How do I prevent this from happening again?

We live in a side-split and have a problem with shingle damage caused by water run-off from the upper roof to the lower roof. The damage is so bad that we have a large patch over the damaged shingles until our new roof is installed.

What has me confused is that our previous roof handled water run-off without a problem. Why are the shingles we have now being damaged so badly? -- an installation problem? bad shingles? something else? I'm hoping someone can look at the pictures below and suggest cause(s). I would also like to hear suggestions of things we can do when we replace this roof so that we don't have this problem again.

As I said, our house is a side-split. In the first photo you can see how water from the upper roof is directed down a small section of roof that links the upper roof to a valley that then channels the water in the opposite direction and down the lower roof. On the extreme right side of this picture, you can see the top of the patch covering the worst of the damaged shingles.


Here is a shot of the lower roof and the 2-foot wide pathway where the run-off from above runs down to the bottom of the roof. The second photo shows the shingles at the bottom of this 2-foot wide pathway.



These photos show the valley between the upper and lower roofs in more detail.



Any ideas about the cause of this problem and how to avoid it in future would be very much appreciated.

Thanks.

No doubt you are in a position of shingle failure. massive granular loss can result from several factors. How many layers of shingles are on the roof? How old is the roof? What type of intake and exhaust vents do you have? Is there a underlayment installed under the shingles (roof felt)? Are you experiencing this same situation over the whole roof deck?

All of these questions can lead to shingle failure. Show us some more pics and we will better understand the problems you are having on your roof.


...and welcome to House Repair Talk.

oldog/newtrick said:

No doubt you are in a position of shingle failure. massive granular loss can result from several factors. How many layers of shingles are on the roof? How old is the roof? What type of intake and exhaust vents do you have? Is there a underlayment installed under the shingles (roof felt)? Are you experiencing this same situation over the whole roof deck?

All of these questions can lead to shingle failure. Show us some more pics and we will better understand the problems you are having on your roof.


...and welcome to House Repair Talk.

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X2. The design of the roof is probably contributing to poor ventilation characteristics of the area in question. A second (or third) layer of shingles is further attracting (retaining) more heat, thus causing the rapid deterioration of your shingles.

First and foremost, it appears that you have lower-quality shingles that have been on the roof for FAR too long. They may have been faulty shingles and/or have hail damage. But they've been on the roof way to long.

You've also got a bad design on that roof. Yes, it can work. But the way the valleys run together, you have rain water pouring across shingles. That alone is a recipe for problems.

I'm also going to assume that there's been snow build-up in certain areas. This will melt & freeze, often causing a lot of damage.

Unfortunately, it doesn't appear that you could install gutters in a way that would alleviate much of the problem.


My guess is that the best you can do is make absolutely sure that any damaged sheeting is replaced, use proper underlayment - including the self-adhering underlayment under the first 3-4 rows of shingles, and use top-quality shingles.

Assuming you'll hire the work done, make absolutely sure that you get a roofing contractor who does good work, as opposed to some fly-by-night outfit that shows up, does shoddy work, and disappears.

...including the self-adhering underlayment...

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The self adhering underlayment that DrHicks is referring to is an ice-and-water shield. Tamko, Grace and Carlisle are good brands. They cost anywhere from $59.99-$109.99 (depending on your area). They come in 1 square (100 sq. ft.) and 2 square (200 sq. ft.) rolls. Here is a link to Carlisle Coatings to further explain underlayment.
WIP 100 Datasheet / Water & Ice Protection (WIP®) / Roofing Underlayment: Carlisle Residential: Leading Manufacturer of Roofing and Waterproofing Materials

I'm not a roofer but I think the shingle pattern existing may channel the water in a straight line as it goes down/across the shingle from wind. Running to the tab edge, skips one, flows down to the third one's tab edge, etc. This keeps the water in tight channels, rather than stagger the pattern more, or go with Architectural shingle next time....

Gary

GBR said:

I'm not a roofer but I think the shingle pattern existing may channel the water in a straight line as it goes down/across the shingle from wind. Running to the tab edge, skips one, flows down to the third one's tab edge, etc. This keeps the water in tight channels, rather than stagger the pattern more, or go with Architectural shingle next time....

Gary

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Believe it or not I had a debate with a homeowner about a 5" offset versus a 6" offset,his statement was he wanted a 5" offset for even water distribution versus a 6" because he thought that since the pattern was more direct then water flow would be faster.,not true water will flow where it may...,unless a 6" offset will make it rain more ? Here is the problem, your roof is in an accelerated process of basically decay.,whether it be from storm damage (hail) or a nasty process brought on by blistering.,I could understand your concerns with water flow if the valley was 15'-20' but at the most its 3'.,When did you purchase your home ? Did you paint the house at anytime ? Or was it painted before you purchased it ? If you did not paint it then in the area that the roof is deteriorating its feasible that possibly a paint removal agent was used to either remove or help remove old paint prior to painting meaning some was spilled or improperly applied resulting in shingle decay.it could be a number of things but my last thought would be water flow related..,bottom line is your roof is worn and a 30yr shingle is your safest choice.