Attic ventilation is so much more important in recent years as it and the science has evolved over the years and a much deeper understanding of the cause and effect or lack there of. Over the years state county's have been enforcing strict building codes on this subject. ARMA which stands for the American Roofing Manufacturers Association recommends a 1/300 ratio for a minimum of a balanced system of intake and exhaust.

(The picture to the left for even minimum building code, does not have enough intake)

I myself have been in the roofing industry for about 12 years now and it is quite a science better left to a roofer that understands it. I run into attic ventilation problems all too often doing roof estimates here in Arlington/ Marysville Washington areas. The problem with new construction homes is usually caused by lack of knowledge and communication between contractors and workers, now with older homes it is happening to, is caused when homes are remodeled or in other words changed or altered and made more airtight such as new siding, windows and doors we have to remember always that the goal when designing a ventilation system is to create a pressure. Have you ever taken a 2 liter bottle and dumped it down the drain? 

it goes blurb, glub and blurb try it, then poke a hole in the bottom then turn it upside down to drain it, it becomes much smoother when draining it the second time. 

The APA American Plywood Association also recommends proper ventilation. With out proper ventilation it usually costs home owners much more the second time they put a new roof on there home. I have priced out the cost difference between having a mold/mildew company spray stuff in regards to having a roofer replace the sheathing and it is half the cost if not more for the roofing company to do it. Usually with ventilation problems that go not taken care of for years can be very costly when its time to re-roof. At All Sound Roofing, Inc. we take ventilation into consideration on every roof of ours we install bird blocks along eves, OHAGIN intake vents, Louvered drip edge and Edge-vent, I feel we offer some of the best choices.

(In the photo below we had to replace all of the sheathing)

     

Installing these vents along the bottom is a BIG no, no they typically leak and they are designed to be vents for at the top of the roof not down low along the eves that and they are not rated for intake.

Arlington Washington

When it comes to re-roofing homes in Snohomish county of Washington state we come across all sorts of weather from some nice sunny weather to rain with in minutes of eachother. Having ice and water shield installed on your home can NEVER be a bad choice when it comes to a huge investment such as your roof. When properly installed along your eves and around all penetration areas of your roof you can be sure you are going to be protected against wind driven rains and towards the end of your roofs life cycle. Its never a bad idea for a little over kill when it comes to your roof. Have you ever used Google for small purchases by reading reviews?  Google the products in your re-roofing proposal from your contractor make sure its a company that produces premium materials. We only use Certainteed and Malarkey roofing products when it comes to asphalt shingles.