Over a period of time, shingles may develop dark brown or black streaks that are sometimes mistaken for soot, dirt, moss or tree droppings.  In actuality, this discoloration may be caused by algae growth. Although most
roofing systems are susceptible to algae discoloration, it is most readily visible on white or light-colored shingles.
Today many  of the newer asphalt shingles have an Algae Resistant granular system that guards against roof algae. The system uses copper roofing granules from 3M to prevent algae growth‚ protecting the roof and preserving the home’s be auty.  Here is a link to a good explanation....  http://roofpedia.com/algae-resistant-roof-shingles/ 

Air sealing and insulation of the exterior top plates is critical to preventing that warm and moist air from warming the roof deck.

Attic ventilation is critical to keep that attic dry and as close to ambient air temperature.

Keep in mind that some ice dams are not preventable regardless of insulation and ventilation.  That being said, I would venture a guess that 90% of ice dams are the result of poor insulation and ventilation. 

+1

Impossible to say without inspecting the roof but some will live quite a long time based on exposure, correctness of installation, ventilation, etc.

There is quite a bit of variance and human contribution when it comes to getting the most out of the roof as well so when you do replace it, be sure to deal with someone that knows their craft and will educate you on the decisions and material selections that will work most effective for your home.

WoW Home Solutions

One easy fix for homeowners to prevent ice dams from the attic is to ensure proper airflow "intake" from the eaves.  In many cases, the insulation is blown tight to the soffit which cuts off the ventilation at the intake.  Installing Styrofoam baffles at the eaves between the joists to create the required 2" separation is fairly easy to do from the attic area.  I normally would not recommend homeowners to take on this challenge unless they have experience working in the attic.  Since the flooring in the attic area is not finished in most cases, the homeowner must be careful to only step on the joists when working or they will potentially fall through the ceiling / drywall.  For this reason, it is recommended that a professional handle this type of install to avoid injury.

Eric Consuegra, Arocon Roofing & Construction

First have your roofer do a visual inspection for obvious areas where water could enter your home.  Then, do a simple water test.  Have one person look in the attic and one person in the home.  Have a roofer go on the roof with a running garden hose. Have the roofer start introducing water at the lowest parts of the roof and work up.  Have all 3 people on a cell phone conference line so that if water is seen coming into the attic or home the person on the roof can shut off the water. 

Hello Terry,

What kind of roof do you have? Is it an asphalt roof? The average lifespan of asphalt composite roofs is 10-15 years. Depending on how extreme the weather is in your area, some roofs made with temporary roofing materials may start to fail as soon as eight years.  

The most common cause of this type of dark spots is a variety of blue/green algae called a  Gloeocapsa Magna. Ths stains often evolve to a moss buildup, as the algae increases moisture. That is not only an appearance problem, as algae proliferation may shorten your roof life and increase energy costs. (You mentioned you recently added more insulation to your attic. Not only that was probably not the cause, but potentially, even the need for the extra insulation is already a sign of an underperforming roof.) 

There are products on the market to clean it, but keep in mind the algae also reduces the composite integrity, so removing it may still keep your roof exposed.

It would be advised to call a professional inspector to do a roof and attic inspection. It can identify any other related issues and give you a timeframe of how much longer can your roof can hold. 

Also refer to your warranty, keeping in mind each manufacturer have a different levels of protection. 

When it's time to re-roof, you may want to consider other lifelong roofing materials (such as metal).  

Feel free to contact us if you have any other question.

Regards,

Carlos (social@interlockroofing.com)

Definitely before you do the roof, masonary work and any flashing around the chimney should be done prior to starting on the roofing.

Hello Nia,

Please give us a call, 469-569-3551. We are a general contractor that specializes in storm restoration. We can handle any project, from the roof to interior repair.

Matt

CTI CONTRACTORS.  We help you through the insurance claim process..

Masonry work first. Best, Ken

The masonry work should be performed prior to repairs to the existing roofing, unless the roof is leaking, whereupon you may need to make intermediate repairs to stop the leaking while the masonry work is performed.

Each case is unique but in general, the chimney should be done first. Special attention should be paid to the roof flashings around the chimney.  If the flashings are behind the stone then make sure they extend far enough into the shingles so the new roof can be flashed properly. If the flashings are surface mounted and there is a counter flashing then the roofer should have no problem making the chimney base watertight   

It is always better to repair the chimney prior to any roofing work. This way the new roof doesn't get damaged.