Adding vented soffits to existing ones

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Old 07-18-09, 06:35 AM
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Adding vented soffits to existing ones

I apologize if this has been asked before. I want to insulate and ventilate the roof of my 90 year old home. I am all ready to go but have noticed that I don't have vented soffits. The soffits are aluminum, so probably not as old as the house. The roof is the type that is not an a-frame, it's more like a four-sided pyramid, with gutters on all four sides. Is there a relatively straightforward way to add sections of vented soffits to a house? I know I'm not providing much information but I tend to ramble, so in the interest of keeping this first post short, I will leave it there. -Dan
 
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Old 07-18-09, 09:50 AM
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Just to clarify, does your roof look something like this one?

 
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Old 07-18-09, 11:04 AM
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Pictures

No, I can't post attachments, so here's a link to 2 pics I've put on my windows Live site. One is the house, one is a close up of the soffit.

http://cid-6f9624a13b4ef546.skydrive...J!DD7qGQlj4%24

It's like a 4-sided pyramid.
-Dan
 
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Old 07-18-09, 11:25 AM
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Just to help u out, that is usually referred to as a "hip" roof, at least in my experience.

Since the aluminum was added later, it is most likely that there are solid wood soffits above the al. Since you have no gables, do you have roof or ridge venting. It looks like some sort of vent in the picture. For good venting you need a low intake and a high exhaust.

Is the attic space all open or has it been finished in any way?

Bud
 
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Old 07-18-09, 12:03 PM
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Thanks, Bud, for the name of the roof and the questions.

The attic is completely unfinished. There are two vents, one on either side of the roof (you see the one in the one pic, the other is opposite). They're pretty high up. During a renovation, a previous owner ran the bathroom exhaust fan up to one (not a good idea, I understand) and now I realize it was probably because there was no soffit vent to send it to (I was told that would be a reasonable way to vent the bathroom though I don't know if that's true).

I'll have to check for the wooden soffit underneath; it's likely that it is there, since the roof itself seems untouched on the inside--it looks like original wood.
 
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Old 07-22-09, 01:01 PM
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More information and more problems

I managed to peek under the existing aluminum soffit, and to my dismay learned that there is no wood soffit--the walls just continue right up and meet the roof. So in profile it would look sort of like an inverted J, with the bottom of the J (the curve part) being the roof, and the straight part being the wall.

This is a huge problem, as far as I can see it, because there is no opening between the roof and the overhang--no space from which to draw air for venting. Is there a way to solve it, to ventilate the attic without cutting holes in the walls?

At this point I think I should just take back the baffles I bought to install in the roof, since there's no use.

Any suggestions, or should I simply plan and budget to get a roofer to redo the whole roof someday?
 
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Old 07-23-09, 07:29 PM
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Can you see your rafters? It doesn't seem possible that there would be no opening anywhere between the top of the walls and the roof framing.

Do you have access in to your attic?
 
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Old 07-23-09, 08:37 PM
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Some older homes, before the al soffits were added, had open rafters under the eves. The rafters were placed on the top of the walls and then blocking was built in between each rafter. Then the siding was added making it look like the walls go all the way to the top. Actually the walls stop around the bottom of the rafters, usually notched into the rafter an inch or so. If that is the case, then holes can be drilled between the rafters up close to the roof deck, then vented soffits added where the solid ones are now.
Does that match what you are seeing?

Another option is to add more roof vents. If you add a roof vent with a vertical shaft down to just above the attic floor, then the warm air exiting the existing high vents will create a low pressure inside the attic and pull cool air in those vents with shafts that extend lower. It works on paper, but I have never had the opportunity to try it. In any case, having all of your venting up high is still functional, if you have a lot of it. Adding the shafts just seems like a workable extension.

Bud
 

Last edited by Bud9051; 07-23-09 at 08:38 PM. Reason: text
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Old 07-23-09, 09:38 PM
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Hi Rob and Bud
I'll have to check the rafters again to see if it is the situation that you describe (I hope it is--it was hard to see, since I was shining a flashlight through a crack between soffit and fascia). I do have access to my attic, but it was hard to see the section where the roof meets the wall--I'll check again. I had thought of drilling holes in the wall between the rafters, so that might be the solution. Or maybe a bit of both. BTW, your idea of the vents with shafts makes sense. Thanks for your thoughts.
 
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Old 07-23-09, 09:48 PM
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A four-square house style. But the top windows are not original.

Figure your net free vent area required: Air Vent: Continuous Soffit Vents Specifications

Check on the new siding soffit's NFVA. It will be different than the web site's, a lot less.

Or........ Cor-A-Vent : IN-Vent

Be safe, G
 
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Old 07-24-09, 12:17 AM
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Huh? Sorry, I didn't understand that post.
 
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Old 07-24-09, 05:13 PM
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Sorry if it was confusing.

The air vent site is how you figure mathematically the amount of venting area for your house. To use it, you need the NFVA numbers from the soffit siding. (How much air passes through the material based on the size and quantity and spacing of holes made). Find a supplier for your particular siding, buy some vented pieces, the number to be determined by the NFVA of the product.

The cora-vent site is a substitute for installing the soffit venting. You still need way more 7" mushroom vent caps on the top.

Be safe, G
 
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Old 08-06-09, 07:14 PM
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Another approach?

Thanks for the clarification, GBR.

So here is my thought, everybody. Stick with me, I'd really like people's feedback.

Problem: I need vented soffits, and air passages into the attic. It seems to me that to replace specific soffits with vented ones would require me to replace all the soffits, because I can't because my soffits are old and any replacements would look odd.

But I can buy, relatively cheaply, soffit vents, the type that would normally be put into wooden soffits, it seems.

What if I did the following:
1) cut holes in the soffits to fit those replacement vents.
2) through the newly cut holes, drilled holes through the top of the wall at the base of the roof (between the rafters) thereby opening space into the attic for ventilation
3) screw (and possibly glue, for a tighter seal) the vents over the holes.
4) put the normal baffles up to those new holes.

I know that there is still not enough roof ventilation in the place, but at least this would open up some soffits, without me being required to fully replace the soffit, and thereby probably replacing the gutters and fascia.

Thoughts? Is this a stupid idea?
 
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