Author Topic: Wooden sub frame directly over concrete  (Read 1719 times)

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Offline waltsuz

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Wooden sub frame directly over concrete
« on: April 11, 2016, 04:54:07 AM »
I was referred to this forum about a cabin design I am ready to start building. The technique I am using I have used before on posts with greats results but I have had to change this method because of the terrain. I have a 20x28' concrete slab I want to build a 2x8 PT frame/subfloor structure directly over the concrete slab to erect our cabin on. I use T1 siding and this allows the bottom of the siding to remain off the ground and allows drains, electric, and insulation in the sub floor. I have not found a method of anchoring nor recommendations for vapor barriers to do this. I have used styro foam insulation in previous buildings as insulation and vapor barrier all in one in the floor structure and built off of that. We are basically homesteading a wooded property, we have no codes and I can pretty much do as we want. Any suggestions would be appreciated. Thanks for taking the time to read this, Regards Walt

Offline waltsuz

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Re: Wooden sub frame directly over concrete
« Reply #1 on: April 11, 2016, 07:34:03 AM »
http://s1100.photobucket.com/user/waltsuz/media/sub%20floor.jpg.html

Hope this works
Picture shows a building base I did anchored with 4x6 posts. I want to do another similar to the picture and anchor it directly on a concrete slab without posts and build a 20x28' cabin on the base. I can't find anything like this online and was looking for opinions, Regards Walt http://s1100.photobucket.com/user/waltsuz/media/building1.jpg.html


« Last Edit: April 11, 2016, 07:52:13 AM by waltsuz »

Offline waltsuz

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Offline Redoverfarm

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Re: Wooden sub frame directly over concrete
« Reply #3 on: April 11, 2016, 09:02:43 AM »
Not sure I am understanding but I will give it a shot from what I think you are describing.

Generally when building on concrete slab the base plate is anchored with wedge bolts or J-bolts.  You could bolt a base plate to the slab and build off of that.  The plate would be anchored and then you attach the rim joist and interior floor joist to them. Grace makes a barrier which I describe below which could be placed between the concrete and PT wood.

But if you are just wanting to attach what you have pictured (complete w/insulation) then you could use Grace Ice/snow guard to the slab (or directly to the joist bottoms in strips) which would give you a moisture barrier.  As far as anchoring without looking I would say that "Simpson" has available a fastener for this application.  But if you use Simpson galvanized fasteners I would use small pieces of either # 15 felt or ice guard between the metal and the wood as the chemical properties of the wood treatment will corrode the fastener.

Offline waltsuz

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Re: Wooden sub frame directly over concrete
« Reply #4 on: April 11, 2016, 09:48:03 AM »
Not sure I am understanding but I will give it a shot from what I think you are describing.

Generally when building on concrete slab the base plate is anchored with wedge bolts or J-bolts.  You could bolt a base plate to the slab and build off of that.  The plate would be anchored and then you attach the rim joist and interior floor joist to them. Grace makes a barrier which I describe below which could be placed between the concrete and PT wood.

But if you are just wanting to attach what you have pictured (complete w/insulation) then you could use Grace Ice/snow guard to the slab (or directly to the joist bottoms in strips) which would give you a moisture barrier.  As far as anchoring without looking I would say that "Simpson" has available a fastener for this application.  But if you use Simpson galvanized fasteners I would use small pieces of either # 15 felt or ice guard between the metal and the wood as the chemical properties of the wood treatment will corrode the fastener.


Thank you Redoverfarm, Your explanation is what I'm asking. I was thinking of laying a layer of #15 felt paper over the entire slab then building/ setting the sub frame over it. I've never used ice guard which sounds interesting and I'll look into it. Hopefully I can find angle clips to attach this to the concrete with wedge bolts or redheads. I'm surprised I haven't found a technique like this online anywhere. Regards Walt

 

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