We live in a Colonial with two dormers. When we have high winds, light, powdery snow will blow in through the soffit vents into the unfinished attic. When the snow melts, we have (small) leaks and water stains. How do we keep it out?
I used to have similar leaks until I installed baffle vents and a plywood subfloor. After installing the plywood, any snow that blew in landed on the floor, melted and eventually evaporated. Baffle vents are also called rafter baffles, attic baffles, channel vents, vent chutes, proper vents, and a boatload of other names. Try this: install Styrofoam rafter baffles and seal them in place. You’ll need to crawl to the end of the eave to access this area and insert the baffle into the rafter bay, keeping the outside edge of the baffle parallel to the exterior-wall sheathing. Staple the baffle against the roof deck about every four inches. Make sure there is a clear airflow path through the baffle. Don’t crush or damage the baffle—it’s easy to do. The goal here is to create a ventilation channel and to seal off the open soffit/eve area. Once the baffle is in, install plywood on the floor joists or rough fit foam board around the baffle to protect the rafter bay below it. Seal the plywood or foam board with a bead of foam sealant, then fit foam-board blocks to close off and separate the soffit area from the attic. Installing baffle vents and sealing them will also increase the effectiveness of your insulation. It’s not an expensive project and can be done with minimal tools and materials.
Tune in for part 2 on venting frustrations later this week!