Hi William, 

Have you looked into ridge vent? Do you know how many LF your ridge is? 

There are two options available for reroofing installations. One would be to tear off the old roof before applying the new one (tear off). The second would be to lay new shingles over the existing roof (lay over). While the second choice is the less expensive of the two options, it is not necessarily always the best choice.
There are advantages to tearing off the old roof before installing a new one. For example:

• If there are any defects in the roof deck, they will be revealed when the roof is torn off. These defects should be repaired before applying the new roof.

• If condensation problems exist in the attic, they too will be revealed when the roof is torn off.
Properly designed attic ventilation can then be installed in order to help eliminate such problems.

• When the old roof is torn off, waterproofing shingle underlayment can be installed before applying the  new roof. This will help protect against leaks created by cyclical ice damage and wind-driven rain.

• Tearing off the old roof and starting with a clean deck before reroofing may result in a smoother finished roof system. Although there is added cost to these advantages, each lessens the likelihood that the validity of the manufacturer’s shingle warranty will be impaired. If the old roof is torn off, your contractor should be responsible for the cleanup and disposal of the old shingles, but make sure your contract states this clearly.

If you do plan to reroof over existing shingles, first check if your local building codes limit the number of roof layers that can be applied to a residence in your area. Most restrict maximum to 2 layers. Your contractor should know the pertinent code requirements.

You may be asking yourself, “What can I expect my roof to look like as this aging
process takes place?” One or more of the following conditions may occur over time:
Curling: As the asphalt hardens over time, the granules which were once securely
embedded begin to break away. Occasionally you may have seen the colored
granules in your gutters. Also, as this hardening advances, the asphalt layers begin
to shrink. Of course, all of this is occurring at a microscopic level and is not
something which will be noticeable on a daily basis. As the asphalt layer shrinks,
it is being countered by the shingle reinforcement, which resists shrinking. We
now have a situation in which the top and bottom coatings are shrinking and the
reinforcement is remaining stable. As a result, the edges of the shingle may begin
to curl over time. In addition, organic shingles may exhibit signs of curling which
might be considered excessive, however, this is not a manufacturing defect and
would be considered part of the normal weathering process of organic shingles.
Surface Cracking: Another manifestation of the normal aging process may
be the development of surface cracks. For example, as the flexibilizing oils of the
asphalt are depleted due to heat, the shingle becomes more brittle, to the point
where surface cracking may appear. The stresses created by thermal shock and
the movement of the roof deck also increase the likelihood of surface cracking.
Blisters: During the course of natural weathering, small bubble-like raised
areas known as blisters may appear on the surface of the shingles. The blisters
may be small and pea-sized or as large as a quarter. The blisters may be open,
exposing the asphalt, or closed. Blisters frequently result when minimum ventilation
requirements are not met.
Staining: Finally, 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.

If you can get into your attic you should be able to see evidence of leaks. Look for staining and/or rotting wood at walls and penetrations.

Roof to wall intersections and pipe collars are probably the two most common locations. What is the height and pitch of the roof? I don't suggest hitting the roof with a bunch of water unless you know how to spray it. Shooting water from the bottom up can facilitate a leak on a roof that is otherwise working properly.

An attic inspection is a good idea an if you can separate out the difference between bulk water and condensation stains, you should be able to put an eyeball on the leak.

Good luck and do not get on the roof unless you know how to walk it and have PPE.

WoW Home Solutions.

One easy way is to simply go into the attic space and look around and see if there is any staining on the underside of the ply wood.  The most common areas are around pipe and chimney penetrations, in the valleys or where the roof terminates into a wall.  If your roof is walkable, and you feel comfortable enough to get up there, you can also use a garden hose and attempt spraying the roof from different angles to see if any water gets through.  Over all though, if you see any discoloration at all, then water is penetrating some way.

Make sure when you have a new roof installed that you check for the proper licenses, insurance & accreditations.  Get recent and old references.  Ask if they are going to use Gutter apron at the eaves and drip edge on the gable.  What type of ridge vent will they use?  Will it have a baffle in it to prevent wind driven snow from entering your attic?  Will they use ring-shanked nails for the ridge vent so the ridge vent nails won't back out over time?  Make sure you understand warranties and the fine print of these, especially the pro-rated portion.  Make sure to address both intake & exhaust ventilation, as well as attic ventilation as all of these properly working will dramatically extend the life of your roof and save on energy costs. A great way to educate yourself is to do searches on YouTube or you can visit our website www.croixco.com for helpful ideas and questions.  Check out our Pinterest page for other great pictures and ideas.

Michael,

Eric pretty much nailed it. 

It is not usually worth it in my opinion and especially given the nature of most leaks and the condition of most sheathing. 

Roofs aren't cheap so I think the math usually plays out that the full tear off is a better idea based on the fact that you get a better install and will likely have a roof that will last longer.

WoW Home Solutions

Hey Michael,

Here's a quick guide to show your the pros and cons of having asphalt roof shingles applied over your existing roof: 

+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

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.