BTW He's an electricaal engineer. Source: www.jlconline.com. The subtle though important issues about hip/valley placement that you've highlighted in our ongoing dialog on the Tale of Two Pitches saga have inspired me to follow your suggestion to do a follow up post showing the "offset method" of framing an off-angle hip roof system. I respect your persistence. square, which is 16.97in., rounded to 17. but there's a better way." With the Orbit capability of SketchUp we can check out some of the various roof features as well as get an overview of how dimension/angle factors influence the resulting configuration. Brejnik team consists of qualified and trusted: Architects, Interior Designers, Appraisers / Lenders, Trades & Suppliers, Geo-technical engineers, Structural Engineers, Arborists, Landscape Architects, Pool & Water Feature. Use these tips to keep cables tight and straight for a professional-looking deck-railing job. ( the same thing that occurs at a 90 corner when 2 different roof pitches are involved)It just so happens, because of the ratio of the roof pitches that you have, 6:9, that the hip will swing to ", This guy drew a lot of things that can't be built. The roof framer would need to use his quality conscience to decide what, if anything, should be done to correct it. I fixed the fascia position by "re-cutting" rafters to make the roof planes line up. Keep in mind that when you change roof pitch it also affects length of overhangs and alignment of fascia. Installing First Rafter. 2) Also, if you will "fly" around in your model and look up the valley you will notice that the valley line does not align to the outside of the inside corner of the fascia as it should. Thanks again.jim. They build fine luxury houses. * The Major Pitch contains the Ridge and typically is the Lesser. This is for 90 corners ONLY, which I assume is your case. With irregulars, the equal thickness of the fascia becomes a factor for proportionate slopes. i.e. Well, here's what you need for joining two roofs with different heights. We both posted the same information at precisely 8:06 A.M. ( you apparently beat me by a few seconds)Anyway, I took a look at the math when a 6/12 roof intersects a 9/12 roof at a 135 outside corner, which would be one corner of an octagon. Apply sealant over exposed nails on the last strip. Save my name, email, and website in this browser for the next time I comment. Then, based on the structural ridge beam size you need draw a beam that passes through the rafters at the proper location. . So if you make the plumb cut on the hip 6/12, it should fit nicely.Here's something really unusual.Look at the drawing. You can join a roof to the top face of another roof and the wall below that roof if you select the wall as the target. That's likely the condition in the field. Although uncommon, there are situations where architectural parameters require off angle hip and valley roof construction. First we should establish the pitch of both roof planes. I believe you have made a couple of simple errors in your drawing that can, and should, be fixed. sketchup is a great program. "I have learned so much thanks to the searchable articles on the FHB website. Or do a shed roof tying into the two hips on the sides and sloping up and tying into the main roof on the back. *Thanks Maurice: Good ol' sq root of 2, should have guessed that, but never too old to learn. (489.78 kB) My business partner and I recently added a large screened-in porch with a gable roof onto a client's home. The wall must be attached to the target roof and the target roof must be a footprint roof. His step 4 & 5 multiplying by 17 and dividing by twelve merely converts these numbers to a new base of 17 and 3.8 on your square. ), The thing about asymmetrical offset H/V rafters that I really prefer is the ease with which they can be processed. Have you ever wondered how roofs tie together? The hip and valley pitch would be 7 9/16"/12 or on your speed square, that would be a 10.7 hip, just a little under the 11 mark.Using a framing square that would be about 10 11/16 / 17.Ken, I have only built one roof where a hip was joining two different pitch roofs at the corner of a house. See if it reminds you of your brother's formula that you lost.Let URL = the Unit Rise of the lower pitch roofLet URH = the Unit Rise of the higher pitched roofThen the Unit Rise of the Hip or Valley is equal to= (.7071 x URL x URH)/sqrt( (URL)+ (URH) - 1.4142 x URL x URH)In you example, URL = 6 and URH = 9Substituting these unit rises into the formula, we getUnit Rise of Hip/Val = (.7071 x 6 x 9)/sqrt(36 + 81 - 1.4142 x 54) = 5.99Therefore, the Pitch of the hip or valley would be 5.99/12, or for all practical purposes, 6/12.Does that look familiar? Or at least at the same time. (Of course, your demo has both ridge heights equal, so either could be considered the Major Pitch, but I always default to the Lesser Pitch as the Major Pitch, for explanation sake. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. The Journal of Light Construction outlines another method you can try for joining two roof pitches. 2023 The Taunton Press, Inc. All rights reserved. That's what Fascias cover up. This video above shows how the finished roof planes in off-angle roof construction will look when completed. To unjoin roofs, click Modify tabGeometry panel (Join/Unjoin Roof). Same with ridges, this is what determines which pitch is the Major and the other Minor. Solved by TimELZ49. Turned out great.We also had to cut the 9 into the 6 at a 135 degree inside corner. The good thing is this time it is all trussed and I know those pretty well.Thanks again for all your help!jim, *Jim,Thanks for writing. Joining these two roofs poses two main challenges: One is getting the two differently pitched planes to meet at the hip (or valley) rafter. The number on the blade of the square is R1. But I'm having a problem with the design of the join , and making this waterproof. The easiest solution is to use a roof butt. 160I hope that passage explains it well enough. On this Wikipedia the language links are at the top of the page across from the article title. The length of the run of the hip(per foot run) is the diagonal or SQR(1 + (R1/R2)squared). A real competent DIY.If I have any roof framing questons in the future can I feel free to ask you? Hopefully by that time I'll have learned enough about the process to post a viable follow up. (The old German Carpenters did them both ways.) Thanks for "stopping by" the Digital Jobsite. A forum community dedicated to Do it yourself-ers and home improvement enthusiasts. Then you have to cricket both sides between the existing hips and the new one. Thanks for your help , I was thinking of keeping the style similar to the rest of the house. Thanks for stopping by The Digital Job Site. Step 2) Find the square root of the sum of the squares of the unit rises, square root(3+6)=square root(9+36)=square root(45)= 6.7082, Step 3) Divide the result of step 1, by the result of step 2.18/6.7082=2.6833, Step 4) multiply step 3 by 172.6833x17=45.6161, Step 5) divide the result in step 4 by 12, Step 6) put the answer in step 5 over 17. And because the modern circular saws can be set to match cheek-cut bevels, this tool geometry is a big part of the ease with which these rafters can be accurately marked and cut (*processed). Can't do it the way you have it drawn. If the 2 roof pitches involved were both the same, then the hip would bisect the corner angle, forming two equal 67 1/2 angles with the plates. There is more to these roofs than "meets the eye". Cutting all rafters on the ground makes sure we aren't slipping on sawdust up above.8:00 - 15:40 Installing rafters.Nailing the rafters on the layouts done earlier on, and down at the sleeper. Go to Solution. Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine. Now how about how to figure the hip and valley when the roofs meet at either a forty five or 135 degree angle.jim, *Woke up at three this morning. joining two pitched roofs together. Amsterdam: Elsevier/Architectural Press, 2008.304, crow-stepped, corbie stepped, stepped gable, List of commercially available roofing material, "Rainbow roof | Article about rainbow roof by The Free Dictionary", https://en.wikipedia.org/w/index.php?title=List_of_roof_shapes&oldid=1129678825, Short description is different from Wikidata, Articles with unsourced statements from December 2014, Creative Commons Attribution-ShareAlike License 3.0. Good luck on your project.Ken. I have only built one roof where a hip was joining two different pitch roofs at the corner of a house. In a hip roof with equal pitches, the unit run of a hip or valley rafter is 17 inches for every 12 inches of run in the main roof. Add 12-inch to the length. Maybe you could do a follow up, "Part Three", showing the fixes that are needed and how to do them? Mr Jalapeno, To Illustrate this using SketchUp and your models dimensions, draw a right triangle with one leg at 25' 9-3/8" and the other leg length at 17'2-5/8", now scale the triangle down so the hypotenuse is reduced to 1-1/2" (or the thickness of the H/V Rafter) I will then use this scaled down triangle to properly place the H/V footprint, in SketchUp virtually as well as on the job reality too. Thanks for your valuable input and feedback on a topic you're obviously invested in. Realized made math error refigured and I'm going with a 5/12 instead.jim. If that is clear. How do I stop my toilet flapper from closing too fast? If we use 1 as the run for one foot it simplifies the calculation to as follows: Let R1 be one rise (3) and R2 be the other(6). *Thanks Steve,No problem spending the 80.00 US Steve, 110.00 Canadian eh! In this episode I'll go through and show you how to join two roofs together to form a valley. It's possible to work out a mathematical formula for any situation, but why bother, when you only need it about once in a decade? Not including fascia thickness in the overhang dimension in the Tale of Two Pitches model was something I realized late in the modeling process. We (he) spent about an hour or so working out the fomula for me and I put it in my lunch box and lost it. Really enjoying the answers to my question. This information should be the secret "clue" for the placement and rotation of the Hip Rafter as you demonstrate the Hip roof construction in your tutorials. Does centering the H/V warp the roof planes or some other subtle distortion? i.e. Your tutorials on using SketchUp are very good but your understanding of the Irregular Geometry is slightly off. Modern Principles of Design". Its a matter of choosing where to compromise in a selection of geometric constraints. I was taught to split the different pitches thus coming up with the hip pitch. ), learns a lesson in the process of teaching. Passmore, Augustine C. (1904). "The Machine Shop and the Works. Ken's answer in step three of 2.6833 is correct when using 2.6833 and 12 on your framing square. 20+ Home Office Decor Ideas For Her. Can't find what you're looking for? I will check however. with a few changes on what you have made it would be a great resource to use to teach apprentices that have a hard time visualizing. Pick the section where two edges will cross. To maintain a consistent ridge height in these situations the roof pitch must be adjusted. Thanks for the detailed answerI really appreciate it. How do you combine two roofs? 5 Jun. (and it is even visible in the small video windows above, that is what made me look at it. Read on to find your favorite flower pot ideas that will add a pop 30+ Green Christmas Tree Decorations.
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