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Mushroom Man
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# Posted: 15 Apr 2017 02:45pm - Edited by: Mushroom Man
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Am I an idiot?!?!?
I want the cabin to be 24' x 12' so everything fits just right.
So do I have to cut 3" off of all of the 2x10x12' floor joist?
Am I missing something?
Thank you.
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razmichael
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# Posted: 15 Apr 2017 05:04pm
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Just to be difficult - you need to cut off enough to make sure each is 11'9". I only mention this in that most will be a bit longer than 12'. I made that mistake after 2 weeks of long days working on my cabin with just my father in-law. forgot to check a couple of long boards (assumed they were 16') and ended up with things slightly out of square. No real issues in the end but frustrating when we had worked so hard to keep everything square.
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Mushroom Man
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# Posted: 15 Apr 2017 05:10pm
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Thank you guys. I'll make the cuts and adjustments. I appreciate it.
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ICC
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# Posted: 15 Apr 2017 06:15pm
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Quoting: Mushroom Man I want the cabin to be 24' x 12' so everything fits just right.
Think further ahead.
If you make the width measured at the outside edge of the rim joist exactly 144 inches, and if you plan to use T&G sheathing for the subfloor you will come up short on the T&G. The actual width of a 4x8 T&G is about 47 3/4 inches, may depend on brand, I dunno for sure. You do not want to have a narrow strip of subfloor under a wall plate, though with this only 12 feet wide it probably does not make all that much difference. At a width of 20 feet I usually cut joists shorter by 2 inches or so, so I end up being able to cover the width from sill to sill with 5 whole sheets with the last one being trimmed off after nailing it down.
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rockies
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# Posted: 15 Apr 2017 06:52pm - Edited by: rockies
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If you keep the foundation length and width to exactly 12' x 24' and build the exterior walls right to the edge of the floor frame then you can wrap the plywood sheathing down and over the rim joist, thereby helping to anchor the walls to the floor system.
The subfloor should be 3/4" t&G plywood (preferably pressure treated).
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Mushroom Man
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# Posted: 15 Apr 2017 06:52pm
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ICC...Great advice!
I am finding that if I trim 3 3/16 the sub-floor should match up perfectly! However, what type of sub-floor do you recommend?
OSB or CAT? What thickness?
Money is a concern however I do want this to be passed down to my kids in about 30 years.
Thank you.
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bldginsp
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# Posted: 15 Apr 2017 06:54pm
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If you make the building exactly 24' long, and space your rafters at 16 or 24, the last rafter will hang over the wall by 1-1/2". No big deal, you just have to set the last rafter in 1-1/2" and watch what happens with the plywood. How much overhang will you have on the gable ends? If you make it 18" then it totally screws up the plywood.
The reason they make the face width of 3/4 T+G a bit less than 4' is because often the T doesn't fit the G the way it s'posed to. My contractor looked at me funny when he saw the subfloor was 2" short of the 4' increment. Oh well.
"Are you missing something? You can only miss what you don't allow yourself to see." - some old monk.
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Mushroom Man
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# Posted: 15 Apr 2017 07:17pm
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bldginsp
I haven't quite got that far on the design (gable ends). I'm using SketchUp Pro which is really allowing me to make changes to my mistakes as I go. I'm not planing on nailing a sing board until I am done with the shell of the cabin.
I'll keep you posted!
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Mushroom Man
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# Posted: 15 Apr 2017 07:42pm - Edited by: Mushroom Man
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OMG! After measuring the TRUE SIZE of the subfloor the frame is coming up 3/4" short!!!!
Why in the %()*^* don't they just have the correct size!!!
I'm taking a break!
measurement_1.jpg
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measurement_2.jpg
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Mushroom Man
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# Posted: 15 Apr 2017 07:50pm - Edited by: Mushroom Man
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Well...actually fixing it wasn't that bad. I'll stop crying now. 
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ICC
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# Posted: 15 Apr 2017 07:58pm
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Quoting: bldginsp The reason they make the face width of 3/4 T+G a bit less than 4' is because often the T doesn't fit the G the way it s'posed to
Not sure what you mean by that, but by design when the T is fitted into the G there is a space left. The T&G panel joint does not look like it is fitted properly, but it is. The T and the G are made to leave a space over most of the joint space just like you would leave a space between the wall sheathing that is made with square edges.
I don't have any idea why the panels come out not covering the actual expected 4 foot distance. When measuring keep in mind the T fits into the G almost all the way. To me it's a lot easier to start with the whole thing a couple or so inches narrower and cut stuff off to fit, rather than end up with a space that needs filling. On a wider floor you can end up 4 or 5 inches short and that is a real problem. The perimeter should have nothing less than a half sheet width in order to tie the lower wall plate to the floor sheathing and the floor framing and have sufficient strength against forces on the building. Wind, seismic and so on.
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Mushroom Man
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# Posted: 15 Apr 2017 08:01pm
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ICC
I know why. Because I didn't use T&G in the model!!!
Thank you for this info. ICC. I'll tweak it tomorrow and see if it all fits.
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ICC
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# Posted: 15 Apr 2017 08:11pm - Edited by: ICC
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Quoting: rockies If you keep the foundation length and width to exactly 12' x 24' and build the exterior walls right to the edge of the floor frame then you can wrap the plywood sheathing down and over the rim joist, thereby helping to anchor the walls to the floor system.
With a pier foundation, I agree with the part that says place the wall framing bottom plates flush with the rim joists. Then buy 9 or 10 foot long sheathing panels for the walls. Then apply the wall sheathing over the rim joists and up to the top plates. Or align at the top and over hang the bottom of the rim. Cut off any excess length. That ties the wall framing to the floor structure.
I don't follow why you think the dimensions of the length and width would need to be exactly 12 or 24 feet. If it's because you want to try to get 100% use out of a 4x8 panel that is simply frustrating. Make it 16 x 26 if that provides interior space that better accommodates what you want to put inside. Cut pieces of wall or floor sheathing get used up for all sorts of things. By the time the project is finished there will be a little noticed difference in cost. Build it to fit the intended lifestyle not to fit some idealized material use. IMO.
MM, before you buy any materials you should have everything figured out and drawn to scale. That way you can better see what bldginsp is meaning when he talks about fitting rafters. Building a great building is harder than many think and many problems come from a lack of forward thinking and fully understanding how all the parts come together.
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Mushroom Man
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# Posted: 15 Apr 2017 08:28pm
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I wanted the subfloor to fit perfectly. I only lost about an 1 or so in both directions. I should easily be able to adjust my framing if I start from the left to right. See below!
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toyota_mdt_tech
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# Posted: 15 Apr 2017 08:34pm
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Quoting: razmichael No real issues in the end but frustrating when we had worked so hard to keep everything square.
This is extremely important, if you are not plumb, level and square right from the start, your trouble compounds itself the further you go in, it slows you down to much also, and by the time you get ti finish work, everything is custom fit. I cant stress how important it is for plumb/level/square enough. If you make an error, take the time to fix it ASAP before moving forward, many times, people think its quicker to just press on. Its not.
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bldginsp
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# Posted: 15 Apr 2017 11:32pm
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I'll level with you- I'm just plumb square.
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Mushroom Man
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# Posted: 16 Apr 2017 10:49am - Edited by: Mushroom Man
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toyota_mdt_tech
OK...I did it! This is exactly 12x24' so all should come out plumb / square.
I must have needed to back away from the model and take a breather because I was making it way harder then it had to be.
Now...on to insulation. I will be posting a new thread shortly. I think this one is over.
Thanks you EVERYONE that helped me with the foundation. I am posting a pic. below JUST IN CASE I did something wrong.
Know that the floor joist NOT 16' center. The subfloor measures 3' 11 3/4" (15 11/16 center). So I will be placing the 2x10's accordingly. This should be a very minor and should not effect anything but make my life a little easier for laying the subfloor.
THANK YOU!
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NorthRick
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# Posted: 16 Apr 2017 11:41am
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Quoting: ICC Not sure what you mean by that, but by design when the T is fitted into the G there is a space left. The T&G panel joint does not look like it is fitted properly, but it is. The T and the G are made to leave a space over most of the joint space just like you would leave a space between the wall sheathing that is made with square edges. I don't have any idea why the panels come out not covering the actual expected 4 foot distance. When measuring keep in mind the T fits into the G almost all the way. To me it's a lot easier to start with the whole thing a couple or so inches narrower and cut stuff off to fit, rather than end up with a space that needs filling. On a wider floor you can end up 4 or 5 inches short and that is a real problem. The perimeter should have nothing less than a half sheet width in order to tie the lower wall plate to the floor sheathing and the floor framing and have sufficient strength against forces on the building. Wind, seismic and so on.
I have bought T&G plywood that fit tight and the face was exactly 4' by 8'. I have also bought T&G plywood where the 4' and 8' distances included the tongue, meaning when you fit it tight, and you could, the face was only 3' 11 3/4" wide. I agree, plan a couple inches short and trim the last piece.
Also with the length of 2by lumber, I found it to always be at least as long as specified 8', 10', 12', etc. but often an 1/8" to a 1/4" longer so some trimming needed there too.
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Mushroom Man
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# Posted: 16 Apr 2017 12:24pm
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NorthRick
I think measurement depends on company. However, once it is in my hands and can easily tweet my floor joist.
Thanks!
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