How to Add Vents to Boxed Eaves That Overhang the Roof
A proper attic ventilation system takes a balance between air consumption throughout the soffits and exhaust through the roof, the roof deck or the gables. The soffits are the boxed eaves, where the roof overhangs the walls of your house, and the vents which you install in them contain little more than holes with metal covers. Installing a soffit vent is uncomplicated; the only difficult part is computing the amount and sizes which will create the desired airflow.
Attic Ventilation Fundamentals
In a properly vented attic, cold enter passes through the lower sections — usually the soffits — warms up, rises and exits through vents in the roof or gables. This movement of air is essential for preventing condensation build-up which may decay the framing and promote mold growth; it also retains the loft — and home — cooler in warm weather. In general, the Uniform Building Code requires that the total venting region be equal to 1/150 of this attic floor space. If the ventilation room is evenly distributed between soffit and roof vents — in other words, the vents are balanced — the signal enables the ventilation area to be reduced to 1/300 of this attic floor space.
Choosing Soffit Vents
Soffit vents come in many forms. The most frequent ones are rotating, but you can also locate around ones and strips which span the whole length of the soffit. Appearance of the vents is an important consideration — they should mix nicely with your home’s layout — but it’s more important to pick ones that will provide the proper quantity of airflow. To determine this, do not forget that the soffit vents constitute just one half to the total venting in the attic. Calculate your attic’s floor space and divide by 300 times 2 to get a balanced system to determine the entire amount of soffit ventilation you require. The areas of all the vents you buy should equal this amount without exceeding it.
Installing Soffit Vents
Prior to cut holes at the soffits to your new vents, you should measure and draw outlines for them to ensure they’re evenly spaced. You must also be careful to not put one in front of a rafter, because the rafter impedes airflow, so use a stud finder to find the rafters if the nails are not visible. Cut the outlines with a reciprocating saw or jigsaw and an all-purpose cutting sword. To get the saw started, drill a hole through which you may add the blade. The port completely covers the hole and then overlaps the edges by a inch or so, and you bend it into the soffit with the screws that have it.
If your attic is insulated — and it should be to minimize energy loss from your home — you need to take steps to keep the insulation from the port openings in the soffits. Simply pushing away the insulation from the gaps usually isn’t enough, because it can fall back. 1 strategy is to build a dam about each vent with wood or cardboard, but it’s even simpler to install baffles. These inexpensive cardboard or plastic corrugated sheets are designed to attach to the bottom of the roof and fit over the vents. They prevent insulation from blocking the vents while providing a pathway for air to circulate into the attic.