ICF construction ( quad lock ) and nailing fin installation windows from fibertec would like to know what do you guys ( pros VS me amateur ) recommend as best pratice for properly flash the windows and protect from water entry the window bucks are of 2by12 wich were placed to finish flush with the exterior ICF wall (8" all around ) i firt planned to install a butyl flashing tape of 9-12" wide on the exterior EPS finishing it inside the window wooden buck, then install the windows and finish with a 3-5" flashing tape on the nailing fin and the first layer of tape then i thought that the double layers wouldn't serve much purpose so now i am up to installing only 1 run of 9-12" wide butyl tape after the windows will be nailed i will install tyvek all around, and the exterior finish will be ACP with an airspace under want the best possibility, as i don't want to have to retouch or think about it ever again ( 25 years ) a bit scared about water getting under the foam and going on the wood bucks in cracks and foam/concrete joint

I have been going thru the same problem. The projecet I am on is a cape with both icf and stick frame (with 1" xps on the eterior of the plywood sheathing). The siding is vinyl so I am real scared of leaks. We are having a brutal cold winter here in new england so the black sticky tape sure is not adhering now. I have experimented in my warm basement with a water based stryrofoam spray glue as a primer on the form prior to pressing on the black tape. The spray glue helped the adhesion by about 20%. Another tip I got from a product rep (Henry blueskin) was to smear a bead of caulking along the outer edge of the black tape to act as an additional seal. I could not get the caulking product he recomended but I used silicone and it makes a much better seal. Good luck trying to find any primer which wont melt the foam.

I really hate the idea of relying on the black tape to stop water from getting in. I would have preferred the framer put the windows in with a bead of silicone under the nail flange first. WARNING: dont use any caulk which will eat the foam. On 2 windows I made a flashing 2"x1/2" with the shorter leg bent at 45 degrees. I cut a slot in the icf to stick the shorter leg into the foam and adhered it there with silicone. Got the idea from the icf forum.
I am frustrated by the whole process and have little faith in the black stuff in the cold weather (even 40 degrees). My current plan is to install a layer of tyvek over the stick frame/1" xps. With all the dormers and step flashing it seems to be the only fool proof method to me. My only concern is there is a layer of Typer (poorly installed) followed by 1" xps and now a layer of tyvek. If someone can point me toward a topic which covers this much thanks.

could you please provide a web link to your "black" tape ?
i can't see exactly wich kind of product that is ...

I also want to overlap the Tyvek and flash it ONto the flashing tape..so there is no water that goes all around the tape
i'll probably keep some flashing tape with a good width ( 2-4" ) to tape the tyvek on the first layer of flashing tape
i don't trust builders tape at all
i've seen too many just ripped off by almost nothing, even when used inside

i also don't know yet how we are going to finish the exterior wall exactly..so i don't believe that i'll install a 1x4 or 1x3 layout on top of the tyvek

by "black tape' i mean Grace flashing tape. today got very warm (50+) with plenty of sunshine shining directly on the Grace tape to bake it on... or so I thought. It still peels back with very little effort. I applied silicone to the edges to help seal it to the icf and will definately run tyvek down to from under the soffit to top of windows and doors.... I figure after that it will run off nicely.

We used some peel stick membrane for the under grade section of my ICF house
it was during hot summer ...25-35C all day
and it seriously sticked to the EPS
it was even hard to remove if misplaced
i have not try to peel it from the ICF during winter time,
but i believe that if someone would want a 100% stick, could use a propane blower to heat up after application, and roll
pressure on it

i don't know the exact composition of that membrane, but it did look a bit alsphatic...though i thought
this would eat up EPS ..might contain some butyl
i'd have to get more info

i'll make a paralell thread in the ICF forum
not much activity here

I have developed and patented anadjustable window and door bucks for wood,steel and masonry construction. The product adjusts to zero clearance and eliminates air and water infiltration.The product name is Window Seal and I am now introducing Simple Seal which is a combination form ,adjustable window and door buck for the ICF industry. Please visit our web site www.bnsusainc.com

your product seems good structurally, but steel is not a material i want to bridge exterior to interior on my house -35c during winter here

I, too, have experienced the problem you describe flashing windows in an ICF wall. Standard flashing tape, which sticks so well to wood, Tyvek, PVC and other materials comes right off EPS. Rather than trying to find a way to seal the flashing to the EPS, I took the approach of trying to manage the existence of any water that might work its way past the window caulking and flashing. Where will the water go? What parts of the internal wall are subject to water damage? How can I make sure the water doesn't become trapped?

The concrete and EPS of an ICF wall are not affected by water. They are not subject to rot. Likewise, the window bucks are made of pressure treated lumber which can stand up to moisture. If water gets into the wall cavity around a window or door, it's important that it be directed away from the interior drywall and the window/door framing to where it can drain to the outside where natural air movement behind the siding or brick can carry it away by evaporation. Pan flashing or flashing tape should installed beneath the window to catch any water and direct it to the outside.

Keep in mind that water vapor will condense within a wall cavity whenever the dew point falls within the wall cavity for a sufficient period. As long as this liquid water can escape by evaporation in a relatively short period of time, no harm is done to the buidling. Water that enters the wall cavity and becomes trapped inside is the cause of rot and mold growth. That is why avoiding a double vapor barrier is so important.

I'm not trying to minimize your concerns, but in homes where water penetration has occurred, it's usually because there was no flashing installed at all.

Clark :

i decided on using some liquid membrane ( similar to epdm ) around all openings, directly on the EPS ...10-12" around and make it go inside on the wood bucks for a few inches
this liquid should also seal the small gap between the EPS and the wood bucks

then i will be instaling the windows ( exterior nailing flange with a brickmould flashing ) from the exterior
fasten on the buck a bit through the nailing flange

seal the space around the window with medium/low expension polyurethane

then i will use some bitumen/polypropylene flashing tape
6" wide ..2-2.5" on the window and the rest on the liquidmembrane ( EPS )

then later setup the tyvek on the surfaces..overlapped etc ..

and then reuse again some of the flashing tape ( 3" now ...wich i get almost at the same price as contractor's tape )
to connect the tyvek on the prior flashing tape surface

i am not 100% sure
but this seems like the most secure way for me to do it right now

then about condensation ..
i will not leave any space in any walls..unfilled

we are laying the gypse directly on the inside EPS
and the other interior finish will use ACP ( alum composite panels ) directly on a plywood 1/2 wich is directly mated on the EPS of the ICF walls

the only sapce available for condensation should be at the exterior,
between the tyvek and the foam, or the tyvek and the APC wich will also be used for all of the exterior

what do you think ?


i was told that no condensation occurs if there is less than 0,5" by 0.5" allowed for air movement


should i use screws on the tyvek at reg. intervals to have it as close to possible
to the EPS so there is not sapce for condensation under it ?

Your plan to flash the windows is very thorough and should protect you for the long haul. If anything, it's probably more than is really necessary, but for the extra insurance, why not? I did not apply Tyvek to the ICF walls at all. There is no purpose for it. The EPS is already a water resistive layer and the ICF wall prevents air infiltration. I would not spend the money and time to install Tyvek over the EPS. It's good to be able to see the joints and to rasp the wall as needed when installing the siding.

There no danger of condensation forming within or on the ICF walls. For condensation to occur, the dew point temperature must be achieved at the wall's surface or interior. Maintain the interior relative humidity such that condensation doesn't form on your windows and you'll be fine.

according to the new ICB residential code R703.8


Approved corrosion-resistant flashing shall
be applied shingle-fashion in such a manner to prevent entry of
water into the wall cavity or penetration of water to the building
structural framing components. The flashing shall extend to the
surface of the exterior wall finish. Approved corrosion-resistant
flashings shall be installed at all of the following locations:

1. Exterior window and door openings. Flashing at exterior
window and door openings shall extend to the surface of
the exterior wall finish or to the water-resistive barrier
for subsequent drainage.

john Rizzotto: ok good
but no code for me

i'm doing it myself...and around here nobdy ever come to check anything

you could build a thaw shack if the town gives you the ok with the plan you presented
and they'd probably never check back again

i know of some horror stories around here :p ( quebec in the countries )

Greetings, fellow flashing and water management professionals. I am frustrated in an ongoing search for legitimate manufacturer installation instructions for Unilux windows and doors. I have a customer who has only recieved verbal instructions from his direct local dealer / supplier, who apparantly has told him that the written mfgr. instructions do not exist. I find this hard to believe, as we have been provided with a copy of the mfgr. limited warranty which clearly states a complete void of warranty if the installation instructions are not followed. I am considering helping our new potential customer (homeowner) with completion / correrction of current sloppy installations, but only with clear manufacturer instructions in our pocession, so we meet or exceed in all required areas. Anyone's help in how to obtain this information would be greatly appreciated. Sam The Builder... (Western North Carolina area)

with regard to the icf wall/window marriage and flashing, this can EASILY be solved by using some of the peel and stick membrane that is used for below grade waterproofing. It's a sticky as can be and i designed to be used with the icf block. Plus it is much wider and can be more easily cut to spec. Buy one roll and the whole house can be done with some left over for the next job.