Replies

1. 
   ronbudgell | Dec 07, 2007 01:25pm | #1

   Zella,

   Would it be difficult to finish the top of the ICF level and add anchor bolts and a pressure treated sill plate and proceed with the wood framing as if you were on a conventional foundation?

   That's certainly the way I would choose unless there was some design limitation that prevented it.

   The way you describe seems more complicated, more expensive and not as good. I must be missing something here.

   Ron

1. 
   Kivi | Dec 07, 2007 03:44pm | #3

   We are finishing the framing stage of exactly the same scenario, and we did it exactly as you described.  Anchor bolts were put into the top course of ICF for sill plate etc..  ICF installer suggested that to insulate the rim joist we will have spray insulation done from the basement to fill the cavity above the ICF wall to underside of the floor (for the perimeter of the house).

2. 
   Matt | Dec 07, 2007 03:34pm | #2

   For anyone who wants to know what the Simpson ICFVL Ledger Connector System is take a look at this:

   http://strongtie.com/products/connectors/icfvl.html

   To the OP - I'm no ICF builder by any means, but still I'm with the above guy who says that there must be a better way to do it.  It would seem that you are sacrificing one of the basic principles that gives platform framing it's structural integrity just so you can have your rim joist super insulated, when the building is standard stick framed from there up anyway.

   Try sending an E-mail or post to this guy: ericicf  he is/was a fairly regular poster around here who appeared to know quite a bit about ICFs.

3. 
   balamson | Dec 07, 2007 05:50pm | #4

   Thanks for the suggestions, the sillplate/joist/floor/framing was considered. Having the bottom well insulated was part of the reason for going with the joists inside the ICFs, using less materials ( less sill plate, rim boards, spray in insulation in the joist cavities) was also thought of and labor. Additionally the 2nd story is constructed using recycled materials. My thought was every little bit helps.

   I am commited to hanging the joist from the inside of the ICFs. Nobody is missing anything and using the Simpson brackets is quite easy. The walls will still be tied together through the connection of the ledger/joist and the floor sheeting over the ICFs and anchor bolts. It was also spec. by an engineer.

   I am not a carpenter by any means, but just notice things along the way that are being done and have questions. I am really just a laborer on my project in my spare time.

   Back to my original question. Will the green concrete as it cures releasing moisture affect the sufloor plywood and bootom plate of the 2nd story, where it covers the ICF and exposed concrete in it? I am wondering if the wood products will rot? Would it be wise to ad somekind of vapor barrior between the ply and concrete?

1. 
   ronbudgell | Dec 08, 2007 12:21am | #5

   Zella,

   Alright, so you are committed to this path.

   I really don't know what you can do to make the concrete surface smooth enough and level enough to put the ply on. I can't help you there.

   Isolating the concrete from the wood is easy and certainly ought to be done. Tar paper will do fine. Waterproofing membrane will work. Roofing shingles will work. The best thing would likely be a sill gasket under the ply to try to stop some of the gaps which will be the inevitable result of this technique.

   Don't forget to leave extra length on the anchor bolts to compensate for the extra thickness of the plywood. It's a real bore not having enough thread to put a nut on. I presume you will have to bolt down your wall plate.

   Personally, I have quit using Simpson ICF hangers. I found them to be expensive both in labour and their initial cost and a pain in the rear to work with. I prefer individual joist hangers by ICFConnect. I think they save a lot of trouble.

   http://www.icfconnect.com/

   Good luck with this.

   Ron

    

    

    

    

2. 
   user-67934 | Dec 08, 2007 03:53am | #7

   Zella,

   I built my ICF basement just like you described.  I ran my bituthene over the top of the wall and then put a PT sill plate on top.  It worked like a charm.  I always see people's bituthene sag and peel in the sun.  I had none of that.  I had the simpson ledger bracket system on the inside of the wall, with the top of the joists flush with the top of the sill.  The difficult part of the simpson system is drilling those ledger hangers into the wall.  They supply self drilling/tapping bolts, but they don't go very easy.  I predrilled them all a bit undersize and it was still a lot of effort.  I had a couple decent 120v drills overheat.   

1. 
   ronbudgell | Dec 08, 2007 08:52pm | #8

   Tony,

   I don't think I'm simply a bit dim, but I really can't see the point of doing it like that.

   The advantage is that you save a few feet of framing material, nothing more.  You will save one full joist by hanging the floor inside and two feet off every other joist run. Except for what might go into that one joist, you don't save any labour.

   The disadvantages are many: the extra cost of another foot of ICF wall, the time and trouble (my experience with them is the same as yours) of Simpson hangers, the extra time and money that will be needed to hang the joists instead of simply end nailing them, shrinkage issues if you are using lumber framing, the extra time that will go into supporting the ply over the ICF wall's imperfections, the hassle of standing up a wall and setting it onto anchor bolts....

   Sometimes, design issues compel you to do things like this. In the absence of design limitations, it seems to me like a good way to throw money away and get nothing for it.

   Ron

1. 
   user-67934 | Dec 08, 2007 09:01pm | #9

   In a normal house I'd agree. I was building a log house with 14" logs. I was looking at a whole lot of blocking around the rim to take the crushing loadsand it seemed like a better system to have the massive weight of those logs sitting on the concrete wall.

1. 
   ronbudgell | Dec 08, 2007 11:30pm | #10

   Tony,

   There you go, a clear design limitation which forces you to take unusual steps. You found a good solution for the problem. Yay!

   Ron

3. 
   redeyedfly | Dec 09, 2007 12:37am | #11

   Why would the subfloor need to extend out over the ICF?Build your floor with the subfloor stopping where your sill plate starts. Then you can frame the wall normally, like a garage wall with a sealed ACQ sill. At most your subfloor will cantilever a couple inches over the ICF and those inches will be right next to a wall where they will never be under load. Use that 1 1/8" subfloor.
   Or frame the floor system an inch above the top of the ICF, bolt down (or better yet strap down)a sill and tilt up a conventional wall atop the already installed sill. Before you put the sill in place you can fill the space between the subfloor and the top of the ICF with a couple cans of foam. It will keep the edge solid and keep the concrete away from the unprotected wood subfloor.
   I can draw it and post if that was hard to follow.

4. 
   caseyr | Dec 08, 2007 02:31am | #6

   There is a copy of the Housing and Urban Development manual on the prescriptive method for ICF construction available for downloading on-line. It might provide you with some useful information. Be warned, however, that it is 1.6 megs, so downloading on a slow connection could take a while. It is available at:

   http://www.pathnet.org/sp.asp?id=1014

5. 
   IdahoDon | Dec 09, 2007 09:26am | #12

   It was suggested to install the brackets so that when the ledger and joist are installed the top of the joist will be level/flush with finished top course of ICFs. I was then told to lay my subfloor down so it covers the form to the outside edge.

   Whoever told you this, an engineer or otherwise, has read this from a book somewhere and has not done it.  It's very hard to do well and the only place I'd consider it is when replacing an existing foundation where the historical codes don't allow us to raise the house over how it originally sat.  The method you described allows the lowest possible floor height, that's about it.

   It's so much easier to build with a traditional sill plate/rim/deck/wall that we'd charge an additional $2k-$3k or so for such a foundation.  Those simpson ledger hangers aren't cheap, the additional hangers also add up.  Mostly you have to detail the top of the wall to line up exactly with the ledgers, which gets expensive as the hours go by.

   Around here you need to have a pressure treated sill on top of the wall, but I can see how a layer of ice and water would protect the decking.  So now if you remove any kind of plate from the top of the foundation you need to have the concrete even more level since it's now not possible to make adjustments on the sill.  More $$$.

   Whoever said this would save money is blowing smoke up your hiney.  A couple of $k can buy a lot of ridgid foam and rim joists aren't that hard to insulate well.

   Happy holidays!

    

   Beer was created so carpenters wouldn't rule the world.