Red/Brown Stains on Cedar Siding

Hello everyone,

I had a client this morning who requested an IR scan of his living area due to major ice dams. I did my IR scan and inspected the attic and advised him on how to properly correct the ice dam issue.

My question is…What the hell causes the exterior cedar siding to stain so bad during an ice dam situation?
Is this stain from the actual cedar siding seeping (tannin bleed) and running down the side of the house?

Here are some pics…


If this cedar siding is seeping, why is it that this church has the same issue, but it is literally seeping out from the soffit area only?

Looks like years of dirt, rodent dropping, etc. picked up by the water and carried out and down.


Ya know, I was thinking the same thing once I saw the church (with the same staining) on the way home from this home.

I just want to be sure that this is what is causing the staining.

I want to see if anyone else has experienced this staining situation and investigated the cause…

 Dave I just saw a graphic of ice dam leakage which was consistent with that photo.

Hi Kenton,

Do you have a link?

It was stuck in a PDF so I took its picture

ice dam graphic.JPG

ice dam graphic.JPG


Thank you. That is a pic of a typical ice dam with typical paint peeling off of interior and exterior walls.

I’m simply looking for references to the red/brown staining of the siding when an ice dam does occur.

I’m still believing that the stain is caused from rodent droppings/urine that got wet (from the ice dam) and dripped on top the siding below.

David: Did both buildings have a new roof installed?

After a tear off, there is a lot of debris in the soffit area left behing sometimes. Asphalt, sawdust, dislodged dirt and “crap” from between the roof materials.

I can’t think of a new england used material that would come apart in an ice dam situation that would hold so much staining material at one time.

The more I look, the more I think it may be exterior environmental…

What town are they in?


This staining is from accumulated dust and mice feces.

This web page explains how and why this brown staining occurred.

No…its ice dam damage.

David, I have had experience with this brown staining of the cedar before.
The jobs I worked on showed similar staining on the building wrap behind the siding, but the leaching was minimal on the surface.

Moisture behind the cedar siding or cedar trim at soffits, if not back primed with an oil based primer that locks in the tannin in the cedar, it will leach out behind the siding or where ever it can come out on the surface of the trim.
Cedar should be sealed with oil based primers front and back before application of any water based finsish paints.
I have pictures somewhere on a disk in files somewhere. :slight_smile:

The reason I mentioned an external source is that I have stains like that on my patio roof (which is not cedar) and there is no overflow etc.

I go with interior “Crap” first, but was trying to think outside of the box if you didn’t come up with something definitive.

There is a lot of stuff to be had in the eave after a few years which will be washed out from an ice dam.

Marcel: You can still buy “oil based primers” in New England!!! :slight_smile:

They are going “nuts” with thoes No-VOC paints up there! My best friend runs a paint shop in Concord, Ma.

Yep, only thing that works on cedar

And how is life treating you Dave.? Hope all is well with you and family.

This one here;

**[FONT=Bliss-Bold][size=3][FONT=Bliss-Bold][size=3][size=2]Multi-Purpose Oil-Based Primer
**[/size][/size][/FONT][/size][/FONT][FONT=Bliss-Regular][FONT=Bliss-Regular]Even though it’s oil-based, this versatile sealer is low odor – making it a great choice for using in occupied
areas. It’s an exceptional whole-house primer that really does live up to its functional name.
[/FONT][/FONT][FONT=Bliss-Regular][FONT=Bliss-Regular]• Can be used on many interior surfaces – including wood, hardboard, cured plaster, paneling and
[/FONT][/FONT][FONT=Bliss-Regular][FONT=Bliss-Regular]ceiling tiles
[/FONT][/FONT][FONT=Bliss-Regular][FONT=Bliss-Regular]• Seals out odors and great at blocking stains – especially wood tannin stains and water-based stains
• Dries quickly and assures a uniform finish


My family and I are doing very well. The kids are growing faster than weeds and my inspection business does just fine. I hope you and yours are doing well also.

Thank you guys for your feedback.