Attic venting

[Tjdeerslayer37]

Question for all the construction guys in here, as i know there are plenty! Gearing up to re-side my house soon and I'm trying to sort out the attic ventilation needs.

A little info on the house- 600 sq ft ~20x30 (yeah, i know its tiny), roof is built in a T shape, there's a gable at the rear of the house and then at the front of the house there's a gable on each end. 1940s build. Some type of loose-fill insulation between the ceiling joists, probably cellulose. no insulation between the rafters. asphalt shingles. southeast Michigan.

Currently there is only 1 gable vent at the rear of the house, with no vent fan in it. i *think* there is a roof vent or two but its been a while since ive been up there. there are no ridge vents, and only 5" of overhang on the sides so not enough room for soffit vents.

So how do I determine if the current vent setup is sufficient? I don't seem to build any kind of significant ice damming anywhere in winter and the snow sticks on top pretty evenly. should I add a vent to each of the front gables to introduce some cross flow? Leave it as is? Some other improvement?

Thanks!

 

[WV Mountaineer]

How old are the shingles? A attic not vented properly will have some tell signs. Any mold? Staining of the joists or rafters?


My guess is if the old shingles lasted to warranty, you have plenty of ventilation.

Not enough ventilation will show pretty quick on shingles.

 

[Tjdeerslayer37]

How old are the shingles? A attic not vented properly will have some tell signs. Any mold? Staining of the joists or rafters?


My guess is if the old shingles lasted to warranty, you have plenty of ventilation.

Not enough ventilation will show pretty quick on shingles.

10 years on the shingles, im sure theyre economy grade as the house was a bit of a landlord special before i got it. ill check joists and rafters when i get a chance, good thinking

 

[TaperPin]

I’ve remodeled a lot of old houses and one out of the 40’s probably has more significant issues than venting, so I’d be careful not to spend a lot on things that don’t matter, and come up short on electrical, hvac, and plumbing issues.

My contractor peers who love to geek out on things spend too much money on ridge vents. Old school contractors some times love the turbine vents, feeling it’s really sucking air, but then they cover them in the winter and uncover each spring - that’s unnecessary to my way of thinking. The standard, basic vent that’s everywhere on new and decades old houses and apartment buildings is popular because it’s the most bang for the buck - less than $20 ea. Cut an 8” hole 16” or so from the ridge every 4’, trim the shingles to fit around the exposed part, goop under the top edge and over any exposed nails/screws, done.

I doubt you will see any active mold as it is now, but extra ventilation will slightly reduce the attic temperature, give a clean penetration to duct a fart fan to, and you’ll feel better, but that might be a project after other things are squared away.

 

[grfox92]

Be sure that loose fill insulation isn't Vermivulite (Google a vermiculite insulation for a picture).

Vermiculite loose fill insulation is full of asbestos and should not be disturbed. That's the first thing I thought of when you said loose fill and 1940s.

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[jags]

Typically there is venting at the soffits in the overhang for air to come into the attic with air exiting at the ridge vent or gravity vents above. I've seen a number of older homes with little to no overhangs use just the gable end vents with a couple of gravity flow vents.

If it looks likes there are problems up there with moisture or mold you might add a vent at the other gable. And as mentioned watch that old insulation.

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[ddavis_1313]

Just put ridge vent across all the ridges and call it good. It’s simple, rather inexpensive and works. It’s way better than wind turbines and air hawks.

Make sure you have vented soffit around the house when you reside it.

I’ve done numerous houses this way. Never any issues and attic space air recycles more than sufficiently.




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[lungpuncher1]

When they cut our ridge vent out while installing our metal roof last July I could literally feel the difference in the house immediately. It was like our entire house sighed from relief


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[Tjdeerslayer37]

Just put ridge vent across all the ridges and call it good. It’s simple, rather inexpensive and works. It’s way better than wind turbines and air hawks.

Make sure you have vented soffit around the house when you reside it.

I’ve done numerous houses this way. Never any issues and attic space air recycles more than sufficiently.




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Everything i have read says gable vents and ridge vents dont go together, and i dont have any sufficient overhang to add vented soffit to.

 

[Drenalin]

Just a thought, even 5 inches is enough space for a continuous soffit vent or perforated soffit panel on your eaves. Not a terribly difficult change to implement while you're replacing siding.

 

[lintond]

Vents are all about cross flow. Ridge vents or more traditional now are the square vent hoods in combination with eave vents gets the air moving. Most houses here in the PNW don’t use soffit vents because they aren’t doing closed soffits. Instead they use vent blocks in the eave bays.

I’d have to review the code but off memory you’ll need 2x the venting if you have eave vents only and no ridge vents. You have to make sure they aren’t blocked by insulation which can be done fairly easily with a vent baffle.


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[dylanvb]

DeckAir Vent

www.lomanco.com

deck air vents allow you to put an intake such as a soffit vent if you don't have enough space for soffit. Pretty easy to install just need to do it when you are shingling the roof.

 

[wyodog]

You can install soffit vents in a 5" overhang/eave. You want to make sure they aren't covered with insulation. with an older "T" shaped roof of that age it is like that there is an addition from the original construction. because of this one section could be closed off from the other this could affect ventilation. bare minimum would be be 1 sq foot of roof vent for 300 sq feet of living space. If I was installing siding I would add gable vents. I would also vent the soffit/fascia when I replaced that as well. I you are installing a new roof I would install "Turtle vents" instead of gable vents. Proper ventilation is important.

The fact that snow doesn't melt on you roof indicates you have decent insulation in your attic.

 

[ddavis_1313]

Everything i have read says gable vents and ridge vents dont go together, and i dont have any sufficient overhang to add vented soffit to.

Then use gable vents. A solar power vent also helps pull heat out as well.

How wide is your current soffit?


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[Flazyj]

Ridge vent along with soffit vents immediately changed the heat transfer of my old house. Seemed to help both summer and winter. No sure why they were not installed during construction.

 

[Tjdeerslayer37]

DeckAir Vent

www.lomanco.com

deck air vents allow you to put an intake such as a soffit vent if you don't have enough space for soffit. Pretty easy to install just need to do it when you are shingling the roof.

i ilke those, thanks!

 

[Tjdeerslayer37]

okay once i got home yesterday i climbed up top and i do have 4 gravity vents up top, i couldnt remember if i did or not. so that gives me the one gable intake, and 4 exhausts. i think adding the 2 more gable vents would compliment the exhaust venting well?

 

[WV Mountaineer]

10 years on the shingles, im sure theyre economy grade as the house was a bit of a landlord special before i got it. ill check joists and rafters when i get a chance, good thinking

10 years. If the shingles has lost their grit, that’s too soon. Add ventilation.

 

[dylanvb]

okay once i got home yesterday i climbed up top and i do have 4 gravity vents up top, i couldnt remember if i did or not. so that gives me the one gable intake, and 4 exhausts. i think adding the 2 more gable vents would compliment the exhaust venting well?

Where are your gable vents in correlation the top of the roof? Are they at the top of the gable or the high point of the roof?

 

[Tjdeerslayer37]

Where are your gable vents in correlation the top of the roof? Are they at the top of the gable or the high point of the roof?

the 1 existing gable vent is just above the attic floor, as low as it can go. the rooftop vents are 24" below the peak or so.