I am in need of advice on the best way to cool unconditioned attic space
in S.C. summers. I have a gable roof with gable vents and continuous soffit vents. The roof pitch is 6/12 with asphalt shingles.I would not be able to take advantage of any solar products because of large hardwoods surrounding the house.
Thanks!
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If your soffit vent is indeed continuos, and unobstructed, you could put a ridge vent on the top. This will pull air in the soffit and up out the ridge.
Any sort of powered system is probably going to mess with the air conditioned space underneith. What kind of insulation you have up there?
Also, you mention hardwoods... is you roof mostly in the shade?
Tu stultus es
Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Look, just send me to my drawer. This whole talking-to-you thing is like double punishment.
xxPaulCPxx'Just getting to read the responses to my question.
Thank you for your input.To answer your question,the
soffit is continuous and unobstructed, but there is
not enough insulation(which I plan on fixing). If
I seal the attic up-seal duct work, ceiling protrusions,
etc. does that make the power vent an option? If so
where is the best(not just the cheapest) place to get them?Thanks again,
Creed
Hi Sauce, and welcome to BT!
Ditto what paul said. A continuous ridge vent can be installed by cutting the roof deck (sheething) back about 3" along each side of the ridge (don't cut the rafters!), installing the vent material, then covering it with matching shingles.
http://www.ebuild.com/product-detail/roofing/vents-ridge/39213.hwx
Also, make sure the attic insulation is not blocking the air flow from the soffits. If you already have a ridge vent but the attic isn't cooling, the soffits may be blocked off with insulation.
Another option is to install a few attic vents, but they're not as effective and not real pretty to look at. Also, they tend to allow leaks if not installed properly. But they are cheaper and easier to install.
~ Ted W ~
Cheap Tools! - MyToolbox.net
Meet me at House & Builder!
Edited 4/18/2009 11:53 pm by Ted W.
TedW.,Thanks for your help with my house issue,you make
several good points. Installing ridge vents seems
to be a good and fairly straight forward solution.
The vents do seem to be unobstructed, this seems
to be the key to the success of that product. The
power vent does intrigue me if I can seal the attic
from the air conditioned space. Thanks for the info!Creed
You said:
>>Installing ridge vents seems to be a good and fairly straight forward solution.The (soffit) vents do seem to be unobstructed, this seems to be the key to the success of that product. The power vent does intrigue me if I can seal the attic from the air conditioned space.<<
Another vote for ridge vents.
To close up the gable end vents you can simply staple heavy black plastic or even tar paper on the inside.
Re the power vents, the jury is out as to weather they use more energy than they save. Further a power vent will likely create a negative pressure attic space environment which will suck conditioned air from the living space below. You said that you want to seal the ceiling penetrations, etc. This is difficult to do without removing all the insulation that is up there. One way is to rake all the insulation to one side. Do the air sealing in the exposed area. Then rake it to the other side. Any electrical penetrations including wires, light fixtures, AC wired smoke detectors, and then pipes, bath fans, HVAC registers are where to start. The next item is the top plate of every interior wall partition. All this is a lot of work in an existing house.
After increasing the venting with passive vents, personally I'd just seal as best I can with caulk from inside the living space. For example, take down light fixtures and seal around the boxes. If you really want to do some work in the attic, address bath fans and any can lights since these are often the site of the worst air leaks. Then increase the attic insulation with more blown in insulation - which won't actually help reduce attic temperatures in the summer but will get you closer to your real goal of reducing energy consumption.
Back to your initial statement, >> I am in need of advice on the best way to cool unconditioned attic space in S.C. summers.<< After modifying the ventilation look into staple up radiant barriers. They can be very helpful, the only caveat being that they are fairly easy to install in stick built roofs (with rafters) but very difficult in trussed roofs. Around here anyway, most home stores sell the material.
I attached some pics for your viewing pleasure...
Matt,Wow, I am overwhelmed with all the responses
to my posting! Thank you for your pics, I think
they illustrate the areas I will need to focus
on sealing. I'm not sure I know what the radiant
barrier is, can you explain what,why,and where to
get it?Thanks again for your time.
>> I'm not sure I know what the radiant barrier is <<
It's basically tin foil that is stapled up in your attic to reflect the sun's radiation up, away from your house. Attached is a pic of some, although it is a little different than what you would use since the pic is new construction and the RB is part of the plywood that was installed on the roof. RB is very popular in the southern states - including (I would think) in SC, but I guess there are parts of western SC that aren't that hot... When building new homes I get the same energy savings results from RB as I might get for some upgrades of the airconditioner - for a lot less $$.
Is your roof framed with trusses or rafters? The pic I attached is a trussed roof - notice all those diagonal 2x4s. These diagonals would make it more difficult to install the RB.
OTOH radiant barrier I think is different from regular insulation: With thermal insulation, if you have a small leak, like what the pics in the other posting showed, the job leaks - like a boat with a hole in it. OTOH, with RB, if you get 95% coverage you get 95% of the benefit.
A quick Google brought up this - it was the first result - to tell you the truth, I didn't even read it.... The second pic is what I had in mind for your house.
Anyway, call Lowes or Home Depot and ask them if they have it. It would probably be in the building materials section. I'll make a SWAG that it might cost $200 or $300 for a house. I've seen claims that it reduces the temperatures in an attic 10 or 15 degreees (I think it was).
RBs aren't as effective or popular in northern states (where many of the folks here at BT are from) obviously because it is not as hot there.
BTW - when typing on this interface, you really don't need to use the return (enter) key at the end of what you think a line might be...
Edited 4/25/2009 2:28 pm ET by Matt
Thanks for the explanation. I have seen the product in your pic. I didn't know that was what it was called. I do have a stick built attic, so stapling up a foil sheet would be relativly easy, I'm not sure what the installation calls for at the attic floor/roof joist intersection. Any pointers? I'm not(as you can tell) a fluent computer user- thanks for the tying tip!
>>I'm not sure what the installation calls for at the attic floor/roof joist intersection. Any pointers? << not sure what to tell you on that. I've only used the foil faced sheathing type.
BTW - is the special sauce for barbecue or what???
Thanks for all you input. Yes, I make a special sauce for steak that everyone seems to enjoy, so I thought it appropriate.
Put in the ridge vent and close up the gable end vents, as they will short-circuit the flow you are trying to create with the ridge and soffit combination.
Steve
Thank you the ridge and gables work against each other good point
mmoogie,As you can see your suggestion seems to be
the most popular. The comment about closing
the gable vents seems to be critical. Thanks
for the sage advise!Creed
A little more extreme would be to use a lighter colored roof at least when you reroof your house. I have galvalume on mine with lots of hardwoods and it works fine. A weekend fix would be the ridge vents.
A thermal blanket might help a little because you still have radiant heat to deal with but probably not that much.
Due to the recent state of the economy, the light at the end of the tunnel has been turned off
There are some new asphalt shingles that have high reflective granulars and they have an Energy Star rating and qualify for the energy tax credits..
William the Geezer, the sequel to Billy the Kid - Shoe
Since you are the master googler.... Got any pages listing a summary of all energy tax credits for homes?
I saw one where you could get a $2000 tax credit if you built a house that was 50% more efficeient than a conventional house.... Lemem see... spend $45k on solar and all kinds of stuff and then get a $2000 tax credit?? NICE.... does that come with a Christmas card from the IRS?
Sorry I don't have any off the top of my head.From what I have seen the IRS does not keep theirs upto date. They probably won't have good information until late fall or early winter when they update the PUBs for next years returns.Energy Star website is usually what pops ups if you google on "energy tax rebates". It seems to list all of them for UPGRADES and even points to the list of specific products or specifications that qualify.And some one else has post a link to a national website that breaks down by state and they government and utility programs. Some are state tax, some are rebates, some are low cost loans, some will do the work. It looked reasonable accurate from what I could tell based on my area. But I am sure that something like that many programs fall through the crack. And are either not listed or have outdated information.But you are talking about something else. New construction. I really have not followed that. But there are some credits for a "manufacture" which I thinks includes home builders.Try google on -production energy tax credits - and -new contructions tax credits-..
William the Geezer, the sequel to Billy the Kid - Shoe
bambam,Hey, thanks for the input! I'm not quite
ready for a new roof yet, but I don't know
anything about the galvalum product. Is that
a generic or brand name?Thanks for the help.Creed
Look into increasing your insulation. You''ll get year round benefit. Power venting can pull conditioned air from inside and no matter how well the attic's vented, if it's 100F outside, the attic will never get cooler than that.
http://www.quittintime.com/ View Image
seeyou,You are right on, I do need more attic insulation!
This is a project that I am planning on doing soon
before those temps get much higher! Thanks for your
help.Creed
Wait - back up - why do you even want to cool the unconditioned attic space? Are there (storage) reasons, or does it just "seem" like a good idea?
Tons of pro & con argumentation about the need for attic ventilation in past discussions- an interesting read, if you can make the $%#* search engine work for you.
Basically, the concern is that if you make the pressure in the attic slightly lower than the pressure in your house (we're talking tiny pressure differential here, on the order of a few inches of water), the attic will draft air OUT of your house through the innumerable openings in top plates and around light fixtures and electrical boxes; air that you've paid to cool.
This is easy to prove. On the other hand, legend has it that shingle life is degraded over an un-ventilated attic. This, however, is much harder to prove - no one has been able to do it convincingly.
If one really wants attic ventilation, I had a plan detailed here once of actually blowing air INTO an attic, through a duct and a fan in a garage, in order to raise the pressure in the attic tio encourage flow.
Forrest
McDesign,Wow, something to wrap my head around! I didn't
mean to say that I want to cool(air condition etc)
the attic I want to:increase the natural flow of
cooler outside air to replace the warmer attic air,
or electrically draw the outside air into the attic.
I understand that there is lot that can be done to
seal the attic from the conditioned space. I would
be interested in your plan with the garage fan.I appreciate your take on this project!
Here was the original thread - http://forums.taunton.com/tp-breaktime/messages?msg=113389.1. I thought I had made a sketch, but it wasn't here.
Forrest
McDesign,I checked out the thread and the following
posts. I am liking the idea of placing
thermostatically controlled fans at either
end of the house and have one pull outside
air in and the other pull the attic air out.
This seems to neutralize the high/low pressure
problems that will pull the conditioned air
out of my living space and into "the neighborhood"
(something that fathers are prone to complain about)
I do have one side of the house that is more
shaded than the other, this seems like the
side I would pull air in from.
The generally (which is to say, not universally) accepted best approach is to close off the gable vents and use ridge vents.
DanH,Thanks for your idea.Creed
Weatherization is thye new craze, and infact, a heck of a good living if you can handle the miserable work enviroments.. Here in Alaska we do things differently than you would there, but no matter where you are, insulation is insulation...Add tons, it's cheap.. Who cares if your attic is hotter than heck..Maybe the bees, but maybe that's a good thing..If it's so hot that it affects your homes temperature check with a local Weatherization Tech..They'll send you the right way...I'd seal all top plate penetrations, light fixture penetrations, and any leaks in your A/C ducts(no matter in the attic or not)..Attic venting is somewhat for "cooling" the attic, but their biggest "concern" is moisture/humidity escape path..Good luck.
All I ever wanted in life was an unfair advantage...