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I’ve been advised by a wonderful young woman at FH to request help at this site concerning acquisition of information detailing the framing of unequally pitched gambrel roofs. The end desire being ridgeboards all sharing the same height. The length of the existing house is less than twice the width. I wish to build double gambrel dormers on both long walls wit their ridges meeting at the exact height as the ridge joining the two end or narrow walls. I own the publication by FH titled, “Framing Roofs”. Beginning on pg. 86 of “Framing Roofs”, the chapter covers unequally pitched gable roofs, I believe this information is applicable to my situation on both pitched but I have a lot more to learn. I need a pro to just shed some light or point me in the right direction of a publication to view and I shall be eternally grateful! Please e-mail me at: [email protected]. Thanks.
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Bruce,
Joseph Fusco
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*Bruce,Your wonderful young woman at FH has steered you in the right direction. Now, lets have some numbers, like, LENGTH and WIDTH, and also desired PITCHES. Think about it, draw it out on paper, and then post the dimensions.Otherwise, you may not get a lot of response. Reason?? Without some numbers, we have to write a CHAPTER, and not just a reply.Once you post some numbers, I think you'll find some people jumping in with some information. I will
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Dear Mr. Fusco,
Your rapid response is to be commended, and I sincerely am appreciative. My impression is that, by your response I have once again failed in conveying my thoughts correctly. Sorry!
My needed assistance is on the correct manner to frame the lower pitch of the gambrel roof structure.
After reading my initial question over and over I realize it is not the unequally pitched valleys I would have difficulty creating. This is my reason for a point in the right direction for a publication to view.
The three gambrel roof, second story additions I was involved in constructing were not my show. The rafters, upper and lower were not set on a wall plumb to their intersection but merely nailed and glued together with a plywood gusset. I was not convinced this was the best method. Upon the introduction of gambrel dormers to these roofs it was apparent ventilation of the under side of the roof sheathing is compromised. This is also where I require your expertise, is there a proven method to rectify this shortcoming?
As the proverb says so I am, “I hear and I forget. I see and I remember, I do and I understand. Thank you Sir.
*Dear Mr. Drake,Your rapid response is appreciated and puts my delay to shame. Your response indicates to me I erred in properly describing my real area of needed assistance. Sorry, I treasure time and do not intentionally waste that of others, like using run on sentences. Oops.The math is not my shortcoming, my true need is the correct manner to frame the lower rafter upper rafter intersection point to facilitate good ventilation to the under side of the roof sheathing. With theintroduction of two gambrel dormers on the long walls of the rectangle half the long walls length I visualize a serious depletion in available ventilation. This is where your expertise is sorely needed. Thanks much!I am as the proverb describes so well. "I hear and I forget, I see and I remember, I do and I understand." A publication or even a picture would be of great benefit to the simple mind.
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Bruce,
Joseph Fusco
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* Bruce,
Joseph Fusco View Image
*Bruce,As Joe has pointed out, please call me by my first name, Ken, as I also have been referred to by other names than "Mr." in the Breaktime forum.I wish I could be of more help here, but I really don't have any suggestions as to how to ventilate in these roof areas. These problems occur in any roof whenever hips and valleys are present.I have seen gambrel dormers built on gambrel roofs, but have never noticed any effort to ventilate each and every square inch of roof.Hopefully, others, with more experience with gambrel roof framing will comment. I'm not sure, by the way, that it is of such a big concern as you visualize it to be.
*From your post 2.1 I gather your main concern is roof ventilation? If you truly need ventilation, and if this meets your inspectors approval, here are a few simple options that don't require drilling and weakening your rafters or top/sole plates. These are based on what I think you are asking. It's late, I'm on vacation, I'm not a "gambrel-guy" and my minds a wandering...those are pre-emptive disclaimers, BTW.First, I gather you weren't thrilled with the idea of the lower and upper rafters being joined by ply gussets, resulting in a continuous rafter bay? You prefer, I'm guessing, sole and cap plates for both lower and upper gambrel sections?A fairly simple solution that I think addresses your concern, would be to use "sole" and "cap" plates that are not as deep as the rafters at the intersection of the lower and upper gambrel roof sections. For example, set the inside (interior) edge of your 2 by 8 rafters even with the inside (interior) edge of your 2 by 6 gambrel cap and sole plates. This will give you a 2" gap between the sheathing and the "plates" at the roof intersection, allowing air to flow up the lower section's rafter bay, over the 2 by 6 cap/sole plates at the roof intersection, and continue up through the rafter bay in the upper section of the gambrel and out your ridge vent. This does nothing, however, to ventilate the areas above and below dormers.Should that be your desire, you could consider:1) Run furring strips right on top (and in-line with) your rafters. You'll essentially be making your rafters "deeper". Go back and every few feet cut out a 4-6" section of the furring strip, allowing it to fall away. Another method to achieve the same result would be to just nail 2-3 foot sections of furring on the tops of the rafters, with 4-6" gaps between the ends of the strips. Sheath over the furring. Insulate from the inside, keeping the insulation 2" off the underside of the furring strips.or 2) Run the same furring strips perpendicular to the rafters, 16" OC. Apply sheathing over the furring. When insulating from the inside, hold the insulation back off the furring strips by 2", as you would if the underside of the furring was the underside of the sheathing. Both these options will allow air to flow up through the lower section of the gambrel, over the lower section's "cap plate" and the upper gambrel's "sole plate" (since the furring stands proud of the plates and thus holds the sheathing off of the plates). It should also allow cross-ventilation between rafter bays via the 4-6" gaps in the furring strips, allowing ventilation above and below dormer obstructions as well.I've really got to be honest with you, I'm not sure if I'm fully understanding your request, so sorry if these answers miss the mark. Once again, see how your inspector feels about the furring strips. Some like full-contact between the rafter and sheathing, some aren't as concerned. What floats in my jusisdiction may sink in yours.A last option (last by listing, not by effectiveness), would be to dense pack cells into the bays and forego ventilating the roof. Putting on my kevlar helmet...MongoPS: Don't overlook the fact that you may have somehow angered that "wonderful young woman at FH" and she sent you here so we could simply frustrate you with answers that come close...but don't quite hit the mark. Best of luck...
*Bruce---Seriously, some dimensions would help. some of us live for a challenge, but trying to picture this puts half a dozen scenarios in my head. You may even be blessed with a CAD drawing if you are descriptive enough. Seems a daunting load of info at first, but well worth the effort....JRNicholson
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Bruce:
How large are the dormers in relation to the width of the
roof? Do you plan to have vents installed in the dormers,
say facing straight out-or to the side? I may have missed
it, but did you respond to Joe's question about the dormer
ceilings? He may be on to something there.
Why are you so uneasy about the plywood gussets?
Also-I didn't see anything about the various pitches/angles.
If you are concerned with the ventilation aspects, and the
lower rafters are quite vertical, they may be more like
walls than that of a roof, not as big a deal, depending on
the space within, the various heights and ceiling
configurations, etc. as well as the ventilation system as a
whole.
How do you plan to ventilate the roof? I must have missed
some of this fairly basic information. Any chance of
posting some sort of drawing or picture? Where does your house
project stand right now, and what is the geographic location-are you
mainly insulating to heat or to cool?
If you want technical information about something as serious as the
roof structure on your house, and are willing to listen to
cyberadvice, you could improve your chances with a lot more detail.
Mad Dog
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*Library and or book store moving ladders........Where can I find the hardware needed to build a custom unit for my oversized book shelf?????
*Joe, There are to be collar tie throughout at the intersection of the upper and lower roof rafters, though the thought of all those converging angles if I followed the roof line border the sublime. I also intend to employ the use a whole house fan.Bruce
*Mongo,I too, liked sheriff Bart. My goodness you must be running for canonization to come to my aid on your vacation, thanks.I do like the last not least option, and this could be the remedy. Kevlar does work to prevent the laceration type would, but my experience lends me to doubt its ability to prevent the puncture. I do not make light all your previous suggestions, it is almost as if you and I were on the same page on all of your other methods. I am beginning to realize it is much ado about nothing. As for the possibly angered “wonderful young woman” my initial correspondence to FH began “Gentlemen” now there’s food for thought .Bruce
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Bruce,
Joseph Fusco
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"The price of apathy towards public affairs is to be ruled by evil men." -- Plato
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Bruce,
I'am currently studying complex roof framing, using a manual by Marshall Gross.It is the by far the best publication I've seen on roof framing. Pro's like Don Dunkley use it.You build a small model roof for each roof described.It's called "Roof Framing" available from Craftsman Book Company Ph. 1 800 829 8123 They also have 2 videos to compliment this book.It looks like Joe's diagram came this book, lol
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James,
Joseph Fusco
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Joe,
I am eternally grateful, your many informative responses are much appreciated.
Bruce.
*James,Thank you for your response. Canadians are our true friends to the north. I had a corporal in my platoon from Quebec, and one of my finest Marines.Long ago and far away. Thanks for the book suggestion. I am on the seach.Bruce.
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I've been advised by a wonderful young woman at FH to request help at this site concerning acquisition of information detailing the framing of unequally pitched gambrel roofs. The end desire being ridgeboards all sharing the same height. The length of the existing house is less than twice the width. I wish to build double gambrel dormers on both long walls wit their ridges meeting at the exact height as the ridge joining the two end or narrow walls. I own the publication by FH titled, "Framing Roofs". Beginning on pg. 86 of "Framing Roofs", the chapter covers unequally pitched gable roofs, I believe this information is applicable to my situation on both pitched but I have a lot more to learn. I need a pro to just shed some light or point me in the right direction of a publication to view and I shall be eternally grateful! Please e-mail me at: [email protected]. Thanks.