Author Topic: Metal connectors for timber frame buildings  (Read 21176 times)

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Offline kyounge1956

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Metal connectors for timber frame buildings
« on: August 18, 2009, 12:37:56 PM »
I am planning to build a very small house, post & beam frame with bale infill. I saw these connectors http://www.socketsys.com/ in a thread on this site. Other threads mention Simpson connectors and beam connectors generically. The appeal to me is that it appears the only skills necessary are cutting the wood to length, drilling the holes, and fastening bolts. Even with my truly minimal carpentry skills, I can do all three of those things!! I know traditional timber framing with the precision mortise & tenon joinery is way beyond my skill level, but with the connectors, maybe I can really do it. For as small a house as I'm planning, maybe I can use 4x4's and 4x6's instead of the whoppers used for larger timber-frame buildings and be able to stand the frames up with a rented winch or maybe only a few people's assistance for a short time (this is going to be mostly a single-handed build).

Are these metal connectors all more or less the same thing, made by a variety of manufacturers, or are there real differences from one type to another?

Karen

Offline MountainDon

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Re: Metal connectors for timber frame buildings
« Reply #1 on: August 18, 2009, 12:53:15 PM »
It would appear the socket systems items are very heavy duty. And very expensive!    :o :o  They also have some very special application brackets that might be hard to find in the Simpson catalog.

alphabetical...
http://www.strongtie.com/products/alpha_list.html?source=topnav
and by category...
http://www.strongtie.com/products/category_list.html
They also have a downloadable catalog someplace on their website.





Just because something has been done and has not failed, doesn’t mean it is good design.

If you didn't have the time or money to do it right in the first place, when will you get the time and money to fix it?

Offline MountainDon

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Just because something has been done and has not failed, doesn’t mean it is good design.

If you didn't have the time or money to do it right in the first place, when will you get the time and money to fix it?

Offline HomeschoolMom

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Re: Metal connectors for timber frame buildings
« Reply #3 on: August 18, 2009, 02:03:32 PM »
Ok, don't kill me for this question, but now where do I find a plan that lets me use these connections? d*
Michelle
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Married to Jason, Self Employed

Wanting an earth bermed hybrid timberframe...just need some inheritance  ;)  Will never have another mortgage again!

Offline Don_P

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Re: Metal connectors for timber frame buildings
« Reply #4 on: August 18, 2009, 05:55:26 PM »
I've built with socket systems once. I think that will be the one time I will. It was I think the most flexible building I've ever worked on. With some relatively minor changes I think you could make it a much stronger and nicer building. One of the main concepts of the building is a high clear ceiling without either a structural ridge or a bottom chord tieing the rafter feet across the building. I don't think it does that particularly well, but if your design can handle ties across the ceiling (a timber truss) or a ridge beam then I think something along those lines would be quite workable.  For the money I would either make my own brackets or have them welded locally. Theirs were quite short and it felt to me like they were just adequate, a few more bucks spent on steel would go a long way. They supply the "plans" with the connectors, you supply the other materials.

One of the things I liked about their system was the tip up bases, the ones we got were mismachined, took several hours of grinding and they worked fair. I made a set that I think worked better for my shop;



I did like several things about their system, the tip up assembly was one. This is my rendition, I've added the bottom chord to make it a truss. The steel angle iron on the bent is to brace it during the lift. To keep the pieces in sizes I could make and handle I spliced the 25' bottom chord around a kingpost, this is a kingpost truss. The rafter feet of this bent are restrained in steel that I welded up. I fitted the top chord/kingpost joint but it could all be made with steel and bolts easily enough. This is much stouter than the socket systems bent. This bent is steel connected so is properly post and beam, the one behind it is all wood, pegged with hickory, it would be properly called timberframe.



  
« Last Edit: August 18, 2009, 06:28:36 PM by Don_P »

Offline Don_P

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Re: Metal connectors for timber frame buildings
« Reply #5 on: August 18, 2009, 06:48:23 PM »
Oh and to answer the original question, connectors do vary or can be custom fabricated. The dimensions of the wood are determined by the loads, spans, species and strength grade of the wood. If you want a quick thumbnail check of sizes... what are the dimensions of the building, 1 story? How far apart are the bents? What is your snow load or where are you? What type of wood do you plan to use?

Offline HomeschoolMom

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Re: Metal connectors for timber frame buildings
« Reply #6 on: August 18, 2009, 07:29:23 PM »
Have you seen this?  http://www.adapt-buildings.com/index.htm  I wonder if they would just sell the hardware?  I actually like the look of mixing the steel with the wood.
Michelle
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Married to Jason, Self Employed

Wanting an earth bermed hybrid timberframe...just need some inheritance  ;)  Will never have another mortgage again!

Offline Ndrmyr

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Re: Metal connectors for timber frame buildings
« Reply #7 on: August 19, 2009, 12:32:47 PM »
I am in the process of building a socket system cabin.  The system is well designed for a DIY'er, but unless you can keep the cost of the 6x6's below retail, I doubt that it is cheaper than trusses and stud walls. That being said, the opportunity to have an affordable quasi timber frame is nearly irresistable at least to me.  If as I did, you can aquire beams at an auction, salvage, sawmill or make your own composite with dimensional lumber and plywood, then it is well within one's reach.

I've taken the option of fabricating some of my own brackets and adding in additional beams for greater strength. Can't go wrong with overbuilding....right?
« Last Edit: August 19, 2009, 12:51:27 PM by Ndrmyr »
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Offline MushCreek

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Re: Metal connectors for timber frame buildings
« Reply #8 on: August 19, 2009, 01:04:25 PM »
Another interesting (and expensive) approach is Timberlinx. When properly done, they are indistinguishable from real timber framing, and extremely strong. I once thought about doing a timber framed great room, but got hung up when I was told I would have to graded timbers and proof of engineering. I may build a gazebo or some such, just to scratch the timber framing itch. www.timberlinx.com
Jay

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Offline HomeschoolMom

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Re: Metal connectors for timber frame buildings
« Reply #9 on: August 19, 2009, 04:10:51 PM »
This might be a dumb question, but with these "connectors" do you just work off your usual timber frame plan and just replace their "joints" with connectors? :-[
Michelle
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Married to Jason, Self Employed

Wanting an earth bermed hybrid timberframe...just need some inheritance  ;)  Will never have another mortgage again!

Offline Ndrmyr

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Re: Metal connectors for timber frame buildings
« Reply #10 on: August 19, 2009, 04:35:37 PM »
To a certain extent.  This is more of a post and beam or post and lintel construction since the traditional mortise and tenon joints have been replaced with steel connectors or "sockets" as socketsystems refers to there system.
Here you use straight beams and "connect" them at intersections with steel brackets. The great thing is, people are so interested that they come by to look and often provide free labor. No doubt about it, it is a fun way to build.
Once my project is done, I don't know what I will do to "scratch the itch" nex time.
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Offline Don_P

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Re: Metal connectors for timber frame buildings
« Reply #11 on: August 19, 2009, 05:26:44 PM »
any structural member has to be sized by load and then the connection has to be sized for the forces it will encounter as well. You'll find tables of loads for simpson connectors and for custom stuff there will be an engineer designing and checking the connections. Socket Systems has an engineer stamping their plans. For something custom a local engineer is probably the best way to go. You can get an idea of bolt design values from the awc.org connections calc but when you get into groups of bolts it requires more horsepower than that calc has. So it's possible to turn a timberframe plan into a post and beam but it is a good idea, and possibly going to be required, that it be engineered.

Like what you did Ndrmyr, that bent adresses the downsides I was concerned with. another fellow on the 'net that goes by Arkansawyer does his own version of socket systems and has pushed the design along as well.

Offline Ndrmyr

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Re: Metal connectors for timber frame buildings
« Reply #12 on: August 19, 2009, 07:13:19 PM »
Thanks Don,

That was my concern also.  I didn't like that long expanse on the roof beam without additional support. That 17' expanse from the ridge to sidewall just seemed to cry out for some additional support and that is why I added in the queen posts mid-point, that and the collar tie added substantially greater rigidity. In addition I will be adding in center posts midway along the floor beam which cuts load points in half. Overkill perhaps, but I will sleep better at night.
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Offline kyounge1956

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Re: Metal connectors for timber frame buildings
« Reply #13 on: August 22, 2009, 04:37:03 AM »
Oh and to answer the original question, connectors do vary or can be custom fabricated. The dimensions of the wood are determined by the loads, spans, species and strength grade of the wood. If you want a quick thumbnail check of sizes... what are the dimensions of the building, 1 story? How far apart are the bents? What is your snow load or where are you? What type of wood do you plan to use?
Hi Don_P
Thanks! After a marathon SketchUp session I have produced a rough view of the building, but after all that I can't figure out how to attach the pictures so I'll have to give you a verbal description. Basically, it's a studio apartment without the noisy neighbors. The usable inside floor area is 18' x 24'.  Allowing 2 feet thickness for the bale walls, the footprint is 22' x 28'. It is one story with no loft. I would like the posts to be at the outer face of the bales so I can use metal siding as a vented rainscreen (the area can get a lot of wind-blown rain) and to make future expansion if any easier to fasten to the original structure.

With an overall building length of 28 feet that would make 14' between bents (if there is one at each end and one in the middle) or 9'4" if there are two in the middle. With this floor plan (which isn't carved in stone at this point) I think one bent in the middle would probably work better. There is a partial crosswise wall more or less in the middle of the building...may as well line up the bent with it. However, splitting the length of the building in thirds might make it possible to use smaller posts, which would be a good thing. The species will most likely be Douglas fir, that's what mostly grows out there. The connectors use rough-sawn wood....it might even be possible to get local timber. Custom metal fabrication is way above my skill level. I've never done any metalwork at all, and don't have either the tools or the knowledge.

I don't know what the code required snow load is out here. I did a quick look online and found the snow load maps for King County. Most places on the map are below 400 ft elevation with snow load of 25 psf. The one place that is a bit above 400 ft elevation has snow load of 32 psf. It probably snows less out by the coast than it does here in town, unless you get up into the mountains, which I don't plan to. Probably the greatest danger with snow here is when it snows one day and then rains on it the next. Our snow tends to be pretty wet here to start off with and when it gets sodden it's really heavy.

I'm for bed. It's 5:30 AM. That's much too early to get up on a Saturday morning!

Karen


Offline Don_P

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Re: Metal connectors for timber frame buildings
« Reply #14 on: August 22, 2009, 07:18:40 AM »
Karen,
Under the "file" tab on sketchup click "export" and then "2d graphic" when you have the drawing oriented to the view you wish to show. It saves a jpeg of the view on the screen. From there post it on photobucket or on your website if you have another host. Then use the image tags here to post it.

Since I want to be lazy, check your PM's for my email adress, please save the sku file and send me a copy of that file, I can then play with it directly.

Offline kyounge1956

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Re: Metal connectors for timber frame buildings
« Reply #15 on: August 22, 2009, 01:17:29 PM »
Karen,
Under the "file" tab on sketchup click "export" and then "2d graphic" when you have the drawing oriented to the view you wish to show. It saves a jpeg of the view on the screen. From there post it on photobucket or on your website if you have another host. Then use the image tags here to post it.

Since I want to be lazy, check your PM's for my email adress, please save the sku file and send me a copy of that file, I can then play with it directly.

The 2d exports were easy (I have Sketchup for Dummies) but I couldn't figure out  ??? how to make them appear in my message. Looks like the reason I couldn't is that I don't have a photobucket or website. On some other lists I can attach a file that's in my hard drive. No way to do that here? I have sent the sketchup file and both jpgs to your email address. 
Karen

Offline Don_P

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Re: Metal connectors for timber frame buildings
« Reply #16 on: August 22, 2009, 02:18:43 PM »
Hi Karen, thanks for your email, the pics and file arrived. i've put the jpegs on my photobucket page and am linking to them from there. this forum does not have direct upload of photos, which is a shame, eventually all the pictures here will become disassociated from their threads. You will need to set up a photo hosting account of some sort to post pics (which we all like), I've had good luck with photobucket and use it on several forums that don't have direct upload capabilities.

I hope you don't mind, your email text was quite informative too so I'm attaching that as well.
We have a dinner engagement so I'll post these for now to keep everyone up to speed;



A few explanatory notes:
I live by myself. I"ve tried to put everything in the house that I would need to live in it long-term, but it also has to be very small to give me a reasonable chance of actually getting it built. My goal is to build the whole thing by myself, using as much as possible renewable materials, and if not renewable at least easily reusable or recyclable. I might use some salvaged materials too, if available and appropriate.


The house is intended to have passive solar orientation. North is "up" on the drawing. The roof might be gable with ridge running from east to west or shed with slope to south, I haven't decided yet. I also haven't learned enough sketchUp to make a roof yet :) I think I'm required by current code to have at least R-38 in the roof and the requirement will probably be greater in four years or so which is when I hope to be able to start construction (schedule depends on whether I can retire from my job by that time).


All the plumbing is in the wall between the kitchen (upper left=NW corner of house) and the bathroom (SW corner of house).


My dining table is not shown but would be along the north wall, more or less under the western of the two windows. It might be a drop-leaf type to take less space when not in use. Chair might fold up and hang on the wall for the same reason


Also not shown along that wall are pegs for hanging coats, brooms, etc on the wall just to the left of the kitchen door


Also not shown, further along that wall, is the comfy armchair for reading, knitting etc—more or less by the eastern window in the north wall.


Also not shown are a concealed ironing board in the crosswise wall at the east end of the kitchen. The gray item in the cubby outside the bathroom door is a stacking washer and dryer, or a combination appliance that washes and dries in one machine.


The circles on the kitchen and bathroom floor are to show 5-1/2' radius allowed for wheelchair turning—the intent is that the house could be made wheelchair accessible in the future if necessary.


The pink item at the lower center of the screen is my mattress (twin size). It is sitting partly on top of cabinets and partly on the sill of the large south facing window.


The brown items along the walls and in the kitchen are cabinets for storage of clothes, books, dishes, a computer desk, etc. The upper cabinets are not shown but there would be some, and probably one of those big pantry cupboards with sliding shelves. The exact arrangement of appliances and cabinets has not been nailed down yet, except I think about the only place for a refrigerator would be at the SE corner of the kitchen. It's possible the kitchen door might get moved to the north wall if that single row of cabinets just doesn't make for a good kitchen layout.


Location and sizes of the windows are also preliminary, except that one of them has to be wide enough so the bed fits on the windowsill


It's not visible in the overhead view, but there is a door to the outside on the south wall of the bathroom. Eventually there might be a porch along this side of the building, which might even turn into the guest room for summer use only. I have an article from This Old House magazine about how to build a porch from screen doors, which sounds like about my speed.


A future carport or garage would probably be located on the west end of the building.


Karen

Offline kyounge1956

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Re: Metal connectors for timber frame buildings
« Reply #17 on: August 22, 2009, 02:57:19 PM »
Thanks Don!!

One more explanatory note. "North is up" refers to the sketchup file I sent Don, which is a view from almost directly overhead. In the jpegs, north is down and to the right (top picture) or up and to the left (bottom picture). IOW the big window with the mattress is on the south wall. Your comments are solicited.
Enjoy the dinner party!
Karen

Hi Karen, thanks for your email, the pics and file arrived. i've put the jpegs on my photobucket page and am linking to them from there. this forum does not have direct upload of photos, which is a shame, eventually all the pictures here will become disassociated from their threads. You will need to set up a photo hosting account of some sort to post pics (which we all like), I've had good luck with photobucket and use it on several forums that don't have direct upload capabilities.(snip)

Offline waggin

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Re: Metal connectors for timber frame buildings
« Reply #18 on: August 22, 2009, 09:21:29 PM »
Oh and to answer the original question, connectors do vary or can be custom fabricated. The dimensions of the wood are determined by the loads, spans, species and strength grade of the wood. If you want a quick thumbnail check of sizes... what are the dimensions of the building, 1 story? How far apart are the bents? What is your snow load or where are you? What type of wood do you plan to use?
Hi Don_P
Thanks! After a marathon SketchUp session I have produced a rough view of the building, but after all that I can't figure out how to attach the pictures so I'll have to give you a verbal description. Basically, it's a studio apartment without the noisy neighbors. The usable inside floor area is 18' x 24'.  Allowing 2 feet thickness for the bale walls, the footprint is 22' x 28'. It is one story with no loft. I would like the posts to be at the outer face of the bales so I can use metal siding as a vented rainscreen (the area can get a lot of wind-blown rain) and to make future expansion if any easier to fasten to the original structure.

With an overall building length of 28 feet that would make 14' between bents (if there is one at each end and one in the middle) or 9'4" if there are two in the middle. With this floor plan (which isn't carved in stone at this point) I think one bent in the middle would probably work better. There is a partial crosswise wall more or less in the middle of the building...may as well line up the bent with it. However, splitting the length of the building in thirds might make it possible to use smaller posts, which would be a good thing. The species will most likely be Douglas fir, that's what mostly grows out there. The connectors use rough-sawn wood....it might even be possible to get local timber. Custom metal fabrication is way above my skill level. I've never done any metalwork at all, and don't have either the tools or the knowledge.

I don't know what the code required snow load is out here. I did a quick look online and found the snow load maps for King County. Most places on the map are below 400 ft elevation with snow load of 25 psf. The one place that is a bit above 400 ft elevation has snow load of 32 psf. It probably snows less out by the coast than it does here in town, unless you get up into the mountains, which I don't plan to. Probably the greatest danger with snow here is when it snows one day and then rains on it the next. Our snow tends to be pretty wet here to start off with and when it gets sodden it's really heavy.

I'm for bed. It's 5:30 AM. That's much too early to get up on a Saturday morning!

Karen



Karen,

Not sure where you are in King County, but here's the county snow load map I used.  Is this what you found as well?

http://www.kingcounty.gov/property/permits/gis/ReferenceMaps.aspx

Once you have the page open, scroll down to this section: "King County Ground Snow Load (four sections):"  I haven't completely figured it out yet, so you may have to explore it a little.  If you look at the NW King County region, then zoom in to Fall City, you see a yellow area marked appendix A.  Note that downtown Fall City at 90' of elevation has a 30# snow load.  Now see the 0.073 in purple?  See where it notes Snoqualmie Falls at 440' and 32#?  Take 440 x 0.073, and you get 32.12, which they round to 32.  Looks like 30# is the minimum, but once you gain elevation, it is 0.073# per foot of elevation in the appendix A area.  I'm only 3 miles away from either the falls or downtown at about 950' of elevation (950 * .073 = 69.35) which is exactly what one of my neighbors was required to design for.  Pretty wild to see the snow load design change from 30# to almost 70# in less than 3 miles as the crow flies!
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Offline kyounge1956

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Re: Metal connectors for timber frame buildings
« Reply #19 on: August 22, 2009, 10:38:48 PM »
(snip) What is your snow load or where are you? What type of wood do you plan to use?
Hi Don_P(snip)
I don't know what the code required snow load is out here. I did a quick look online and found the snow load maps for King County. Most places on the map are below 400 ft elevation with snow load of 25 psf. (snip)
Karen

Karen,

Not sure where you are in King County, but here's the county snow load map I used.  Is this what you found as well?

http://www.kingcounty.gov/property/permits/gis/ReferenceMaps.aspx

Once you have the page open, scroll down to this section: "King County Ground Snow Load (four sections):"  I haven't completely figured it out yet, so you may have to explore it a little.  If you look at the NW King County region, then zoom in to Fall City, you see a yellow area marked appendix A.  Note that downtown Fall City at 90' of elevation has a 30# snow load.  Now see the 0.073 in purple?  See where it notes Snoqualmie Falls at 440' and 32#?  Take 440 x 0.073, and you get 32.12, which they round to 32.  Looks like 30# is the minimum, but once you gain elevation, it is 0.073# per foot of elevation in the appendix A area.  I'm only 3 miles away from either the falls or downtown at about 950' of elevation (950 * .073 = 69.35) which is exactly what one of my neighbors was required to design for.  Pretty wild to see the snow load design change from 30# to almost 70# in less than 3 miles as the crow flies!

Hi waggin,
Thanks for the heads up, and yes, that is the same map. I saw the purple 0.73 but didn't know what it meant, so I just looked at the cities with elevation and snow load. For example, Seattle (where I live now) says "350'= El/25 psf"; Bellevue "100=El/25 psf" and so on. I admit I missed Fall City which appears to be the one exception to the pattern I noticed that the places that are under 400 ft  elevation use 25psf. I also did another quick search this evening and found this checklist from the City of Aberdeen, which is actually in one of the coastal counties, though further inland than I am planning to be. The code there also says 25 psf, so to get a ballpark idea of whether the building will stand up or fall down, I think that is a safe figure to use at lower elevations. High winds and earthquakes are probably a bigger threat to structural integrity than snow—high winds because they happen more often than big snowstorms, and earthquakes because, well, they're earthquakes.

Karen

Karen

Offline Don_P

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Re: Metal connectors for timber frame buildings
« Reply #20 on: August 23, 2009, 10:12:12 AM »
This is a first idea. I've no experience with strawbale, I stuck the timbers in the bales, not sure how that works.  I've pushed some walls around a little to fit things in. I moved the kitchen/bath wall ~3" to centerline and am using it as a ridge support. When sheathed it acts as a shear wall. I moved the T wall ~3" at the end of the center wall, in line with the center rafter set and am using it as a brace wall as well. From there across the LR I've drawn in a structural ridge beam. I moved the bath entry door about 1'.

  The rafter pairs are roughly on 7' centers, I've varied a little bit. The gravity load on the rafters works out like this; 10 psf dead load + 25psf snow=35psf total. 7'spacing x 11' span=77 square feet X 35 lbs per square foot...2695 lbs on each central rafter.
This is a beam calc for sizing heavy timber;
http://www.windyhilllogworks.com/Calcs/beamcalc.htm
Inputs are;
Load- 2695 lbs
Span- 132"
Width= 5.5"
Depth- 7.25"
Fb- 1350 psi
E-1.7
Fv-170 psi

Anyway that will check, which means #1 Dougfir 6x8's would work for the rafters. Checking the AITC manual 2x Tongue and groove decking will work spanning across those rafters. From there I've built up layers of foam, 2x4 strapping over that and either plywood and shingles or metal roofing.

On the right track or have you got other ideas?

Offline kyounge1956

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Re: Metal connectors for timber frame buildings
« Reply #21 on: August 23, 2009, 12:54:20 PM »
I have no experience with straw bales yet either. However from what I've read, the timbers can go on either face of the bales or the ends of the bales can be notched and fitted around the timbers so they end up in the middle of the wall. I've also seen photos of one house where the roof was supported by timbers and the wall kind of meandered around below on its own footing, sometimes in line with the timbers and sometimes not. Nothing that complicated for me. I am planning on timbers to the outside of the bales but the way you have shown them is pretty close to where they would be, because the 2-foot wall thickness in the model included the bales, timber, siding on the exterior and plaster on the interior.

I'm trying to remember why the wall between the kitchen and the bathroom was slightly off center. I think it was probably to get both wheelchair turning radii to fit. Does moving the wall over to the center affect either of them? If not, then it's no problem.

I realize now that I see the model with the roof on, that I told you the wrong direction on the ridge.  d*  My building plan (before I saw the connectors) was something like this:

Step 1, acquire temporary living space (e.g. camper, tent, yurt) and set it up on site.
Step 2, set vertical posts at required intervals for kitchen/bath half of building
Step 3, add beams, then joists, then planks to form room ceiling/attic floor.
Step 4, stand on ceiling/floor to build roof (shed with the high side at the center of the completed building). Insulate roof with cotton insulation made from reclaimed manufacturing scraps. (foam doesn't fit in with the all renewable/recyclable materials idea. Unless the code changes require a roof R-value that's impossible without using the foam, I don't plan to.) Complete roof with sheathing as required and metal roofing.
Step 5, stack bales leaving openings for windows & doors.
Step 6, finish everything else (plaster, siding, install windows, wiring plumbing etc etc.)
Step 7, build the other room, a mirror image of above, as a "lean-to" against the kitchen/bathroom part of the house. The other room was possibly going to have a cathedral ceiling.

I have to keep everything in manageable-sized pieces, because I can't assume I will have assistance available and don't want to hire someone unless I absolutely have to. (The only thing I'm planning on subbing out is the wiring. I just don't understand electricity enough to feel confident I would do that right, and I'd feel so dumb if I burnt my house down a with faulty electrical system. And I've heard some places, the code requires it to be done by a licensed electrician anyway.) The need to deal with things in small pieces is why I originally thought pole type frame rather than timber frame, because I knew the bents would be much too heavy for me to stand up. However, my carpentry skills are very limited and the connectors appear to bring down the needed skill level to something I believe I could accomplish. ISTM that with the connectors there is less need to get the ends of timbers exactly square or at the precise angle the rafters meet, and also no birdmouth cuts required on the rafters. As long as I don't cut something off too short, I'm good! It also seems likely to me that in building the roof from scratch, I might easily fail to get the rafters all at exactly the same slope, resulting in my sheathing not lying flat and making it hard to get the metal roofing to go on correctly. The connectors look like they would just about force the roof to be right, provided all the vertical wall posts are the same length.

So the connectors were looking real attractive, but there's a fly in the ointment, which is that if it needs a 6x8 to span half of the building going the short way, they aren't an option for me, and even less so with the roof ridge going the direction I meant to say. With a roof slope of 4:12 the hypotenuse of each of those roof triangles is 11.6 feet, so the necessary piece of wood might be 13 feet long or so, including the eaves. I'm going to guess that a 13' 6x8 weighs about as much as I do--probably too big for me to handle even one at a time. It really surprised me that it takes something that big for my wee housie. The website says they can do a building of up to 30 feet wide with bents 8 feet apart in "northern" locations (I assume this means heavy snow load) or 16 foot spacing in southern areas, with no ridge beam (does have a collar tie and haunch braces though if there is no second floor—I don't know if that makes any difference to the size of timbers needed). I was hoping with my smaller building and lower snow load, I'd be able to use 4x6's, or even 4x4's. No such luck, it looks like. Also, IIRC from the website, the connectors say they fit 6x6 rough sawn timber, so I'm not sure it would even be possible to use a 6x8 with them.

Would I be correct to think that to use smaller timbers, I'd need more bents, closer together? That might work, especially if I tweak the windows so they line up on both faces of the building, or if I put the roof ridge back to running north and south (there's only one opening (the kitchen door) in the ends of the building and that one could go around the corner onto the north wall. I was thinking possibly of adding some high windows above the cabinets on the east end (not shown in the model I sent you), but those could be any size they need to be to fit between the bents.

Decisions, decisions....
Karen


This is a first idea. I've no experience with strawbale, I stuck the timbers in the bales, not sure how that works.  I've pushed some walls around a little to fit things in. I moved the kitchen/bath wall ~3" to centerline and am using it as a ridge support. When sheathed it acts as a shear wall. I moved the T wall ~3" at the end of the center wall, in line with the center rafter set and am using it as a brace wall as well. From there across the LR I've drawn in a structural ridge beam. I moved the bath entry door about 1'.

  The rafter pairs are roughly on 7' centers, I've varied a little bit. The gravity load on the rafters works out like this; 10 psf dead load + 25psf snow=35psf total. 7'spacing x 11' span=77 square feet X 35 lbs per square foot...2695 lbs on each central rafter.
This is a beam calc for sizing heavy timber;
http://www.windyhilllogworks.com/Calcs/beamcalc.htm
Inputs are;
Load- 2695 lbs
Span- 132"
Width= 5.5"
Depth- 7.25"
Fb- 1350 psi
E-1.7
Fv-170 psi

Anyway that will check, which means #1 Dougfir 6x8's would work for the rafters. Checking the AITC manual 2x Tongue and groove decking will work spanning across those rafters. From there I've built up layers of foam, 2x4 strapping over that and either plywood and shingles or metal roofing.

On the right track or have you got other ideas?

Offline Don_P

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Re: Metal connectors for timber frame buildings
« Reply #22 on: August 23, 2009, 05:28:51 PM »
On size, I'm a carpenter so tend to keep it brutally basic. If they stand behind it and if you are comfortable with it, that's cool. A 6x8 in #1 Dougfir at that spacing makes me comfortable. By my math at 6' bent spacing or less in the ridge direction drawn its ok with a #1 DF 6x6.

BUT, lets back up.
There is no reason for timbers above the bale level it sounds like. If there is a ceiling/ attic space then there is no reason not to stick frame the roof if we can get you over the fear of miscutting a board. Let me list some pro's and see if it works for you;

Cost and ready availability- this roof framed on 24" centers, in the ridge direction I drew, uses 2x6 ceiling joists and 2x8 rafters.

Weight- see above. Go to the big box and heft a 6x6 from the pile to a cart and think about moving many of them solo. If you can keep it down to posts in the walls, a beam of some type on top and then common rafters I think it'll go easier.

Ease of cutting-It's a whole lot easier to cut a small piece of wood than a big one and if you mess up, its a whole lot easier to replace. A rafter isn't all that difficult to cut, cut a pair, check them, then use one for a pattern. Basically stick framing has evolved for a reason.

Also don't overlook cellulose insulation.


Offline kyounge1956

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Re: Metal connectors for timber frame buildings
« Reply #23 on: August 23, 2009, 07:18:15 PM »
On size, I'm a carpenter so tend to keep it brutally basic. If they stand behind it and if you are comfortable with it, that's cool. A 6x8 in #1 Dougfir at that spacing makes me comfortable. By my math at 6' bent spacing or less in the ridge direction drawn its ok with a #1 DF 6x6.

BUT, lets back up.
There is no reason for timbers above the bale level it sounds like. If there is a ceiling/ attic space then there is no reason not to stick frame the roof if we can get you over the fear of miscutting a board. Let me list some pro's and see if it works for you;

Cost and ready availability- this roof framed on 24" centers, in the ridge direction I drew, uses 2x6 ceiling joists and 2x8 rafters.

Weight- see above. Go to the big box and heft a 6x6 from the pile to a cart and think about moving many of them solo. If you can keep it down to posts in the walls, a beam of some type on top and then common rafters I think it'll go easier.

Ease of cutting-It's a whole lot easier to cut a small piece of wood than a big one and if you mess up, its a whole lot easier to replace. A rafter isn't all that difficult to cut, cut a pair, check them, then use one for a pattern. Basically stick framing has evolved for a reason.

Also don't overlook cellulose insulation.

I will have to go back to the website and check, but I think if you buy the connectors they have engineers look at your plan to make sure it won't fall down, so it wouldn't just be a matter of what I'm comfortable with, which is a good thing, because I don't know diddly-bob about engineering. I'm still trying to think this all through. Maybe the way I originally intended to build (which would have ordinary roof framing) will work better after all. It just seemed like the connectors might be a way to simplify the carpentry and get better results, and I don't know if it's possible to use them for part of the structure and regular frame construction for the rest. Some of these proprietary systems are all-or-nothing, you either use it throughout or don't use it at all. I do recall from the website that the Socket System connectors are sold in sets, enough to make one bent. I think you can order "a la carte" too, but I bet it costs more if you do.

I see what you mean about "easier to cut a small piece of wood than a big one". I've got a 20-foot piece of PT 2x6 left over from a project that I sometimes have to move out of the way, and I can do it easily. If I did my math right it's bigger in total volume and hence weight than a 13-foot 2x8, so rafters at that size shouldn't be any problem. The appeal of the connectors is that (ISTM) cutting a lot of pieces of wood on an angle, and particularly when it needs to be the same angle on all of them, would be harder to get right than cutting straight through a few pieces and not even really needing the cut to be perfectly straight or perfectly square to the end or perfectly identical from one piece to another. Maybe someone makes connectors that fit the smaller wood so I can get the advantages of both smaller pieces of wood and a method that seems a bit more forgiving of my low skill level. Maybe I need to go build a garden shed (except I live in a townhouse so there's nowhere to put it) and see if cutting rafters is as hard as I think.

I don't overlook cellulose, and if I were having the house built rather than wanting to build it myself I might well go with it in the roof, but from what I've been able to find out it's not practical for me as an owner/builder. The blower is probably too big to go in my car, it's certainly too heavy for me to unload, and it takes two people to operate properly, one to load the hopper and one to direct the nozzle. If I have access to a truck, rented or borrowed, and if there is a parking spot on the site from which I could reach all the areas I need to with the hose so I could leave the blower sitting in the truck, and if I have a second person, it might be possible, but I really don't want to go there. I am pretty set on the idea of doing as much of the work myself as I can. I got an overdose of trying to get other people to do stuff the way I want it done, not the way they want to do it, when I was a supervisor on my job. It was a miserable experience, and I'm not up for an encore performance. If there is something I just can't do, like the wiring, I'll hire someone else to do it, and stay out of their hair while they do. But if there are two ways to do something, like insulate the roof, only one of which I can do by myself, I'll go for that way.

Offline kyounge1956

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Re: Metal connectors for timber frame buildings
« Reply #24 on: August 28, 2009, 06:40:16 AM »
(snip)  The rafter pairs are roughly on 7' centers, I've varied a little bit. The gravity load on the rafters works out like this; 10 psf dead load + 25psf snow=35psf total. 7'spacing x 11' span=77 square feet X 35 lbs per square foot...2695 lbs on each central rafter.
This is a beam calc for sizing heavy timber;
http://www.windyhilllogworks.com/Calcs/beamcalc.htm
Inputs are;
Load- 2695 lbs
Span- 132"
Width= 5.5"
Depth- 7.25"
Fb- 1350 psi
E-1.7
Fv-170 psi


Anyway that will check, which means #1 Dougfir 6x8's would work for the rafters. Checking the AITC manual 2x Tongue and groove decking will work spanning across those rafters. From there I've built up layers of foam, 2x4 strapping over that and either plywood and shingles or metal roofing.

On the right track or have you got other ideas?

Those last three values that I have turned red—are those constants for any given species and grade of wood? If so, I think I have figured out an alternative idea that will work. I don't have time to make a sketchup of it now. Maybe later today....

Karen
P.S. maybe the reason the connector manufacturer does not specify a ridge beam is that there are multiple purlins running perpendicular to the bents? Wouldn't these tie the whole roof together?