trimming a house built from ICF’s
I was just offered a job trimming out the inside of a new home built from insulated concrete forms. The forms used have no nailer strips on either the outside or the inside of the walls. The homeowner thinks he will glue the wallboard directly onto the foam form. Although there is 2X wood framing out the window and door openings, my concern is that I will not have a solid nailing surface to attach the window and door casings or the baseboard mouldings. Has anyone worked with ICF’s before, or come across a solution? Any help is greatly apppreciated.
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I built a 6000 sf luxury home and could give you more info than you may care to know. I dealt with just about every problem you could imagine ( and some you wouldn't want to. ) My biggest concern for you would be getting to the house before it's drywalled. Then you could prep it out to make your job a breeze, ( or at least a lot easier) If that is not an option, remember its only the outside walls that are foam everything else is S.O.S. Before you commit, do yourself a favor and do a thorough walk thru with a long level and straight-edge to see what you might be getting into. ICF's aren't always the straightest walls you see. As for fastening trim with no backing, load up on liquid nail.
Good luck,
Mike
Yes mine have nylon straps every 4 inches to hold the blocks apart prior to pour and then hold the blocks together after the pour.. you can screw into those straps (they are designed that way)
If there really isn't any connections in the foam (doubtful) then you can use tapcons. Drill into the concrete with a hammer drill and then screw tapcons in.. I use a Hilti hammer drill and it's like drilling into wood..
I've neer heard of any that don't have the attachment points. Are you sure? Sometimes they are exposed and sometimes just in under a quarter inch of the foam.
Either way, You'll be using more glue and adhesive than normal
Excellence is its own reward!
Thanks for your reply. I do have one of the ICF's and cut it apart to look for a nailer, but found nothing but foam. The form looks exactly like a traditional cement block but instead it is all foam. The homeowner is getting me the manufacturer's info., but I think I will be using alot of glue.
Two brands come to mind having used them both. Rastra blocks and Cempo blocks. They are both formed blocks using a mix of recycled polystyrene ( I believe, some kind of plastic anyways) and cement. The size of each block is 32" x 48" x 12". They stack using a polyurethane foam adhesive. Infill the channels with a slurry mix of mud, usually pea gravel/ 7 sack mix around here.
Usually the windows and doors get a double 2x wood trimmer or buck, anchored into the concrete. Use 1/2 anchor bolts with the boards serving as forms. Then trimming inside is no problem, just like standard stick frame. Base trim as suggested by another post, 5/8" cdx is glued and tapconed into the blocks prior to drywall.
Since these two blocks take plater so well without a substrate like rock lath, often we will cut out the block styro and insert a 2x for nailing for wood. Glued and screwed.
Building with ICFs is not cheap no mater how you calc it out.
walk good
Edited 8/14/2003 9:01:45 AM ET by DTHODAL
My understanding of Rasta is that you can attach with screws pretty well. True?.
Excellence is its own reward!
That is what they claim. However in real life unless glued well, the screws can loosen up. It is like screwing into styrofoam. However, one can use 6" screws and install nail backing prior to a pour and allow the screws to be embedded in the concrete. That works quite well, but takes forethought.walk good
You have talked to the ICF representative, haven't you?
As previous poster noted if house has not been rocked yet. You can determine widths of trim and glue 1/2" or 5/8" plywood rips before rocking to give you nailing surface. Would make rips a 1/4" less overall. If it has been rocked get out the glue and nail trim on at angles with nailer. Figure for cabs, towel bars etc. As Piff said I have never seen ICF without some kind of web.
I have looked at quite a few of the ICFs and it seems to me that at least one of them did not have the webs. It was one used for the "matrix" type of cement where the ICF was like a solid piece of styrofoam with some circular channels cut through it. Most of the ICFs do have the metal or plastic webs and are like two flat styrofoam panels held together with the webs. The matrix type was a solid block that had more styrofoam than spaces for the concrete. They claimed that type of construction was "plenty strong", but they sure didn't look as strong as the solid cement walls with the styrofoam on the outside and inside.
we did the siding on one of the polysteel houses acouple yrs ago,my advice run dont walk away.inside corners 3"out of plunb in 8' sheetrockers took forever the electricians did nothin but bitch was absolutely no fun.its possible they have gotten more refined by now but i will still never( lol never ) bid on another one.cabinet guys all messed up cause nothings plumb or even straight,no where for blocking etc.could go on but i reckon you know how i feel about these jobs lol
Having an ICF basement that's dead square and plumb, my take is that most problems with ICFs orignate with the installer, not the system. It's not something anyone should attempt the first time without some research and competent advice. The salesman I bought my ICFs from spent several evenings helping me get started, then came and checked me out before the pour. Getting them right takes time.
Eco-Block, the ones I used, have plastic ties every 8-in. They take nails and screws quite well. Andy Engel, The Former Accidental Moderator
andy i agree with you about the dead onplunb etc.we dont have basements here but i sure hope the contractor builder has figured it out better than the one i got stuck with.guess practice makes perfect but why do i seem to always end up with the practice ones lol
I've been stuck with a few framed houses like that, one where the framing made hanging one particular door plumb impossible. And I can easily imagine an inexperienced, underpaid and underskilled crew getting ICFs wrong. I think one problem with ICFs is that they can look so easy that folks with no business building any part of any house will try them out. Sorry you got a bum one. Andy Engel, The Former Accidental Moderator
The best method if the sheet rock isn't in is to use the plywood that is 1/4" short of the finished trim and tapcon and glue the plywood on to the foam and screw the tapcons to the concete. If the sheet rock is up you can angle nail and glue the trim on with PL or Foam adhesive. I have done this a few times. It worked well. I would rather us the plywood method. That method will work on ICFs that don't use any tabs to screw into. If there are tabs you can just screw normal sheetrock screws into the tabs and skip the tapcons.
Just my 2 cents Brian
Thanks very much for your input. The house has not been drywalled yet, so I will stress to the homeowner, the importance of letting me install the plywood nailing strips before the drywall. I can see from all the various input, how important it is to plan things out before hand when dealing with the ICF's. The ICF technology sounds promising, but I don't know if it is worth the learning curve.
I've built a few ICF houses, and it's hard to imagine a system that didn't have some kind of attachment system in general, but pretty well impossible for me to imagine one that didn't use treated material for door and window bucks--how else would you stop concrete from blowing out?
Maybe you can detail this system for us? If you end up using tapcons, you better bill by time and materials or you'll probably end up going mental.
Dog
As I stated in my first inquiry, there are 2X pressure treated window and door bucks, which will allow me some fastening surface for window and door trim, but not enough for my peace of mind. However there are no nailers for baseboard, crown, cabinets, etc. The homeowner is not having any upper kitchen cabinets(thankfully), but I still need something to nail trim to. I have dissected the sample block every which way and have found nothing but foam. The blocks are set up to take 3 horizontal rebar pieces centered inside the block, with vertical rebar running through every 18" or so. The horizontal rebar rests on a tiny plastic "chair" which is placed inside the block once the block is in place. I am still waiting to hear which manufacturer the homeowner used. Will let you know when I do.