Advice sought for attic/roof venting
I would like to get some feedback on attic/roof venting. I’m getting a new roof in a few months.
My house is 105 years old and it has a hip gable roof. The job will entail a complete tear-off of all roofing layers down to the skip sheathing with new plywood sheathing nailed over the skip-sheating. I don’t have vents @ the eaves right now and am not too interesting in adding them. But I have some options for taking care of getting airflow:
Option 1: Use an assortment of eyebrow vents positioned high (by the ridge) and low.
Option 2: Put in a ridge vent and then use eyebrow vents lower down.
Option 3: Put in a ridge vent and use smart vents lower down. This will eliminate the need for any eyebrow vents.
Option 3 is the most expensive and I’m leaning towards that solution as I think it may be technically the best option and worth it. The smart vents would have to be installed at the lower parts of the roof and there would have to be 4 total: 1 @ each of the 2 gable sides & 1 @ each of the 2 hip sides. For the hip sides, there isn’t a ridge condition directly opposite it as there is for the gable sides, but I’m thinking that’s not a problem. I’m thinking there should still be some airflow over the hip rafters due to the gaps between the skip-sheathing boards.
I like Option 2 as well and Option 3 could be modified slightly to eliminate the smart vents @ the 2 hip sides and use eyebrow vents instead. That would essentially make it a hybrid of 2 and 3 or perhaps call it Option 2.5.
Does anyone feel that Option 3 is overkill?
thanks,
jonR
Replies
not overkill
the lower the vent the better. I would opt for #3.
I'm not sure I follow your reasoning; 'lower the vent the better' & 'option #3' are not necessarily EXCLUSIVELY related compared to the other two options. 'Low' could be achieved with any of the options using eyebrow vents. The eyebrow vents could simply be placed lower and 'lower' is a given in all 3 of the options. I guess you didn't understand the gist of my question: 'linear / continuous' vents such as ridge vents and smart vents are more expensive than 'spot vents' such as eyebrow vents. I'm wondering if they are worth the extra cost. The 'high / low' thing could be achieved with any of the options.
of the options you are considering, the "eyebrow" vents are the least effective because they are installed in very poor locations most of the time.
you could not get eyebrow vents close enough to your eave without it begin an incredible eye sore.
absolutely it is worth the relativly small expense to add ridge vent and smart vent (or the like).
the high/low can be installed with your three options but are essentially useless in option 1-2.
your best option for obtaining a properly vented roof is option 3, ridge venting and smart vent at the eaves (hence the lower the better) I worded it that way because you said you are considering option 2 which means you are considering placing vents somewhere in the middle half of your roof and this is not advisable. Lstibureks stuff is good but sometimes hard to achive in retro fit situations due to the reality that most people work with a limited budget.
In your case it does not sound like it would be to difficult to achieve a properly vent roof.
Mark,
Thanks so much for the elaboration; I really appreciate it. I'm glad that my initial hunch of going with Option 3 is consistent with your logic, because the reasons you have given were things that I had been thinking about.
Btw, for a simple gable roof, you could take care of the entire roof with a ridge vent and two smart vents, one down low on each of the gable sides. I have a hip gable and am considering 4 smart vents, 2 more that would be used for the above mentioned gable. Do you think it is absolutely necessary to have smart vents at the bottom of the 2 hip planes? The attic space is contiguous with no blockage and am thinking the hips could do without the smart vents if I was going to try and limit costs. However, the cost savings is not worth it if the venting would be severely hampered. What do you think?
i understand budget constraints but if you can, i would do the 4 vents, at least 3. If the venting at the soffit or in this case the eaves is not sufficient, you will be loosing more money over time than the cost of the additional smart vent. If the air flow coming in the attic through your vents is less than the air leaving the attic through the ridge vent, you will be pulling conditioned air from your living space. This will cause your heat/air to cycle more frequently to condition the air replacing the air that just made up for your lack of venting... so if it were my house and i could fork out the additional expense i would.
I'm having trouble....
What the heck is a hip gable roof?
could be what happend 100+ yrs ago when the framers got pissed at a pushy homeowner...
I know of a clipped gable ......
And a Dutch hip.
and that apron hip sometimes below a gable.....
but
"what is hip (gable), tell me tell me,
what is really hip......."
Yeah, I was wondering that as well. Google did find a couple of pages that use the term, but they don't explain what it means.
IF you're looking for good advice on roof venting for your home (whether its a gable or a hip; or a combination thereof) instead of a meaningless sound bite, then read Joe Lstiburek's article "A crash course in Roof venting" in the August/September 2011 issue of F.H. His information is as relavent today as it will always be. That's because the science behind his advice doesn't change.