DIY Home Improvement Forum banner
1 - 18 of 18 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter · #1 ·
My home is 24 years old. I am the original owner.
While my roof is in relatively good shape, considering its age, I am planning on having new shingles installed.
I currently have a power fan vent. I have had to replace the fan motor twice in 24 years.
I have had several contractors provide estimates for my roofing job.
They have offered different opinions regarding the advantages/disadvantages of keeping or removing the power fan vent and putting in a ridge vent.
I have researched the subject online and believe that there is no right or wrong answer.
My thinking is that if my existing powered fan has done an adequate job for 24 years, why change to a ridge vent.
Maybe I am wrong—but I have thought it would be beneficial for the contractor to have taken a look at my attic from the inside –and measured it to determine my ventilation needs—which not a single contractor has done even though I have asked about it and have easy access to my attic. I believe I have sufficient soffit ventilation.
I have concerns- regarding the ridge vent—I understand the advantages of the ridge vent.
Could cutting the necessary vent space for the ridge vent installation effect the structural integrity of the roof?
I am also trying to determine the size fan which would be required.
I have a peaked/sloped roof and the dimensions of my attic are as follows:
Height 8.5 feet
Width 29 feet
Length 45 feet
Can you provide any recommendations of keeping the power vent fan or removing it and installing a ridge vent?

Any advise or recommendations would be greatly appreciated.

Thanks

Jay
 

·
Registered
Joined
·
2,384 Posts
Powered Attic Ventilators consume more energy than they save, based on research done by the utility commission studies.

It draws conditioned interior air from the climate controlled living quarters and purges it through the PAV on the roof.

Also, not all Ridge Vents actually do work as promoted.

The style with an external wind deflecting baffle, such as the Shingle Vent II is the one you should consider and not one of those flattened out roll vent products.

Cutting the proper sized vent slop along the peak of the roof has never posed a problem in 25 + years of installing them on my customers homes.

What is the toatal floor plan square footage of your attic?

What is the total NFVA of the existing Intake Vents?

Until you know those precise numbers, you are only guessing.

What types and hw many? Are they free flowing and uninhibited?

Ed
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #5 ·
I appreciate your advise.

My contractor is proposing to install GAF/Elk Cobra Ridge Vent.. Any opinion?

I was wondering if anyone could tell me if how to calculate if I have sufficient soffit intake vents? I have a peaked/sloped roof and the dimensions of my attic are as follows: Height 8.5 feet, Width 29 feet, Length 45 feet. I have 2 5" wide perforated panels every 50", (the 2 perfortated 5" panels are seperated by 8 nonperforated 5" wide panels) along the length of the back and front of the house.

I live in PA and we run the A/C for most of the summer.


 

·
Registered
Joined
·
8 Posts
If adequate free inlet area for air from outdoors to enter the attic (usually gable or soffit vents) is provided, an attic fan will not draw climate controlled air from the living space. The fan will reduce attic temperature in the summer, reducing the load on your air conditioner and prolonging the life of your roof.

This attic fan sizer calculator at the link below will size both the fan and the required amount of free inlet area for you:
http://www.ultimateatticfans.com/attic-fan-sizer.php
 

·
Banned
Joined
·
17,248 Posts
If you run an AC for most of the summer then you may want to pass on an attic fan. They may pull that AC air up into the attic & make your AC work harder

I don't use the AC (rarely) so I will have an attic fan
But I also have a walk up attic that is a room w/windows & skylights
 

·
Registered
Joined
·
2,384 Posts
I will do the intake NFVA calculations later tonight for you.

How many of those Double 5" panels are present on each side and for a total?

Ed
 

·
Registered
Joined
·
2,384 Posts
Okay, each double 5" panel will provide about 6 to 9 square inches of NFVA for Intake, so when I get back to my desk with a calculator, I will figure out the totals of Intake and Exhaust that are present and needed.

Ed
 

·
Registered
Joined
·
2,384 Posts
I looked through the previous posts, but did not clearly see where you may have said how wide the soffits extend out past the exterior wall.

Lets make some assumptions, just to show you what is really needed.

On perforated soffit panels, every Square Foot of Actual Vented Panel surface only provides between 6-9 square inches of Net Free Ventilation Area provided, so the 2 Five Inch Wide panels would need a soffit oferhang of 14.4" to be One Square Foot Of Panel, which would then provide the 6-9 square inches per vented panel section.

I doubt that your overhang is 14.4" so do the math accordingly for your actual calculations. i.e., if it is a 12" overhang x double 5" which is 10", then you have 120 square inches, or 120/144ths of a square foot of surface.

When you gave the 45' x 29' sizes for the house measurements, was that just the house wall perimeter dimensions or did thay include the soffit perimeter dimensions?

Also, is your home a Gable Style or a Hip Style? You stated earlier you had sloped sides. Did you mean on Just the Front and Rear or did you mean on all 4 sides of the home?

Shingle Vent II Ridge Vent, with External Baffles provides 18 Square Inches of NFVA per lineal foot that is installed.

No, cutting the slot at the peakl of the roof does not, "typically" cause any structural soundness issues.

Ed
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #13 ·
I have attached several picutres of my home to this reply. (Due to the limit of 6 attachments, I am attaching additional picutres to my next reply).
The soffits extend out from the exterior wall varies, as you may be able to see from the pictures attached--average is 10".

The 45' x 29' dimensions, were measured in the attic and include the soffit perimeter dimensions.

I hope this helps in providing me with the information I need to make sure I have proper ventilation in my attic.

From the pictures provided what type of roof do I have?

Thank you all.
 

Attachments

·
Registered
Joined
·
96 Posts
You did not mention what was on your roofdeck for sheathing.
I do not reccomend ridgevent on 3/8 plywood.
It sags enough (on 24" centers)without having the ridg cut away from the blocking.
1/2" plywood, shiplap or 16" centers with 3/8 ply are all ok
Dale Chomechko
DC Roofing Inc
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #16 ·
Dale

I am not sure about the thickness of my roofdeck sheathing.
But am thinking of going with the power fan vent anyway, since it is what has seemed to work well for me over the past 23 years.
I am still trying to determine how much more soffit venting I need.


Any recommendations on that would be appreciated.

Jay
 

·
Registered
Joined
·
32 Posts
Some framers will let a 4 inch wide piece of plywood suffice for the last piece on the peak.
In this case cutting an inch away for the ridge vent is not a good idea.
Unless one plans to add blocks underneath.
 

·
Registered
Joined
·
2,045 Posts
In answer to your question: You have a gable style roof. It also looks like you have some additional Gable end venting of a type I've never seen before that looks like short horizontal slits built into the siding up near the peak of the gable.. Unless that's one of those optical illusions that seems to happen with some digital cameras.

Why run a power vent when gravity will work for free?
 
1 - 18 of 18 Posts
Top