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#33970 - 09/15/16 09:10 PM Floor Dead and Live Loads for Small TF
EPops Offline
Member

Registered: 09/14/16
Posts: 3
Loc: Buffalo, NY
Hello all, this is my first post here on the forums. I have a timber frame (TF) workshop designed (for working timbers in inclement weather). I have a question on loading for floor systems. And possibly suggestions on sizing/spacing on floor joists.

First, my TF is 16'8" x 24'8" (including size of the 8x8 sill plates). Made of Eastern Hemlock. I am considering 4x6 floor joists.

My question is: what should be considered for dead and live loads on a flooring system? I am a civil engineering grad student, and know about the loading values stated in code books. But for a small workshop TF, I cannot find much reliable info. And I have no experience in analyzing timber structures.

I have seen as high as 12 psf for dead loads and 40 psf for live loads for a flooring system. I highly doubt that my structure will see values as high as those. The live load will consist of:
1.) Maximum of three people (600 lbs)
2.) Maximum of two timbers at a time, with sawhorses (600-700 lbs)
3.) Two or three workbenches - unsure of weight
4.) Wood stove
5.) Tools (mostly hand, very limited power tools - and none larger than circular saws or chain mortiser)
6.) Tool storage

With a very conservative estimate of 2500 lbs total live load, across a 16x24 (384 sq. ft.), I am looking at 6.5 psf live load. With a deflection limit L/360, that would be about .39".

And for the dead load, I assume that only the floor joists and floor boards would actually contribute, since the sill plates are resting on concrete piers. Would the sill plates come into the value of dead load? And would 1" flooring be adequate, or should a sub-floor also be used?

So I have seen in one of Sobon's books, 5x7 joists with max spacing of 2' 6". Assuming he is using the code standards of Dead=12 psf and Live = 40 psf.

Can 4x6 joists be spaced maximum of 2' 9" O.C. while spanning nearly 12', in my case described above? Or does this sound bad? Spacing varies in my design (non-uniform), with min=2' 8" and max=2' 9". I would need dead load to get load combos in LRFD, to get my actual deflection.

The joists are tapered to 4" to avoid shear failure. And the center joist in each bay is dovetailed.

Any suggestion for alternate joist sizing/spacing/span would be appreciated.

Thanks a bunch if you followed me all the way through this post. I, along with my brother (who is also an engineer and worked as a timber framer for a year), are hoping to get more involved with TF and help bring this great style of building back into the mainstream. I appreciate your help and look forward to getting to know people on here.

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#33971 - 09/16/16 07:03 PM Re: Floor Dead and Live Loads for Small TF [Re: EPops]
TIMBEAL Offline
Member

Registered: 12/10/07
Posts: 1873
Loc: Maine
Welcome aboard Epops. I would be concerned with a bouncy floor if things are under sized. One guy chopping or pounding away and the other trying to hold the square in an lousy position, the bouncy floor will only add to the already lousy position. As a student of such matters we know the loads we choose for the direct use of the structure can and does change in a few years. A heavier system will ensure that change in the future will be met. I would not have any issues pushing those 4x6 out to 4x7 or even the 5x7. Also consider the center dove tail to be exchange for a tusk or soffit tenon and tenon it into the face of the center beam, this will keep the top cord of that beam in tack. What size tractor will you park in there? Got some spare engines that also need cover lets put them in the shed.

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#33973 - 09/16/16 11:19 PM Re: Floor Dead and Live Loads for Small TF [Re: EPops]
EPops Offline
Member

Registered: 09/14/16
Posts: 3
Loc: Buffalo, NY
Thanks for your reply, there won't be any tractor or other heavy equipment, just a few guys with a couple timbers. That is why I thought the design loads in code books are too high for this structure.

I was already thinking of decreasing the spacing between the joists, but have been hoping to save money while also keeping it safe. I will try out a few more calculations for deflection with those other members, and look into the other types of joints.

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#33974 - 09/16/16 11:32 PM Re: Floor Dead and Live Loads for Small TF [Re: EPops]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 479
Loc: Vermont
Hi EPops,

I second everything Tim suggested, and probably would take the joists up to 6x8 or place closer. In most frames I've experienced like this they are seldom further apart than 24".

I would add, that PE and Timberwrights alike don't just design a structure (as long lived as timber frames often are) for only one intended purpose. You personally may not need a combined load capacity as high as some would suggest...Nevertheless, what is reflected in Tim's humorous (but very accurate) "tractor" or "engine" storage comment at the end of his post has much weight and wisdom...This frame could have all manner of intent placed on it (as such structures often do in the course of time) and its our job to think of this in our design and building of them.

Just some food for thought...
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#33975 - 09/17/16 06:36 AM Re: Floor Dead and Live Loads for Small TF [Re: EPops]
TIMBEAL Offline
Member

Registered: 12/10/07
Posts: 1873
Loc: Maine
The tractor and engines were on the lighter side. But I would reinstate the aspect of a springy floor and layout, bouncy work is irritating. I would also suggest the thought of a concrete floor for a work shop setting. I do see the benefits of a wooden floor though. Then flipping again I could not give up my concrete floor for my shop. It makes a great lay out lofting place for those time scribe work comes into play. But now we are venturing in redesigning the building which I don't think is appropriate for this topic.

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#33977 - 09/17/16 12:44 PM Re: Floor Dead and Live Loads for Small TF [Re: TIMBEAL]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 479
Loc: Vermont
I do agree entirely that the floor joist as presented (and for this frame as described) does seem that it could be possibly a bit too springy to me as well. Too much spring is as bad as too hard/stiff a surface to work on...

We will have to disagree on the concrete flooring Tim. I have too many friends and collegues with severe to chronic lower back and leg issues from standing and working on concrete floors...

Beside the environmental impact the entire industry has on the environment, and the less than questionable durability of modern concretes (e.g. our steel and concrete infrastructure is falling apart)...there is clear evidence of the health risks associated with standing and working on concrete. Yes one can lay matting down as many factories now do (and some areas require by law) yet just using wood solves the issue nicely, and fits a timber frame much better (in my view aesthetically.) I have seen great Lofting Floors in wood as well so that isn't really a challenge to not using wood. Even a stone paver system laid in sand is more giving than concrete is, and these too have been employed for lofting when installed neatly and for that intent.

Just a sampling of info about concrete floors...There is a great deal more out there:

Redfern and Chaffin (1995)
"...Flooring did affect workers perception of discomfort and all floor surfaces were rated better than concrete...."

Krumwiede et al., (1998)
"...investigated the effects of floor surfaces on comfort ratings in 3h of prolonged standing with 1h on each type of floor surface. Mat compressibility (ranged from 2.2 to 8.9%) was important in the comfort ratings and all surface types rated better than concrete..."

Originally Posted By: Hazards.org
Flooring
Hard, concrete floors are about the worst possible surface. Materials that provide flexibility such as wood, cork, carpeting, or rubber are gentler on workers’ feet. Concrete or metal floors can be covered with mats...
...Avoid standing on concrete or metal floors. Recommended for standing work are wooden, cork or rubber covered floors. Ensure that the floors are level and non-slippery. Cover concrete or metal floors with mats. Slanted edges on mats help prevent tripping..




Edited by Jay White Cloud (09/17/16 12:48 PM)
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#33978 - 09/17/16 01:33 PM Re: Floor Dead and Live Loads for Small TF [Re: EPops]
TIMBEAL Offline
Member

Registered: 12/10/07
Posts: 1873
Loc: Maine
To clarify, my shop floor is also my milling operation, which sees much heavy use from my small 9 ton excavator to 40 foot logs skidded across it to joinery and truck repair, as well as lofting. I do appreciate a wooden floor, though.

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#33979 - 09/17/16 02:18 PM Re: Floor Dead and Live Loads for Small TF [Re: EPops]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 479
Loc: Vermont
I apologize if my other post sounded like you should undo what is working for you...By all means keep it if it works, and you're happy with it...

Additionally just food for thought Tim, and our other readers...

I have been in a number of operation over the years that have massive floor load requirements and then some, such as storing a tractor collection, Sawyer operations and other Mass Related storage needs. This can be found both on first, second and third floors of old bank style barns and vintage Factory, Mill and Dock Warehouses.

This isn't to negate your shop, but just to suggest that perhaps anyone designing and/or having what you do, could improve the work area (and its comfort/safety) by adding matting...even Wood Matting...to such a system where primary walking/working is done. We have placed wooden floors over entire concrete floors just for this purpose and reason to good effect. Even now we avoid concrete whenever possible by employing vintage approaches to to foundational systems and using gravel for first floor systems. Instead of concrete slabs, a floating wooden floor is installed over sleepers on the gravel.

Just an alternative suggested system to concrete...

Regards,

j
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#33980 - 09/17/16 06:04 PM Re: Floor Dead and Live Loads for Small TF [Re: EPops]
TIMBEAL Offline
Member

Registered: 12/10/07
Posts: 1873
Loc: Maine
I have thought about doing some of those things. Very worthy of consideration.

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#33981 - 09/17/16 06:51 PM Re: Floor Dead and Live Loads for Small TF [Re: EPops]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 479
Loc: Vermont
I don't think you would regret this augmentation to your current system at all Tim, and with your tool and skill sets, it should be a relatively easy addendum to the concrete floor system you have now...

I haven't had (or seen) a complaint of noteworthiness yet from anyone switching from concrete to wood, nor those that upgraded to their current slab system with wood...

Those of us with the luxury (and/or skill sets) to install wood floors (floating or fixed) thus far have all been rewarded with less Back and leg pain for our efforts. I would also note, that it is a great way to take an old, cracked or uneven concrete slab and more cost effectively improving it without removal of the original materials...I have seen or done this to Basements, Garages, and many other structures with slab floors. Where gravel is in place on contemporary systems, the use of wood over gravel (in my view) is a vast improvement both ergonomically and environmentally, to ever employing concrete.

For radiant heat systems, a simple layer of geocloth over the gravel layer, then sand or stone dust to hold the tube labyrinth is more than enough to facilitate all manner of tile, stone or related Hard Surface flooring material...even wood...Yet, because of the sand/dust embedment material still offers much greater cushioning than a monolithic slab system. It is usually much more cost effective as well (big picture) in the long run, and facilitate repairs/upgrades better than any monolithic system.

Regards,

j


Edited by Jay White Cloud (09/17/16 07:01 PM)
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#33983 - 09/17/16 09:51 PM Re: Floor Dead and Live Loads for Small TF [Re: EPops]
northern hewer Offline
Member

Registered: 03/17/02
Posts: 1095
hello everyone tonight

great discussion, and one that one needs to ponder somewhat

this is my take

up until the 20th century there was virtually little or no concrete at least as we know it so-----

what were the floors made up of----well--surprisingly a clay surface --no stones--compacted and leveled--just a great healthy environment to work on just like outdoors

when you think about it 99% of hewing took place in a special outdoor area with about 6" of topsoil to protect the tools

a small section could be floored--if it is an area like the one you have utilizing t&g flooring place on top of bedded timbers

I personnaly have worked, hewed and timberframed in a variety of areas-- wood floors--2" flooring on joists,--threshing barn floors--again a wood floor, of about 2.5" in thickness-slip tongued- placed over timber, also on cement shop floors, my preference is outside under a nice tree.

I have applied a wood floor structure over cement--worked well--and nice to work on,

The cement floor has its good and bad points, nice to clean up for sure, not a good environment for sharp tools, and will take heavy loads

wood floors--well the nail heads a sore point--also not a nice environment for sharp tools--this can be avoided by using wood pins as a holding medium or hidden nails

in summary though I will admit that I worked many winters in heated areas that had wood floors covering a wide spectrum of joists, timbers--a lot of threshing floors--great areas--but for my money I like the outdoors and ground covered with chips, if the weather is favourable

like the subject

Richard
NH

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#33984 - 09/17/16 11:23 PM Re: Floor Dead and Live Loads for Small TF [Re: northern hewer]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 479
Loc: Vermont
Great Post Richard, thanks for adding your voice to the conversation...

I have been to a number of conferences over the years where those in the Cement Industry try (erroneously I would suggest) to compare modern portland cements (OPC) to the vintage cements and pozzolanics of acient Europe, Middle East,Asia, and even the wonderful Natural Rosendale Cements of New York state (now once again in production.) There is simply no comparison of modern OPC with natural and/or vintage cements/pozzolans/geopolymers as we still can not build anything like the Pantheon even today...This acient technology evades most (not all) contemporary builders.

I love your point about being under a tree on a robust layer of chips...It's wonderful I do agree and perhaps one of the best places to joint a frame!

As to wooden floors with nails...I could not agree more with your observation, and why I float and/or joint my wood floors to exclude any metal fasteners whenever possible. This turn in the conversation also reminds me of traditional Puncheon Floors (of which I have restore and/or laid a few) and how they rest, just as you eluded too, on a clay or gravel dias often the same as the sill or plinth stones rest upon. This even has merit for our OP (EPops) as he could just frame the structure onto plinth or sills and lay an independent Puncheon Floor to work on. These are both very solid, yet forgiving to dropped tools and old backs (ha, ha.)

Clay (cobb, adobe, etc) floors to are still a common example throughout the built world even today. Probably one of the most common floor systems still employed by most vernacular builders (worldview) in domestic architecture at least for a section of the architecture and/or the entire ground floor areas.

EPops has lots of choices to choose from...

Regards,

j


Edited by Jay White Cloud (09/17/16 11:25 PM)
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#33986 - 09/18/16 07:02 AM Re: Floor Dead and Live Loads for Small TF [Re: EPops]
TIMBEAL Offline
Member

Registered: 12/10/07
Posts: 1873
Loc: Maine
To continue... I also have a 20'x 60' shed attached off the back of my mill building where we process blueberries for fresh pack. This has a concrete floor as well with a long drain in one section. During the harvest season the machine gets washed down and a concrete floor is a part of the system. One of the evils we have to contend with.

Back in the mill building there are times when there is a good layer of wood chips on the floor, a natural floor that comes and goes.

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#33988 - 09/18/16 07:29 PM Re: Floor Dead and Live Loads for Small TF [Re: EPops]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 479
Loc: Vermont
As a side note Tim (perhaps of interest??) these types of buildings in times gone by (yet coming back) like Cranberry Barns and related, had brick floors bedded in sand which provided a surface harder than wood but still very drainable and less stiff than monolithic concrete. Some had wood only made of something like White Oak...sometimes of just engrain bedded in sand like the brick.

Some of the contemporary versions (one I know of in Rhode Island..I think? it's RI..is a timber frame) where they use a hardened rubber brick made of recycled material. These are often now used in Equine Barns as well. It turns the entire floor into a drain system of sorts, with the drain piping accessible in Service Troughs for clean out, much friendlier to stand and work on. Some slabs are getting covered with these as well now as an upgrade to the surface.

I liked what you shared about the wood chips...I know of many folks that leave a shallow layer on there concrete slabs just for the reasons we have discussed thus far.
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#33989 - 09/18/16 08:26 PM Re: Floor Dead and Live Loads for Small TF [Re: EPops]
TIMBEAL Offline
Member

Registered: 12/10/07
Posts: 1873
Loc: Maine
The chips are deep enough to require a tractor to pull it out. Barn drainage may be different than mashed blueberries, but good info. We do put mats down at the pick over table to stand on. In the future I have thought of a metal mesh floor to stand on and drain. I almost put a clay floor down in the shed off the back of the mill building but was I labeled radical, and it got canned.

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#33990 - 09/18/16 08:42 PM Re: Floor Dead and Live Loads for Small TF [Re: EPops]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 479
Loc: Vermont
Well...I liked your idea about a clay floor system...!

There is lots of water use in the Cranberry industry...most things get really wet since the fruit grows in bogs. I am glad you at least have mats to stand on...that's great.

Most folks today would think it radical to have a clay floor system...I am sure. You know that if it can't be bought at a Big Box Store...or...from and industry factory..it's not a good idea. I am too often asking folks what they thich we did (so often much better with better materials) before all the modern consumer products came about.

Clay and/or a clay matrix dias on gravel would have been superior to concrete other than a freeze thaw issue perhaps, but that too can be worked around and is better than concrete slabs...
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#33991 - 09/19/16 02:51 AM Re: Floor Dead and Live Loads for Small TF [Re: EPops]
D Wagstaff Offline
Member

Registered: 02/17/12
Posts: 246
I work on a clay floor in one section of the barn. It can be a bit dusty. Had rabbits once that liked to dig in there and now the dog. One day I'll get to repair the damage done.

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