Hi All,
I'll keep this short and sweet- it's my first post and I don't want to get labelled blabby until at least my third.
I'm planning on erecting a square frame (29'x29') over a set of existing adobe walls as a restoration project. My plan was to put a simple metal hip roof on it, but after running that idea by my brother (who has slightly more experience than my "next-to-none") and his friend (who is a professional tf), the consensus was that a hip roof is, at best, gonna be really difficult for anyone and probably impossible for a newbie like myself. But I really want a hip roof- it'll make the overhang I need on all sides so much easier....
So I feel the need to increase my sample size- I'd like to hear the opinions from the wizened framers out there: to hip or not to hip? Any information is greatly appreciated!
cheers,
randy
Welcome!
You are talking about a roof with 4 hips, coming up from the outside corners of the building, and all coming together at the peak (center of the building), creating 4 seperate roof planes...not a Gambreled roof system...right?
Rooster
I've framed hundreds of homes, and many many of them were handcut hips. Now I haven't done a lot of timber framing yet, I don't think that it would be that hard, I think that the principles are the same. But maybe that's my inexperience talking.
Hi Rooster, thanks for the words of welcome.
And yes, we're talking about the simplest hip roof you can picture; 4 hips, no gambrel.
Dave, it's apparently cutting the joints at the compound angles where the hip rafters meet the other structural roof members that scares my other timber framing consults. One of them even suggested I cut joints for all of the simple part of the roof and stick-frame the hips.
cheers,
randy
its all in the angle with computer imagery soft ware it should be a piece of cake ask you local truss company for the angles you need to do.
I believe your friends are correct. A hip timberframe roof is goning to be next to impossible for a newbie w/o building experience. Draw it on skectup, and see how difficult it is to design. It can be done, just very difficult for a newbie.
i have only done one timber framed roof , but have done a LOT of framing. mcmansions with some really cut up roofs. hips, valleys, lay ons..all the good stuff. framing them was difficult for me to understand until i got with a very experienced carpenter that taught me how to read and use a speed square. it's all geometry and can get really confusing. theres a lot of measuring and layout before a cut is even made with stick built rafters/ roofs.
any chance you could hire yer brothers friend to give ya some help with it?
http://www.blocklayer.com/roof/roofeng.aspx
this might confuse ya, but could help
http://www.johnsonlevel.com/files/manuals/RAS-1.pdf
this explains some on a spped square.
Randy,
If you are going to build on the outside of existing walls, what type of framing will keep the roof from the thrusting the walls/corner posts apart?
Do you have some photos of the project?
Rooster
Thanks for the links, TomSteve- they are a bit beyond my pay grade at the moment, but I'll have to get to the point where I understand that stuff at some point, so it's good to have the references in hand.
Rooster, I'm a little confused by your question (and I'm building inside of existing walls- really wonky, leaning adobe walls, which is why I don't want to put a roof load on them). My understanding is that the joinery and construction details (beam size, etc.) in the bents and connecting members of the lower frame, coupled with design elements of the roof itself, are what keeps the roof forces from pushing the walls apart. I figure I may be misinterpreting your question, though.
randy
It may be that your first post was confusing, since you said you were building over existing adobe walls.
Hey, it's not that hard to do a simple hip rafter and pockets or housings for the tops of the jack rafters. I would do a developed drawing using the common roof pitch to determine the hip and jack rafter angles. Drawing the angles out always helps to visualize the roof planes and how they interact.
This is a Developed Drawing for a 9/12 common pitch hip.
(https://forestryforum.com/gallery/albums/userpics/14727/FRENCH_COMPOUND__9-12_v2008.JPG)
I would not want to do a purlin roof system into hips because purlins where they intersect with a hip or valley are longer on bottom than they are on top and it would be very hard to assemble.
Tom edgewrks@gtec.com
I think you can do whatever you put your mind to and spend enough time on. If hip is what you want, don't settle for less because of a lack of knowledge or experience. "Experience" tends to come easy when you lack knowledge, it is just not always kind or economical.
I like to think outside the box. I would differ with the prior poster.
I don't see a hip being as diffcult done with trusses and purlins or principle rafters and purlins as it would be with common rafters and jack rafters. There are a lot fewer joints to cut.
Many of the old frames left the purlins proud on the rafters and didn't join them directly into the sides of the rafters or trusses. This method is simple, uses less joinery and is very interesting visually from the underside if left exposed.
Fancy joinery is not always advisable or most durable in a TF. Keep it simple.
The way I see it, you mill or hew 4 - 5 sided hip rafters at the correct angle for your hips and then lay your purlins on them and leave them proud useing very basic purlin cleats under each one to secure them. Omit the jack rafters. No complicated joinery work is needed, just a very simple M&T on the under side of the cleat to hold everything in place. I'll see if I can dig up a picture of this for you. You can even go with a layer of common rafters over these if so desired. TF rule of thumb is the best joint is the simplest and strongest joint to get the job done.
since your building is square you can have all this intersect into a central post. Think of it as a four way Kingpost truss with purlins and a mid span principle rafter.
for me, it's easiest to do with a speed square, and a framing square, but a newbie can pick up a construction master calculator and figure it out with the instructions.
Hardway,
I like the box you think outside of, and I'm exactly of the same mind about joinery, simple is best but it has to get the job done properly. After my relatively intense first framing experience, my forearms and hands were so wrecked that I vowed to keep joints as simple a they could be to avoid unnecessary wear on my poor aging bones.
I'd love to see a picture of what you're suggesting; I think I get the general idea, but I'm not quite certain. Essentially my picture of what you're talking about is a roof that's all hips and no ridge (a pyramid, basically), purlins laid proud across all of the hip rafters with cleats, no jack rafters at all.
Do you think some version of this would work with a ridge beam and 4 hips? I'd like to leave some more headroom for a loft.
cheers,
randy
Dave,
I'm thinking it's going to be all pencil, paper, and re-learning my high school trig. It's the only thing I can trust not to misguide me 'cause as you point out, I have no clue how to use a speed square properly (except as a straight edge)- I'd always be afraid I was screwing something up.
randy
moorerp,
I've framed homes well over the 10,000 sq ft mark, and I've never taken trig. It's really not that hard to learn a speed square. It could be taught in 10 min if someone is paying attention. I don't know where you live, if you're close to southern Mi, I could teach you in person. If you're not going to build for a while, I could teach you at the pig roast in August. If you get desperate, maybe my wife can show me how to upload a video. Let me know if I can help. feel free to send me a IM,
Randy,
Do a quick Google image search on the term "Purlin Cleat" and you should find a picture on Builder Bill's site which shows a picture of exactly what I am talking about. I will try to draw it and post when I get time but this will give you a good mental image of the purlin cleat and how it attaches to the rafter with a simple 3 sided mortice and tenon which is super easy to cut. (much easier than a 4 sided mortice)
As for the hands and forearms:
1. You likely need a proper mallet. Using the right mallet weight and material will soften vibration and impact on the hands and will also drive your chisel better.
2. You may need a different chisel or a keener edge. Different types of woods require different angles on the chisel for efficient cutting
3. After a week of steady chisel work your forearms will swell like balloons and the pain will begin to subside
What kind of hammer and chisel set up are you using?
I see no reason you couldn't use a ridge purlin. This will of course complicate some of the geometry as it will not all be symmetrical if your base building is square rather than rectangular but your roof frame is rectangular.
Perhaps a very useful learning exercise for you would be to build a model of the project using some scaled timbers made out of 2X material on a table saw and then do a mock up of the joinery and the angles. It is cheap, gives you a great grasp on the concept you are trying to build, and you can pull a full cut list from it when you are done. The model will make a great doll house if you have any kids in your life. There are some great pictures of TF model on this site you should check out.
The confidence and reference this scale model will give you and the reference it will serve as, is much better than just having a drawing. Especially if you are trying to engage family and friends in the effort. Being able to see how things all fit together is very important and ensures you don't end up with an oops moment at raising.
Have fun with it!
Cheers, Bob
I did a hip roof as my first TF (see avatar) but would not recommend doing it without someone experienced. There is enough that can go wrong on a timber frame without adding that complexity on top of it. It could be the straw that breaks the camels back so to speak. There were times I would describe layouts which seems such a simple thing as a nightmare, but a finished hip rafter is an amazing thing to see. There are a couple ways of approaching layouts for a hip roof. A traditional way is to reference the Hawkindale angle tables which you need to study how to use. I did this and found it very time consuming, but it works. My advice would be to use google sketchup all the way: draw your whole frame including hips and jacks then grab the angles. If you are already very good at sketchup this will be a snap. And if you aren't, this could take a few weeks to get to this level and afterwards you'll get dividends as sketchup can be useful for countless things in the future.
Thanks for the input Canopy- yours was probably the first example I looked at for timber framed hip roof; it's quite a beautiful thing.
I think I've decided to go with hips of some kind after a lot of backing and forthing, mostly because I just can't see any other way to get the overhang I'm going to need that's as simple and elegant (design-wise, not joint-cutting-wise) as a standard hip roof. I figure if I take my time while I'm doing it, and plan the thing out completely using Sketchup (which I'm only OK with, but I'm very excited to have just discovered TFRubies- thanks Clark!), then I should be able to pull it off, especially is use some of Bob's simplification ideas.
I'll send pictures once I get the thing drawn up so that everyone can rub their hands over their faces and point how many of my design elements are (to be charitable...) unwise.
Thanks for all the help so far, everybody-
cheers,
randy
Howdy,
After all this good discussion, I've decided to suck it up and go with simple hip roof. I ordered an Alpha roofing protractor (from Jim, as it turns out) off of ebay to help with the layout of the nightmare angles of the hips and the jack rafters (as few of the latter as I can get away with).
thanks for all of the help! I'll post progress notes.
cheers,
randy
Randy:
Most timber framers layout a hip rafter with the timber being full, and after all the other joinery is layout and cut the last thing they do is cut the backing angles. That is the surface of the upper face of the timber to create the slopes that match the roof plane.
I see from your other drawing that the hip rafters aren't going to come off the ridge at 45° angles. This is going to make your hips even more complex. You should try and see if you can make them come from the corners at 45° in plan view.
If the two roof slopes aren't the same angle then again you're making the roof even more complex.
Good luck and keep asking questions.
Thanks again for your purchase.
Jim Rogers
I have cut several hips. Is it difficult? Yes it is! I am not ashamed to admit that I often struggle when getting into the compound stuff. What helps/works the best is to take a block of wood, cut a mock up and see if it looks right. If I (we) as timber framers did the compound stuff all the time it would be easy. I don't get alot of calls for people who want hips. Valleys/ dormers we do quite a bit of, but hips there cool and fun to put together and see the end results of but I just don't get alot of calls for it. Last time I did a hip it was for a covered porch and the hip rafter was only like 5' long. Well good luck! And I Tip my hat to you for such a energetic way to start framing!
Quote from: moorerp on March 18, 2012, 05:26:18 PM
Howdy,
After all this good discussion, I've decided to suck it up and go with simple hip roof. I ordered an Alpha roofing protractor (from Jim, as it turns out) off of ebay to help with the layout of the nightmare angles of the hips and the jack rafters (as few of the latter as I can get away with).
thanks for all of the help! I'll post progress notes.
cheers,
randy
armed with SU and the Alpha protractor, you should fly through the process no problem... I love the big protractor, for me it turned this intimidating aspect of TF into an empowering experience. Once you cut that first crazy joint, the smile on your face will stick around for days... :D
Have fun and keep us posted ;)
As has been mentioned there is a joint that was used in England to allow a hip to be supported at the corner of a building called the dragon and cross joint.
One of my first drawings with Dietrichs was for a client/student timber framer who wanted to make a shed with a pointed roof. That is four hip rafters coming to a point.
I researched this and found a book from England that had this picture in it.
(https://forestryforum.com/gallery/albums/userpics/10095/Dragon_and_cross_joint.JPG)
And I drew this, with help from the software provider:
(https://forestryforum.com/gallery/albums/userpics/10095/Ex2.jpg)
I would not recommend the corner joint where the dovetail is but that's what the client wanted.
In a tour of old building in Portsmouth, NH, we did see a full size dragon and cross joint in the attic of a building that is now a museum.
This house was once owned by the man from NH who went to continental congress and signed the Declaration of Independence.
He brought home, from PA, in a saddle bag a tree sapling, and planted it in his yard.
It is still alive today and is on of the biggest trees in NH and in Portsmouth.
I have seen it, and it is huge and was growing fine when I last viewed it.
Jim Rogers
That is a cool joint ,but how do you cut the hip beam if you want a large or small over hang?
Quote from: Don_Papenburg on May 05, 2012, 10:21:02 PM
That is a cool joint ,but how do you cut the hip beam if you want a large or small over hang?
The dragon beam, the one the hip connects to, can extend out beyond the outside surface of the plate and tie, which is or could be the outside of the walls.
The above drawing was for a small shed with no large overhang.
Jim Rogers
Quote from: Jim_Rogers on March 20, 2012, 12:14:25 PM
I would not recommend the corner joint where the dovetail is but that's what the client wanted.
Jim Rogers
So what would you recommend for that corner? I am putting a porch on my house and it needs some corner joints, and I'm wondering what would work best. The posts are 7x7 and the beams 7x9.
Thanks,
Nick
Quote from: nas on May 12, 2012, 02:55:32 PM
Quote from: Jim_Rogers on March 20, 2012, 12:14:25 PM
I would not recommend the corner joint where the dovetail is but that's what the client wanted.
Jim Rogers
So what would you recommend for that corner? I am putting a porch on my house and it needs some corner joints, and I'm wondering what would work best. The posts are 7x7 and the beams 7x9.
Thanks,
Nick
Normally you don't design a three way joint.
A three way joint usually takes away too much wood from all of the members.
You would offset one or two of the pieces so that the height of the plate or the height of the tie beam is lower then the other.
You have to consider the order in which things are going to be put together and design so that it can be put together easily.
Some things can be drawn that can't be assembled.
You have to consider all aspects of the design, including raising it.
There are joints that could work, but each frame has to be reviewed for the entire structure.
And I can't say for sure what will work best for you without knowing all the details about the complete design.
If you have a sketchup plan of it you could post it in the plans section and we could look at it.
If you don't have one, but you have paper drawing of it, you could take pictures of the drawing and post that.
Let me know if I can be of any further help to you.
Jim Rogers
here is my attempt at the drawing. I'm not great with sketchup so bear with me :)
I can't figure out how to draw the hips and valleys. The joints in question are the corners on the beams. I don't want to use a lap or tongue and fork because one side will not bear on the post. Any suggestions?
Nick
Quote from: nas on May 15, 2012, 08:13:43 AM
Any suggestions?
Nick:
I reviewed the Historic American Joinery series from the guild and found a joint that may work for you.
You can download the free pdf's from the guild site.
In section 2 on page 5 and 6 are some corner joints where the tie and plate meet at corners at the same (or nearly same) elevation.
I opened your sketchup plans and got your dimensions of your post and plates and made up a version of your joint using one of the corner joints shown in the above pdf.
Here is one way you can make your corner joint:
(https://forestryforum.com/gallery/albums/userpics/10095/corner_joint-4-ff.JPG)
Here you can see that the post tenon is set back from the end of the first plate. And that there is a housing under the plate for the top of the post to fit up against the plate so that there is plenty of bearing area.
Next is the second plate attaching to the first one. This is where there maybe some problems.
If the post shrinks then the bearing area of the second plate onto the top of the post is going to get reduced. I have drawn it with a 1/2" housing but you may want to make it a lot deeper. Maybe even 1", or more. So that there is plenty of bearing area for the second plate onto the top of the post.
If you don't when the second plate shrinks in height the plate could lift up off the post until the tenon splits the plate and lets it sit back down.
I would make sure that the second plate's tenon is loose in the mortise so that it has room to move down if the second plate shrinks. And not split the second plate.
I'm not sure what type of wood you're using so you may need to modify the tenon sizes and lengths to allow for more relish and pegging.
Here is a picture of the joint with the pieces all together but "see through" so you can see everything inside:
(https://forestryforum.com/gallery/albums/userpics/10095/corner_joint-2-4-ff.JPG)
I hope this helps.
Jim Rogers
Thanks Jim, that is exactly what I was looking for. I am using white pine timbers. It's funny how you can over think something, and when you ask someone, the solution is fairly simple.
Nick
Jim,
Would you peg those connections? What's the best way to do that since the pegs can't go all the way through without penetrating the adjacent timber?
Thanks, Brian
If you go to the section of the Historic American Joinery series mentioned above you can see how it was pegged.
You would blind peg the post tenon to the first plate and then blind peg the second plate to the first plate.
A blind peg is one that has the long tapered end cut off so that the peg is nearly the same shape from tip to end.
Draw boring would be a challenge with such a peg.
Jim Rogers
I needed 14 ft of 6"x8" per mare and colt, with 42" decks.
http://keeperbarn.com/2012/05/17/plymouth-hip-roof/
Pretty cool. The photo labeled "Hip Rafters-1" is pretty funky. Looks like that joint would just snap off, but apparently it held up quite well since 1790!
WoW! I feel like such a slacker for starting this thread and only just now getting back to it; so much new information! Sorry for the long absence, but my life becomes one big blur of work in the 4 months of late spring/early summer, but I'm back in the saddle now and gearing up to think about the design of this frame again.
Jim: Thanks a zillion for posting the pictures of the dragon and cross. That joinery will look amazing, be relatively easy to cut (or so it looks), will make the hip rafter-to-plate joinery much easier than it would have been, and I'm assuming it will make the whole structure much more sound than without it?
If that last point sounds like a question, it is.... I'm assuming that the hip rafters cause unwanted thrust at the corner joints, and that the piece of this dragon and cross that spans the plate/tie works to counteract that thrust ('thrusting the tie and plate back together)?
cheers,
randy
Hi Randy;
You are probably well on your way but I thought I would mention that historically it was common in 19th century framing in my area (Maine) for the common rafters which join to the hip rafters to be tenoned at the bottom but nailed to the hip rafter. Nailing these rafter tops makes life much simpler. If that sounds too easy you can always make your own nails!
Good luck;
Jim
Quote from: Housewright on November 12, 2012, 09:56:23 PM
You are probably well on your way but I thought I would mention that historically it was common in 19th century framing in my area (Maine) for the common rafters which join to the hip rafters to be tenoned at the bottom but nailed to the hip rafter. Nailing these rafter tops makes life much simpler. If that sounds too easy you can always make your own nails!
Hi Jim,
Hey, my whole family lives just down the way from you- Mom in Rockland and everybody else near Camden! I'm out that way pretty regularly.
And my brother (the one who thinks I'm crazy to try a hip roof on my first frame) had the same suggestion; make it a hybrid by cutting the main roof elements and essentially stick framing the minor elements. As I get further into the framing process, I'm sure that suggestion (minus the making my own nails) will start to look more and more attractive....
And just for full disclosure, I haven't even started on my way.... ::)