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I think you got some poor advice from your contractor. They went at the situation all back-asswards.

Gable end vents don't anything. You want soffit and roof (or ridge) vents.

You can't do that now because there's no way to get in there to install baffles which are necessary to prevent insulation blocking the eave/soffit vents. Why they blew the insulation in before installing soffit vents is beyond me.....(?).......they weren't thinking.

There's ways to go at this, but they're backward approaches to the task. I'm going to think about it, and let some other folks chime in while I cogitate.........

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You may want to sit down with your contractor and go to the Air Vent Inc. web site and review the material they have on the proper way to ventilate. http://www.airvent.com/professional/index.shtml

I think that it is important enough of an issue to cut scuttle holes in the ceilings to install the proper air channels (baffles) and soffit vents.

Ezra Malernee

Canton, Ohio

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Ventilation is probably not going to do much to reduce attic heat coming into the space below. It helps a little, and with asphalt roofing it would also increase the life of the roofing itself, but with slate that's a non-issue. The main problem is solar loading, the sun hitting the dark slate and radiating thru into the attic, which then heats the house. The best thing to do is to adequately insulate the attic floor, as much as R-60. Of course you could also go with a light-colored, reflective roof, but I'm guessing you're not going to want to do that.

Curious about a couple of things. One, what is the roof construction? Plywood, skip sheathing, felt, etc., or what? And, what type of insulation did they blow in, and how much?

Realistically, if there is physical access to the attic, a guy could go in, rake the insulation out of the way, and add the baffles. Perhaps it should have been done, but again, I think that venting alone is not usually enough in these situations, and that insulation is the answer.

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No one is considering that this is a 90 year old building that leaks like a sieve. Adding insulation will lower your heating costs. As Dave has mentioned you need to reduce or counter the solar heat gain to lower your cooling costs. That means a radiant barrier or gobs of air flow, and you can't get either without gaining access to the attic space. If it were mine; I'd want to know it was insulated to R-50 or R-60, and then air seal the ceiling plane, then I'd take a flashlight with me every few years when I climb up to paint the gable vent so I could peek in and check on the condition of the roof frame. My guess is that the nearly century old framing will breath well enough on its own to not need any extra vents, it did survive to 90 without them after all.

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There is no information that shows heat load reduces lifespan of modern mfg. shingles. It's another of those HI myths.....just sayin'......

Of course insulation is necessary, but venting will reduce the temperature. I've done tests and studies on my own house, and the average temp reduction is somewhere around 12degF. Not a lot, but it does help.

That said, I can imagine this might be one of the very few times when an exhaust fan might help.

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One has to read the work of William Rose and Joe L. to understand there are no "pat" answers to these questions.

You can have a freakshow of building construction contradictions in an old house with old growth wood and original materials, and nothing bad ever happens. Do the same thing to a new structure, and you might see damage that results in catastrophic failure in some small number of years. Punch a bunch of new materials into that old house and significantly alter it's moisture and vapor permeability creating lots of little microclimates in places one can't see,, and you might find yourself with an interesting science project.

Point being, I'd have to know a bunch of stuff about this house that I can't know unless I saw it in person to be able to make reasonable and accurate assumptions about it.

So much for science, now back to the weather............

Big old gable end vents in an old house might be doing *something*, i.e., if the wind is blowing perfectly in line with the axis of the vents, yes, I'll concede they're doing something. Not much, but something. They're not doing a darn thing on a windless day. Most old houses with big old gable end vents lack all the vapor resistant materials of modern construction, so whatever those vents are doing or not doing probably isn't significant.

Established information sez gable end vents combined with soffit vents might actually work against you in some instances. Again, they're definitely doing something, but something you don't want, and these instances are fine tuned and variable as all get out.

For this gentleman with the 90 year old house and the contractor that doesn't understand much about logistics, I doubt anything significant is going to happen regardless of how you vent or insulate. That's why my commentary has been general and nonspecific.

At this point, get it as close as you can, and if it were me, I'd wait and see what happened, if anything. If I saw there was moisture or some other vapor issue that was unacceptable, I'd figure out a venting configuration that fixed it.

At the risk of muddying the water, here's an article in JLC:

http://www.jlconline.com/cgi-b...2763&p=1

Kevin

I love that article. It doesn't muddy the water at all. It shows how a lot of the stuff we're talking about is subject to all manner of considerations.

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Nope,

You mentioned Dr. Rose and it just so happens that JLC Update revived one of his articles this morning so I thought I'd point it out to folks.

Only oldtimers that I'm noticing is when I look in the mirror.

Very stylish hat, Kurt; it makes you look like that Peter Sellers guy.

ONE TEAM - ONE FIGHT!!!

Mike

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Ahem,

https://www.inspectorsjournal.com/forum ... C_ID=12897

ONE TEAM - ONE FIGHT!!!

Mike

My bad. I get the JLC newsletter also, and I didn't notice that it had already been posted on TIJ.

And...by saying "muddying the water," I simply meant that the article makes it clear that there are no hard and fast right and wrong practices. Some things work some times and some places and not in others.

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