Dark or light stains on your roof might be more than discoloration.  They could be signs that your roof is infested with mold, algae, lichen, moss, or other small organisms.  It's possible that all your roof needs is a good cleaning, but these organisms can cause (or be an indication of) underlying roof damage.   Only a trained roofing professional can tell for sure.   And if your roof has already suffered damage, it's critical to have your roof repaired or replaced before the damage penetrates to the underlying structure and causes further deterioration. 

What all these have in common is a damp roof.  Asphalt and wood roofs can get damp, and if they stay that way in warmer weather, they can be the perfect breeding ground for things like mold.  Once any of these growths get a foothold in a spot on your roof, they will reproduce and spread, and will also attract others like themselves, as well as other organisms.   Moss, lichen and algae are like other plants - they have roots, and once they put those roots down into your roof, they will cause deterioration of the shingle.  Eventually the roofing is compromised, and you have a prime spot for a leak.

Why are some roofs prone to this?  There are many factors, but the common cause is a damp spot on the roof.  It could be that your roof has overhanging tree branches that keep it always in the shade, or your roof pitch is low and at times doesn't easily shed water from heavy rainfalls.  Or perhaps your roof is already damaged or you have loose shingles that are trapping water.  Whatever the cause, and whatever the organism,  it's important to have it inspected and taken care of right away.

Even if your roof doesn't need a repair, just a good cleaning, it's only a temporary "fix."  Unless the conditions are changed that caused the problem in the first place, it will recur.  Quarve Contracting, Inc., the St. Paul/Minneapolis area's leading roofing contractor, has a great permanent solution for moldy and similar roofs.  Quarve highly recommends steel roofing.  By its very nature, steel is impervious to mold, mildew, and other infestations from damp conditions.  Microscoping roots can't get a hold on it.  And steel naturally sheds water much better than asphalt or wood.

Roof stains?  Don't ignore them; Call Quarve Contracting today for a free evaluation.  Now serving Roseville and Vadnais Heights.