There is nothing like a beautiful sunny day to enjoy. The warm light raises ones spirits as high as the sun itself. There are many days where I find myself atop a roof, a gentle breeze brushing my sun warmed face and I think how nice it would be stay up there a while longer.
As most everyone knows, while that sun light may feel great, too much can be detrimental to ones health. With houses, the sun can be a blessing and a curse. Warm light through a window is a delight on a cool morning. But on that same warm roof top perch, the shingles are baked continually. If left on to long they can become similar to overdone pieces of toast.
Below the roof covering is the attic which becomes like an oven from the baking being done from above. It has long been known that an attic without a means of relieving the built up heat will cause numerous problems for the building. Attic ventilation has been the answer for many, many years. The other reason for venting is to dry out the attic when the temperature drops. Moisture diffuses into the attic from the conditioned spaces below. It must be dissipated or it can collect, condense and cause decay.
Recently I found the results of excessive moisture which has been accumulating and condensing on the roof sheathing in an attic. The entire slope was in this condition. You can see the soffit vents in the photo. The vents were properly installed and as best that I could tell were open. The ridge vent was checked and found to be clear. When all systems appear to be properly installed and working the culprit should be looked for below the insulation and inside the house.
In an attic where the ventilation is working and not being over whelmed the roof sheathing should look like the second photo.
Or should it?
The second picture is from the same roof but the opposite slope. The difference is dramatic. The reason for the difference is the roofs orientation to the sun. This slope faces the sun, while the other is shaded. There was some confusion as to why this would be happening because the clean side of the roof was shaded by large trees.
Trees in Connecticut loose their leaves in the fall. The sun is unobstructed for a good five months during the cold weather. This issue, as I mentioned, is more of a cold weather phenomenon. As the sun can dry out a puddle, so can it dry out the underside of a roof.
The sun has in this instance been a benefit to one side of the roof. Unfortunately the condition of other side of the roof doesn't look so bright.