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Roof valley connections

Started by Algorythm, February 22, 2019, 08:22:13 PM

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Algorythm

Hi,
 
I am a forest engineer from eastern Canada with knowledge in ecological housing. I was raised on a tree farm. I have a wood mill and what it takes to harvest my lumber. Me and my wife have the project of building our own ecological house.
 
I am currently making plans for a timber frame structure 24'x48' with 45deg angle roof. The main frame consists in 2 similar 24x24 high posted cape frames (3 bents each) but oriented differently. I wanted to optimize solar energy and also wanted to eventually later have a good spot to build a greenhouse next to the south wall (we live in the north so the having access to a greenhouse in winter would be nice).
 
I am starting to work on the roof valley connections and I have a few questions:
 
1. Is it best to keep both frames at the same roof elevation (for the central king post) or is it better to join both frames at a different roof elevation (for later works on the envelope and metal sheeting)?
 
2. I have opted for horizontal rafters to close both 24x24 frames. Then when I started working on the roof valley junction, I was wondering if I could keep using horizontal rafters or if I had to change the design for vertical rafters? Do both work and if yes which is best?
 
3. I could not find any joinery designs for the bottom and top roof valley connections (to main post and king post). What is the best way to make those connections? Bolts/nuts are used for reinforcement somewhere?
 
Any general comments, suggestions or help would be appreciated.
Frank

Algorythm

Here is a picture of the framing

Offsite photo link deleted by ADMIN, linking to offsite photo hosting sites not permitted. Refer to rules posted at bottom of every page.
Frank

Mike W

Algorythm,

Welcome to the FF, you'll find great info and great people here lurking around.  I am unable to provide solid advise to you on your questions, however I am sure Don P or Jim R will chime in when they are available and would be the ones to get you on the right track.  IMHO - they are guru's on the topic on this forum from everything I have been able to glean from all the various projects others have sought out advice on "how" to make their timber frame project become reality.  I as well am in the design stages of my first timberframe project, been a conventional framer my entire life and this is the next step in the saga of life.  I am just at this point reading all info I can and incorporate everyone's questions being resolved here into the initial design before  I fully engage with those mentioned to help with problematic connection points and loading I am unable to resolve myself.

again, welcome aboard, grab a seat and start browsing all the threads relative, sure you'll gain as much insight as I have thus far, just looking forward to learning so much more here as well.

I look forward to their responses and will be following this thread, looks like a good build in the making

Mike

Don P

Hi Algorythm,
Welcome to the forum. First just a point of forum order, please put your pics in the forum gallery, at the bottom of the posting frame there is a tab "Click here to add photos to post". If you can post the sketchup file it might be easier to navigate it. Until I can replace my old computer I'm limited to the 2016 version myself.

I think Jim can be of more help, his design services are listed here;
http://forestryforum.com/board/index.php?board=23.0
Do count on design and engineering for something this ambitious. I'll throw in some general comments. As you develop the joints start with thinking about the mortises, keep them with the grain and bring the tenons into them. You can use either common rafters in the valley as drawn or purlins as in the rest of the drawing. In my mind the load on the valley is increasing towards the foot as drawn or towards the peak if purlined. The red design book on the TF Guild website does have a series of articles on hip and valley design.

Try drawing the kingpost supporting the head of the valley wider and bringing the valleys into the wide faces to see if you can get more joinery room.

Algorythm

Hi guys,

Mike, thanks a lot for the information and the warm greeting. I have a great deal to learn and also some stuff to share so I will make sure to look around the posts and see where I can be useful. Being part of the community was the next step and I am glad I made it.

Don, thanks a lot for the tips, I will work on my model considering those (I joined my actual Sketchup model). I have some joinery built in Sketchup already (from Steve Chappell book) and I am good at drawing in Sketchup (I have some computer design skills). Everything is not polished in my model yet since I am still moving things around but I am comfortable with design, engineering and I want to build shop drawings myself using Sketchup. I need some general word of advice and tips concerning design mostly.


Frank B. (Algorythm)
Frank

Don P

Hi Frank, I tried to open it but it was a newer version that I don't have enough graphics card to support. In sketchup if you hit file>save as> then in that popup under "save as file type" click, dropdown appears in mine, see if your version will allow saving as 2016, mine will allow all the way down to version 3 but I'm not sure if newer versions still have that option.

One thing I can say with valleys is think through raising order very carefully, it may take many hands or a couple of pieces of equipment, or both. There is not much worse than having to take everything already assembled back down because the raising order isn't right.
And watching the crane operator reading a novel at full wages while you get it together  :-X :D

Algorythm

Hi Don,

Here is the model saved as a 2016 version. Let me know if you can't open it, I will try something else.

I worked for a wind farm construction contractor for the past 8 years so I could saw crane operators read the newspaper a lot thanks for remembering me :D. When you can't call it a wind day and you have to look hopelessly at 700T cranes doing nothing it makes you want to cry :'(. I will not forget about it and make sure to think about everything twice. I hope everything goes well when it comes down to it (fingers crossed).

Frank
Frank

Cosmo52

 

 I am currently erecting this one - roof levels at different elevations


The connection to the king post is similar to this joint.  It is a wedged tenon.  The mortise is cut through the king post and tenon extends beyond the post.  Bottom part of the mortise matches the profile on the tenon

Don P

Thanks Frank, got it and have taken a quick look around. It looks like the top of the valleys are well supported. I'd be tempted to notch the top, compression side of the ridge, maybe making it deeper, rather than notching the bottom tension side of the valley. The bottom tenon should run with the axis of the timber, I'm thinking just remove that corner of the post, looks like about 2-1/2" wide and running the tenon through clipping it at the intersection with the other post, so unhoused just sitting on a notched corner but trapped by the other post, if there is enough bearing.

I kind of like the common rafters there and the dropped ridge, it makes less clutter at the king and is not weakening the principle rafters. I wonder about that everywhere vs the purlins. It does concentrate the load on the kings though. You've doubtless looked at this for a lot more than 10 minutes :)

One other thing I noticed, on winder treads we cannot be less than 6" at the narrow side. Codes do vary there.

Algorythm

Don,

Thanks a lot for your time I really do appreciate it. I was wondering if the design (purlins vs common rafters and the dropped ridge) was viable and I would stick to it or if there would have been a better way to do it. I definitely like the look that the common rafters provide (looks like a leaf!). If you like it also that is a very good reason to keep it like that. Would you consider adding bolts/nuts to hold the 2 valleys together at the top? I was thinking about holding both principal posts at the bottom with bolts/nuts also.

The design keeps me awake at night, I keep thinking about it all the time :D. I really like to draft but I am still a rookie and sometimes I need to have someone with more experience telling me if I am wrong or right. I still need to figure loads out and do some tweaking here and there. I believe I understand what you are saying concerning the king post. I need to redirect some of the weight away from it towards the central post. I also need to think about adding additional support to the roof valleys as well. I need to build some additional support involving the central post in order to make sure everything is solid!

All your help really gives me a second breath, back at the drawing board. Thanks for the winder treads tip also I will check that out. ;D


Frank
Frank

Don P

Yup, I was thinking bolting the 2 posts together to form that notch/pocket. Bolting the valleys together is a good idea as well. I don't mind running Simpson strapping up the valley and over the ridge, over the ridge and rafters at any of those points up top, its cheap insurance if a big wind hits and storms are not going to get friendlier.

We lost your pic in post 1, hope you don't mind me reposting it for those who aren't downloading the sketchup file. One thing I was just thinking about. A valley is a beam with load increasing uniformly towards one end. With the common rafters the load is increasing towards the lower end. As snow accumulates in the valley it also loads toward the lower end. If you use purlins instead of common rafters in the valley area the purlins load the valley towards the upper end and the snow loads towards the bottom, a more even load distribution. The appearance of either ceiling is going to be dendritic, leaflike. I'm not pushing one way or the other, just an observation.  





Zooming in on your joinery I see you have Cosmo's wedged half dovetail through mortise and tenon in there.
Cosmo, do you have a sketch of your roof?

Cosmo52

Some roof sketches - 

 

 
 

 

Algorythm

Thanks for the sketches Cosmo, I like them. Did you use AutoCAD to make these?

With the help you guys provided, I will try to do a bit more drawing and see if I can keep the common rafter idea and put some more effort into bracing and supporting the valleys using the central post.
Frank

Jim_Rogers

Do you need to have the section going from the main frame to the side frame open to walk through?
The part where the valleys are holding up the jack rafters from the dormer roof.

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

Algorythm

Hi guys,

I have polished a few things so I attached the updated version of the Sketchup file (version 2016).

- I added braces under the king post
- I added tie beams under the valleys
- Modified the king post a bit to support the ridge beam
- Adjusted secondary layers to the timber frame model

I have more than the timber frame layer in the file so you can toggle other layer's and see the floors, annex, divisions, etc.

Jim, I think the answer to your question would be yes for the first floor and only on one side for the 2nd floor. You can have a look at the division and floor layers in the model and see where the openings need to be from what I figured so far. I have been wondering if I would not be better off making the interior bent of the side frame differently.

For those wondering about the house plan:

The main frame's 1st floor would be dinning room&kitchen oriented south with pantry, locker and storage in the back. The 2nd floor of the main frame would be opened with living room in the back. The side frame's 1st floor would have bathroom south with master's bedroom north and the second floor would have a small bathroom with 2 secondary bedroom. Since I have 4 kids I would probably use the 3rd floor to place a few beds and some storage.


Frank
Frank

Cosmo52

Quote from: Algorythm on February 24, 2019, 04:00:39 PM
Thanks for the sketches Cosmo, I like them. Did you use AutoCAD to make these?

With the help you guys provided, I will try to do a bit more drawing and see if I can keep the common rafter idea and put some more effort into bracing and supporting the valleys using the central post.
Frank - I had these drawings supplied to me, I would think they were generated with autocad though.  I trying to become more proficient with sketchup.

Algorythm

Cosmo,

If you want to have a better understanding of Sketchup, I suggest:

3D Base camp 2016: Timber framing and Sketchup.

This video really shows what Sketchup can do and is about creating timber frames. Also, if you want to draw with Sketchup, Clark Bremer's videos on YouTube are very instructive and give essential tricks to build joinery and speed up the process of making a frame.
Frank

TimFromNB

Hi Frank,

Interesting project. What part of Eastern Canada are you in?

Tim

Algorythm

Hi Tim,

Quebec, between Rimouski and Matane near the peninsula. I am 15 minutes from Metis Beach. I am 37 years old by the way. I have a nice and quiet spot for the house.

I am seeking new opportunities right now while preparing myself for the right moment to build a house. Our 4th child was born last summer and my wife has been interviewed for a job just now. If she finds a job before I get called or find another job myself, I might get stuck with the 4 kids at home. If so, I should have some spare time to start working on a frame for myself.

My dad has one of those old barns full of old school tools. You never know what you can find in there. He can pull something from an old pine cabinet
that has been totally forgotten to my generation :D. To see all those old wood crafting tools line up in the barn is magic. You only want to give the old tools a second life. I really like traditional crafting.
Frank

TimFromNB

Frank - no kids yet, but I can only imagine you'll be busy with four!

Algorythm

Hi everyone,

I spent some time reviewing joinery and making sure everything is clean. Still a long way to go before I can call it done. Here is a picture that shows the joinery connections between the roof valley and the two main posts. That valley might be hard to cut perfectly given all these angles :-[. Not sure the tenon is worth it but it seemed to fit with the rest. The valley can rest on a 3 inch wide support provided by enlarging one main post from 7x10 to 10x10. Any ideas on how to improve the model? Am I doing it wrong?



 




 



 
Frank

D L Bahler

I feel like that tenon on the hip rafter is going to have no strength, since the grain will run out. I would probably set the hip rafter into notches in the adjoining timbers, and secure it with a heavy peg or big lag screws.
However disclaimer: I'm not used to working with this sort of roof support system, so all I have to give is general impressions

Algorythm

Hi M. Bahler,

Thanks for your input, I appreciate. I agree whit you that the tenon on the hip rafter is definitely not for strength (if anything some stability) since the tenon is not made parallel to the grain. It is most likely more effort than it's worth to do it that way especially if it breaks so I will look for another option. :-\

Ideally I want to avoid cutting into the other members to fit the hip rafter. I will focus on making a steel bracket that holds everything together with bolts and see how it pans out before trying anything else. The valley already seems pretty solid resting upon the corner post. Adding a good steel bracket would most likely be sufficient. I will try to sketch something out for the bracket and post it.
Frank

D L Bahler

Im certainly tempted to try to help you come up with a solution, but like I said this is way outside of my comfort zone. There are other people far more qualified than me to work with you on this, hopefully they'll come along and give you some suggestions. 

Algorythm

I made the steel bracket for the rift valley tonight (i made it 3/8" thick). Seems like this could do the job what do you guys think of it?



 

 

 
Frank

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