ICF window sill water leakage

10-10-20

https://www.boards.ie/discussion/comment/120884957#Comment_120884957

Two small observations on that detail: there is no upstand on the cill and there is no drip-channel drawn in. The drip-channel will most likely be included in the cill anyway, but just make sure that it's specified. As for the upstand, I had my EPS cill (cavity block house) fitted with a specified upstand height to help mount and seal off the window.

Scoopsire

https://www.boards.ie/discussion/comment/120886990#Comment_120886990

Would you mind sharing the details of the manufacturer please?

10-10-20

https://www.boards.ie/discussion/comment/120889659#Comment_120889659

Passive Sills in Cork.

Scoopsire

Thanks!

sydthebeat

ICF essentially hopes the mastic bead keeps water out.

That's the draw back of what is essentially a single skin construction

10-10-20

https://www.boards.ie/discussion/comment/120890052#Comment_120890052

Mastic bead and DPC under the sill, if correctly fitted, to be fair.

rednoggin

Update on mine was that the sill was bedded too high on the DPC and the plaster went up to the cill. Water couldn't get out. The real question is how the water gets into it in the first place. I had to pull out 3 windows and redo the DPC. Luckily i had not plastered the inside , but caused major delays to everything. I still have to get the render patched around the cills but no water has come in since.

Its seems to be a common issue that is everywhere. I had numerous people look at it, including amvic and nobody could tell me the issue.

10-10-20

https://www.boards.ie/discussion/comment/121248934#Comment_121248934

Thanks for the update!

Explain that again though... so the DPC running under the cill was bedded in two layers of mortar and one layer was too thick, meaning that it was pooling at the rear? Am I right?

I guess that most of the leakages occur at the junction of the cill and the render at the reveal, just in by the window. Seems to be a weak spot if you don't have good fall on the cill.

Satcran

Don't know whether I'm relieved or worried that there's a few people other than me having issues with ICF windows leaking. Moved into my new ICF build about a month ago and the next day we started to get a leak under a window. Window is above a flat roof area so initially thought it was where the roof met the gable wall that was the problem. The roofer came and had a look and said it couldn't be the roof as the water was coming down the inside of the block as opposed to the outside. Water is only coming in too when it's driving rain. At the time the outside was being plastered I noticed the plasterer was cutting the dpc right up to the wall and then sealing up to the cill. He said that was the best way as it stopped water getting in under the cill. I argued that if water did get in then there was no way for it to get out but he said if it's done right no waster should get in anyway...

Has everyone managed to sort their issue by pulling out the window and sill and then redoing the dpc? Also how big a job was it? Did anyone manage to solve it without having to take out the window?

hadoken13

Having what sounds like the very same issue. Did you have to take out your sill? If so, how did you get it out? We have the exterior rendered and concrete behind the sill between passive sill and insulation on the inside.

rednoggin

For mine, the DPC was to low compared to the bottom of the sill. ie the mortar was between the sill and DPC, approximately 1 inch. This resulted in the dpc being too low. The plasterer cut the DPC and rendered over hence trapping any water. Only way out was to trickle down the ICF and out at floor level.

I still cant believe how much water is getting into the dpc tray in the first place. I siliconed all junctions and around the window but it made no difference.

Luckily I did not have plastering done inside at this point so it wasn't too difficult to remove the problematic windows, albeit very time consuming. No water has come in since on those that I redone the DPC. I kept them as tight to the cill as possible and made sure the DPC came out by the render. I tried to make the cutout as small as possible and lifted the window sill back into the direction of the house to keep it small.

Since the really bad weather, windows that were previously fine now have water coming in. House is plastered inside now so dont really want to have to take these windows out also. It would cause depression. Every night when the rain is pouring down it keeps me awake thinking of the water that might be getting in.

Some pics of the window removed and DPC re-done.

hadoken13

https://www.boards.ie/discussion/comment/121486049#Comment_121486049

Thanks Rednoggin. We think that is exactly what is happening with ours. I am as confused as you in that the water shouldn't be getting in at all in the first place.

Unfortunately for us, we cannot take out the sill from the inside as there is concrete there. The ICF contractor never left the ends out for the sills and I had to notch out the concrete at the front but left half of it at the back. Will be messy.

rednoggin

I also left the DPC up at the side of the sill. The second pic doesn't show it. My thinking is that any water getting in at the side could go over the DPC so keeping it upright keeps it in the DPC tray.

I'm waiting on the plasterer to come back and patch the sills, and no water is getting it despite the big gaps of missing plaster. I have pieces of insulation foamed in ready to plaster. Goes to show that once the DPC on the sill is done right, the water gets out rather than down the internal wall.

You'll get that concrete out no problem. Now is the time to do it while you can.

Another pic of the original leaking sill for reference. I dug it out from behind and drilled a hole out under the DPC. The hole is the level of the DPC. Way too low and cant get out.

bfclancy2

https://www.boards.ie/discussion/comment/121486049#Comment_121486049

you'll need more images so we can assess what you have done is correct, last image you showed doesn't look correct anyway, water will just run in on top of cill and back into wall

10-10-20

https://www.boards.ie/discussion/comment/121490394#Comment_121490394

I do see a drip-channel to prevent back-tracking of the water onto the wall/DPC.

bfclancy2

https://www.boards.ie/discussion/comment/121490451#Comment_121490451

i meant last picture from second last post with the dpc coming up the side of the sill and then across the top

rednoggin

https://www.boards.ie/discussion/comment/121490642#Comment_121490642

Don't have a photo of it currently but will take one later. I put the DPC up on the side as explained in other post so that if forms a tray. The wedged the gap with foam and cutout of insulation.

bfclancy2

https://www.boards.ie/discussion/comment/121494008#Comment_121494008

yeah that looks right in initial image it looked as if the dpc was continuing horizontally where the white shaded area is, is there any vertical dpc detail in the reveal in the ICF or is it not required

rednoggin

Vertical DPC is in place. From numerous hours hosing the window/reveal, no water came in at the reveals. It only came at the sill junction. From removing 3 windows there was no dampness around this area at all. I even got the reveals re-plastered but that didn't work either.

Another angle of the sill before removal.

hadoken13

We tested our windows and sills over the weekend with a hose, no water coming in. Then it rained and it was damp above the windows. Think it might be wind-driven rain coming in between the gap in the slates and fascia.

rednoggin

Is there are windows above the windows that are leaking, it could be them thats the issue. I've seen it come down from upper window and make its way down and out at top of the lower window.

If it is coming from your fascia/slates then that's an easier fix.

When I tested with the hose it could take 45 minutes before I'd see anything but hopefully your on the right track now.

hadoken13

No windows above. Wet way above the windows. Engineer is convinced its wind driven rain coming in the gaps between fascia and slates.