[Rlcky]

I'm shopping now to change my roof, the length of my house is 40x26 bungalow with a basement.

right now i have 1 maximum 301 and there's exhaust fans for bathroom it goes directly to perforated soffit but i don't have one for range hood which all heat goes into the attic.

my main concern is should i need 2 303 maximum or only 1 301 and keep the existing one? how to calculate how many ventilation maximum roof do i need? is it length by width? i did few quotation and some of them says to install 2x303 and some 1x301 and some 2x301.

i will be asking to install a CT-6 a 6" roof exhaust vent for the range hood, does it make difference between CT-10 and CT-6?

my last question is, should i install a roof exhaust vent for the bathroom and remove the one already installed in soffit (I heard its not good practice to install and to avoid dumping air of any exhaust fans like range hood/bathroom/dryer in soffit as this will void all moisture control efforts in any house)

Thanks guys.

 

[Bud9051]

Hi Ricky, your location will help.
And welcome to the forum.
First you will have to help this old guy out. What are you referencing with your 301 and 303? And what are the CT-6 and CY-10?

Attic ventilation is most often provided by passive vents, soffit, gable, roof, or ridge. What do you have?

All appliance or bathroom ventilation needs to go directly to the outside and not in the attic, even at the soffits.

Bud

 

[craig11152]

Maximum is a vent manufacturer and 301 is a specific product as are CT-6 and CY-10.

http://www.ventilation-maximum.com/English/index.html

 

[Rlcky]

Hi Ricky, your location will help.
And welcome to the forum.
First you will have to help this old guy out. What are you referencing with your 301 and 303? And what are the CT-6 and CY-10?

Attic ventilation is most often provided by passive vents, soffit, gable, roof, or ridge. What do you have?

All appliance or bathroom ventilation needs to go directly to the outside and not in the attic, even at the soffits.

Bud

I'm from Montreal, I have roof shingles, along with soffit and 1 maximum 301 which is cover up to 1200 sqft. as i already mention dimension of my house is 40x26 which is 1040sqft. one maximum 301 will be enough? or i have to to go with 2x303 (800sqft each).

 

[Rlcky]

in addition to craig11152 more info can be found here http://www.ventilation-maximum.com/English/pdf/all-slope-roof-models-2016.pdf

also CT-6 or CT4 are exhausted roof trap http://www.ventilation-maximum.com/English/product-roof-exhaust-traps.html used for both bathroom or kitchen range hood.

as for the installation of executed roof trap for both bathroom and kitchen best practice to install them closer to the gutter slope?

Thanks.

 

[Bud9051]

Hi Ricky,
I'm still reading so will be back later. I have seen a few similar units (from a distance), may well be Maximum, but I have never read over their guidance. Having trouble making the transition from the standard 1/150 and 1/300 guidelines over to their "per sq ft" recommendations, which surely are not simple.

Basically, an elevated vent column is an excellent idea for adding effective height to the attic and keeping the top above the snow. So far I have found little guidance for soffit NFA or modern advice related to insulation, vapor barriers, and air sealing. They seem to cover that by simply referring to code requirements. They could do better.

Despite my picky nature I like them, I just need to be comfortable with their guidance. I'll be back.

Bud

 

[Bud9051]

I'm back.
The next link you provided does give the NFA for each vent, that's good. As to whether their design provides anything more than extra height I'm not certain, since their language is still buried in the past. But the extra height is good and I'm sure their products are built well.

But, for determining the recommended ventilation we should, as they advise, go back to see if your home meets the current building codes. Since you are shopping for a new roof that tells me the house wasn't built yesterday.

How old is the house?

More than 15 years and it probably didn't receive the detailed air sealing that is currently recommended. Have you done any extra air sealing in the attic. Link below for reference. https://www.energystar.gov/ia/partners/bldrs_lenders_raters/downloads/TBC_Guide_062507.pdf

Next would be to determine what you have for vent area (NFA) and location of those soffit vents. Describe what is there including length and width.

How much insulation is in the attic. Insufficient insulation requires more insulation or more ventilation. More insulation is the better way to go.

As for the CT series of roof vents I would say that is determined by the fan venting into them. If you feel you will at some point increase the fan size, now would be a good time to increase the vent size.


If we use the 1 ft² of vent area for every 150 ft² of attic floor we would be looking for a total of 7 ft² of vent area, 3.5 up high and 3.5 down low. If you address the air sealing issue those numbers drop to 1/2 that suggestion.


But even at 1/2 that would be 1.75 ft² for high venting and the 301-12 has only 1.0 ft². We need to know the size of your 301.


Bud

 

[Bud9051]

I hate having 3 posts in a row, but I continued to read and found another reason why I'm uncomfortable with this companies claims. From their web site.
http://www.ventilation-maximum.com/English/general-information.html
under patents it says " Maximum ventilator is a patented device. Our products are patented in Canada and in the United States (Canada Patent # 2 467 956, USA Patent # 6 932 690)
So I took a look considering how proud they are of their wind enhanced ventilator. The product listed in those patents is only the adjustable roof jack. They sure are making it sound like their ventilator design has been patented. Shame on them.

Bud

 

[Gary in WA]

If you install the 144" (12x12 = 1/1000 for your roof) vent, make sure to air seal the attic first- and get insulation up to code;http://www.waptac.org/data/files/we...esources/woods_reexaming_roof_ventilation.pdf

Check the attic monthly for signs of moisture/frost/condensation on the framing/sheathing, if so, add another one.

Gary