Hybrid Help.

[way up north]

Hi Guys,
Well... Ive been on a multiple year learning expedition... you guys were great help on my last endeavor. Im hoping you can steer me in the right direction for this next build.

So. Im Building something like this for my house.  

 





 


This is the size I'm looking for. 16' center, 12' sides.
Id like to do the center in Timberframe and the sides stick frame.



 
looks like the walls are 16 to 17'.

of course to make it impossible id like to do the center part with a hammer beam like the plans from timberframehq.
So its going to be 40'x36'  and I want to make just the last rear 12' section of upper floor to be a loft. the rest of the room open



hope this makes sense.

So the questions...
can I just extend the legs/ posts of the Timberframe hq plans to 16-17'
and add the second floor tie beams to support it, and keep it from spreading outwards? Or am I missing something?

can I leave the middle tie beam(second from the front) out? Or better yet, HOW can I leave the middle (second from the front) tie beam out?

Is it a waste of time trying to hybridize the center section? Does it make more sense just to do it all Timberframe? (I'm trying to keep from having to wrap and strap anything but the roof, as well as getting it done as fast as possible.)

Im doing a 6"x 3' cement stemwall on footing around the perimeter for a foundation. Should I make it 8". or should I just build out the wall where the posts are.

Ive saturated my brain with books, videos, and blueprints. I need to extract/distill a plan of attack and Im hoping y'all can help.

Im sure Ive missed some questions, and more will come up, but lets start with this.



By the way I finished my "barn/shabin" Thanks to all of the advice on that thread. Ready for a new challenge.

 

  



Cheers.

[Don P]

Jim and I have been pm'ing a set of ideas back and forth, it has a similar detail. Pay attention to sliding snow from the upper roof impacting the lower, and then sitting there on the lower roof. I'd be brutal and size the lower rafters to take the entire roof load concentrated at midspan for when that hump slides down.

Hammerbeams are form ahead of function, just so we are all clear on that. Its a broken truss. My first try is to talk people out of that nonsense. Are you sure this is what you want to do, or would you prefer a strong roof?

You ask if the legs on the TFHQ plan can simply be extended. Check buckling on the posts, as posts become taller the slenderness ratio reduces capacity due to buckling.

Let's find some restraint. The side sheds and roof are an opportunity to provide some rigid restraint to the horizontal thrust. Design the shed roofs as rigid plates tied to braced walls that carry the flow down to the foundation. Imagine cutting all the tie beams out of the upper roof of your previous build and relying on the rigidity of the shed roofs to keep it from sagging and pushing the tall posts outward. That is pretty close to what we are talking about. Yes 8" thick foundation walls minimum. I'm working off of 12" thick reinforced walls currently because of unbalanced fill against full height basement walls, except where we are doing 16" thick rubble stone walls. Check your conditions and deliver load to soil appropriately.

[way up north]

Jim and I have been pm'ing a set of ideas back and forth, it has a similar detail. Pay attention to sliding snow from the upper roof impacting the lower, and then sitting there on the lower roof. I'd be brutal and size the lower rafters to take the entire roof load concentrated at midspan for when that hump slides down.

Hammerbeams are form ahead of function, just so we are all clear on that. Its a broken truss. My first try is to talk people out of that nonsense. Are you sure this is what you want to do, or would you prefer a strong roof?

You ask if the legs on the TFHQ plan can simply be extended. Check buckling on the posts, as posts become taller the slenderness ratio reduces capacity due to buckling.

Let's find some restraint. The side sheds and roof are an opportunity to provide some rigid restraint to the horizontal thrust. Design the shed roofs as rigid plates tied to braced walls that carry the flow down to the foundation. Imagine cutting all the tie beams out of the upper roof of your previous build and relying on the rigidity of the shed roofs to keep it from sagging and pushing the tall posts outward. That is pretty close to what we are talking about. Yes 8" thick foundation walls minimum. I'm working off of 12" thick reinforced walls currently because of unbalanced fill against full height basement walls, except where we are doing 16" thick rubble stone walls. Check your conditions and deliver load to soil appropriately.

Thanks for the reply Don P.   
You bring up some great points, and this is exactly the kind of advice Im looking for. 
By the way, we are dealing with Sitka Spruce. That's what I have. 
Also no building codes.

Im trying to see if its realistic to even entertain timber framing in this situation. That's why Im asking about hybrid framing. Im assuming its quicker.

Great point on the snow and lower rafters...will reinforce rafters. Check

8" foundation. Check.
Sounds like you are doing a serious stemwall there.

Bigger posts if lengthened. Check

I totally understand what your saying about the hammer beam truss spreading like from cutting the rafter ties.  Not what I want to do.
For some reason I assumed  TFHQ engineered the plans to work. But it sounds like I'm incorrect. Good to know before I start. I suppose that means I can alter them a bit if needed and it won't matter much.



Yeah.. the hammer beams .....Again I appreciate the hard truth here.

 yeah I really want that hammer beam esthetic, but not at the cost of a strong roof. So sounds like real hammer beam are out.  Sadly.


I keep toying with a couple blasphemous ideas however.

1. Just stick framing the whole thing except the central leg/beams and the second story loft floor. 
Then, just raising rafter ties up a 3rd every 48" (leaving the rest out of course), and hanging some fake hammer beams off that every 12'. Or some variation on that theme. 

Im sure you guys have seen something like that before. 
Does it look terrible? 
Like don't bother?
I know its blasphemy..


2. Putting up a ridge beam, split at the loft. And again hanging the hammer beams off that.

3. Build it as it is rendered.


Any of these plans sound semi logical, or should I just build the plan below with the side sheds on both side like the previous plan instead? Again stick framing the sides.

Thanks guys. The focus is narrowing.



 

 

Way up north.

[Don P]

It is not uncommon to run a steel tie rod across the break in a hammer beam to create a true tied truss with most of the aesthetic of an open hammer beam roof.

All the plans I have seen from them state that they do need engineering. 

I'm not a purist, the roof is where timber shines aesthetically, the walls get covered up by the occupant's decoration.

Sitka spruce... I didn't anticipate needing those design values but they are in the NDS tables.
5x5 and larger #2, Fb 650, E 1, Fv 140

[jake pogg]

It is not uncommon to run a steel tie rod across the break in a hammer beam to create a true tied truss with most of the aesthetic of an open hammer beam roof.

Didn't have much time for internet lately,but when i look in on occasion i never fail to enjoy some of Don's wonderful engineering wisdom.
This latest was great,thank you Way up North for bringing this up,and thanks to Don as always,and particularly for that "iron rod" open-mindedness,after such prudent,sobering physics!:)

I'm Not an engineer,alas and alack,but a lousy romantic in woodworking.
Fortunately,sober-er minds have kept me out of mischief in the past for the most part.

I've restructured an old log cabin once in Fairbanks that had a framed second story added to it in the early 1930-ies. There was no tie-beam nor any other provision to prevent the long walls from spreading and falling out,so 3 runs of 1" dia. rod-rigging was used under the loft floor.

It must've been robbed from a dredge or a crane,and each length had an Uber sculptrural forge-welded turn-buckle in the middle. Really nicely forged and welded,by hand,under a heavy mechanical hammer,probably steam back then.
We planned on re-using those as a part of railing but never had used that plan....

The mention of Sitka spruce made me think of some Stavkirke design features-go Tall,and and make the span narrow! Use entire trunks,going up and up! 
(and hide some dragons and monsters up there in the gloom )

On the more practical note,there was a large frame (3 stories) built in part as a student project at the old Black Rapids roadhouse. In checking it out once in passing i noticed that many of the more critically loaded tenons were plywood,male on both ends. I think those guys found some Micro-lam-ish product of the right gauge and used that.
Seemed like a cool idea,i love and worship spruce ( the only material available to me), but must admit that it's not the sturdiest in that particular application-a relatively thin tenon with sharp shoulders.
Even housed,even with very careful grain selection.....

[way up north]

Thanks again for the response Don P. And Jake pogg.

Don P. 
Yeah I have seen the steel rod solution. Somehow that destroys the magic of the hammer beam for me.
Id honestly rather just do a different style.

However I am contemplating whether or not it would be possible to do a post and beam (metal plates bolted on the faces or hidden ones) hammer beam. 

Would that work, or am I wrong in assuming the joints are the weak link? You call it a broken truss. What part is broken? Or is that a technical term?

Agreed the ceiling or roof and all those huge beams is where the magic and mystery are. 

As embarrassing as it is to admit,  I have to confess that those NDS tables with what appears to be a sine wave and algebra are terrifying.
Math was never my strong point.  I may be mistaken, but I have to imagine that people building Timberframes back in the 1200's were also not great at math, but were able to build strong buildings none the less. Of course they stuck to simpler designs.

Well. This is why Im here. Trying to find out what is possible, and what is biting off more than I can chew.


Jake Pogg

 Galena..I have not been up there. Looks like a similar population to my town of Gustavus. AK is a magic place, is it not?

You mention stavkirke design.  Coincidentally, I am using stave churches as my inspiration. The dragons and monsters way up there in the gloom ambiance is exactly what I am trying to recreate. Will recreate!

I was hoping going narrow (16') and a 12/12 pitch would be enough to pull off a hammer beam , but apparently not.
Still that look is what I am going for. so heavy beams overhead, car decking, and some nice curved knee braces hopefully will give that feel.

Sounds like the black rapids road house project used something stronger than spruce at the tenons. Maybe my idea of metal plates or hidden metal blades may be on the right track...?


My hope is to eliminate the impossible, and too difficult,  thereby revealing the best path to take.
That's the problem with no building codes. You start to think you can just make anything, without thinking if its structurally possible or not. Still, I wouldn't trade it for the world.

Thanks again for the input guys.
Happy Friday!

Way up north

[Don P]

Although I am flattered by Jake's comments, I'm not an engineer. I tell people I'm a highly opinionated framing carpenter. Find a real engineer before you build, as one said, "if you have to ask the question, you need to hire me" There's more than one old church stabilized with iron or steel rods, one could even conceal a big plate that could support a rod later if needed.

Look at the hammerbeam in section and think about it as a barrel vault, an arch. That is what they were mimicking in timber. Arches thrust too, steeper and deeper less so, but you have to restrain that thrust somehow..

How do you keep the arch from spreading without a bowstring to restrain it. Bury it between the rock walls of the gorge, spread is restrained.

If you somehow rigidly brace the untied bents, are we talking one, or two? If there is a braced wall in the shed on each side, well, if you are building a church instead of a bridge, take the section view of the bent and draw a flying buttress within the sheds. Those old farts whittled every unneeded scrap away in a delicately braced and balanced gargoyle encrusted way but structurally a sheathed wall filling those wings would brace the roof from spreading. Use the sheds as the walls of your gorge. Lock them hard to the floor, thrust wants to overturn them.


A scissor truss is another vaulted roof, that is tied.

[way up north]

Although I am flattered by Jake's comments, I'm not an engineer. I tell people I'm a highly opinionated framing carpenter. Find a real engineer before you build, as one said, "if you have to ask the question, you need to hire me" There's more than one old church stabilized with iron or steel rods, one could even conceal a big plate that could support a rod later if needed.

Look at the hammerbeam in section and think about it as a barrel vault, an arch. That is what they were mimicking in timber. Arches thrust too, steeper and deeper less so, but you have to restrain that thrust somehow..

How do you keep the arch from spreading without a bowstring to restrain it. Bury it between the rock walls of the gorge, spread is restrained.

If you somehow rigidly brace the untied bents, are we talking one, or two? If there is a braced wall in the shed on each side, well, if you are building a church instead of a bridge, take the section view of the bent and draw a flying buttress within the sheds. Those old farts whittled every unneeded scrap away in a delicately braced and balanced gargoyle encrusted way but structurally a sheathed wall filling those wings would brace the roof from spreading. Use the sheds as the walls of your gorge. Lock them hard to the floor, thrust wants to overturn them.


A scissor truss is another vaulted roof, that is tied.

Of course! The flying buttress!!

That might just work! And look even better...when was the last time you saw a flying buttress in a kitchen...?
Great suggestion.

Lol, yes I guess I am building a church.

I like the embedding a metal anchor in there should one need it in the future.

Yes, just one untied bent. Not a must,  but would be nice if possible. I imagining walking in and looking up  at the loft and there is a tie beam in the way...

So, if I hear you right your saying the hammer beam may be "possible" if I was to brace the bents with sheathing and (or?) a flying buttress.. Id opt for the buttress. 
That's just an awesome idea Don.

And of course, yeah I should ask an engineer to look at it. Do you guys have a budget friendly go to guy? Or a reccomendation?


Yeah scissor truss. I assume you recommend that because it is structurally superior to the hammer beam?
Yeah Ill mull that over.

Great tips. Don. Thank You Sir.

[way up north]

Looks like a good example of the bracing you are talking about Don P.


 

[Don P]

Bingo  ;D

[jake pogg]

Following this with interest,i'm already challenged beyond any possibility of any practical suggestions. the difference between a hammer-beam and a scissor truss boggles my pea-brain hopelessly.

I believe that the` best "engineer" is someone exactly like Don,without an official degree to hide behind but with a great store of applied,hands-on physics undef one's belt. plus,a certain turn of mind,an artistic vision(what's a builder without a flightless bird..),all of which of course must be tempered by certain degree of prudence,for the God of Gravity is a jealous God,and our building must stand,and lastingly so...

Historically,i'd hesitate to call the precedence: have those Normans in copying older Byzantian work elements have carried the stone designs North,or the other way around-bringing their spruce-based structural knowledge South,to use stone as they were used to in their spruce-thinking?

Are those great Gothic cathedrals with their obscenely-tall walls necessitating flying buttresses the tell-tale sign of someone who was used to that enormous capacity for end-loading of wooden stave-work?

Way up North,you seem to've done Great on that car-port,a lovely structure for sure. I think you can do It,design something that has the maximal cool-factor yet be sensible and prudent structurally,i admire your goal.

Gustavus is a magical spot,by all accounts. Never had the pleasure of visiting,my time down in South-Eastern has been limited by a short stint down in Haines (where i took part in destruction/remodel/restructure of parts of structures belonging to Fort Seward,tearing out loads of old-growth Doug fir,crying as i did so...).

As a side-note: Alaska coastline is dotted with old structures made out of the finest sort of that species of timber. Hauled North from the PNW by schooner in large cants and off-loaded easily and re-sawnfor specific structural use. Canneries and salteries and tons and tons of dock planking. Much of it in surprisingly fine shape even yet,despite of the weathered look. In another coastal location,north of the mouth of Naknek river,i used some of this stuff that was being torn out. A mere 1/8th underneath the weathered surface that wood was pink and new and as solid as the day it was logged...It's a great shame someone doesn't contract a push-boat+barge and go salvage a large amount of what remains....  

[jake pogg]

 

 

And now Totally off topic,maybe to inspire more monsters/gargoyles silliness,here's an old work of mine,my take on the medieval concept of so-called Sanctuary knocker,a common feature in a number of bigger cathedrals.

[rusticretreater]

That is really cool and also a sign of a man with too much time on their hands.

[jake pogg]

That is really cool and also a sign of a man with too much time on their hands.

....but what's Time,to a pig?!"

[way up north]

Following this with interest,i'm already challenged beyond any possibility of any practical suggestions. the difference between a hammer-beam and a scissor truss boggles my pea-brain hopelessly.

I believe that the` best "engineer" is someone exactly like Don,without an official degree to hide behind but with a great store of applied,hands-on physics undef one's belt. plus,a certain turn of mind,an artistic vision(what's a builder without a flightless bird..),all of which of course must be tempered by certain degree of prudence,for the God of Gravity is a jealous God,and our building must stand,and lastingly so...

Historically,i'd hesitate to call the precedence: have those Normans in copying older Byzantian work elements have carried the stone designs North,or the other way around-bringing their spruce-based structural knowledge South,to use stone as they were used to in their spruce-thinking?

Are those great Gothic cathedrals with their obscenely-tall walls necessitating flying buttresses the tell-tale sign of someone who was used to that enormous capacity for end-loading of wooden stave-work?

Way up North,you seem to've done Great on that car-port,a lovely structure for sure. I think you can do It,design something that has the maximal cool-factor yet be sensible and prudent structurally,i admire your goal.

Gustavus is a magical spot,by all accounts. Never had the pleasure of visiting,my time down in South-Eastern has been limited by a short stint down in Haines (where i took part in destruction/remodel/restructure of parts of structures belonging to Fort Seward,tearing out loads of old-growth Doug fir,crying as i did so...).

As a side-note: Alaska coastline is dotted with old structures made out of the finest sort of that species of timber. Hauled North from the PNW by schooner in large cants and off-loaded easily and re-sawnfor specific structural use. Canneries and salteries and tons and tons of dock planking. Much of it in surprisingly fine shape even yet,despite of the weathered look. In another coastal location,north of the mouth of Naknek river,i used some of this stuff that was being torn out. A mere 1/8th underneath the weathered surface that wood was pink and new and as solid as the day it was logged...It's a great shame someone doesn't contract a push-boat+barge and go salvage a large amount of what remains....  

Jake pogg,
Thanks for the response.
Yeah its hard to tell who influenced who.

Yeah I've still got most of my hands left, and my motto has been, if it has been built by human hands, then I can build it too.  We shall see.


Haines is beautiful. Wish I could have found a place up there.. the fates have decided otherwise


Yeah its all relative. If spruce is what you have, people will figure out how to make it work.
Im going to make it work.

If you ever find yourself in Gustavus, your welcome to come by, raise a flagon, and quench your thirst in my ale hall. 


I love that dragon knocker. Nice forge work there. 
I do intend to setup a forge when I get some free time. But for blade making.

So lets see what this old man can do.

Thanks again
Way up north

[way up north]

 

 

 Back with more questions.

Which connection at the plate and hammer beam would you guys use or prefer? the one with the hardware or the other one?
Ive seen conflicting opinions...

thanks! getting closer.