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matt90
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# Posted: 16 Jul 2012 12:59
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Hi everyone,
I recently just bought a piece of land on a the edge of a beautiful canal and I plan on building a small cabin on it in the next year (perhaps two).
The cool thing about the land i just bought is that it already has a platform build on it. It's very solid with concrete pillars and stone walls and it's over a slope, so it sticks out too.
My question is, how would i secure the base of the walls i erect onto this platform? It's made of 2x10 joists with plywood on top. Would i simple drill into the plywood? Or remove the plywood to secure it right to each joist?
Any info or link is helpful, thanks!
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toyota_mdt_tech
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# Posted: 16 Jul 2012 13:58
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Its just nailed in. Use lone 3" or 3.25" galvanized nails. Toe nailed is even stronger. In high wind areas, they have strapping they tie into the concrete and anchor the walls in the corners.
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MtnDon
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# Posted: 16 Jul 2012 14:03
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The bottom or sole plate gets placed on the plywood. (wall framing is assembled flat on the floor deck. Then nailed through to the rim joists, that's the ones that fasten to the ends of the regular floor joists. Also nail to the floor joists. Use 16D common nails (3.5" x 0.135" shanks).
Apply sheathing on side that faces out when it's still flat on the deck as it's easier to square the wall. Of course that only works if you have help to raise the completed wall and also if the floor deck is absolutely level.
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matt90
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# Posted: 16 Jul 2012 15:46
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Ah, its that simple huh? I didn't think nailing it to plywood would hold it down well. I might add a little extra support, maybe some l brackets here and there.
Thanks guys!
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VTweekender
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# Posted: 16 Jul 2012 16:42 - Edited by: VTweekender
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Quoting: matt90 Ah, its that simple huh? I didn't think nailing it to plywood would hold it down well
If your in a high wind area maybe some extra supports for uplift would be good...
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MtnDon
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# Posted: 16 Jul 2012 19:53
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Quoting: matt90 I didn't think nailing it to plywood would hold it down well.
Read my post again. I said nail through the plywood to the joists! You are correct in thinking that nailing to the plywood (only) would not be good.
Thabove assumes you use a 3 1/2 inch long nail and that the plywood is only 3/4" thick. Longer nails would be even better, the 3 1/2 is minimum by code. Along the rim joist nail every 16". Again more is better.
The above all assumes you are not in a special seismic or wind zone.
Brackets are only as good as the nails used and the materials being nailed to. Nails in shear have great strength, nails have much less pull out resistance.
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Borrego
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# Posted: 16 Jul 2012 22:06
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Yeah, find the floor joists and snap lines for your nailing. 16d's are correct and toe-nailing is stronger. If you have concerns with uplift, you could add some straps top and bottom to tie floor joists to walls to rafters. Good idea anyway actually....
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MtnDon
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# Posted: 16 Jul 2012 23:37
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Using 4x9 or 4x10 sheets of exterior sheathing is also a great idea to assist with tying the walls to the floor. The big box stores more than likely will not have the longer osb sheets but a real lumber yard should. We used 4x9 sheets. With out single story standard 8 ft tall walls the 4x9 sheets let the osb fully cover the rim joists.
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Malamute
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# Posted: 16 Jul 2012 23:41 - Edited by: Malamute
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You shouldn't have to tie the wall to the floor joists, the wall sheathing (most often 7/16 OSB) will go down from the walls over the sides of the floor platform, generally to the bottom of the floor rim, and be nailed on with 8's, making a very strong shear.
Looks like Don and I were typing at the same time. 
Without longer sheets, let the sheathing cover the floor rim, then fill in the upper edge of the wall with rips to tie in the top plate.
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MtnDon
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# Posted: 16 Jul 2012 23:52
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Quoting: Malamute Looks like Don and I were typing at the same time.
Longer sheets are nice. In areas where there are code inspections it is possible the inspector will want blocking wherever two sheets butt to each other, if that joint does not fall over a stud. Code does state structural sheathing must be nailed every 6 inches on the panel edges, 12 inches in the field.. So a strict interpretation means blocking those edges. That does greatly increase the racking strength of the wall sheathing so it is not simply a matter of being obeying codes. It can make a difference. Closer nailing may be called for in seismic or high wind zones.
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MtnDon
Member
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# Posted: 16 Jul 2012 23:59
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Also, if using filler strips to attach to a top or bottom plate it is a good idea to use strips 24 inches wide as a minimum. That provides more strength than say a 8 inch strip used to connect the top plate to the studs... not enough nails into the wall studs.
FYI; Same thing should be remembered for floor sheathing. Often it works out that a narrow strip is required when using T&G panels. Thay're often only 47 1/2 inches wide. In that case where the sheets are nailed to the rim and the joists, there is almost no lateral resistance to hold the rim, if the strip is only a few inches wide. Cutting the panels narrower along both edges and having a narrow filler someplace down the center is preferred. That does introduce some waste but it also make a stronger building.
BTW, what shape is that plywood subfloor in?
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Malamute
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# Posted: 17 Jul 2012 00:03
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Interesting point Don. I haven't seen longer sheets around here, or blocking at the joints, tho it makes sense from what you said. We do have high winds (100-120 mph fairly regularly in the immediate area) but haven't heard of any wall failures.
Most of the troubles around here are rocks kicked up by the wind breaking windows, and roofs, mainly shingles going. Most give up on the shingles after repairing them a few times, and go to metal. A whole barn roof and end wall was taken down, but it wasn't very well built, no rafter ties, just purlins for the roof metal nailed onto the trusses.
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MtnDon
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# Posted: 17 Jul 2012 00:07
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Those are some winds!  It does pay to build with that in mind, just in case. The highest we've recorded ourselves is 66 mph and we were there for it. Not sure I want to experience double that. 
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Malamute
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# Posted: 17 Jul 2012 00:34 - Edited by: Malamute
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Gets interesting at times.
The stuff I've built has always been with the wind in mind. The first fall I was here, there were sustained winds of 100+ for 3 days straight. That was a bit unusual. Made an impression though. A day or night here and there through the winter and spring is more like it. 50's 60's mph we just call breezy. I close my shutters if the forecast is for over 75 mph or so.
The saving grace is at this elevation, 4500 ft, the air density is less than sea level. The wind speeds we get here are mostly annoying, but don't do much damage to well built structures.
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matt90
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# Posted: 17 Jul 2012 07:45
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Ah, alright. I'll have to design the cabin walls to align with the joists. The area is very mild, we have some harsh winters but very rarely will there be strong winds. It helps that its in a forest too.
I'll be going up this weekend to measure the size of the joists that were used and get you guys some pictures. Maybe you can tell me if the foundation was built right as well  As for the subfloor, its garbage. Rot has set in and I can kick holes through parts of it (hopefully the joists are alright!).
Thanks for all your help everyone!
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MtnDon
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# Posted: 22 Jul 2012 21:05
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Quoting: matt90 I'll have to design the cabin walls to align with the joists.
Not necessarily what I meant.... The wall sole plate (bottom 2x4 or 2x6 that lays flat on the floor has the studs nailed to it).... the sole plate can be nailed to the floor joists and rim joists through the sub flooring.
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