Roof venting opion needed

[Jeff Monson]

I'm in search of some help here, I have a lake cabin, A-frame constuction, and this spring I noticed a water stain on the ceiling upstairs. I know the shingles are in good condition and when it rains I get no leaking from the roof.

What appears to be happening is snow is blowing into the roof vent, and melting in the spring and causing the water stain. There is no attic to look in which makes it difficult to inspect. The entire ridge on the roof is a vent so my question is, can I remove the entire ridge vent and shingle over the peak, or will this cause me more problems like dry rot??

A little more info, this is a seasonal cabin so we are not there in the winter, also the roof is very steep and about 30 feet to the peak so I'm not looking forward to getting up to the peak.

[Randy Cohen]

i don't think you need a roof vent....but describe the construction...where is the insulation?

[Jeff Monson]

The cabin is mostly roof as it is an a frame with 8' sidewalls, the walls and roof are 2x6 with insulation on both, the upstairs walls are tapered as they are just the inside of the roof, the ceiling upstairs is about 4 feet across so there is a small dead space between the ceiling and the peak of the roof, I'm unsure whats up there as we have only owned it for a year now, the guy who built it is who we bought it from and he said its insulated the same throughout.

From the outside of the cabin you can see the ridgevent that runs the length of the roof, its easy to see the slots in the vent system, rain could never enter the slots but blowing snow could easily filter into the slots.

I'm unsure if the small deadspot from the ceiling to the peak would need venting or not???

Hope this helps you visualize my situation.

[Ben Grunow]

You must keep some ventilation and gable vents would do fine but might be more work than you wanted.

Look into different types of ridge vents as they have come a long wayand there are many types/mfgrs.

I have never had this problem to the degree you describe.

[Craig Summers]

I think you need to inspect in that crawlspace /mini attic you describe. Is there an access panel to get in there?

You might be able to see water stains from where the leak is coming from

My thoughts
1) The ridge vent might be loose or cracked. Depending if its the plastic baffle with shingles capped on, or if its the sheet metal. Does it look like any of the ridge vent has come unglued? In order to place either on an A-Frame roof, they require a pretty tight bend at the peak.

2) Is there a chimney with the cabin? if so have you checked the flashing?

I agree with Ben, a gable should be enough ventilation for just a tiny attic, assuming that the soffits are not vented

Ridge vents only work well when you have soffit vents. You need incoming cool air equal in volume to the hot air you are expelling. If the prior owner installed baffles between the roof and insulation (now buried under the sloping ceiling), then i would keep the roof vent

Before you close off the ridge vent, i would try to rule out other sources of water entry. Remember that water will travel accross drywall, looking for a low point to penetrate. You might be better getting a better roof vent, they aren't expensive, use plenty of roof tar, and that might be easier than recapping the peak (to shingle it, you first have to backfill the slot at the peak and reinforce with aluminum H pieces)

[Jeff Monson]

Craig,

That is a really good point you have about the tight bend on the ridge vent, to me it appears he used a vent for a normal sloped roof and the tight angle this roof is at makes it bend more than it was designed.

There is no chimney or other vents in the roof, no soffit vents or gable vents. A gable vent makes sense to me but would be very difficult to install in the peak as its a long way off the ground, I'd feel more comfortable installing something on the roof.

How about if I remove the ridgevent and shingle over the peak and install a small square roof vent on the top side of the roof where the wind isnt so prevalant? (this being the east side of the roof as its protected by trees and the west side is wide open and wind coming off the lake blows directly on it)

[Craig Summers]

Jeff

Take a look at this website, it has some of the basic concepts http://www.dspinspections.com/atticventing.htm
You mentioned that the problem occured during the winter. Could that have been condensation freezing inside the attic, then melting?

http://www.dspinspections.com/images/AtticVenting1.gif http://www.dspinspections.com/images/AtticVenting2.gif

For venting, you need to figure your square footage of attic space, and use either local code or a rule of thumb 1 Sq ft of vent per 150-200 sf of attic. Keep in mind that is 1 sq ft intake, and 1 sq ft exhaust

Also re-reading your post, since you are not there in the winter, is it possible you had a big enough snow to cover the ridge (via drifts etc) and the melting snow dripped into the house?

If size matters, you might consider a turbine vent (stays higher so the snow doesn't cover as quicly) or a solar powered fan. I presume you "winterize" and turn off the electricity?

[Jim O'Dell]

Jeff, the ridge vent I put on my shop last year has a filter type material in it to keep blowing snow and rain from getting through. I know that one is not going to be easy to get to since you can't crawl into the attic to see or do a repair, but if your's doesn't have that type material in it, you could probably get something like that, cut and insert it. Might look to see how the ridge vent is secured to the roof, and see if you could easily pull up one side to insert it. Jim.

[Jeff Monson]

Thanks for the really good info, the snow doesnt get deep enough to make a drift on the roof, I do stop in from time to time in the winter to ck on things. I'll calculate the square footage above the ceiling and use the formula you have posted, thats also a good link!!

The vent looks very easy to remove as its put on the outside of the shingles???? I just dont like when things arent done right!! I'll follow up with the correct sized vents on the side of the peak and all should be good.

Thanks alot for the great advice :D