How Important Is Attic Ventilation in the Winter?Posted by Nicole on February 26th, 2019

Many homeowners believe that ventilation is only important in the summer, but it is just as important in the winter! Did you know that the primary cause of ice dams is lack of ventilation, not necessarily lack of insulation?

Ice dams are barriers that occur near the gutters and eaves of the roof, causing water/ice to back up under the shingles at the drip edge. The cycle begins with heat being trapped in the attic (lack of exhaust ventilation) which traps heat in the upper attic near the ridge. This condition melts the snow/ice at the top portion of the roof and prevents the snow/ice from melting near the bottom of the roof (at eaves/overhangs). The melted snow/ice then runs down the roof and collects at the eaves where it freezes/refreezes, creating an ice dam.

Large snow events are rare in Portland, but severe ice damming can cause the shingles, roof sheathing, rafter/truss tails and top plate to be damaged. If not fixed, the damage can cause mold and mildew.

Although adding more insulation can slow down the heat transfer from the interior living space, the heat transfer will still occur and, without appropriate ventilation to take that warm air away, the ice dam will occur.

It is important to note that your attic should be very close to the exterior temperature! A well-ventilated, well-balanced ventilation system ideally keeps the top of the roof and the bottom side of the roof close to equal temperatures, eliminating the conditions required to form an ice dam.

Call me if you’d like an evaluation of the ventilation and insulation in your attic! Building science is my passion.

Ice dam

Diagram courtesy of Connell Insurance.

Why I Used to Specialize in Houses Built Before 1947Posted by admin on April 5th, 2013

So many people have asked me why I have such a passion for homes built before 1947. Why 1947? What significance does that year have? In the architecture and urban planning realm, this year is pivotal. World War II ended in 1945 and veterans returning to the US were finding themselves in need of affordable housing. Because of this, President Truman approved a program called the Veterans’ Emergency Housing Act on On May 22, 1946.

Essentially, the Veterans’ Emergency Housing Program (VEHP) was to create lots of houses (one million were planned to be started in the first year) to be built very quickly and consequently sold for less money due to the volume. This essentially created a factory of mass-produced homes that ended up looking mostly the same, lacking the quality construction and detail that homes built before this time had such as Victorian, Tudor and Craftsman. This also made construction materials more affordable and created jobs. Building materials were decontrolled and channeled into these low- to mid-price houses.

The land that was used for these new houses was generally on the outskirts of established towns and city cores- the land was cheaper the further from the city center it was. This created a reliance on the automobile which was just getting popular and becoming considerably more affordable during this time. No longer did people need buses or public transportation- they now had cars and along with it- complete freedom. These developments are called the suburbs.

Now, any architect or urban planner will tell you that the suburbs are not the place where innovation happens or where communities thrive. Density and high walk scores are better for successful cities and communities. Suburbs create and nurture sprawl and sprawl is a waste of resources. I could go on and on about this, but I’ll spare you the theorizing. If you are interested in the exact source of my specialization/interest and some really good info about suburbs and how they came about, I highly recommend the film “The End of Suburbia”- it’s available at your local library for free.

Radon in Portland HomesPosted by admin on January 24th, 2013


You may have heard about radon recently- I’ve read about it on oregonlive¬†and heard about it on the radio. Radon is an odorless, colorless radioactive gas that is known to cause lung cancer. New construction in Portland requires radon venting from the soil to the exterior of the home, but older existing homes don’t usually have this venting. Where is your home located? Are you at risk? If one in four homes in the Portland area are at risk for radon- don’t you want to know if you are one of them? It may be time to get your home tested- it’s well worth the cost!

Cascade Radon has some great links as well as info about a $10 test kit and a free radon forum on Thursday, January 24th (tonight!) at Portland Water Bureau’s Water House (1616 NE 140th Ave.).