|Forum topic by RonInOhio||posted 01-12-2013 09:12 AM||13413 views||0 times favorited||8 replies|
01-12-2013 09:12 AM
Excuse the long post.
I will soon be insulating my shed and have come up against a few issues I need to resolve. Was hoping someone with a knowledge of insulation and proper venting techniques could weigh-in on my situation.
I have some round two inch vents. I was thinking about using them in the gables for exhaust vents. Easy to install just drill a two inch hole in the gable and push the vent into it. The problem is , I’m not sure if the little 2” gabel vents I have will be sufficiently big enough.(They are not installed yet.)
The plan is to put one at both ends of the gable.
I have read where its just as bad to have gable vents too large, as not having any attic/gable vents. I suppose if design and proper venting calls for something like a 4” vent, I could put two in each end or cut out a 4 inch hole, but hopefully that won’t be necessary. A hassle. Don’t think I have a 4 inch hole saw attachment
Along with the gable vents I will have soffit vents.
Apparently a proper design rule is to have 1 sq. foot of inlet and outlet vent for every 144 sq. feet of attic floor. Or, 1 sq.inch of vent for every sq.foot of attic area. Do the soffit vents count into that total ? I assume they do.
Not worried too much about the soffit vents as I will be using the vinyl soffit material which are perforated along there entire length and width.So there will be plenty of intake. Just not sure about the exhaust vents up on the gable ends.
So I need to calculate the area of my little attic (or space) that needs to be vented to determine if my gable vents are large enough. But more on that later.
For now, The illustration below shows how I plan on insulating the rafters and attic. The parts shaded in blue will be insulated. Additionally I will be installing batt baffles from the wall plates , up to where the collar-ties meet the rafter. These baffles provide about an inch or so of air space . The air space will remain cold during cold outside temps and so condensation won’t form inside and cause rot and ruined insulation.
Now moving into the little attic area . I will be insulating the collar-tie bays with at least 6 inches of insulation. Above the collar-ties I’m stumped. It would seem against logic to insulate the rafter bays above the collar-ties, no ? So as the illustration shows I don’t have those insulated. Is this correct ? I am probably over-thinking this but don’t want to screw this part up and end up with condensation , wet insulation , rot ,mildew or other damage.
My attic is a triangular shaped space. So I’m assuming I just find the area of that triangle right ? Been awhile since I used this math.
The shed is about 10×12 and the collar-ties only leave about a foot up there to the roof and maybe
~ dimensions of attic.
The width of the collar-tie is about 5 feet.