Adding vents to soffits - recommendations?

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Old 06-17-20, 10:31 AM
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Adding vents to soffits - recommendations?

We're getting our house painted later this year and want to take care of things that have been hanging out.

roof over our garage has a gable vent for years - installed before we bought the house 25 years ago. But no soffit vents.

Our crap roofer 2 years ago put in a ridge vent and said he would put in soffit vents. But never did (besides loads of other screw ups... so it's not for him to do. But for me to do now). Would you bother? it's an unheated area / no insulation since it's over garage.

We have these every few feet apart on soffits of main roof:

https://www.homedepot.com/p/Master-F...6X8W/100023618

The box they were in say they are 50 sq. inches of ventilation.

There's 4" round vents but they say they are 5 sq inch. ventilation. These woudl be much easier to install with a hole saw, but I'd have to put in 10 of these to equal 1 of the rectangular ones.

What would you use? Is it hard / any tips on cutting a rectangle above your head in the soffit while up on a ladder? what tool woudl you use? A jig saw?

But you can't control the depth when you hit a joist : ) (I like the idea of cutting the ridge vent with a circ saw set for shallow depth.


2nd - we have a whole house fan (in ceiling of 2nd floor). It blows air up into main attic, then out the vents.

For years, I can feel air coming out from wall switches on 2nd floor - (attic air gets compressed / can't get out only from gable, ridge, soffit vents. so it finds ways down wiring holes back into house) I think there was a drop in this when ridge vent was put in. But still there. and certainly not going to move your hair (not strong, but noticable).

Would you add more soffit vents to give air more space to get out? I checked the gable vents and they aren't blocked. I have to check the soffits to make sure they are working.

And for the rectangular soffit vents, what do you use to secure them? Tiny screws? nails / brads? stainless? or galvanized OK / don't leave rust marks on underside of soffit?

THANKS!
 
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Old 06-17-20, 10:50 AM
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If the garage is unfinished (open ceiling) I dont see the point. Generally you dont need to use gable vents and ridge vents together. They suggest you close gable vents with ridge vent because wind is more likely to suck water or snow into the ridge vent if there is an exhaust vent right on the end of the roof. If you want to cut 6x12 vents in you can, you just need to set the skilsaw 1/2" deep and cut them. Finish the corners with a jigsaw or hand saw. Screw them on with stainless screws. Small holes really arent as effective at venting, the velocity of air movement slows as openings get smaller.

Attic ventilation is a simple ratio calculated by the sq ft of attic space with the sq ft of ventilation. Any sort of powered device is going to screw up that simple ratio. When it is on, it is probably blowing air out of any place it can. Your soffit intake becomes an exhaust. If you have positive pressure in the attic and air is also coming out of your outlets it means you have poor air sealing... penetrations that aren't sealed, and air is being forced down those holes in your top plates. Positive pressure is simply what is pushing that air out. If there wasnt any positive pressure, none of that air would be forced out of the attic. It does not in itself mean you need more ventilation.
 
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Old 06-17-20, 12:17 PM
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Thanks! Don't see the point? Of soffit vents?

The circulation in the atttic - from soffit up and out gable or ridge - that's partly to keep the attic cooler for living space below? but also keeeps roof cooler?= longer life? and ventilation helps with moisture? yeah, no showers / people below for humidity to come up from garage. But humid day moisture gets in? Then gets out on dry day so not an issue?

Positive pressure - you say things sooo much better than me : )

yeah, I was going to acknowledge - I didn't seal penetrations for wires going down from attic.

yes, I heard the no gable AND ridge vents.. .reminds me - that was another thing the roofer said he was going to do - close the gables. Thanks for the reminder.

Oh, and I had / he put in a roof power vent also. He left that unhooked up (yes, he was supposed to wire it / get an electrician. But didn't. There wre other issues I discovered before adding 'and you didn't hook up the fan', so it wasn't that I pointed it out too soon - he said he was done. maybe forgot to get his guy in there, but that's just 1 more of a load of things he screwed up.

What's your thought on having all these - power roof vent, gable and soffit?
 
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Old 06-17-20, 12:22 PM
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If the garage is unfinished, I think the garage has a lot more ventilation when you open a garage door, than by cutting in a few 6"x 12" holes in the soffit. And if you already have a gable vent, I dont think you will even notice a difference by adding soffit vents.

I dont think much of any power vents. They also exhaust conditioned air from the house, which you have to replace and either heat or cool.
 
 

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