I’m a finish carpenter so pardon my ignorance. I am putting a 16 X 24 2 story addition on my house. The walls will be built with Durisol ICF’s which are different than most in that they are made of a portland cement/pulverized wood mix rather than foam. I hired a recommended sub (now fired) to pour my footings and slab. The forms are to be bonded to the footer with mortar (Type S). When I went to set the forms I found that the footings are from 1/2 inch high to 1 1/2 inch low (thus the fired sub). The sub said that I should just build up the the low spots 2 inches with mortar and set the forms. This sounds like a lot of mortar to me and I am concerned as to whether it will be a strong enough bond etc. Should I use something to bring the footings up to level or will motar do the job? Thanks for any suggestions/ thoughts.
Bruce
Replies
No wonder you fired the sub. My footings for ICF's were +/- 1/4" and I thought that was a bit much.
To try and answer your question - the ICF's don't really hold any weight or provide structural support, do they? I don't know for sure about the Durisol ones. If not, you can use shims, mortar, spray foam, whatever you want to hold them up. The concrete wall inside the forms is what holds the weight. Making sure the footings are level just makes laying the ICFs easier. The other thing you could do, which is time consuming but probably a better idea, is to find your high spot and low spot, set some stringlines, and scribe the blocks to the footing. It will be better in the long run because your forms won't settle on the wall pour, and your second course of block should work out to be dead level or close to it, if the scribing was done right.
If the mortar sounds too weak, you could set your forms in wet concrete - the aggregate will help hold things level.
ICFs need level footers to start, or you will be fighting them all the way up.
Once you fill them with mud they will be plenty strong.
Epoxybreth,
The scribe method would be my first choice, second would be to pour a grout cap on the footer that is level at least in the 1 1/2" low section then scribe the 1/2" off the balance.
When setting the IFC use mortar only under the form not under the center where the wall is sitting on the footer. It only holds the forms up during the pour.
Garett
I've never worked with durisol either. Some price, ain't it?
Like the others, I agree that ICF's must be level when you start or the job will be needlessly difficult. I don't see much need to bond them solid to the footing, though. Is that what Durisol says must happen?
Think about this: assemble a couple of courses on the layout line and tie them together well. Starting at the highest spot, shim everything to level. Use bits of rock, broken brick, broken forms - anything you don't mind leaving there forever. With foam forms, you only need to shim every two feet or so. Your results will tell you what interval you need to use with Durisol. Foam the gaps between the shims.
With gaps that you have of up to two inches, it couldn't hurt to reinforce the foam a bit with some board screwed to the forms. Another thing about dealing with these large gaps is that you will have to have someone doing the outside while you are doing the inside so as not to put too much stress on the forms. And you might have to raise it in stages.
I did this alone on a job a while ago by hanging all the tapes I could find from the forms at about two foot intervals, shooting the whole lot with an autolevel and shimming.I had five vertical feet or so of forms up then. It's easy. It will work.
While that time I was only correcting for vertical errors of less than 3/8", on other jobs I have scribed ICF 's to solid rock and sometimes ended up with gaps of two or three inches. It's nothing you can't fix with a bit of foam and some scrap wood.
How are you going to key the concrete to the footing?
Ron
Thanks for the response Ron.The price didnt bother me too much when I figure in not needing to frame a wall inside the forms plus my wife is real big on the enviromental side (no outgassing, made from recycled materials etc.) On top of it I picked them up in Ontario and just had to do a little fishing on the way back. Anyway I am keying them to the footer with rebar every 2 ft. embeded into the footers. Bruce
Thank you all for your responses. Sounds like no worries. Think I may pour my own footers next time. Enjoy, Bruce
They do need to be bonded to the footer, but it's not the mortar that does it, it is the rebar. You should have rebar embedded in the footers sticking up a foot or so. The rebar ties the wall to the footer. It does not matter if the insulating walls of the block are tied.
However you level and set the forms, they have to be secured from moving around when they are filled. Usually scrap 2 x 4's are fastened to the footer on either side of the block, then removed after the concrete has set.
Been there, though with ARXX not Durisol. I had great success on 2 different occasions with expanding foam/adhesive. I'm not sure of the weight of your forms but I pulled off 2 flawless pours after battling the same problem. Good luck.