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Sreid
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# Posted: 6 Aug 2024 12:58pm - Edited by: Sreid
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Hey, new member here. I've been searching all over the internet for tips, ideas, advice, but I am still getting conflicting information.
I keep finding myself coming back to this site as it seems to have a lot of related info and knowledgeable members.
So here goes...
I am building a cabin, 24x32. I have 16 concrete piers already poured. Posts are every 10 feet on the 32' length for the beams, with 12" running out past the outside posts. So I will have a 11' beam, 10' beam and a 11' beam. The beams are then spaced 8 feet apart, thus my floor joists will span 8 foot sections on the 24' length across the beams.
Now for the dilemma, LOL. I was thinking that a 2 ply, 2x10 would suffice for the beams, and 2x8 16"OC for the joists. Some sites I've found suggest that I should use 3ply, 2x10 for my beams. Also considering a 3ply, 2x8 for the beam to reduce the overall height off the ground.
Does anyone have a similar build? How is it holding up?
Thanks
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jsahara24
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# Posted: 6 Aug 2024 01:21pm
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So if I'm following you correctly you are planning on having 3 beams, running the 32' length. Each row has 5 piers or a pier every 8'?
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Sreid
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# Posted: 6 Aug 2024 01:51pm - Edited by: Sreid
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Quoting: jsahara24 So if I'm following you correctly you are planning on having 3 beams, running the 32' length. Each row has 5 piers or a pier every 8'?
Each row has 4 piers. And minor error in my post. Beams will be 11', 10', and 11', fixed it in my original message. See picture.
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gcrank1
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# Posted: 6 Aug 2024 02:14pm
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So a 1' cantilever out over each end.
Any such overhang on the sides?
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Sreid
Member
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# Posted: 6 Aug 2024 02:16pm
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Yes 1' cantilever with the beams. No overhang the other way.
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gcrank1
Member
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# Posted: 6 Aug 2024 02:19pm
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The full length of the beams and the piers will be exposed to the weather, snow drop, etc.
Imo these will need to be ground rated pressure treated to hold up.
I think you will want to have the 'siding' cover all the way down.
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Sreid
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# Posted: 6 Aug 2024 02:22pm
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@gcrank1, yes I plan on installing vinyl siding all the way down. Also, the cabin will be off the ground about a foot on the back, and 6 feet on the front. I'm on a hill. Only the back will have any snow touching.
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Brettny
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# Posted: 6 Aug 2024 03:13pm
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Use tripple 2x12 for the beam and a large head structual screw. I would also recommend 24' 2x10 floor joists if your only doing 3 beams. Your sono tubes are alreaty spread way out.
I have a 20x32 cabin with 5 tubes per beam. Trippled 2x12 beam and 2x10 floor joist. I also subfloor glued the 3/4 sub floor down. It's very strong with no squeaks. Going with a cheaper lumber may only save you $400 but having a floor that's like a trampoline will haunt you for ever.
I would also suggest pulling in all the sono tubes to be under the building envelope. Like the picture shows. Even with no gutters my siding stays prety dry. I also have a decent sized overhang.
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Sreid
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# Posted: 6 Aug 2024 03:48pm
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@Brettny, I plan to skirt install some skirting around the bottom. Keep the weather out and the critters.
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Sreid
Member
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# Posted: 6 Aug 2024 04:16pm
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Quoting: Brettny I would also suggest pulling in all the sono tubes to be under the building envelope. Like the picture shows. Even with no gutters my siding stays prety dry. I also have a decent sized overhang.
So I can extend my joist to cantilever out over my beams a bit to keep the piers and beams under the cabin on the long side, but my rim board would be kind of unsupported then.
I don't see how you would be able to extend on the short side of the cabin where the beams end. The first/last joist will be on the end of the beams, nothing to extend out over.
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gcrank1
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# Posted: 6 Aug 2024 05:24pm
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If the end of the beams are cantilevered out a foot the joist on the end of the cantilever will be out that far and you use a joist length that cantilevers to each side.
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Sreid
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# Posted: 6 Aug 2024 05:35pm
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gcrank1 I re-read Brettny's post, and I realized he was mainly talking about having the piers under the cabin. At least that how I take it.
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Sreid
Member
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# Posted: 6 Aug 2024 07:49pm
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So back to the original question, I was thinking that a 2 ply, 2x10 would suffice for the beams, and 2x8 16"OC for the joists. Some sites I've found suggest that I should use 3ply, 2x10 for my beams. Also considering a 3ply, 2x8 for the beam to reduce the overall height off the ground.
Thanks Brettny for the suggestion. Anyone else?
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Brettny
Member
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# Posted: 6 Aug 2024 10:55pm
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Quoting: Sreid he was mainly talking about having the piers under the cabin. At least that how I take
Yes this. You will have to extend the siding way down to cover the beams too and those should be pressure treated anyway so not needed.
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ICC
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# Posted: 6 Aug 2024 11:23pm - Edited by: ICC
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Will there be a loft or a full upper level floor? Or just a ceiling? If there is a loft or upper floor will the upper floor joists be supported on a center interior load bearing wall or load bearing post supports over the main floor center beam and center beam posts?
If this is constructed with a normal gable end roof, the two outermost beams will support much of the floor loads as well as all of the loads from the roof and exterior walls. The center beam will support some of the floor loads and some of the upper level loads (if any) so the center beam size could be reduced.
BUT, there is one more important detail.
Snow?
Is this in NL, Canada?
Newfoundland and/or Labrador?
Could be a very important detail to load sizing beams and other stuff.
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Sreid
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# Posted: 6 Aug 2024 11:32pm
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@ICC no upper floor or loft. Just 1 story using regular trusses.
Yes Newfoundland Canada. There will be some snow loads but minimal in my area. Considering a 4/12 pitch roof.
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ICC
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# Posted: 7 Aug 2024 12:19am - Edited by: ICC
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In that case, I believe the two outermost beams should be triple 2x12 to be able to span the 10 foot distance. Quad 2x10 would also work, and would be my preference. Quad 2x work very nicely over rough cut 6x6 piers. They are more stable than fewer layers and the beam to pier dimensions align well making 3/4" plywood gusset pairs easy to sandwich the beam to pier joint. I have used quad layers on many beams (including my cabin) for those reasons. Personal preference. All joints must be above the posts. Ideally, the layer joints would be staggered, which is one reason I don't believe in maximizing the pier spacing.
With its lower load, the center beam could be one layer less.
Those sizes would be good up to about 30 PSF. With zero snow load maybe twin 2x12s could work. No heavy iron stoves or Sub-Xero fridges or water beds.
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Sreid
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# Posted: 7 Aug 2024 12:35am
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Appreciate the insight ICC. I'm building in a remote area so getting machinery in is dam near impossible. Materials alone are a struggle to get in there.
But, I know the key to success with this build starts with a good foundation.
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Grizzlyman
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# Posted: 8 Aug 2024 02:35pm
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My suggestion: 2x10s for floor joists. Dont mess around with 2x8s. The price difference isnt worth it. Even if it technically ok you definitely dont want any bounce in your floor.
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gcrank1
Member
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# Posted: 8 Aug 2024 09:21pm
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As in: Overbuilt is always better than just adequate 
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Sreid
Member
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# Posted: 14 Aug 2024 04:42pm
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So next question, see if I can explain this properly.
My cabin build is in a remote area and any material longer than 12 feet is difficult to get to site. So for my floor joist I am going with 8 foot lengths. So I will have 3 pieces to make up the 24 feet, breaking on the mid span beams.
Instead of using blocking between the floor joist over the beams where the joist join, can I use a full span joist perpendicular to the floor joist similar to the rim joists on the ends? And what is that called if it exists?
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ICC
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# Posted: 15 Aug 2024 12:50am - Edited by: ICC
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Quoting: Sreid can I use a full span joist perpendicular to the floor joist similar to the rim joists on the ends?
How do you propose securing the floor joist ends so they can not rotate? Anti-rotation is the purpose of full-height blocking where joists are meant to overlap.
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Floor joist ends may be butt jointed if a wood scab is securely nailed to one side of each butt joint. Metal tie plates may also be used over the butt joint. But solid blocking would still be needed.
There is no special name for such a joist spacer between butt ends that I am aware of. ???
If such a perpendicular joist was used on top of a beam the butt ends of the joists could be secured to the perpendicular member using joist hangers. Hangers would provide anti-rotation is all the nail holes were used.
Another solution could be to hang all the joists with properly sized and nailed joist hangers, between all the beams instead of the joists being placed on top of the beams.
Or depending on the exact placement of the existing piers (and therefore the beam placement), it may be possible to obtain floor joist overlap by using 10-foot joist lumber for the middle span and using full-height blocking at the beam overlap in the normal manner.
In retrospect it would have been better to think through all these aspects of assembling components before commencing any actual construction. I mention this more as a possible learning tool to anyone reading this while thinking about building something. Reducing the overall width of the structure by maybe 6 to 9 inches would have allowed overlapping of the 8 foot joist segments over the center 2 beams, for example.
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Sreid
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# Posted: 15 Aug 2024 12:26pm
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Thanks, my original plan was was(is) to toenail the ends of the joists to the beams then use a scab at the joins, then full height blocking in between. I'll probably just stick to that. It's just with all the information out there these days it's easy to get conflicting information.
I've read that you don't need blocking if the span is over 10 feet. Technically my span is only 8 feet where it is supported again.
So I am wondering if I need blocking at the middle of each 8 foot span? Or if I just need blocking at the joins over the beams?
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gcrank1
Member
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# Posted: 15 Aug 2024 12:54pm
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Depends on if you want the best floor, good floor or just adequate
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ICC
Member
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# Posted: 15 Aug 2024 02:25pm - Edited by: ICC
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Quoting: Sreid It's just with all the information out there these days it's easy to get conflicting information.
The correctness of the information depends on the source. My online experience has been to be wary of many popular sources; some videos, forums and blogs express opinions more than industry-recognized best practices.
Quoting: Sreid I've read that you don't need blocking if the span is over 10 feet.
Incorrect. That was either read incorrectly, misinterpreted, or came from someone's alternative universe.
First, there is blocking and there is bridging.
Blocking refers to solid wood, 2" nominal thickness x full depth of joist. Blocking is used at joist ends where there is no band or rim joist.
Bridging refers to "X" shaped straping or 2x2 wood bracing nailed in between joists in a X-shape. Bridging is installed between joists when the run distance from one end (block or rim) to the other end (block or rim) exceeds 8 feet.
Bridging helps stiffen a floor and helps to prevent joist rollover. It is easier to install especially when using metal straps. However, properly installed solid blocking provides greater stiffness and better joist rollover.
The IRC Chapter 5, section R502.7.1, calls for blocking or bridging to be installed at intervals not exceeding 8 feet. Remember the IRC rules are minimum rules, so more frequent bridging can be superior.
Chapter 5 link There is a newer version (2021) but I couldn't find the link on my phone right now and nothing has really changed in that section anyhow.
Overlapping joist ends should be over supports like a beam or a bearing wall. So there should be blocking used wherever one joist ends and another starts.
Blocking should also be placed wherever there is a wall built on top of the floor, perpendicular to the joists.
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Brettny
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# Posted: 15 Aug 2024 02:36pm
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The 8' mark is a good spot to put blocking at because that's where the ends of sheet goods should be landing.
I would really lay out your framing drawing really well if you can only use 12' lumber and make sure your sheet goods will fit on the dimentions of your floor joists properly. Sheet goods arnt all 4x8'.
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ICC
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# Posted: 15 Aug 2024 02:53pm
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I just remembered that this project is in Canada. There are some differences between the Canadian and the US rules. Canada's codes are similar and sometimes exactly the same. Blocking and bridging info I supplied is IRC US correct.
So IF the Canadian rule stated use bloc
kling/bridging when the distance exceeds 10 ft, or something in meters, That would be correct for Canada, but 8 feet could be better wherever the structure is located.
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