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Link44
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# Posted: 25 Apr 2022 10:45pm
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If lumber comes down to reasonably I plan on building this spring/summer. I am working through some stumbling blocks with my framing. I am not an expert but have built some sheds and read alot.
I am hoping to build a 16x20 or 16x24 on skids. I can't have a permanent structure but am allowed up to a 400 sqft shed. I have read about a gentleman named Owen Christensen who built everything on skids. Going along with that idea I want to run 2x8 floor joists 16oc with each side cantilevered 1 foot.
For the loft i was hoping to run 2x8's set on jack studs sistered to the wall kings studs. 2x8's don't show they can span 15'4".
I plan on having a wall 6ft off of 1 of the support walls. That would drop the span to within limits except that wall won't sit directly on a skid.
I'm trying to save space for head room but I want it to be safe.
Any thoughts would be appreciated.
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Brettny
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# Posted: 26 Apr 2022 05:07am
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Useing taller loft floor joists would help. 10' span for a 2x8 is pushing it a bit.
Are you going to use 16' lumber?
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Cedar Fever
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# Posted: 26 Apr 2022 08:01am
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My 16x24 is built with 2x6 floor joists 8 foot long. It’s not super solid but it’s also not falling apart. I also built a 2x6 framed loft with 10 foot spans for storage that is super solid. You could always over build it more but I would pay attention to how much weight you stick in there. If I could do over, I would pour sono tubes for my foundation and some cubes to strap the cabin to.
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Link44
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# Posted: 26 Apr 2022 09:02am
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I will be using 16' lumber. May have to refigure for 2x10's
I can't have a concrete foundation. The ground is very rocky and drains well. I dont think frost heaves are going to be an issue. I've been onsite in the winter before its covered in snow. I've seen some crystallizing on the ground but not much. Water doesn't puddle anywhere long before it drains straight down. I'm considering putting in a french drain on 3 sides to make sure water doesn't condense under the building.
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travellerw
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# Posted: 26 Apr 2022 10:03am
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Quoting: Link44 Going along with that idea I want to run 2x8 floor joists 16oc with each side cantilevered 1 foot.
2X8 can not run that long of a span unless you plan 3 skids (one down the middle). Having skid down the middle can cause problems if you have heaving issues. If it heaves in the middle you will get a hump in the floor.
2x10s can run that distance (depending on the type and rating). I suggest you google "span tables" and use that to help you design. You just need to know the type of lumber sold in your area and the ratings.
As to skid buildings, I did a bunch of research before I started building. Location prep is key. A proper gravel bed is most common.
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gcrank1
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# Posted: 26 Apr 2022 10:19am
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Iirc your 1' cantilever idea may be too much? Remember, the roof load to the walls and all included is transferred down to that area, then to the ground.
Imo, unless a small one story shed type structure, 'overbuilding' a bit on the foundational and deck side is smart. You are getting to a pretty good sized and heavy structure.
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happilyretired
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# Posted: 26 Apr 2022 10:53am
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Quoting: gcrank1 Iirc your 1' cantilever idea may be too much? Remember, the roof load to the walls and all included is transferred down to that area, then to the ground.
I agree. The entire load will be carried by the cantilever and will likely bend the joists over time. I doubt (but don't know for sure) if it would be allowed by code either.
I'd cantilever a deck, but not the structural wall of of a building.
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BRADISH
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# Posted: 26 Apr 2022 02:48pm
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Have you priced out using engineered BCI's as opposed to dimensional lumber? These days the cost may not be that far off given the insane prices for dimensional? For my build I am using BCI's and have very much appreciated the information included in the Boise Cascade Western Specifier guide (Found Here: https://www.bc.com/wp-content/uploads/2018/09/W-spec-guide-BCI-and-VL.pdf ) There is also an Eastern Specifier guide if you find yourself in that part of the country.
I found their span tables/photos etc to be very helpful as I am also not a pro, just avid DIY-er.
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Link44
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# Posted: 26 Apr 2022 03:06pm
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I had looked a span table. It looked like 2x8 would go 12'9". I was thinking with the 1 foot cantilever and a 6x6 beam I'd be close with a smallish building. Maybe I'll look into the BCI's or 2x10's instead. I am in the PNW.
I'm trying to avoid the 3 skids but maybe with good site prep and a french drain it will be ok.
Any thoughts about the loft with 2x8's? I suppose with a 3rd skid the load would come down through the floor from the wall close to the skid.
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gcrank1
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# Posted: 26 Apr 2022 03:27pm
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I used 2x8's in my 12x12 loft, end supported only, no issues. Wasnt a lot of heavy stuff in the 'bedroom' loft.
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travellerw
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# Posted: 26 Apr 2022 08:31pm
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Quoting: Link44 Any thoughts about the loft with 2x8's? I suppose with a 3rd skid the load would come down through the floor from the wall close to the skid.
I originally used 2x8 on my 16ft loft as the plan was to have a support wall down the middle (carrying some of the load to the lower joists). The plan changed and only 1/2 the joists were supported by the wall. However they were up for 6 months before we upgraded them to 2X10 #1. They seemed absolutely fine to me (at tiny bit bouncy).
One thing to remember about "human occupancy building engineering" is its not about "what is strong enough". Its about "what is strong enough in a worse case scenario plus some". Its engineered to ensure the occupants are safe, or have the most amount of time in a disaster (i.e. fire). So even if something seems fine, it may not be considered safe building practices. You want to make the safest building you can.
However with that said. I definitely considered just sandwiching the 2X8s with 3/8 OSB as I had just about enough on hand and it would have saved me pulling them out (would have saved me 1/2 day). I'm pretty sure that a glue/nail sandwich like that would have brought the strength close to a 2x10. Sigh, in the end I just bit the bullet and spent the day switching them out.
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Link44
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# Posted: 27 Apr 2022 12:24am
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All of my loft joists will sit on the interior wall. What did you use for the loft floor sheeting?
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Brettny
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# Posted: 27 Apr 2022 05:10am
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Quoting: travellerw One thing to remember about "human occupancy building engineering" is its not about "what is strong enough". Its about "what is strong enough in a worse case scenario plus some". Its engineered to ensure the occupants are safe, or have the most amount of time in a disaster (i.e. fire). So even if something seems fine, it may not be considered safe building practices. You want to make the safest building you can.
This is very true. Building a building that is proper dosnt mean it's over built. It also means you prob wont have to rebuild things later. With a soft floor you can get alot of squeaks, pops and groans out of the floor moving. It can also limit your choices on flooring types.
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Brettny
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# Posted: 27 Apr 2022 05:11am - Edited by: Brettny
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Quoting: Cedar Fever My 16x24 is built with 2x6 floor joists 8 foot long. It’s not super solid but it’s also not falling apart
Do things rattle or wiggle when you walk by them on the floor? Also the fact that it's still standing is hardly a indication of anything.
I have a shed with 2x4 floor joists, but it's just that a shed so the floor dipping down 2in in the center dosnt really bother me.
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Link44
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# Posted: 27 Apr 2022 09:01am
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I agree with all the comments. Sometimes the frugal side of me argues with the safety conscious side of me.
I have built a shed floor with 2x6 24oc with 5/8 sheeting that was springy. I don't want any springy floors again. I really didnt like that feeling. So much that I laid another layer of 5/8 the opposite direction glued and nailed. I had to raise the door but the floor felt solid when I was done. Would have been cheaper to go 16oc and 3/4 sheeting from the beginning.
Thanks all for the nudge in the better direction.
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BRADISH
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# Posted: 27 Apr 2022 02:48pm
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Quoting: Link44 I agree with all the comments. Sometimes the frugal side of me argues with the safety conscious side of me.
I have been known to be a cheap ass at times, and even I won't sacrifice on a floor. Beyond springy/squeaky floors being a personal pet peeve, it is literally the part of the building you will be interacting with the most - forever! You are literally always touching it, or something connected to it if you are in that building. Not the place to cheap out imo.
Best of luck! Let us know what you end up doing!
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