Why is there foam in my gutter??

Today I received a call from a homeowner who had a GAF roof installed about 5 months ago by another local company. Every time it’s rained since the roof was installed, he finds foamy water in his gutters. He was a little concerned as to why this is happening and whether it would hurt his plants, so he called the company that installed the roof and was simply told “this is normal”.

Unsatisfied with this answer, he started calling around and reached me. In the few years I’ve been here, I’ve never heard anyone mention this issue. I apologized that none of our roofers were here at the moment for me to ask, but suggested he contact GAF directly.

Since I prefer to give helpful answers rather than pacify clients with “it’s normal”, I couldn’t just leave this alone even though he was not our client. I also felt it was important for me to know the answer for anyone else who may ask, so after some unfruitful searching online, I decided to ask our rep at Owens Corning.

He replied that during the manufacturing process for all shingles, a soapy water is used to cool the shingles and prevent the bundles from sticking together. Sometimes too much is applied and it leaves a heavy residue. Then when it rains for the first time after installation, it foams up and looks like your shingles are being washed. This is nothing the homeowner has to be concerned about as it will not stain surfaces or harm plants, and should only happen the first or second time it rains. (The homeowner said this has happened during every rain for the last 5 months, but it’s been a relatively dry spring so it may just not have rained heavily enough to have washed it all away.) He also informed me that in very rare instances, the copper used in shingles to prevent algae can cause the water to foam.

I called the homeowner back to tell him what I’d learned. He had already contacted GAF who will be sending an inspector out, but he was very surprised and thankful that I’d taken the time to call him back with answers. I told him it was a new question for me so I wanted to know the answer, and wanted to make sure he got the answers he was seeking. He said he appreciated this and wished the people who installed the roof would have told him this.

It felt really good to have an opportunity to provide him with answers after his roofer couldn’t. I did not initially have the answers he needed, but was able to get them within minutes of asking our rep. I work with a knowledgeable, wonderful crew, and our company has formed great relationships with our vendors and manufacturers. I am surrounded by the best team I could ever ask for, which in turn helps me provide better service. It’s things like this that make me love working here.


-Shannon Gassaway, Office Manager

Overlay vs. Tear-Off

Thinking about a new composition shingle roof?  Wondering whether to opt for an overlay or a tear-off?  Although each roof must be evaluated individually, there are some general guidelines to help make an informed decision.

What is a Roof Overlay?

The new shingles are applied over the existing layer of shingles.  While overlays save on time, labor and disposal costs, they can only be done if certain conditions are met.

What is a Tear-Off?

First we remove all the old shingles from the roof.  Then we inspect your roofing deck (the wooden base over your rafters) and replace or seal it as needed.  We then completely re-cover your roof with new underlayment and shingles from top to bottom.

Which option is better for you?

If there are already two layers of shingles, an overlay is NOT an option, as Nevada County only allows up to two layers.

If you only have one layer, the existing roof is in good condition, lays flat (no bumps or rolls) and has no leaks or any problems with the underlying roof deck (soft spots), then an overlay may be the best option for you.

However, a tear-off will probably be necessary if:

  • The condition of the existing shingles is so rough and distorted that it would not be practical to flatten all raised areas enough for the new roof to lay flat.  Installing shingles over existing shingles that aren’t flat can make the new roof look bumpy and make it harder for the new layer of shingles to form a seal.

  • The roof structure shows signs of sag across the ridge or truss lines.  If the roof does not look straight and feel solid, there may be structural defects.  Shingles are heavy, and adding a new layer over an existing roof adds weight to the rafters and to the structure in general. Older roofs, sagging roofs or substandard rafters may not safely bear the additional weight.

  • If spongy areas are noticed when walking on a roof, or an inspection of the deck reveals rotted/warped wood or large gaps between the deck boards.  Any rotten or damaged boards must be replaced before applying the new shingles.  Deterioration can occur when there is delamination in the plywood due to glue failure.  Dry rot is wood rot caused by certain types of fungi and if it isn’t taken care of, it can spread. If there is any suspicion of bad decking, then a full tear-off should seriously be considered, as these conditions are not always evident until the roofing is removed.

Lastly, if you are considering the benefits of the Owens Corning Preferred Protection Limited Warranty, a tear-off is required to qualify for the warranty.

The experts at Gold Country Roofing have decades of experience installing quality roofs, both overlays and tear-offs.  Contact us today for your free roof estimate, and we will give you our recommendation based upon the condition of your current roof.