vented soffits in house overhang

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Old 01-05-14, 08:52 AM
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vented soffits in house overhang

We purchased our home three years ago and are trying to find way to make it warmer, conserve energy, etc. We live in a bi-level ranch and have vented soffits for our attic, but we also have them in the overhang that runs down the entire side of the house. A roofing guy the other day told me to not use vented soffits down the aide of the house where the living area is. Is this true? I am afraid cold air is getting into our home. My wife and I were thinking about taking caulk or silicon bathroom sealant and closing up every hole in the soffits.

I tried Google'ing vented soffits in the living area, but every result if for attic. Why would they install vented soffits in the living area overhang? I also need to insulate our garage better. We have the problem of our master being above the garage, and it gets very cold in the winter.

Thanks in advance for the help.
 
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Old 01-05-14, 09:31 AM
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Some pictures may be of some help.
I can not think of a case where you it would be a good idea to cover up the soffits.
That's the only way for the roof vents to work.
That air flow is needed in winter and summer to remove the moist air from the attic.
The house envelope needs to be properly air sealed and insulated.
An attic needs to be as close to the outside air in temperature as possible to stop ice dams in the winter.
In you area it's suggest to have at least R-40 of insulation in that attic. Is there about 12" of insulation up there?
attic insulation - Bing Images
 
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Old 01-05-14, 09:40 AM
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I am guessing by the way you worded your post, that your soffit has been covered with aluminum soffit, and that all the aluminum soffit is vented (perforated) rather than solid (non-perforated).

This does NOT mean that ALL of your soffit is "actually vented". They may have installed perforated aluminum soffit on both the gable end soffit and the eves, but there is nothing wrong with that... it simplifies things to just have one type of aluminum soffit so that it all looks the same. The only place ventilation actually takes place is at certain predetermined locations where a hole has been cut into your plywood soffits (hidden above the aluminum soffit that is covering them). The amount of ventilation is usually based on a predetermined sq/ft that equals roughly 1/300th of your house sq/ft. So, for example, if the house is 3000 sq ft, you would need 10 sq ft of ventilation... 5 sq ft at the ridge and 5 sq ft at the soffit. So around the house there might be ten 6" x 12" holes cut in the soffit to give you that 5 sq ft of fresh air intake. Above those holes, a space is left between the rafters for fresh air to come into the attic, which then exits out the ridge, taking heat and moisture with it. All other rafter bays will usually be completely stuffed with insulation.

If you have the type of home where it is split level, and the upper part of the home cantilevers out over the lower part of the home, then no... you would not want to ventilate the cantilevered floor joists. That would be stupid. But again, if it has perforated aluminum soffit, that is not something to be worried about.

Your master bedroom probably gets cold because it is surrounded by exterior walls on all sides, plus you lose heat out the ceiling AND FLOOR.... unlike the rooms in the rest of the house.

Why would they install vented soffits in the living area overhang?
Pictures might help us see what you are talking about. Sounds normal to me.

My wife and I were thinking about taking caulk or silicon bathroom sealant and closing up every hole in the soffits.
Yeah, don't do that.
 
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Old 01-05-14, 11:25 AM
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Here are the pictures. These soffits are the exact same thing in the front of my house under the attic overhang.
 
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Old 01-05-14, 12:08 PM
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Those vented panels may have been installed over solid soffits just for looks as X said. Is there any area not finished inside where you can see what is in there from above? It would be really strange for them to vent that area.

As for the cold garage, you may need to cut an access hole in the garage ceiling to inspect to determine how much insulation is up there. Put the opening in the right spot and you might also see what is out in the overhang.

Quite often they will have just 6" insulation in a 10" cavity. Now, 6" isn't terrible, so there may be perimeter issues of air leakage that would be more beneficial to address. Not easy, but getting the space above warm is important.

What type of heat do you have?

Bud
 
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Old 01-05-14, 12:22 PM
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I see now that it's vinyl soffit, not aluminum.

Since it looks like your pictures are of SOLID soffit, not vented soffit (the kind with hundreds of tiny holes on each panel), I can only assume that you are thinking of caulking the "gaps" where the 4" on center soffit meets the j-channel next to the house.

Don't do that.

I don't know what your roofer said to freak you out, but I see nothing wrong here.
 
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Old 01-05-14, 12:56 PM
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They are vented; the holes are just in the grooves between each soffit. You can't really tell from the picture. It's not like the ones where there are tons of holes on the front face.
 
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Old 01-05-14, 01:04 PM
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Like this?

Take a piece of wire and poke up into the holes. i think you will find that the soffit above it is solid so the holes in the soffit don't vent anything where there are no holes in the plywood above it.
 
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Old 01-05-14, 01:07 PM
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I'd guess under the vinyl soffits is solid plywood.
A simple way to check would be to stick a small drill bit in sone of the holes to see if it's solid.
Even if they had of used unvented it still would not be air tight. The plywood is what seals it up.
 
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Old 01-05-14, 03:13 PM
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Yup, X -- just like those.

Bud -- we have a gas furnace.

You guys were right about it just being plywood. I stuck a screwdriver in there and it's just solid. Attached are two pictures from the unfinished laundry room side (right above the back door under the deck); there were two insulation bats in there that i had to pull out.

So i guess those soffits are not causing our house to be drafty, then. The first thing i want to tackle is fixing all of the normal problems in the garage -- insulating the garage doors and sealing around them better, sealing every hole/crack in the ceiling, etc. The ceiling is finished drywall with some pink insulation above it, but i should check how much there is. I was also thinking about possible spray-foaming up into the finished drywall, but I've heard that it can be insanely expensive.

That sliding glass door that leads out to the deck was either not installed correctly, or horribly weather-stripped; the wood floors right there are very cold in the winter.
 
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Old 01-05-14, 04:30 PM
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Something I have found to be the biggest blunder in construction is that too many times the insulation and air sealing around the rim joist is VERY inadequate. When it's windy, cold air blows down the floor joists like a wind tunnel. I've noticed this on multiple houses... cut a hole in the floor and cold air is coming out as if you opened a window.

Spray foam around the perimeter of a house to air seal and insulate the rim joist would be a very wise use of your $$$. In one house I worked on, we actually removed a section of drywall all along the load bearing exterior walls so that it could be spray foamed. The found out they had a problem when the electrician put in can lights and they were so cold they dripped water every winter. So that might be an idea for you- especially if the house has a lot of cantilevers like in your initial photos, but it would be pretty intrusive.

If you were thinking of spray foaming the floor joists above the bedroom, all the drywall would have to come down. If you just wanted to spray foam the rim joist around the perimeter, they would need maybe 16" of drywall torn off around the perimeter of the garage.

Fiberglass works best in a dead airspace. Wind can pass through fiberglass just like it passes through a t-shirt. A t-shirt might keep you warm if it's 40F and sunny but stand outside in a 30 mph wind and the t-shirt is pretty ineffective at keeping you warm! Same principle applies to fiberglass. It only has it's advertised r-value in a DEAD airspace. So if air is moving across the fiberglass, it's not providing you as much insulation as it otherwise could. What I'm getting at is that by spray foaming the perimeter of the garage you can provide a dead airspace for whatever fiberglass is already up there, making it more effective.
 

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Old 01-12-14, 09:23 AM
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thanks for the suggestions guys - i appreciate it.

These plywood areas above the panels don't have much insulation in them. Should i add more, what kind? Just some bats?
 
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Old 01-12-14, 09:54 AM
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Being sure they are air sealed is the highest priority. Filling then solid with Roxul would be my choice. Fiberglass allows too much air flow. more like an air filter. If the inside space is heated, you can leave a gap at the top to allow warm air to get in. Be sure to insulate the rim though.

Bud
 
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Old 01-12-14, 01:03 PM
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The soffit immediately above the garage doors would need to be both air sealed and insulated, since it is cantilevered and there is living space directly above them. If there was no insulation, it would create a cold spot on the floor upstairs. The same can be said for the entire garage ceiling perimeter, as well as the entire garage ceiling.
 
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Old 01-12-14, 04:24 PM
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Thanks X. The easiest ones for me to get to are the ones in the laundry room, under the kitchen. The kitchen floor right above them is definitely very cold. How do i "air seal" them? Just run my finger around where the plywood comes together and see if i feel air? Should i just run a bead of caulk where the boards meet?
 
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Old 01-12-14, 04:46 PM
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You could caulk any gaps, that would help keep air out. In a cantilevered floor/ soffit you have a lot of edges though, so I'm not sure that's practical. The Roxul product Bud was referring to would be a good choice since it is more dense than fiberglass. You can just cut the pieces to fit nice and snug and fill the entire cavity. Don't compress it too tightly, though.
 
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Old 01-13-14, 12:26 PM
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After i fill it snug w/ Roxul, do you think i should seal the open side that faces the room w/ a rigid foam board or plywood? I also read online that you need to be sure it's sealed between each floor joist. Thanks for telling me that it's called "cantilever," now i can google search this and get a lot of results.
 
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