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Putting living space over workshop in a TF

Started by Dave Shepard, November 28, 2007, 02:17:36 AM

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Dave Shepard

I am planning a workshop with an apartment over the top. I want to have a free span downstairs, with an aprtment upstairs. How practical is it to do this and not have posts in the workshop area? Can it be achieved with a kingpost type truss to support the load upstairs? I would really like to have the entire apartment upstairs, but putting it in the rear of the building with both an upstairs and downstairs may work better. One of the buildings at Hancock Shaker Village has a huge upstairs, but also has some seriously huge beams, and a variety of trusses. I think it has king post to support the floor, paired with queen post to support the roof. The span is at least 30' clear, possible more. :o


Dave
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

Jim_Rogers

Before you spin your wheels a lot, you should check with the town where this workshop/apartment will be and see if they'll allow it.
Some towns don't allow duel use without a special permit.
If it is to be built near your place you could see if they'll allow it as a in-law apartment. Sometimes these are allowed if restricted to family members only.

To have an apartment you'll need to connect to water and electric and have some type of septic installed. These all require permits and will have to be reviewed by town boards, so every detail will have to be planned out....

Good luck with your research.
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

Dave Shepard

An apartment over a garage/workshop shouldn't be too much of a problem around here. There are a lot of them. I have to solve two building problems, somewhere to work on timbers and woodworking projects, and somewhere to live. I don't know if it would be easier to just build a small cabin and a workshop, or to try and combine the two.


Dave
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

Don P

I posted a couple of pics under "a truss I like" or something similar a week or two ago.  It's basically a modified queenpost truss with a floor load on the bottom chord, roof load on the top chords the clear span was about 23'. Looking at the truss printouts; The girder trusses, which were simply three trusses nail laminated together, spaced 10' apart, have reactions totalling about 16,000 lbs at the two walls.  They checked multiple combinations not just gravity, wind, uplift, unbalanced snow with wind, etc. The highest compression member in the top chord heeljoint area was about 6000 lbs. Tension with bending in the bottom chord floor area ran around 3500 lbs, one relatively short web member carries 11,000 lbs compression down to the wall.

In those numbers I don't see anything that I don't think could be handled in reasonably sized heavy timber members.

We get plenty of houses with a garage below. We must provide a 30 minute seperation between the garage and living spaces. We need an exit that does not go through the burning garage. That's usually 5/8 sheetrock and steel doors. Heavy decking and heavy timber should be able to do that though.

Where I was talking recently about compression members with a side bending load (top chords), this would also have a tension member combined with a bending load, the floor on the bottom chord. This would be calculated on the same principle as the combined compression with bending formula. The higher the tension in the bottom chord, the less strength is available to handle the bending load and vice versa.

I'm game for some early design wheel spinning  :)


Furby

I know you are talking wood working and I know lots of folks that do all types of work in their basements and garages, but week before last, a house just up the street from me burned down.
The owner was welding under a car in the attached garage and the fire started and was out of hand before he even saw it.
Just some thing to think about.

Dave Shepard

Thanks Don. I like the idea of having the area above the workshop, but Furby is right. I, too, worry about just such a thing. I start out thinking of an efficient little building that will take care of my needs, then I start to rethink it when you mention fire. Perhaps I could put some office space and light storage over the workshop. Would still need the clear span below.


Dave
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

Furby

About 12 years ago I helped insulate the crawlspace on the house that burned.
I'm pretty sure the garage didn't have anything close to the 30 minute seperation that is now required, but the required seperation is more or less there to give you a chance to get out of the house alive.

I like multi use spaces, but there is always a trade off.

stonebroke

How about flat trusses to support the floor upstairs. I know this would not be pure timber frame but your could hide them so it would look ok.

Stonebroke

logwalker

Another thing to consider is insurance. The underwriters are getting very particular these days. I built my house over the shop. It is a 32' main span with a 2200' home over the top. Big covered decks front and back for covered storage. The main span was done with recycled 7x22" beams from a supermarket. I think every city of average size has a yard selling them. 
Let's all be careful out there tomorrow. Lt40hd, 22' Kenworth Flatbed rollback dump, MM45B Mitsubishi trackhoe, Clark5000lb Forklift, Kubota L2850 tractor

Thehardway

I considered what is being discussed here for the first phase of my homestead project, a 2 or three car garage/workshop with "in-law suite" above.  Here are the factors that I considered.

Cons:
1.  All access via stairway
2.  Fire hazards (I do a lot of welding and work with flammable materials regularly)
3.  Fumes. (exhaust, welding, finishing componds, smoke etc.)
4.  Dust.  (shop dust, sawdust etc.0
6.  Noise.  Much of my work is done late into the night or early morning before my 9-5, the wife and child would not like the noise below.
7.  12' plus headroom needed for overhead rigging made stairs long.
8.  Shop/garage would not be as big as what I really wanted to end up with


Pros:

1.  Convenient location
2.  Share heating/cooling loads.
3.  Cheaper to build one roof than 2
4.  Easy access to underfloor plumbing piping
5.  Quick


As you will notice from these the quick and easy usually do not follow along with the long term and safe.

On the other hand a quick walk through any old town will give you hundreds of examples of living space or apartments over a shop workspace or storefront. 

Depending on the type of work you plan to do in the shop there are multiple ways of getting the free span you need using TF construction.  A bridge truss (parallel chord truss) is one that comes to mind as do the kingpost and the queen post trusses.  All capable of supporting large loads and spanning long distances. 

What kind of footprint and ceiling heights did you have in mind?
Norwood LM2000 24HP w/28' bed, Hudson Oscar 18" 32' bed, Woodmaster 718 planer,  Kubota L185D, Stihl 029, Husqvarna 550XP

Raphael

  I'll have to stick my head in at my neighbour/engineer's tomorrow and see if I can snag a drawing of his barn frame.  It's ~30x40 and all clear span below, you can turn a 40hp tractor loaded with implements in there.  I'm not sure what his second floor is rated at but he's got all his heavy cabinette grade tools up there and an office.
... he was middle aged,
and the truth hit him like a man with no parachute.
--Godley & Creme

Stihl 066, MS 362 C-M & 24+ feet of Logosol M7 mill

Dave Shepard

Thanks Raphael. That would make a nice size workshop. I am leaning away from an apartment upstairs now. It would be nice, but puts all the eggs in one basket, so to speak. Although having storage, or office space up there would be nice.


Dave
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

Raphael

He didn't make it up this weekend...  Don't blame him given the temperature difference between here and his Fairfield area residence.  I'll catch up with him sooner or later.

I believe he said New England Barn cut it for him, if you know those guys.
... he was middle aged,
and the truth hit him like a man with no parachute.
--Godley & Creme

Stihl 066, MS 362 C-M & 24+ feet of Logosol M7 mill

Don P

These are both simple kingpost trusses of the same dimensions. The first one has the 100 unit load applied to the top node of the king, in other words a roof load. The second truss has the same load applied to the lower node at the king, or a floor load. Notice the bearing reactions are the same, the red and yellow support nodes. The axial tension and compression forces in the main members are the same. The only real change is whether the kingpost takes any tension load.
This is overly simplified since the load is a single point load, not uniformly distributed but hopefully shows a little about how the truss works. A short covered bridge is often a drive through king or queenpost truss.




scsmith42

Landon, your shop/home is way cool!  Love the toy, oops I mean tool collection out in the yard too!

Dave, what you're proposing isn't much different than a garage apartment, where the garage is used as a shop.  I think that if you're going to be doing welding, etc frequently, then maybe you have a concern.  However, if it's just woodworking, as long as you have a good fire stop and smoke alarms in the shop, it should be just fine.  I have a garage apartment here on the farm where the downstairs is the woodworking shop and the upstairs an apartment - it works great.

Don, what if collar ties and some additional members were added to help transfer the upstairs floor load to the rafters?

I've made some modifications to your drawing below to illustrate the concept.

I'm in the process of remodeling an old farmhouse on my property.  The old house is an old Sears "kit house" that was sold in the 30's.  I've added an upstairs (went to a 12/12 pitch roof), and wanted to add some support to the floor members.  The concept below is what I came up with.  I have a 12/12 pitch roof though instead of the 10/12? depicted in your drawing  In my case, the vertical members that run from the rafters to the floor are spaced every 2' (same as the rafters), and the diagonal members are spaced every 4'.  The collar ties are spaced every 2'.

(I also added additional studs to the outside of the existing ones used in the downstairs perimeter walls to increase the wall capacity - i.e. I made each stud into a "t" post, instead of relying on the original 2 x 3 studs). 

It sure stiffened up the upstairs floor.  Since you can't really use space under a steep pitched roof near the outer edges, there wasn't much loss of living space either.

Scott

Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

Thehardway

Scott,

The basis of your design can be found here
http://www.tfguild.org/publications/queenposttrussTF71.pdf
in Figs. 1 and 5.

For maximum benfit the "colloar tie"  should be located at the top of the queenposts to function as a "straining beam" and to create 3 roughly equal triangles within the truss.  This would probably not allow you much head room though.     
Norwood LM2000 24HP w/28' bed, Hudson Oscar 18" 32' bed, Woodmaster 718 planer,  Kubota L185D, Stihl 029, Husqvarna 550XP

scsmith42

Yup - same concept.  I'm glad to learn that I didn't go off the reservation with the idea!

Unfortunately, if I moved my collar ties to the top of the queenposts the only people that could live upsairs would be midgets - oops - I mean "vertically challenged" people...
Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

Don P

Its out of my comfort zone sizing the parts of your roof Scott, it does work, I'm just not there yet, that's basically the attic trusses we've been installing. I think the theory goes like this; The top chord being a single piece rafter, instead of a true truss that is pinned at every node, is analyzed as a beam over multiple supports. This determines the proportion of uniform load each point carries in bending. Combine that with the axial forces down the rafter and see if the combined loading is acceptable. Where I'm lost is the forces around the kneewall to straining beam. I do have some truss sheets with member forces etc for that type truss if it would help. If you want a scan just holler.

One thing that also seems to stiffen them up is a plywood diaphragm on the kneewalls

Dave Shepard

Don P, you say you are ready for some early design wheel spinning. What about a 30'x40' workshop with office space upstairs, nothing heavy? Maybe narrow it up, if that is what the numbers tell you. Would prefer EWP, or hemlock. Just curious as to what the frame might look like. Thanks.


Dave
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

Don P

Shuffling feet hoping Raphael will throw a rock and get some pics  ;D

I'm thinking of a queenpost truss, we need an idea of truss spacing, snow load and preferred pitch. I like a 12/12 it keeps things simple, at 30' wide thats 15' tall though, lower stress than a flatter pitch, just more to think about.

Dave Shepard

No rush, Don P. I like 12/12 as well. I wish I had some pics of the Tan House at Hancock Shaker Village. They are shut down for the year though. Hang on, I've got a key for that, I'll have to make a call and see if I can get permission to take a look. ;)


Dave
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

Don P

Some stuff from messing around;
I sketched a 30' queenpost truss and made a few quick assumptions. I put them 10' apart and put a total load of 16,000 lbs on each truss top chord from dead load and snow. I put 6000 lbs on the 14x10' floor area. All loads are in black, distributed on their corresponding panel points. The forces in the truss are in red and blue, add 2 zeros for pounds.


Below is a pic of a queenpost truss I slapped together this afternoon out of some sticker stock. The bottom chord is 3 pieces. There is a single pin in a predrilled hole at each panel point. There is an X of tie wire across the center box to stabilize it. The span is 6', I'm standing midspan on a 1x2. I'm about 175 lbs, there is no way a six foot 1x2 by itself could support me.












Dave Shepard

Wow, that's awesome! I have to do a little studying in the engineering department do I can understand it better. What size beams, and of what species make up the truss? Thanks.


Dave
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

Don P

The truss is white pine and poplar 1x2's.

This is an analysis of the forces in the truss members.

I've divided my weight and entered a 90 lb load on each queenpost bottom. Remembereing your trig or carpenters rules of thumb, to get the hypoteneuse of a 12/12 pitch you multiply the side by 1.414. Multiply the vertical load of 90 times 1.414 and you have the 127 lb compressive force on the top chord.

The top chord can be checked on the column calc for a compression member;
https://forestryforum.com/members/donp/columncalc.htm
length is 34"
EWP is good for 875 psi compression parallel to grain
E is 1.1 million
Since there is no bracing I checked the 1x2 as a 2x1 also, it could buckle either way.
It passes fine.

The bottom chord has 90 lbs of tension on it. EWP can take 275 lbs in tension parallel to grain, per square inch. We have a 1x2, or 2 square inches so it can safely take 550 lbs in tension before risking pulling the wood apart. We pass that fine also.

Connections, I used a 10x3 common nail for my pins. In single shear through a 1x into a 1x. From the NDS tables I'm good for about 100 lbs. I've got 127 in the top chord so I'm in overload there.

One other point, my feet are bearing at midspan so I not only have 90 lbs tension in that member, I have 175 lbs in bending also. I won't subject you to that check now but notice the difference in stress on that member if my feet were spread to the panel points at the base of each queenpost. We'd have the same load but no bending.

Dave Shepard

I've been thinking about this a lot, again. I know that there is a fire risk, but there is that risk with building.:( Don, could you detail some of the joinery in this truss? I am guessing that having the bottom chord be a one piece timber would be paramount to success? Thanks.


Dave
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

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