With ICF-11, 6" core, used as foundation under two-story woodframed house, deep snow country, GSF (ground snow load) 85 psf, full width roof trusses mean entire roof load borne by foundation below . . . Whaddya tell a client (I'm the designer, not the owner who is self-building this) who has built without the tapertops at top course? Is it a big deal? Aren't a number of ICF makers selling block, supposedly a "full line" of products, and do not make or sell tapertop forms? For those exterior walls that parallel his first floor deck framing (open web trusses), his exterior walls will be transferring the load down through a small pony wall of 2x4 framing, and that framing will bear on a mudsill, the outboard 2.5 inches of width of which has essentially no support underneath. The walls perpendicular to the floor trusses will transfer their loads down through the upright 2x parts that frame the ends of trusses, but once again, they only have bearing underneath, beginning 2.5 inches from outside face of ICF.

Ideally you want taper tops if the ICF terminates and then floor system/conventional frame on top.

Not all ICF companies make a taper top and no one makes a corner taper top. They are not too difficult to make yourself on site, use a drywall keyhole saw.

It is possible to transfer the load from the exterior back 2 1/2" to where the concrete meets the plate, this requires some blocking and can be achieved, consult a local design engineer for an acceptable method.

Just so you know, when I run ICF to the roof I don't use taper tops, I have the truss company set the point load to center of the ICF wall giving 3" bearing to each side from center.

Would installing a double thickness mudsill over the ICF wall help address some of the concern with cantilevered load over the exterior foam?

Another more secure option would be to cut and strip some of the outer foam away to allow drilling and anchoring a heavy steel angle along the edge or even a treated 2x4 to provide additional support.

I'm using Lite-Form ICF (the Xtra 2.5" thick EPS 8"x48" planks, not the fold forms) and they don't have a taper top available. But I need a taper top where I am transitioning from my 8" basement walls to my 6" main floor walls to create an interior ledge to hang my floor trusses from. So I decided to make my own taper tops. With a slight modification to my 10" table saw, I was able to install a 12" metal cutting abrasive blade. This will make a 4"+ deep cut in the foam. I then set my blade to the desired angle and the fence to the desired width leaving ~1/2" at the very top and cut the foam planks as needed. It works pretty easy. Note that I am going to reinforce this taper top edge prior to the pour with some light gage galvanized sheet metal angle 1/2" x 2.5" bent locally at a sheet metal shop and then screwed to the ties. I don't see any reason this wouldn't work with block type ICF forms as well. Obviously, this needs to be done before the wall is poured rather than after.

Arkie6,

You can make your own Taper Tops as you describe, but a word of caution. Most Taper Tops do just that taper, the reason is that if you create a sharp angle, 45 degree or greater, you are inviting the concrete to crack at that point. That is why a taper is prefered over sharp angles.

One quick question though. If you are attaching a ledger board anyway, why do you need the taper. Why not use the Simpson ICF-VL, Anchor Bolts, or the host of other methods to attach a ledger. We commonly pour 6" basements with a 6" home above in a seismic zone that is rated the highest in the IBC and IRC and there is no need to rest the ledger on anything except the ledger connection itself ie ICF-VL, A.B. or other.

As for the mudsill, Like Chris said, if your load is carried over the wall with the truss you don't have a cantilever problem.

ICF Contractor

ICF Contractor,

I may not have been completely clear on how I was making my taper top forms. I am planning on splitting the entire 8" tall x 2.5" thick foam plank at an angle so that I end up with two equal halves, with each half being 8" tall, 2" thick at the bottom, and 0.5" thick at the top. I'll have to run the foam through the saw once (~4" deep cut), then flip it over and run it through again to completely split the 8" tall foam plank. This results in an angle off vertical (x) of only 10.6 degrees (tan x = 1.5"/8").

I am not installing a ledger board on my walls to support the floor trusses. I will be creating a 3.5" wide concrete ledge on the top inside edge of the basement wall. Note that this will require a modification of the 6" ICF forms for the main floor when I get to that point (cut off ~4" of the inner foam plank) to allow me to get a 3.5" wide ledge. When the basement wall is poured, I will wet set 1/2" anchor bolts ~4' OC into the ledge portion and then install a 2x4 flat on this inner ledge. My custom built open web floor trusses will be top cord hung and secured to this 2x4 on top of the ledge. This is a lot easier to see how it will go together using a drawing than it is to describe it with words.

My basement is 62' x 34', so I have ~192 linear feet of wall. I looked at several options for hanging the floor trusses. I priced Simpson ICF-VL, ICF Connect, 5/8" anchor bolts w/anchor tunnels and 2x12 ledger, 5/8" anchor bolts w/anchor tunnels with LVL, and finally increasing the concrete wall thickness from 6" to 8" for the top ledge. All options were ~$1000 give or take in materials. The anchor bolts with 2x12 was the cheapest option, but also the one involving the most work.

But the thicker basement wall with the ledge seemed like much less work than any of the other options, especially considering that I will be doing much of the work by myself. Plus the thicker basement wall with top ledge allows plenty of flexibility on where the trusses are placed. And it adds strength to my basement wall which will have up to ~7' of clay backfill against it. And the top ledge with sheetmetal angle over the corner of the foam provides a fire stop as well as a termite shield.

Alan