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helot13
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# Posted: 31 Dec 2010 12:06am
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Has anyone considered dimensions to mitigate waste material?
I am looking to design a square building in the neighborhood of 20x24. What I want to be able to do is build something with dimensional lumber where I don't have to make many cuts. I assume anything based on 4' would do the trick, but we all know wood is never exact.
As well, I am thinking of using a gambrel roof and would like to know if anyone sells these prefab in the Pacific NW.
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MtnDon
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# Posted: 31 Dec 2010 11:40am - Edited by: MtnDon
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About the only lumber that comes cut tp precise lengths are 2x4 and 2x6 that are specified as wall studs; 92 5/8 inches and 104 5/8 are common. All the other lengths can vary slightly and may need trimming if your are building precisely. There are also a lot of cuts when you consider the jack studs around windows and doors.
Even if a floor joist measures in at exactly 16 feet and that is the width of the planned building, you may want to trim the length. When the rim joist is nailed to each end that 16 feet becomes 16'3" and that distance is hard to cover with 4x8 foot OSB or plywood panels.
Ditto the problem on sub flooring with 4x8 T&G panels. The T&G removes material from the panel and they are no longer going to cover 48 inches of floor width. You usually need to add a small strip down one side unless the floor joists are cut to a shorter precalculated length.
It is hard to eliminate waste but it can be reduced with planning. I also hang onto all cut offs until the job is completed. We clean up every job dayin order to make it easier to find things and not have things in the way. What is then left I used for kindling as I have a wood stove.
Making your own drawings starting with the foundation and working up just as if you were building helps. Thinking through each step can help eliminate material waste as well as eliminate or at least reduce, surprises while the actual build goes on. I believe that every hour spent planning is repaid with interest in time and material savings during the build.
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helot13
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# Posted: 31 Dec 2010 01:33pm
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This is exactly what I am talking about, though. Has anyone developed plans with this in mind. I definitely have the idea in mind, and would like to design around the idea, but it would be nice to have access to plans where someone else did all the leg work.
As well, I still would like to know if anyone knows of a place in the pacific NW that prefabs gabrel roof trusses. Knowing this would allow me to see if they come in a standard size or if they could do custom work. Kind of a top down approach as opposed to designing from the foundation up.
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islandguy
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# Posted: 31 Dec 2010 01:57pm
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When I put down my 6x6 pressure treated foundation beams, I couldnt get them square no matter how hard I tried, so I finally discovered they varied in length by as much as 3 inches from each other. Since I didnt want to cut the pressure treated end grain off the beams, a couple of them stick out an inch or so from the siding on my cabin.
I actually discovered my studs were abour a half inch shorter than they were supposed to be...after driving 50 miles to get them and then getting them on the site. I opted to use a half inch "shim" to use them for interior framing, but never bought another piece of wood without measuring again.
I also went to buy the above mentioned T&G subfloor for my exactly 16x24 floor, when I also discovered the sheets are no longer 4x8 after the machining...went with ordinary 3/4" 4x8s, but have already developed some slight creaky spots.
Dont mean to hijack your thread, helot 13, but have you considered building your own trusses? They can be shipped unassembled, then put together on site.
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MtnDon
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# Posted: 31 Dec 2010 02:24pm - Edited by: MtnDon
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Pressure Treated wood is the worst for being off size, especially if you get it when it is very wet. You can buy brush on treatment for cut ends. I do that to all my cuts. I've bought it from both HD and Lowe's as well as my local Ace Hardware.
Factory made trusses are almost always custom made. You supply the building dimensions, roof height or pitch desired. Their engineer then designs the truss (his computer does). Any truss shop should be able to give you a free estimate if you tell them what you want to do. When you pay them they also supply you with a engineer stamped drawing that you can use with your plans for any building permits that may be required.
You can also build trusses. However if there is a building inspection/permit process it may be difficult to get owner built trusses approved without an engineers stamp. There may still be plan books for trusses available from ag extension services at some universities. I have an old one from Missouri U and have seen them from ND and IA as well. Usually the plans are too old to meet current codes. But I have a garage/shop that was built 20 some years ago with trusses I built. No issues with them. It's a lot of work. Plywood plates or gussets are cut to overlap each joint. One on each side, glued with waterproof glue and nailed to a pattern. If using an air nailer each nail has to be finished off with a whack or two from a big framing hammer as air nailers don't draw the materials together tightly, as a rule.
I have not built from purchased plans too often but as I recall the ones I used (years ago) did not take things like sizing for T&G machine losses into account. If plans are purchased you can sit down and do the math, making adjustments where necessary. It seems like a lot of work, but as I previously stated I find that working through on paper and in your head before the build might save making errors during the build. I have seen many instances where an owner builder runs into something unexpected while building because of insufficient foresight. Myself included.
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nathanprincipe
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# Posted: 31 Dec 2010 06:30pm
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May I ask why the need to make minimal cuts? Is it because the time factor involved in doing so? or maybe you dont own or feel comfortable using power tools? or maybe you just really, really, really dont want to be wasteful?..... Anyway maybe you will find a different insight to what you are trying to achieve if you share your full thought process behind not wanting to make many cuts
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fooboo
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# Posted: 31 Dec 2010 06:37pm
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There is software to do this, but it is expensive. Vertex BD is probably the most sophisticated framing software out there, and it will create a bill of materials that will leave you with only a few small scraps of wood on even the largest mcmansion. Unfortunately, Vertex BD runs about $20,000 and typically requires about 50 hours of training to begin using the software.
You can use Google Sketchup to completely stick build your house in your computer. There are ready made components for lumber, plywood, simpson ties, etc. You can assemble your entire cabin, piece by piece, in Sketchup if you want to. This might help you work out some issues in advance, but even with Sketchup you won't catch the small details, like the T&G flooring issue that MtnDon and islandguy mentioned above. The T&G flooring issue is an example of how a small 1/8" dimension on one board can add up to a much bigger dimension when taken across the entire flooring system and you are unlikely to catch this in Sketchup.
If you are just starting out, just put some extra money into your budget for bad lumber cuts, add a few extra days to your timeline, and chalk it all up as a learning experience.
Your question brings up another point though. You mention 20x24 as the desired size. That is 480sf. You might save a HUGE amount of dollars by changing to a 16x30, which is also 480sf, but completely changes the way you need to support the rafters and may require substantially less lumber and up to 1/3 or fewer piers.
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toyota_mdt_tech
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# Posted: 31 Dec 2010 07:26pm - Edited by: toyota_mdt_tech
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Quoting: MtnDon hard to cover with 4x8 foot OSB or plywood panels.
And if you have a rim joist (wooden floor) you had better think about the 9 foot siding if you use 8 foot walls. Or you will come up about 9" too short and the bottom and have an exposed rim joist and have lots of scrap.
I made mine 16X18 and the pitched roof was about a 7/12 and rafters where 16 foot, my gable ends both used only 4 sheets of the T1-11, if you cut it right, the scraps fit the opposite end.
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toyota_mdt_tech
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# Posted: 31 Dec 2010 07:28pm
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But yes, 8 foot walls, gable ends not over 4 feet high, sides in multiples of 2 feet, but 4 foot even more desireable
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helot13
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# Posted: 31 Dec 2010 09:03pm
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No real reason for wanting to minimize cuts. It just seems to be that a lot of people would love to be able to have a kit to build a cabin, or at the very least be able to buy lumber and get something put together without having to constantly measure your stock.
I am well aware of the philosophy of measuring twice and cutting once, but in an ideal situation you wouldn't have to make any cuts unless you wanted to add an opening.
My desire for prefab trusses is the code requirements.
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helot13
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# Posted: 31 Dec 2010 09:32pm
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I suppose what I am getting at is, where is the use of dimensional lumber going to be the most efficient. Every time you cut you run the risk of making a mistake. Certainly a mistake on a 2x4 is a lot less critical than a pressure treated beam or plywood.
I suppose in the grand scheme of things it's not about money. Having $300 of scrap out of $6000 worth of lumber isn't terrible. It is more of a philosophical debate. Can we change the way we look at building construction, or is it more effective to look at the way lumber is produced.
It appears no matter the dimensions I choose nothing is going to fit precisely with the materials available. I suppose I am just being lazy. More measurements and more cuts makes it harder to keep things square, takes more time, more tools, more design, and more thought.
No wonder people pay contractors.
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MtnDon
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# Posted: 1 Jan 2011 12:42am
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It is possible to use construction techniques that use metal connectors to replace things like jack studs by a window or door. They clip and secure the header to the full length studs. That eliminates some cutting and some lumber. Fewer studs in the wall also means better insulation (in theory). That is achieved by using 24" spacing instead of 16" as is traditional.
There are trade offs though. Thicker drywall must be used inside to prevent a waviness that will occur with regular 1/2" drywall. Fewer studs also means fewer studs to secure electrical boxes to. That can reduce your options for switch and receptacle placement.
There are also clips that can be used to reduce the number of studs in the typical corner. The installation of drywall is maybe slower at inside corners, but the corner can achieve better insulation.
As for measuring I do not assume that any piece of dimensional lumber is the length it is supposed to be, with the exception of the precut fraction inch studs I mentioned above. Other than those I measure everything. It is infrequent that a piece will be shorter than advertised, but I have seen plenty that were a little long. As a single unit 1/4 inch in a 10 ft length is not much.
But let's assume you are building a wall, laying out the frame work. One 2x in used for the bottom plate and another for the top plate. If the top plate is 1/4" longer than the bottom that is going to throw off the correct placement of at least one stud. In a wall length made of two or three plate sections you could have a discrepancy of maybe a half inch in the top and bottom runs. That's going to throw a wall out of plumb with no easy way to correct it.
So measure everything (twice) and cut where necessary. That's my opinion.
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nathanprincipe
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# Posted: 1 Jan 2011 03:56pm
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There are Cabin Kits available that come complete with precut materials that advertise only assembly required. I have no experience with this but maybe its worth a look for you, just simply google "cabin kits" and see what you come up with
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