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-   -   ridge vent ?'s (http://www.diychatroom.com/f9/ridge-vent-s-44322/)

Zel1 05-11-2009 11:07 PM

ridge vent ?'s
 
Hello again,

I had a thread around here about the roof replacement and ridge vent. The ridge vent was in the estimate, but the installers didnt have it here and went ahead and installed the new roof without it. Most of the advice here was to have the contractor do what was agreed on, instead of trying to get him to remove an appropriate portion from the bill. I had spoke to the contractor and he appoligised for the mitake and assured me it would be installed as described in the estimate. They also had to order one spigot trim box to complete the vynil siding job. I paid him for the work and had a slight uneasy feeling that it would be like pulling teeth to get him to come back and finish the job. We then had 2 full weeks of rain and wind, so nothing was accomplished. On the first sunny day, last week, the siding guys came back and installed the spigot trim. Siding is now complete and looks great! 2 days later, Saturday, the roofing crew was back and was installing a Cobra ridge vent. I asked him about the potential of leaks and he said he's been installing this same product without incident for years, no leaks or other problems. I did not realise there were so many different Cobra ridge vent products, so I dont know the exact one they installed. I took a peek up into the attic to see what the cut looked like. I can tell the cut was probably not done with a straight edge or guide, but overall it is relatively straight. I would guess that the width of the cut is about 1.5-2". The one thing I noticed that I am not sure about is that it appears they did not cut 3/4" off each piece of sheathing to achieve the 1.5", they took the full cut off of one side of the roof sheathing. I hope I explained that right. I dont know if this is standard practice or just a "shortcut". The good thing about it is that the side they did not cut from is where we get the strongest wind gusts during big storms.

Chemist1961 05-17-2009 08:52 AM

OK Zel, my undesrtanding is that in the return trip they trimmed the opening on only 1 side of your roof peak. This saved a second cut.. 5 minutes or so in labour.
In theory you still should have the same overall opening size in the sheathing, so you should be fine and there should be no leak issue if it's installed correctly.It's not rocket science but does require pride of workmanship.

My bigger concern would be a roofing contractor who runs short of day to day materials...as he approaches the end of his job and takes a while to return. Luckily he's come back so no harm done.

Did the roofer also inspect your soffit ventilation to be sure you have adequite air flow upward between your rafters. Some roofers do, some don't it's kind of a grey area. There is a correct ratio for this job and if you are in an older home you may want to ensure your soffit venting is adequite. Did you have new soffits installed with the siding, if so what was underneath the soffits. Did he leave old plywood and simpley sheath over it or were the soffits opened up to breath better? The ridge vent works in unison with air carried from the soffits.
Check this out www.buildingscience.com

Zel1 05-17-2009 11:12 PM

Thanks Chemist!

You are correct, they made one cut instead of 2. Its not the way I would have done it, but if it works correctly, then I guess its ok.

I have to admit, I thought they were going to try to stall and delay as long as possible, but within a couple of days of the dry weather, they were here doing the ridge vent before I even got a chance to call and ask them when they were coming.

As far as the soffit, we had all the soffit vents replaced as part of the roof/siding job. I believe the soffit has vented pieces alll around, or at least every other section. I would imagine that its enough venting.

Also, should we not use and even close off the opening to the attic fan? Is the attic fan hole acting as an intake or since it is at the top of a ridge would it have no effect either way?

Chemist1961 05-18-2009 09:11 AM

Sorry Zel , that one I can only speculate on. My guess is that you would eliminate it and let the updraft from the soffits carry heat to the ridge vent if the soffits are channeling properly. But if it is near the peak it may not hurt to leave it there ...
If you did not have adequate venting prior the fan likely boosted it but it is likely redundant now unless the attic is still undervented.
Very important though to also have a clear path from the soffit vents via unobstructed airway or joist liners towards the rooftop. Can you see any indication of these baffles or liners in the attic on the underside of the roof????They would look like large inverted egg crates and would be visible every 3-4 rafter spaces starting at your eaves, running about 4' up the underside of the roof.

Zel1 05-19-2009 08:31 AM

I've been in the attic and never seen any baffles. There is about a 1' soffit (maybe bigger). The attic had insulation blown in and some of it had blown onto the old soffit vents. When they removed them, we lost a little insulation, and you could see stright up into the attic. Are those baffles necessary? It is a clear shot from the eaves to the ridge vent. The only obstruction is the tips of roofing nails through the sheathing. lol

Chemist1961 05-19-2009 07:31 PM

Zel if air can pass freely, say 2" or more across the width of the rafter space over your blown insulation, between the soffit and roof you are OK.
I have 2x4 rafters on a low pitch roof so there is very little air space. In addition I will be adding an extra R30 blown in so I want to maximize my air flow before adding insulation.
For the cost of the baffles, I would check them out and install them on the underside of the roof regardless, every 3rd space, overlapping your top plate of the wall below, while retaining the insulation above the top plate

Zel1 05-19-2009 09:53 PM

Thanks again Chemist! The roof is kinda steep, so there plenty of room, but I'll look into the baffles anyway. Theres a couple of pictures in the "general" section if you want to get an idea of what the roof pitch is and how the house looks.


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