
• Snowmelt
• Rainwater runoff
• High humidity levels
• Moisture condensation
• Excessive heat
• Low air pressure
• Vibrations due to construction activity
• Heavy rainfall

How to Prevent Roof Valley Leaks?

Preventing roof valley leaks is easy if you follow some basic guidelines. First, make sure that your roof has good ventilation. Your roof should have at least 1/16th inch per foot of open space between the shingles. Second, keep your gutters clean. Third, inspect your roof every year. Look for signs of damage like holes or missing shingles.

The best way to prevent roof valley leakage is to keep your roof dry. That means keeping it free of leaves, sticks, and other debris. Also, make sure that the gutters are clear of obstructions.

FAQs

Should roof valleys be sealed?

Yes, they should be sealed. However, you don’t necessarily need to do it yourself. There are plenty of companies that specialize in sealing roof valleys.

Can I seal my own roof?

If you know what you’re doing, then yes, you can. But we recommend hiring someone else to do the job instead.

What kind of materials should I use to seal my roof?

You can use either a silicone-based product or a latex-based product.

Is it necessary to install flashing when sealing roof valleys?

It depends on where the leak occurs. Installing flashing is not required in all cases. However, it’s highly recommended if the leak happens near the eaves or ridgeline.

Check our previous post here: What Is GRP Roofing (UK)?

It is possible to prevent condensation from forming on your metal sheets by taking certain precautions. Here are a few tips from our roofing team on how to prevent condensation on roof sheets.

1. Keep the area around the edge of the roof dry

Condensation forms when water vapour in the air comes into contact with cold surfaces, such as metal roofs and walls. The most common cause of this is when rainwater runs off the roof and hits cold areas like gutters or downspouts. If you have any standing water on your roof, it will create a perfect environment for condensation and water damage.

2. Make sure there’s no moisture inside the building

If you notice that your home has unusually excess humidity, check to see if there are leaks in the roof or windows. Water can enter through these openings and then collect on the exterior of the house. This can lead to condensation problems.

3. Seal up all cracks and holes

Cracks and holes in the roof allow water to penetrate the structure. You should seal them up so they don’t let water in.

4. Install attic fans

Attic fans help keep the air circulating in the attic, keeping it cooler than the rest of the house. They also reduce humidity levels in the attic.

5. Roof Pitch

Low pitch roofs are more likely to have a condensation issue. A low pitched roof makes it difficult for water droplets to slide the roof slope making them accumulate and eventually enter your house. A corrugated metal roof is better placed in terms of letting excess water flow preventing water accumulation.

A steep pitch prevents moisture and water droplets from staying put on the roof thus eliminating the possibility of water or moisture entering your building.

6. Ensure proper ventilation and air circulation

Ventilation helps remove excess heat from your building which reduces the chances of condensation. It also allows warm air to escape and cool air to come in.

7. Use dehumidifiers

Dehumidifiers work by pulling water vapour out of the air. These molecules get trapped in the device and are later released back into the atmosphere. Dehumidifiers are beneficial because they take care of excessive humidity levels in the air.

8. Be aware of weather conditions and patterns

The best time to install a dehumidifier is during periods of high humidity. During the winter months, installing a dehumidifier may be unnecessary because the temperature is much lower. In summer, however, installing a dehumidifier would be beneficial.

9. Roofing material

Metal roofing materials are prone to condensation issues. In order to prevent this from happening, the metal roof should be insulated so that the panel temperature never reaches the dew point.

10. Check for signs of leakage

Check for signs of leaking at the edges of the roof. Look for dripping or puddles of water near the eaves. If you find any, call a professional immediately.

11. Improper Construction Techniques

Improper construction techniques can make your roof prone to developing excess moisture that develops into condensation. Make sure that your contractor uses correct installation methods so that your roof doesn’t develop condensation issues.

12. Poorly Maintained Roof

Poorly maintained roofs can become damaged over time. This can lead to the development of condensation.

What Can Condensation Do to Your Roof?

Condensation on roof sheets can cause damage to the sheet itself, such as rust, corrosion, and even pitting. It also causes problems with the appearance of the roof, which could lead to leaks in the future.

The best way to prevent these issues is to keep your roof dry. If you live in a humid climate, you’ll want to make sure that your roof is well ventilated so that the moisture doesn’t build up.

Use Anti-condensation Roofing Sheets

You may want to consider using special anti-condensation roof sheets if you’re worried about having issues with condensation. To protect your roof from moisture, these sheets feature thick insulation of an anti-condensation membrane. As the membrane absorbs water, it prevents it from condensing and trickling down. The membrane dries out when the air becomes warmer, and the stored water evaporates.

If you do decide to use these types of roofing sheets, make sure that you have them installed correctly.

FAQs

Is condensation a problem with metal roofs?

Yes, metal roofs are likely to have condensation problems which leads to corrosion and shorter roof lifespan.

Why is my tin roof sweating?

The difference in temperature between the inside and outside of the roof results in humidity and condensation leading to water droplet formation on your roof.

Does a metal roof need a vapour barrier?

Yes, to ensure condensation does not form on metal roofs and buildings, the roofs and buildings must be sufficiently insulated and vapour-proofed.

See our last post here: How To Stop A Leaking Roof During Heavy Rain