Brick and mortar chimneys exposed to water over time will deteriorate. Though bricks are more or less indestructible the mortar holding them together is prone to damage and eventual failure. Once the mortar between the bricks cracks and begins to fall out the bricks and structural integrity of the chimney are sure to follow.
These pictures show some typical long term water damage to the mortar between bricks on a above roof chimney. Someone noticed this problem before and attempted to fix the failing mortar with silicone caulking. This is not the correct repair technique - caulking is not going to do anything to stabilize the brick.
This chimney needs repair - the bricks need to be "re-pointed". Re-pointing is the process of removing the old mortar joints and replacing with fresh mortar. This is within the realm of ability of most homeowners but it is a tedious job and depending on location could pose some safety concerns. If this project doesn't appeal to you or you are not comfortable being on your roof, look for a masonry repair specialist to do the job.
The following is a link to a nice overview of repointing-brick on the This Old House website.
It seems like an easy solution. Put this zinc strip on your roof one time and you never have to worry about moss accumulation again. Do these zinc strips actually work? If you read the marketing the answer is yes, but reality is a bit different.
Zinc strips do help prevent some moss, but they aren't totally effective. The theory is that you attach the zinc strip to the peak of the roof and use rainwater running over the strip carry particles of zinc down the roof to kill existing moss and prevent future growth.
The picture below shows a zinc strip in real life. It's been in place for a few years and rain run off has been carrying zinc down the roof. As you can see, the top of the roof is fairly clear of moss growth but only for a few feet of roof surface. The zinc can't get all the way down the roof and moss is still growing on the bottom 2/3 of the shingles.
So are they worth it? Probably not if you only put them at the peak of the roof. They only control moss for a short distance down the roof and don't prevent the need to clean the lower portion.
You could put a strip at the peak, a second strip about 1/3 down the roof and a third strip 2/3 down. This would probably do a better job of moss control but it is a bit unsightly and putting nails through the shingles to attach the strip can lead to other water damage.
I wouldn't recommend using zinc strips for moss control. The better option is a yearly cleaning of the roof with a broom and applying a moss control agent to the entire roof surface.
The picture above shows a common problem in the Northwest; moss growth and piles of pine needles on the roof. Our frequent rains and lack of sunny days lead to a lot of water on our roofs . If the roof is not kept clean of pine needles and other organic debris, water will stick around on top of the roof and eventually be a prime area for moss growth.
Moss loves these wet areas and likes to grow on top of and in between the roof shingles. The shingles are raised up by the moss which allows water to get underneath which will lead to damage of the roof sheathing. If you trap enough water next to the roof you will eventually get a leak.
The pictures above are the same area before and after cleaning. This corner of the roof had heavy moss growth from a few years of neglect. The tree branches that hang above this corner aren't helping. They provide shade and an extra source of water from dripping branches.
It just takes a few minutes of work with a push broom to get all the moss off the shingles. You do have to be a bit careful to avoid taking all the granules off the shingles. Moderate pressure with the broom is all that is needed. Too heavy of a push and you can damage the shingles.
DON'T USE A PRESSURE WASHER. Seems like it would be a lot easier but if you use a pressure washer you are guaranteed to damage the shingles and shorten the life of your roof.
You can't see it in the pictures but the last step is to sprinkle a moss preventer on the clean shingles. I like to use the shaker bottle of Moss Out. A 6 pound container will take care of most roofs. This should be repeated every year to maintain a moss free roof.
Clogged gutters are generally out of sight and out of mind until you start to notice that slow dripping after a rainstorm.
Roofs are a water shedding system and gutters are designed to take all of the runoff and direct it away from the house. For the system to work properly, the gutters need to be capable of collecting a large volume of water and directing it to the downspout.
The gutters in the pictures above have a bit of a problem. They are filled with tree leaves, pine needles and are a prime breeding ground for moss. Water draining from the roof is supposed to enter the gutters on the eaves and have a controlled path to the ground through the downspout.
With these gutters, water can enter but it can't flow toward the downspout. Water will pool and eventually overflow the edges both next to the roof and over the far edge. This moisture will wick up into the roof sheathing and under the edge shingles causing damage over time.
As you can see in the pictures below, prolonged pooling water has damaged the eaves of the roof and are causing rotting on the sheathing and fascia. This weakens the connection of the gutters and they have started to pull away from the house. Water from the roof will not get all the way in to the gutter and will instead run drip over the fascia and wick into the eaves. If this goes on long enough, damage will start to occur on the walls of the house.
The solution to this problem? These gutters need to be thoroughly cleaned and re-attached to the house. That will help mitigate the immediate problem but to help prevent future problems, the homeowner needs to start a regular, yearly cycle of gutter cleaning and maintenance.
Check out the video below from This Old House on repairing an aluminum gutter system.
Brian Jovag, owner of Jovag Home Inspection.