rusty valley on a tile roof

Roof valleys are the Vee shaped metal channels that run up and down the ‘folds’ of a roof.

The pictures on this page show where roof valleys are located on a roof.

Roof valley replacements are fairly common – especially on tiled roofs.

A valley on a tile roof

This is because the old valleys used to be galvanised and they start corroding with time (especially if they trap leaves).

You will know when you are getting a leak from a rusted valley when you start experiencing a stained ceiling under the area on the roof that has a valley.

When a rust hole develops on a valley, there will be a leak that gradually gets worst – rather than a sudden big leak.

There are times when roof valleys in good condition gets blocked with leaves and debris. There will be a damming effect during very heavy rain (especially after a long dry spell) and a large amount of water can then pour into the roof cavity.

So, roof valleys are important elements on a roof to be maintained properly…

Sometimes, it is even advisable to put leafguard over valleys to limit the amount of leaf debris jamming up and causing leaks.

The following video shows what happens when a valley on a tile roof has to be replaced on a tile roof.

https://youtu.be/ERODVZSp8Bk

A while ago, I posted this about valleys:

“Most roofs will have one or several valleys on it.

…And it is the roof element that will deteriorate over time and will need replacement to stop or prevent roof leaks.

Valleys can last for a long time. Even over 20 years. But there are some valleys that have short life spans and this is usually caused by leaves caught in the valley – creating a corrosive environment. When your roof is under trees – especially gum trees, the valleys on your roof will have a short lifespan. This means a frequent roof repair.

What finish should the valley be? …In the case of the Sydney roof in the video above, the valleys were galvanised metal and the roof was under a big gum tree. The sap from the gum tree that drop down with the leaves are very corrosive and this eats away the galvanising coating very quickly. Rust bubbles start forming and soon, holes start to develp and a roof leak starts.

My advice to property owners is to NEVER consider installing any valley that has not got a minimum finish of colorbond. It does not make sense to have to spend money to change valleys too often. It is often more economical to install a colorbond valley at the very start and have the life of your valley increased by another 10 years… So do not even consider a galvanised or a zincalume finish metal valley. Go straight for colorbond.

When to change a valley? Another point to to remember is this. To change a valley on a tiled roof, the ridge capping at the top of the valley has to be removed. Then it has to be reinstated after the valley change. So when it is time to have your ridge capping repointed on your tiled roof, take a good look at the valleys. If they are showing any sign of rust, it makes more sense to change the valley before the ridge capping work. Otherwise, if the valley is changed after the ridge caps are repointed, all the ridge capping work has to be Re-done! again. Not very clever. “

Why does the sarking on the sides of the valleys get wet and will it cause leaks?

A lot of roofers do not know that the sarking alongside the sides of the valley should NOT be cut and left overlapping onto the sides of the valleys.
The sarking has to be folded back onto the valley batten instead.

If there is sarking on the sides of the valley, it will draw water into the roof cavity and cause roof leaks.

When the tiles are lifted up. you should not see any sarking on the sides of the valleys at all.

detail od sarking at roof valleys
There should be NO sarking seen along the sides of the roof valleys. It should be kept away from the edge of the valleys,

 
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Raj
Raj
4 years ago

Thanks for the video.Do you have any branches or do you know any roof repairs in Brisbane? I need to fix my valley leakage.

Christiane
Christiane
2 years ago

What is Prestite as materials?

Helen
Helen
1 year ago

The old valleys on my tiled roof were pointed. Is it advisable to re-point them where they are damaged?

helen
helen
1 year ago
Reply to  Jack Yuen

thanks Jack.

Vicky
Vicky
1 year ago
Reply to  Jack Yuen

Hi Jack
When you mentioned not to bed the tiles along the edge of the valley, do you mean putting cement at the edge of the tiles at the valley? I’m trying to understand the meaning of this professional term. Thanks!

Debra Ottway
Debra Ottway
1 year ago

I have a cement valley with terracotta tiled roof. the Valley constantly leaks with driving winds. Will gutter guard help keep it clear of debris? What other measures can I take to fix it from leaking again

Stormygirl
Stormygirl
1 year ago

How much as a ball park figure would it be to replace 5 valleys? 1k, 2k??

Glenn Sampson
Glenn Sampson
1 year ago

Is there a difference in performance from using a colorbond valley vs a valley seal foam strip impregnated with bitumen?

I’m looking to get my tiled roof restored my roof plumber says colorbond whilst the restorer says valley seal

thanks

Pat
Pat
1 year ago

When replacing valley, do you recommend to use valley press ?

Rishad
Rishad
8 months ago

Hi.
I have recently installed a new tiled roof with a valley. Its only 4 days gone and we have some moderate rain. I notice the roof membrane is wet on either side of the vally.
What can cause this

James Roofing
7 months ago

well done you have explained this really well 🙂

Tony Jones
Tony Jones
6 months ago

In heavy rain I seem to get over flow from my gutter at the point the valley terminates to the gutter. I have a corrugated iron roof but gutter and valley are free of debris. Am I corre
ct in thinking the valley is not terminated correctly into the gutter & if so how do I correct. Tony , Semaphore.

Frank
Frank
4 months ago

Roughly much does it cost to replace a single valley roughly 4m long on a tiled roof?

Rawender Guron
Rawender Guron
2 months ago

The original builder did not install the valleys properly some 30 years ago. The problem is that the top of the timber fascia was not trimmed to match the valley’s profile and the valley itself was bent upwards as it flowed into the gutter. The result has been leaking on the sides of the valley and ponding and rusting on the valley at the bottom. How much the top of the fascia needs to be trimmed? The typical valley profile is 58 mm from to top of the side to the lowest part that should sit on the fascia internal corner. Trimming 58mm seems excessive and that means top of the gutter (and internal corner bracket) would also need some trimming. That does not sound alright.

Rawender Guron
Rawender Guron
2 months ago

Hi Jack,

Thanks for sharing your knowledge and experience.

My house is 30 years old and has 2 valleys. Both of them are rusty at the bottom where they flow into gutters. The reason is that the original installation was faulty. The bottom of the valley was bent upwards to flow over the fascia instead of trimming the top of the timber fascia to fit with the valley’s profile. It caused ponding on the valleys at the bottom and leak from the sides right at the bottom. I am looking to replace the valleys and my question is how much off the top of the fascia should be trimmed. It appears that fitting the valleys’ profile might require upto 50 mm trimming at the internal corner. It might also require trimming the top of the gutter including the top of the internal corner bracket. How should this problem ne approached?

Thanks in advance.

Danny Massa
Danny Massa
29 days ago

Hi Jack,
Hoping for some advise please.
I have two roofs fairly steep maybe 45degrees flowing into a valley. Can it be that in heavy rain and the correct angle the rush of water can run down the roof, into the valley and go under the roof overflowing and leaking? I’ve had a leak in an area where the top of the valley starts. Also I had some workers seal up a leak in that area but looks like it’s leaked somewhere else now. They basically filled up where the two roofs meet at the higher point of the valley, filled up under that roof point with foam so water would not flow down an area, then they painted bitumen on it, well that cracked. I’ve removed that bitumen and that foam and cleared the top of the valley. My question is, is there any product I can put on the sides of the valley so water won’t gush and pass under, even the lifted edges on the sides of the valley under the roof? I think this rush of water is able to splash over those sides due to the steep angle of the roof. I can’t find any other theory. If you can advise? I’m ripping up gyprock for a second time thinking those guys knew what they were doing, obviously not . Thank you so much Danny