Nailing It Down
By Dave Murnen
and Pat Beaty
One good look at the roof of a house will tell a lot about what is going on under it. Many major house problems have to do with trapped moisture and built-up heat. A roof’s many parts and surfaces reflect any lack of proper ventilation, no matter where the source, in a house
Shedding water and sunlight away from the living space is your roof's function. An unventilated roof will hold heat and moisture in the attic. Trapped moisture and heat create a terminal problem. A composition roof shows loss of granules and curling shingle tips, while wood roofs tend to rot very early. For most roofs, wood or composition, trapped moisture can reduce its life by half.
To keep your whole house healthy, take steps to prevent built-up moisture laden air. Prevention begins at the foundation by placing black plastic sheeting on the ground, under the house. Install enough skirting vents to equal 1 square foot of venting for every 150 square foot area of the foundation (length times width divided by 150). In the living areas of the house, remove moist air with operable windows and vented power fans in the kitchen, every bathroom and the laundry room. Finally, and the focus for this article, eliminate built up heat and moisture through proper attic venting.
The concept to remember, here, is that heat rises. On a hot day an unvented attic can easily reach 130 degrees or more! Hot air absorbs a tremendous amount of moisture and virtually creates its own weather, a rain cloud in your attic! This stagnant, moist cloud is a monster that wants out of the attic! It is eating your roofing, creating dry rot, supporting bug infestations and robbing your roof of its potential life. The solution, however, is so simple; high and low roof venting.
When you go into your attic, the air temperature should not be any higher than it is outside. The proper mix of high and low roof venting creates its own air movement, removing the heat and moisture as a chimney removes smoke.
There are many kinds of roof vents; gable end vents, powered vents, continuous ridge vents, under the eave or soffit vents and cap or pot vents. To do the job properly, requires combining
some of this system types.
You are probably wondering about your roof by now. This is what you want to see:
• Roof vents that follow the rule of 1 square foot of venting for every 150 square foot of attic floor. The best combination of high-low roof ventilation is ridge venting in combination with under the eaves strip vents. They will help your roof meet—even exceed—its designed life-span.
• Quality roofing material. There are many types; from clay tile to metal panels, wood shake or shingle, to a vast line of composition types. Our rule of thumb is not to use any material that does not have at least a 25-year guarantee rating.
• Factory painted galvanized or stainless steel metal, called flashing. Metal flashing, used at all edges of the roof and where the roof meets a wall, chimney or skylight, is vital to weatherproofing.
• Good roof jacks. These are the weatherproof gasket you should see at each plumbing vent-pipe and at your electrical mast. Made of lead, rubber or rubber-with metal, roof jacks are weatherproof as long as they are not brittle, sun-warped or have holes.
• Varge boards. These are the trim board at the side- edge of the roof from peak-to- eave, and fascia boards, the trim board at the bottom of the roof. These two types protect the roof’s ends and edges from rain and separate the exposed framing parts from water and contact with moist gutters. Both, usually made from cedar and kept well painted, will last for the life of the house.
• Gutters and down spouts. This combination prevents excess rain water from damaging the windows, doors, siding and trim. Gutters collect rain water closest to the source, right off the roof. When conveyed, even a few feet away from the foundation, it will reduce, even stop this water from getting under the house. Splash blocks or storm drain pipes do this best.
• Power fan vents. Cooking and bathing produce tremendous amounts of moisture. Opening windows helps it to escape, but powered fans in these rooms, vented through ducts to the outside are by far the best. These vents will have a flapper so the wind cannot push air back into the house.
So that is what you want to see, but what if you see some of the bad things we have mentioned? Here’s what they mean and what you need to do:
Curling, rotted, damaged roofing? Too late! Hire a reputable roofing company to remove the old material, repair any structural damage and properly ventilate the attic.
Rusty flashings or no flashings. Proper roof replacements have new flashings. If the roofing, however, is still good, replace the bad flashing before leaks and interior damages occur.
Moss, leaves & plants. Vegetation belongs in the garden. Anything growing on your roof is a sign of poor maintenance and will shorten a roof’s life substantially. Make a point to remove anything on your roof that is growing or has fallen from trees. Install zinc strips to prevent moss growth.
Now, look at your neighbors' roofs. You will begin to associate with good roofing materials and flashings, proper ventilation techniques and routine maintenance with a good roof. Remember, it covers the two largest investments you will ever have—your home and your kids.
Do you have questions about home repair or need help in becoming a homeowner? Call Aberdeen Neighborhood Housing Services at 533-7828 or visit us at 710 Market St.. ANHS is a non-profit organization committed to creating safe and affordable housing for all residents of Grays Harbor County.