How many square inches is a 2 inch round hole?

Question

I'm venting my attic prior to a new roof install, and figuring out proper intake/exhaust, and need to know the net free area of a 2 inch vent, and it's figured in square inches. I actually need to know the net free area of a 2 inch hole with 1/8 inch screen, but just the 2 inch hole would be a good start. Thanks!

Answer 1

The area of a circle is, pie x radius squared.... = 3.14in.

If it's 2" pipe you need to remeasure.  The outer diameter is normally larget than the listed size.

Answer 2

It sounds like you are installing the 2" circular vents in the soffits.  Listen, you can put in as many as you want, the reality is that you cannot over ventilate your roof.  The whole goal is to make the attic space the same temp as the outside air.  The reason that these little vents exist is because they are less noticable and easy to install, but in reality they don't give very much air flow.  These in conjuction with a power roof vent or gable end vent(powered), ridge vent and any other type of vent will be a great asset.

Answer 3

jim, most of the screens that i've seen for soffit vent holes have aluminum louvers on them, so you're not getting a true 2" opening. when you consider that many homes have a 1" soffit vent opening down their whole length, (14.5" of flow between rafters), i'd put at least 2  2" vents per rafter bay. anyways, i'd suggest that you try a few practice runs on a piece of scrap plywood or pine before you start in on your soffits, if the hole saw wanders as you drill, those vents might not stay in the holes. i've seen it happen, there are even soffit vents that look kind of like the old 6X9 car speaker covers, you may want to consider them instead. hope this helps, good luck.

Answer 4

Pi x r sq so its 3.1415926"sq