Why is the ridge doubled? Is this a cathedral ceiling in which you are going to wrap the LVL with something during the trim stage? In that case, this would not be considered a ridge board but instead a ridge beam. A ridge beam actually sits below the rafters and the rafters are notched to fit onto the beam. You can see what I am talking about if you look at the picture at this address: http://www.timberframedesign.net/files/ridge_beam.jpg. Even if this is not a cathedral ceiling, you will still frame it this way if you have to use the LVL's. Then you will be able to use any standard ridge vent. If this is a cathedral ceiling I would suggest that you consider substituting a Glulam for the LVL's. A single Glulam will do the job and you can stain it and therefore save money on the trim (although the Glulam will be more expensive than the LVL's). Below is a picture of a Glulam that I used in just that way (not as a ridge beam but as a stained exposed member.
Hello,
Thank You
Doubled as per architect - it is a 24 Floor span.
I'll make the question simpler. The ceiling rafters will be "hung 'on the beam, so as to keep the look inside the room clean as it is a cathedral ceiling . I do not want an 18" beam protruding, and the angle on the rafter when cut will mesh well with the beam.
One answer is just to get a wider ridge vent, but the question is:
PLease provide a source for this product, or accpetable alternative for venting, please.
Can you tell me the size of your rafters and the pitch of the roof?
Rafter 2x12
Don't have pitch - probably 5/12 / 7/12
There are no wider ridge vents that I am aware of. Ridge vents are made so that you can cover them with a single tab of a three tab shingle or other standard ridge material and therefore they are all about the same width. You could have a metal vent custom built, but I have some other less expensive options for you. With a 7/12 pitch, your top plumb cut on your rafter will be approximately 13-1/2" long. The ends of the rafter must be covered completely by the ridge board or the opposing rafter. In the case of "A" in the image below, the two LVL's will be hanging below the rafters 4-1/2" and even further if your pitch is 5/12. Since you do not want the beam to hang down into the room, you will have to have a small attic space above short ceiling joists/collar ties as shown in "B" of the image below. If you use this method, you will have to use either passive or fan driven metal roof vents as shown. Another method which would allow you to use the continuous ridge vent would be to notch the rafters as in "C" in the image below. This would allow you to use the continuous ridge vent. If you use any of these methods, you will either have a portion of the beam hanging down into the room, or you will need a small portion of flat ceiling.
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