Does Every Rafter Ask Ane?

When I started my investigations into attic insulation, I idea you alone needed baffles if the soffit panel below was vented. However, when I studied the International Residential Code (IRC), I establish that this was non the instance.

Baffles serve 2 main purposes. They protect soffit vents from being blocked by insulation, together with they channel air up through the attic. Without a baffle-per-rafter setup, this moment role is non performed, together with the kickoff tin readily be compromised.

If air-permeable insulation is installed in vented attics, and so baffles are required. They must be installed continuously, i.e., inwards every rafter, according to code. The reason is to preclude the incoming air from moving into the insulation equally opposed to existence funneled to a higher place the insulation via the baffles.

Purpose of Baffles

As mentioned, baffles serve ii functions for attic insulation. This start, preventing soffit vents from beingness blocked, is the 1 that most people focus on, which is what leads just about people to assume that if in that location is no soffit vent below that rafter infinite, y'all don’t involve a baffle.

At beginning glance, you lot power think that this reasoning as well applies to the moment purpose, which is to funnel air upward from the soffit vents to the upper vents, creating proper airflow through the attic.

If air is exclusively coming through vented soffit panels, then surely the not-vented ones don’t require baffles.

However, if you expect at the mode a typical roof is constructed, you lot tin meet why this is not advisable. The eaves are a continuous space, in addition to the soffit makes upwards the “floor” of that infinite.

The rafters extending past the acme plate to create the eaves offering just about separation but make non create perfect “walls” between next spaces.

This way that insulation, especially unloosen-fill up insulation, that falls into the eaves at a non-vented soffit has the potential to migrate to embrace a vented soffit panel.

Note: Batt insulation nonetheless requires baffles

It as well way that air coming inwards through the soffit vent can act sideways instead of following the class of the roof.

Insulation slows or stops the passage of air, and so this is not going to promote proper airflow.

Why Airflow Is Important

If an attic space is not finished, it must live ventilated. This is to protect it against heat as well as humidity that may build upwards over fourth dimension.

Since estrus rises, it oftentimes gets trapped inwards attic spaces. Ventilated attics are as well in contact with cooler air exterior. When the hot together with common cold air come up into contact amongst each other, the hot air cools, releasing any wet it is carrying. The event is condensation.

A hot as well as humid surround is non practiced for wooden beams, metallic fasteners, and insulation. All tin can degrade over time. Rotting wood too rusting metal compromise the structural integrity of the habitation, together with moisture insulation cannot end thermal transfer effectively.

In improver, there is a really real take chances of mold, which tin further harm these materials together with which poses a chance to the wellness of the people as well as animals living inwards the house.

Proper airflow agency that the hot air in addition to the moisture it carries are pulled out of the menage together with are replaced every bit opposed to mixed with cooler air from the exterior. It too prevents the stagnation of air, which is not good for air quality.

Continuous Baffle Installation Required

Baffles are required past code, together with if y'all look at the rule stating this, it speaks most situations where soffit venting is non continuous.

It says in Section N1102.2.three that inward these cases, baffles must be installed continuously, meaning one inwards every rafter.

The reason is fifty-fifty provided in the IRC. This reason is to forestall the air from bypassing the baffle. In other words, it prevents the air from moving sideways in addition to getting lost in the insulation of next rafters.

Sources

https://homeguides.sfgate.com/important-using-baffles-attic-insulation-78043.html

https://attic-air.com/2019/11/xiii/baffles-rafter-vents/