Hi.
Please forgive me in advance if I have posted this to the wrong group. I’m a subscriber to the magazine, I put myself through college working for a renovation contractor, and I now own an older 1930’s home. I looked in the archives to find an answer to this, but didn’t find one.
To the point: I’ve got a two-story 1930’s home in Southern California. The attic is really just a crawl space, with a low-pitched roof. In a 1980’s renovation, the previous owner put a heater/air-conditioning unit in the crawl space. (Some these were recalled for causing fires. Mine wasn’t part of the recall.)
My problem: Although the roof has soffit vents (under the gables), there’s no other ventilation. In the summer, the temperature soars under the roof; the air-conditioner works overtime; the upstairs becomes oppressively hot – even on days when it’s cool enough outside that I shouldn’t have to use air-conditioning.
I want to have a roof vent put in, but I’d like some advice: What’s the best kind? A turbine? A flat vent? Is there a brand that’s better than the others? I’d prefer to go passive (as opposed to a fan unit,) and don’t want to do a complete re-roofing for a ridge vent.
Again, please forgive me if this question seems simplistic. I’m going to hire a licensed contractor to put it in. (As Clint Eastwood says: “A man’s got to know his limitations.” I may be a good amateur, but I know when to get a pro.) In fact, I’ve got a great roofer. But I’d like to have some knowledge about this beforehand. Particularly with regard to the materials.
Thanks.
PS: The size of the crawl space area is 45′ x 20′, with a 5′ rise at the peak.
Edited 6/1/2005 3:41 pm ET by BruceJackson
Replies
You don't say what type of roof you have, so an answer is kind of hard. I'm prejudiced against turbines and power vents (moving parts break or wear out), although there are cases where they might be the only solution. You don't need to reroof to install a ridge vent, just redo the ridge. A bunch of roof pots might be the answer if you have a hip roof with limited ridge space. Give us some more info and we can give you more.
Edit: what does your great roofer have to say?
And by the way, welcome to Breaktime.
The razzman invented cordiality.
Hey Mister Sushi, you forgot to cook my fish.
"Am I dead or alive? What's this? Linoleum? I must be in hell." -The Salton Sea
Edited 6/1/2005 5:13 pm ET by greencu
Hi. Thanks for the reply.
It's an asphalt shingle roof.
And the "great" roofer says he'll be here - to look at it (as opposed to actually doing the job) - in early July, after he finishes all the work from the storm damage all over LA this spring.
(And as hard as this is to believe, he's doing me a favor. On my block alone in LA, there are three houses still tarped over from the rains, awaiting new roofs.)
I know it's not like this guy is the only roofer in LA who can do this. But he's worked for me once before, and I liked the quality and care he put into the work. So I'm going to wait for him.
In the meantime, I'm just trying to educate myself, so I can make a better choice when he makes his recommendations.
Thanks again.
I do not having ac in attics for any reason. Its like keeping Ice cubes in the oven. you could save a bundle by moving the air handler down stair. i know it will take up a closet, but you got to do it.
Greencu - I've seen some ads for roof vents that were solar powered. I think I remember them as turbines, not 100% sure. Any opinions? Ever work with solar powered stuff?
Don
Naw- the only difference is you don't have to run wiring. They still have limited life and most people don't check them to see if they're still running.Hey Mister Sushi, you forgot to cook my fish.
"Am I dead or alive? What's this? Linoleum? I must be in hell." -The Salton Sea
Yeah, in my experience vent motors have a working life of 3-4 years. The bearings go bad (gum up) or the motor develops internal shorts. Solar powered won't prevent either of those -- just adds complexity and expense.
First off, the exhaust of the AC should be ducted out through the gable end or some such.
Generally, ridge vents are considered best, though it depends somewhat on the individual situation. There should also be at least one 8x16" soffit vent every four feet, on an average roof -- you need vents both high and low to be effective.
If asphalt shingles, I would ridge vent the roof. Installation of a ridge vent does not involve a re-roof.
Before slicing the 2" wide strip out of the roof peak. You need to acertain that you have sufficient vent area at the soffit. The only way ridge vents work is by having an equal or greater free vent area at the soffit as compared to the free vent area provided at the ridge.
Figure out a way to remove any heat produced by that air handler.
Jim
We had a fascinating discussion on hot attics just recently (well, crud, I forgot to copy the link first, <grrr>). Said discussion also included venting attics.
So, this may sound weird--but an answer might be to insulate the bottoms of the roof rafters with rigid foam sheets. That would keep the attic from picking up the heat radiated from the roof deck (which venting may or may not carry away). This is unconventional wisdom at best, and not the way "e'erybody else does it."
But it might be the right answer. I'm guessing that a 1930 vintage SoCal house has hardly any closets in it as is. I'm going to also guess that it has a slab foundation, rather than a crawlspace--so, there's no "snaeaking" the unit into the c/s (which would then need insualtion and "conditioning" . . . )
You'd need, ideally, a second floor closet that can fit a ±27x33x60 vertical hvac unit (which will not be the one presently in the attic). Said "ideal" closet would also "communicate" to any first floor ducting, both supply and return. That could be a bunch of work.
I don't think that will do much good when the AC is in the attic.
Hi --
First, I want to thank everybody for the help and insight. Let me respond to a few things:
- You're right. Putting the heating/ac unit in the attic was a dumb idea. I wouldn't have done it - but I guess the HVAC guys convinced the previous owner that this was the best way to put in a second zone. (There's another heater/ac unit for the first floor in a tiny 10 x 10 basement. The rest of the house sits on a crawl space.)
- Unfortunately, I don't have the space - closet or otherwise - to move the unit out of the attic.
- There are more than enough soffit vents running around the entire perimiter of the roof. I suspect they were fine - and did the job - before the a/c unit was put in.
- Finally, I didn't know that a ridge vent could be put in without an entire re-roofing. And now that you guys pointed it out, it should have been obvious to me.
So, I guess that what I'm thinking is:
- I don't want to worry about something mechanical/electrical breaking down, or needing maintenance. Even after five years. I've got enough "systems" in the house already.
(And forgive the digression here, but allow me to explain: I'm a techie. I worked as an electrician's helper. I'm the guy you call when you have a problem with your computer. But lately, I've started to say enough is enough. My wife can't work the TV/VCR/DVD/Surround sound with it's six remotes. No one - save me - can figure out how to program the phones/answering machines. Or the new lawn sprinkler timer. Or the energy-staving termostats. It's not that I'm buying hugely complicated stuff. But as you all know, everything today comes with lots of bells and whistles that makes it all too complicated. So the last thing I want is one more 'device' - solar or otherwise - that needs to be programmed, adjusted, fixed, etc.)
So I guess where I'm coming out on this is that I'll put in a ridge vent - especially since it already looks like I'm going to have to have the ridge re-capped in a year or so.
Thanks again. I really appreciate everyone who took the time to respond.
Edited 6/2/2005 6:51 pm ET by BruceJackson
"I have always wished that my computer would be as easy to use
as my telephone. My wish has come true. I no longer know how
to use my telephone."- Bjarne Stroustrup, inventor of the C++ programming language.
This is the thread that CapMac was talking about.http://forums.prospero.com/tp-breaktime/messages?msg=57947.1The concept is called Conditioned Attic. The attic space is "moved" into the "inside" and the underside of the roof is insulated and there is no vents.And here.http://www.buildingscience.com/housesthatwork/default.htmAnd you can find more information at the website.
that will do much good when the AC is in the attic
¿Por que no?
Moving the unit? Putting in vertical units behind louvered closet doors gets the all-too-important filters down where the people are--which means there's a better overall chance that the filters get changed. It also allows for a vertical or near vertical filter, which unlike a flat-to-ceiling installation, does not drop a cloud of dust and particulates from ceiling height. (Get the idea I've learned this the hard way<G>?)
Insulating the attic? There's some new evidence out there--and Ray Moore has the best links, not I--that insulating a non-venting attic, to "protect" the attic from the heated roof deck, is a much better solution than mere venting. From a practical aspect, I certainly agree with him. The .25 CFM per lineal foot of ridge vent just will not change enough ambient air as fast as the roof will radiate stifling heat into the attic. Two layers of foam will be R17-19, which should keep the heat out of the attic until nightfall.Occupational hazard of my occupation not being around (sorry Bubba)
> I'm guessing that a 1930 vintage SoCal house has hardly any closets in it as is. I'm going to also guess that it has a slab foundation, rather than a crawlspace--
You're right about closets in old houses here. But sometimes you get lucky and there's a service porch.
Slab foundations, though, are mainly a post-WWII innovation. Pre-war, footings were dug by hand labor, and concrete was mixed on-site. Tracked earth moving machines weren't produced in quantity at a reasonable price until after we had made all those Sherman tanks. That's what made slabs cost effective.
-- J.S.
when U do the ridge vent and new ridge shingles ...
do yourself a big fanor and don't use those stupid "folded" ridge shingles they have out there.
double the cost and half the life.
who thought "pre-curled" shingles was a good idea?
let's make folds in them so they crack faster!
Jeff
Buck Construction
Artistry In Carpentry
Pittsburgh Pa
Hey Bruce, I'm a new arrival to SoCal and my full time job is renovating my house. We bought the biggest dirthole in Cypress so we could just barely survive the price jump coming from Chicago.
I'm reroofing my garage at the moment, and also installed solar powered gable attic vents. Here's my take:
Solar vents are easy to set up. Bolt on fan housing, bolt on solar cell to eave, aim it to the afternoon sun, connect the two wires. Done. It only runs when the sun is heating your roof.
However...
After doing it and then figuring out the cost difference of the $277 Solar fan vs. the $60 thermostat controlled ac powered fan, basicly ment that I had to recoup $200 in electricity costs from running a small fan - I think I break even in about 135 years!
I'd stay away from putting a mushroom on your roof. Ugly - nothing but. Unless you covered it with Nuclear Cooling tower shaped coverings... hmmm...
When you eventually need to reroof, take the existing deck off and put on Radient Barrier OSB/Plywood. It reflects heat back up the roof deck instead of down to the attic.
BTW, does anyone who is suggesting installing sheet goods in a space that is 24" tall AT THE PEAK have a suggestion of how to get those sheet goods into the attic?
Rebuilding my home in Cypress, CA
Also a CRX fanatic!
I think it's been pretty well established here that a "radiant barrier" under the shingles will do no good. A reflective surface will help (to a degree not well quantified) if installed on the inside of the roof, facing the "attic".Plain old insulation will also help, but there's no real advantage to putting it in the roof vs the ceiling unless the "attic" has a modicum of ventillation.
"
I think it's been pretty well established here that a "radiant barrier" under the shingles will do no good. A reflective surface will help (to a degree not well quantified) if installed on the inside of the roof, facing the "attic"."
DanH, did you get the impression that I was suggesting installing Radient Barrier OSB or Plywood upside down?Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Not sure what you had in mind. If you do indeed rip off the deck and place some reflective material shiny side down, exposed to the "attic" space, that will be effective (though how effective is not well established). It doesn't "reflect the heat" upward, but rather keeps it from being re-radiated downward -- complements the insulating effect of the air space.A reflective layer sandwiched between other layers is not effective.
"It doesn't "reflect the heat" upward, but rather keeps it from being re-radiated downward -- complements the insulating effect of the air space."
Thank you for correcting me on that. It's a fine point but an important one that I do remember reading in that discusion.
But just for future refference, when I suggest taking off a deck and replacing it with a Radient Barrier OSB or Ply material, I am also implying that it would be installed as the manufacturer intended. I would like to declare that if I recommended filling a pool with water, I mean the water goes in the pool itself and not the yard next to it. If I suggest taping a note to the refridgerator, let it also be known that I mean to use the sticky side to adhear both the paper and the surface of the refrigerator. ;)Rebuilding my home in Cypress, CA
Also a CRX fanatic!