Onyx Xteriors

How to choose the right shape gable or attic vent for a house...

The best questions would be how much vent-able space is available and how much air needs vented? Going off the calculations for net free air is not always perfect.
These computer calculations are just that, text book. If the home is a square or rectangle box, venting is easy. A vent on both gables of adequate size for venting with proper cornice vents for intake.
And do not fill the attic full of extra boxes. Once the loft is blocked by too many obstacles, the air flow is greatly restricted. The attic is not a storage unit.
Too many items in the attic can be a fire hazard. Items that need stored there can be placed safer towards the center of the attic still allowing air to escape from both gable ends.

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The simplest way to order a custom size round louver vent.

https://onyxxteriors.com/products/louver/round.php

 

 Now, on page questions answered. Just hit any question mark

https://onyxxteriors.com/products/louver/triangle.php

But live help is still here also 901.281.2887

By clicking any "?" on the page a popup will show a quick description of the option being answered or chosen.

Roof pitch calculation

https://onyxxteriors.com/QA/roof-pitch-calculate.php

Actual step by step

Start with the common that every roof pitch ends with /12.

Example: 6/12 pitch or 8:12 pitch.

The 12 means the measure is based on how many inches the angle rises for every 12 inches or 1 foot of the width.

To keep everything simple, we will use a 24 inch base on the vent.

So for every 12 inches of base, the pitch is how many inches the rafter rises in the center.

If the center height is 12 inches then you might think this would be a 6 pitch with the base measure of 24 inches.

No. The rise is only calculated once, not for both sides.

So, you must first divide the base or width in half.

Now the base for only that rise area is 12 (half of 24 inches).

Now put the rise of 12 inches right up the center in junction with the half base width to make 12/12 as the pitch.

A more difficult one would be a base width of 70 inches and center height of 30 inches.

Same way...divide the width by 2 first.

So, 35 is the workable base.

Now 35 divided by the height of 30 is 1.16666

Finally, 12 divided by 1.16666 is 10.28 for the pitch.

So, this is a 10.3/12 pitch roof, rafter and gable wall.



To calculate off the height of the vent, just reverse the calculation.

Warning, using the height to calculate the pitch is even more unreliable for the actual roof pitch.

But, why does Onyx Xteriors not use roof pitch for ordering vents?

Feel free to call with any additional questions...901.281.2887

 

True custom triangle louver vents manufactured for homes, garages and out buildings and designed for easy install by contractors, builders and even homeowners.

https://www.onyxxteriors.com/products/louver/triangle.php

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