Does an attic with windows need ventilation?

[Jackson Landers]

Last night I woke up at what was probably about 2 am from a very vivid dream about cutting slots in rafters for outriggers and realized that I had given absolutely no thought to the question of attic ventilation. I lay awake for at least half an hour staring at the moon-lit ceiling as I pondered the matter.

Yeah, ok. I know that this suggests I have a serious compulsive construction disorder.

So here's my question. In a small attic that has a double-hung window at each gable end with a screen, is there any reason to install any other ventilation components? With 16" overhangs on each gable end, I'm thinking that I'd probably be ok just having the window on either end cracked for air to pass through and I wouldn't expect any rain to get in.

[PEG688]

Moon -lit ceiling ? Is your roof glass? Dis-order ,    maybe ,   waking it night is common if it's blown 30 + and you have a tarp on a roof covering a remodeling job , at least for me 

As far as your windows  / venting , I'd say no as you'll end up closing them in winter when you need the ventilation the most. You also need soffit venting or bird block/ anti rotation venting to promote air flow from the bottom up under the roof sheathing and BETWEEN the insulation and sheathing bottom side . You did not mention  exactly how this attic will be insulated and that is the key item as to exactly how it SHOULD be vented.

So "It Depends"  is the "closest" right answer to this question.     

[Jackson Landers]

The full moon was shining in through the window at such an angle as to light up the ceiling a bit.

I intend to insulate the attic with fiberglass batts. Does that mean that I need soffit venting? I have no idea what bird block or anti rotation venting are, so I will go google those methods right away.

[MountainDon]

I intend to insulate the attic with fiberglass batts.

Insulate it by placing the batts in between the roof rafters?

That would usually mean you need a lower vent (air in) and an upper vent (air out). Lower vent at the soffit, upper vent as in a ridge vent.

Now with that said are you finishing the interior all the way to the peak? Or are there rafter ties in the upper third or so area? If there are ties yielding a narrow flat ceiling then insulation could be placed on those, combined with insulation between the rafters to that point. Then you could install gable end vents for the air exit (in place of a ridge vent).

[Jackson Landers]

Mountain Dom,

Yes, batts between the rafters is what I intend to do (whenever I can afford the insulation).  It's a rather small attic without even enough room to stand up in. 12 in 12 roof, building is about 10 feet wide.  But I'm planning to set it up it as a sort of sleeping loft and will be finishing the space out nicely. There are no collar ties, since the rafters are face-nailed to the joists.

Sounds like I'm going to have to go with soffit vents and a ridge vent. Bah. More stuff that I have to buy rather than make myself. I appreciate all of the advice.

It's a frustrating point to get to in the course of construction, isn't it? On the one hand, it's so easy to kid myself and say 'look, I'm sheathing the roof next week! It's almost done.' And yes, once it's dried in it looks like a proper little house. But then I've still got to spend the same amount of money I've spent thus far all over again on insulation, drywall, wiring supplies, vents, siding, etc. etc. Like getting up to the 'peak' of a mountain only to find that it's actually just a ridge and the real peak is another mile away.

Still beats the heck out of sitting on the couch, though.

[TheWire]

It's amazing how one's mind appears to continue to contemplate building problems while we sleep.  When I was building my log home in 1997, I suddenly woke up at 3am with the realization I may not have proper clearances for the chimney flue from the supports that where holding up a 6" x 20" structural ridge beam.  I had to drive to site at 3am to verify it.  I was right.  Luckily a fairly simple repositioning of a short LVL support solved the clearance problem.

Jerry

[TheWire]

While we are on the subject of attic ventilation.  My cabin will have rafters with collar ties.  I plan on insulating the rafters from the top of the knee wall to the collar ties then continuing the insulation across the collar ties to the other rafter(s).  I'll end up with an open un-insulated space above the collar ties.  I'm going to have eve vents and will make sure there is an air space between the roof decking and the insulation that's in the rafters.

My question is about the top vent.  Being that its all open above the collar ties could I use gable vents or should I stick with a ridge vent?

[MountainDon]

My question is about the top vent.  Being that its all open above the collar ties could I use gable vents or should I stick with a ridge vent?

A properly sized gable vent at each end will be fine. That's what our suburban home has; that and soffit vents along the eves.