Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Roofing/Siding

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 04-04-2007, 06:01 PM   #1
Newbie
 
Join Date: Mar 2007
Posts: 10
Share |
Default

Q? for Grumpy the Roofer re attic ventilation


Grumpy,

I read in a searched post your statement that one should NOT mix attic ventilation styles. In that case - soffit/ridge vents and gable end vents.

(original post here -) Are you having ice problems?

Would you elaborate as to the "why not mix"?

I am currently Owner-Building a second home and the plans call for BOTH full length ridge vents with matching soffit vents AND gable end vents. We have already installed the roof - so the soffit and ridge vents are in place. We have not cut out the gable end vents at this time - so if I need to rebut my architect - now is the time.

Thanks,

Rick

Ricky D is offline   Reply With Quote
Old 04-04-2007, 07:13 PM   #2
Lic. Builder/GC/Remodeler
 
AtlanticWBConst.'s Avatar
 
Join Date: May 2006
Location: New England
Posts: 7,556
Default

Q? for Grumpy the Roofer re attic ventilation


Quote:
Originally Posted by Ricky D View Post
Grumpy,

I read in a searched post your statement that one should NOT mix attic ventilation styles. In that case - soffit/ridge vents and gable end vents.

(original post here -) Are you having ice problems?

Would you elaborate as to the "why not mix"?

I am currently Owner-Building a second home and the plans call for BOTH full length ridge vents with matching soffit vents AND gable end vents. We have already installed the roof - so the soffit and ridge vents are in place. We have not cut out the gable end vents at this time - so if I need to rebut my architect - now is the time.

Thanks,

Rick
When was the last post that Grumpy made?
Not sure if he is still posting on here....
You might try also posting this question to any knowledgeable roofers that also contribute to the forums...

AtlanticWBConst. is offline   Reply With Quote
Old 04-04-2007, 07:19 PM   #3
Commercial Roofing
 
AaronB's Avatar
 
Join Date: Jan 2005
Location: Illinois
Posts: 927
Default

Q? for Grumpy the Roofer re attic ventilation


cuz thats what the shingle mfgs say...

I know a guy named Dennis in Chardon, OH that proves many points tothe contrary.
__________________
www.roseroofing.net/ Free inspection within 12 miles
Seamless Polyurea Roofing Membranes for Metal Roofing, Roof Leak Repair, Seamless Commercial Spray Foam Insulation, Seamless Commercial Roofing, SPF Roofing, Industrial Insulation, Our trucks are red but our roofing is GREEN!
AaronB is offline   Reply With Quote
Old 04-05-2007, 01:35 AM   #4
Member
 
Join Date: Jan 2007
Posts: 2,384
Default

Q? for Grumpy the Roofer re attic ventilation


The theory behind not having opposing or competing ventilation systems for the same attic air ti ventilate, is that it would be a short circuiting of the ventilation system.

It is not only promoted by the shingle manufacturers, (who provide the warranty), but from the ventilation manufacturers as well.

More precise information can be found on the Air Vent Corporation website.

Ed
Ed the Roofer is offline   Reply With Quote
Old 04-05-2007, 07:16 AM   #5
Lic. Builder/GC/Remodeler
 
AtlanticWBConst.'s Avatar
 
Join Date: May 2006
Location: New England
Posts: 7,556
Default

Q? for Grumpy the Roofer re attic ventilation


Quote:
Originally Posted by Ed the Roofer View Post
The theory behind not having opposing or competing ventilation systems for the same attic air ti ventilate, is that it would be a short circuiting of the ventilation system.

It is not only promoted by the shingle manufacturers, (who provide the warranty), but from the ventilation manufacturers as well.

More precise information can be found on the Air Vent Corporation website.

Ed
Welcome to the DIY forum Ed... (it's about time )
AtlanticWBConst. is offline   Reply With Quote
Old 04-05-2007, 10:36 AM   #6
Member
 
Join Date: Jan 2007
Posts: 2,384
Default

Q? for Grumpy the Roofer re attic ventilation


I think I made one or two posts before. I get caught up on the other site.

Getting back to the original posters question though. Stop at a local ABC Roofing Supply, Bradco, or Allied Building Materials distributorship and ask for the Air Vent brochures which deal with "short circuiting" the attic ventilation system.

Ed
Ed the Roofer is offline   Reply With Quote
Old 04-05-2007, 02:24 PM   #7
Newbie
 
Join Date: Mar 2007
Posts: 10
Default

Q? for Grumpy the Roofer re attic ventilation


Thanks for the info - I have downloaded a few of the docs from Air Vent and will look them over more thoroughly this weekend.

I do recognize the term "cool roof" - as that is the intention of our design. A quick scan of some of Air Vent info appears to suggest that gable end vents combined with soffit/ridge would cause disrupted air flows such that neither system would work to its fullest capabilities.

What I need to do is ensure that I have sufficient soffit venting to match the full length ridge venting we installed before winter. Our soffit vents are screened 2.25 diameter holes cut 3 per truss block. Can't wait to figure out the actual air flow through these things - thank goodness for online cfm calculators.

Thanks again for the input.

Rick
Ricky D is offline   Reply With Quote
Old 04-06-2007, 02:26 AM   #8
Member
 
Join Date: Jan 2007
Posts: 2,384
Default

Q? for Grumpy the Roofer re attic ventilation


Oh Heaven forbid,

Those mini-louver vents will NEVER add up to the equal amount of ridge line exhaust ventilation capacity.

Do not just calculate the square inces of the opening of each of the circular vents, as the total NFA or NFVA, (Net Free Ventilation Area), will be approximately 50 % less than the calculated opening area because od the restriction of the air flow.

I believe tha Lomanco web site lists the common NFA/NFVA for various sized mini-louver button hole vents.

As an aditional note, the NFVA of the Intake air should be equal or greater than the total NFVA of the ONE STYLE of attic exhaust ventilation product.

Research indicates that a more functional ratio would be 60 % Intake to 40 % Exhaust.

Please provide for a continuous soffit vent assembly, either by under soffit strip venting, 100 % perforated, (Not Lanced) aluminum soffit panels, or the Drip Edge Vent product offered by Air Vent Corporation, or the Smart Vent product offered by DCI Products Incorporated.

Shingle Vent II, by Air Vent provides 18 sq inches per lineal foot. The Drip Edge Vent and the Smart Vent each provide 9 sq inches per lineal foot, so when combined on the front and the rear in their entirety, they will precisely match the output of the previously mentioned ridge venting product.

Ed
Ed the Roofer is offline   Reply With Quote
Old 04-06-2007, 06:18 AM   #9
Commercial Roofing
 
AaronB's Avatar
 
Join Date: Jan 2005
Location: Illinois
Posts: 927
Default

Q? for Grumpy the Roofer re attic ventilation


Just put in some nice big old school gable vents....not the kind that look like theyre 12' across but only have a 12"x4" vent space that is bug screened.
__________________
www.roseroofing.net/ Free inspection within 12 miles
Seamless Polyurea Roofing Membranes for Metal Roofing, Roof Leak Repair, Seamless Commercial Spray Foam Insulation, Seamless Commercial Roofing, SPF Roofing, Industrial Insulation, Our trucks are red but our roofing is GREEN!
AaronB is offline   Reply With Quote
Old 04-06-2007, 01:16 PM   #10
Member
 
Join Date: Jan 2007
Posts: 2,384
Default

Q? for Grumpy the Roofer re attic ventilation


The problem with gable end vents:

If they are used in conjuction with an additional exhaust ventilation system, see the previous answer regarding short-circuiting the ventilation flowage.

If they are used in lieu of either intake or exhaust:

Intake: They are located to high on the contained attic space to completely "wash" the entire air cavity with free flowing air exchange.

Exhaust: If they are utilized as an alternative for the continuous ridge vent exhaust system, the will allow cooler air to enter the windward side opening, and as cool air enters, it displaces the hot air in the contained area. Therefore the path the air funnel will take, is to enter at a higher point, travel along the lower attic floor space, then continue flowing until it heats up and rises and escapes through the leeward side gable vent. Gable vents primarily work best when one of them has an exhaust fan to promote more functional air flowage continuosly. It would be rare cases where the exterior wind effect would be intense enough to do so on its own merit.

If you use any motorized device, then check out energy efficiency studies regarding, "PAV", (Powered Attic Vents), which prove the operating costs incurred are greater than the energy costs saved.

Spend the time and money to do it right the first time for the greatest long term rewards.

Ed

Last edited by Ed the Roofer; 04-06-2007 at 07:57 PM. Reason: punctuation and spaces between some words
Ed the Roofer is offline   Reply With Quote
Old 04-06-2007, 03:38 PM   #11
Commercial Roofing
 
AaronB's Avatar
 
Join Date: Jan 2005
Location: Illinois
Posts: 927
Default

Q? for Grumpy the Roofer re attic ventilation


BIG gable ventilation.
__________________
www.roseroofing.net/ Free inspection within 12 miles
Seamless Polyurea Roofing Membranes for Metal Roofing, Roof Leak Repair, Seamless Commercial Spray Foam Insulation, Seamless Commercial Roofing, SPF Roofing, Industrial Insulation, Our trucks are red but our roofing is GREEN!
AaronB is offline   Reply With Quote
Old 04-06-2007, 10:53 PM   #12
Lehigh Valley PA
 
Join Date: Mar 2007
Posts: 76
Question

Q? for Grumpy the Roofer re attic ventilation


Don't mean to jump on this and butt-in but.... I'd like to understand this a little more.
Reading the posts has left me a little confused.
My house is a one story ranch built on a slab, the attic is completely open end to end. There is a whole-house fan in the hallway ceiling that pushes air into the attic.
I have a large opening on each gable end of the roof, about 36" X 24" or so. I know the soffit also has louvered panels and perforated panels in it.
Is this a good set up? What should be done to make sure this works as best as it can?
Last question... the previous owner has a sheet of plywood over each gable vent that is hinged at the top. Should these be closed off at a certain time of year or left open all the time?
I have been closing the one closest to the house fan on that end of the house and leaving the farther one open to try and push all the hot air out of the attic in the summer.

Confused.
Nhrafan is offline   Reply With Quote
Old 04-07-2007, 12:45 PM   #13
Member
 
Join Date: Jan 2007
Posts: 2,384
Default

Q? for Grumpy the Roofer re attic ventilation


Typically, when the gable vents were sealed off, it would mean one of two things.

1) Wind driven rain or snow was allowed to enter the large opening would be one possibility.

2) There is another exhaust ventilation system in place and the home owner or contractor followed the widely accepted premise to seal off alternative competing ventilation systems.

You did not mention if there was another exhaust system such as a continuous ridge vent, static air pots aka mushroom vents or turtle vents, wind driven turbine whirlybird vents, or a powered attic exhaust fan.

Your post seemed descriptive, so I will assume their is no other exhaust ventilation scenario present.

Therefor, where does the air get exhausted?

Hot air rises from its own natural thermal buoyancy effect, which would need an escape method near the top of the roof.

Cooler fresh air would then displace the exhausted hot air by funneling through the soffit air intake vents.

If the existing gable vents show no signs of previous leakage, then they should not be closed off at all for any season, including the winter.

You should check the soffit vents to verify that they are not clogged by any attic insulation.

I personally love the instantaneous cooling effect of turning on a whole house fan, as long as there are sufficient window openings to allow for the proper pulled in forced air intake.

I hope this helps and does not just confuse the issue further.

Ed
Ed the Roofer is offline   Reply With Quote
Old 04-07-2007, 02:48 PM   #14
Commercial Roofing
 
AaronB's Avatar
 
Join Date: Jan 2005
Location: Illinois
Posts: 927
Default

Q? for Grumpy the Roofer re attic ventilation


I liek whole house and a static system for this very purpose.
__________________
www.roseroofing.net/ Free inspection within 12 miles
Seamless Polyurea Roofing Membranes for Metal Roofing, Roof Leak Repair, Seamless Commercial Spray Foam Insulation, Seamless Commercial Roofing, SPF Roofing, Industrial Insulation, Our trucks are red but our roofing is GREEN!
AaronB is offline   Reply With Quote
Old 04-08-2007, 12:07 PM   #15
Member
 
Join Date: Jan 2007
Posts: 2,384
Default

Q? for Grumpy the Roofer re attic ventilation


Aaron,

So do I. In my own home, I have 1 whole house fan and a continuous ridge vent. I can evacuate all of the internal radiant heat built up in the attic with the flip of a switch. I cools down the interior environment tremendously.

For anyone not familiar with a whole house fan, think of sitting on a screened in porch and having a continuous breeze blowing by. When enough windows are opened to allow for the whole house fan to pull the fresh outdoor air inside, it just feels very comfortable.

Ed

Ed the Roofer is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Attic Smell from A/C - I'm at wit's end! cidsamuth HVAC 17 09-06-2008 12:59 PM
Attic Ventilation - importance of balance FatAugie Roofing/Siding 7 08-04-2007 10:57 AM
Ridge vent only on highest peak or all? Shasta Roofing/Siding 15 07-19-2007 04:35 PM
Attic Ventilation Questions AllGoNoShow Roofing/Siding 4 11-26-2006 12:02 PM
Proper Attic Ventilation kmhill35 Roofing/Siding 2 04-01-2005 08:11 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.