ICF window sill water leakage

lebuck · 09-01-2010 11:28am #1

I realise there was a thread posted about ths issue previously but the thread was closed so i have opened this subject again.

Basically we have recently constructed an ICF house and we have encountered water leakage underneath the windows inside the house. At first any of the water appearing, occured in the first floor of our house and it always occured directly underneath the window on the first floor screed and it was dependent on the wind direction of the driving rain. Both i and the builders beleive the water is penetrating the area around the sill and subsequently finding its way down the concrete layer of the ICF before it meets the first floor concrete screed. I should add that the sills are limestone and that we have not encountered any problems in an area of the house where larger limestone sills were used in conjunction with stonework.

Recent torential rain also managed to find its way into the ground floor of the house - again appearing directly beneath the windows. We are now at a stage where we want to move into the house and this water issue is holding up the whole project, expensive given the fact that we are renting another premises. Any experiences or advice here would be greatly appreciated.

Poor Uncle Tom · 09-01-2010 2:45pm

Did you use dpc's around the cills and is there a stone veneer on the outside of the house?

lebuck · 09-01-2010 8:46pm

Yes we did use DPC around all the cills in the house. A portion of the house has a stone veneer hence the requirement for bigger cills and a portion of the house was finished using an IAB approved acrylic render. All of the leakage so far has occured in the portion of the house with the acrylic render finish, here a cill with less length would have been used.

Poor Uncle Tom · 09-01-2010 9:43pm

Yes, I have seen where the DPC's were not tightly fitted to the cills and allowed some moisture run in underneath and gain easy access, it may be the same in your case.
Get your builder to check the dpc to insulation joint, this needs to be sealed tightly.

zziplex · 10-01-2010 3:01am

Dpc as said above but it could be a number of things,

Do the limestone cills have a sufficent capilliary groove on the underside of the cill? I presume they have but you never know..When you say leak is it actually a leak or more moisture? Dirty wall cavitys can be common enough and can lead to moisture.

Poor Uncle Tom · 10-01-2010 8:52am

zziplex wrote: »

Dpc as said above but it could be a number of things,

Do the limestone cills have a sufficent capilliary groove on the underside of the cill? I presume they have but you never know..When you say leak is it actually a leak or more moisture? Dirty wall cavitys can be common enough and can lead to moisture.

ICF...
http://www.youtube.com/watch?v=nUoWsmRD9mA

no cavities...

zziplex · 10-01-2010 4:26pm

Sorry my bad

I did not read thread properly was a bit drowsy at 3am this morning haha........

lebuck · 11-01-2010 12:46pm

A number of weeks ago the builder excavated the area behind the cills of 2 of the affected windows to examine the DPC. On investigation the DPC appeared to be sitting snugly against the cill and fitted correctly. We patched up the windows again with even more insulation and as soon as we had driving rain the water re-appeared. It really has left us scrathing our heads!!!!

gillad · 11-01-2010 1:59pm

You have checked the dpc at the back of the cill,bit if the dpc under the cill is not going ALL the way to the outside then this could be your problem

lebuck · 11-01-2010 2:11pm

You could be onto something Gillad. We do know that when the plasterer prepaperd the walls and reveals for plastering he cut the DPC that was under the windows right back against the wall which he duly plastered. We recognised this as a weak point and we applied a silicon that was compatible with limestone and acrylic render at the window/cill joint all around the window. Again this failed to solve our problem as the water, particularly with high wind keeps seeping in.

gillad · 11-01-2010 4:08pm

My vision of what may be happening is that the rain is seeping down between the dpc and the cill and is pooling under the cill.(I have seen this happen before)and maybe a rip in the dpc or because its only going to the inside of the plaster,the water is running down between the wall and plaster.
Sealing the outside joint as you described will only trap the water inside,if this is the problem.Some limestone is porous and this could be how water may be pooling.

Easy test for porosity: On the unsealed stone place a drop of water and wait about 10 minutes. Use a clean towel to wipe dry. Superior quality will either be dry immediately or become completely dry in under 1 minute. Poor quality stones, due to their porosity will absorb the water and, remain wet for an hour or more, even after being wiped with the towel.
The easy way to test if this is your problem is to seal the limestone cill with a good sealant,there are plenty to choose from.

lebuck · 11-01-2010 6:11pm

Thanks for this Gillad, we have already sealed the cills with a prescribed sealant which is supposed to be the best around. I think your pooling theory could be on the money. The next step for us is to find out exactly where the water is seeping in through the plaster. The builder and i have a theory that it maybe the joint between the cill and the plaster and the window frame and the plaster, even though we have siliconed it. What do you think?

gillad · 11-01-2010 7:37pm

You seem to have done everything possible and there is nothing else i can think of.
To find out for sure if the cill is your problem,you need to take out the cill (from the inside is the easiest,window can be left in) during or just after wet weather when you have dampness and investigate .

lebuck · 12-01-2010 10:29am

We have had plenty of rain overnight so we might just take out cill to have a look. Thanks Gillad.

onq · 12-01-2010 3:52pm

I haven't used this form of construction in RL and I'm assuming the wall is a sandwich of :

external render
insulation
concrete in situ
insulation
internal wall finish.

The weak points seem to be:

The impermeability and continuity of the external render
The back up provided by the insulation / its jointing
The level of cavitation/vibration of the concrete
The daywork joints in the concrete
Cracking in the concrete not controlled by the joints
The penetration of the window
The penetration of the sill
The DPCs around the window and sill
The action of the internal insulation near the window and its reveals
The protection of the wall and internal insulation from condensate of water vapour [vapour check].

I have previously been advised by a Building Control Oficer in relation to cavity walling that he wanted his DPC coming up the back of the cill, but not wrapped over the top, in case water got past the seal and down the back of the DPC and past the sill

The DPC should be checked at the sides of the window to see that it correctly tucked in to the sill DPC/tray.

The DPC should be checked below the window to see that it projects beyond the external render to protect it.

(I am assuming there is a DPC here and I stand corrected if not - its another pressure point for the driving rain)

Is it possible that this is water from within the building condensing on the face of the concrete wall and running down?

Has limited opening up work been carried out inside and outside below the window to trace the fault?

If this is a generic fault with either all the windows as opposed to just one window or with the walls, then once the wind shifts you may see it elsewhere in the house.

FWIW

ONQ.

lebuck · 12-01-2010 5:56pm

Hi ONQ,
Many thanks for your comprehensive email.
1. Answer is yes to all of your initial questions.
2. We have excavated the area behind the cill (inside the house). We have not carried out an excavation outside under the cill. But to get to the bottom of this we will carry one out during the week. We certainly think the area beneath the cill is a very susceptible point even when it is siliconed.

Say a prayer for us!!

onq · 13-01-2010 2:22am

lebuck wrote: »

Hi ONQ,
Many thanks for your comprehensive email.
1. Answer is yes to all of your initial questions.
2. We have excavated the area behind the cill (inside the house). We have not carried out an excavation outside under the cill. But to get to the bottom of this we will carry one out during the week. We certainly think the area beneath the cill is a very susceptible point even when it is siliconed.

Say a prayer for us!!

Better to find out now than at completion - ablessing in disguise, maybe.
It pays to consider all the facts you can brainstorm when faced with a mystery.

In summary:
If you're relying on your render have it checked for waterproof-ness.
If you're relying on the insulation have it checked for splits, cracks, joints.
If your relying on your concrete have it checked for daywork joint continuity, cavitation and cracking.

HTH and best of luck.

ONQ.

PS Although I'm not a great fan of the thing checking the concrete with a moisture meter might also help determing if there are paths through it where its damp.

hyland · 20-01-2010 5:51pm

Hi Lebuck,

I would be very interested to know how you get on with this. we moved into our ICF house in July. we also have limestone cills. we have a terrible problem with leaks in the house that maybe related to the limestone cills. we have had numerous people look at it and nobody can solve this issue. we had to taken up floors and our windows are destroyed.

if you need any information from my end let me know

lebuck · 23-02-2010 10:58pm

Dear Hyland,

Please give me a cal please <SNIP>, sounds like we have a common.

Lebuck

Edit: No Phone Numbers on thread, infraction given.

onq · 25-02-2010 2:25pm

Lebuck,

How has this worked out?

You were to come back and let us know.

Did you trace the problem and stop the leaks?

ONQ.

billybobby · 15-03-2010 7:07pm

im a window maker and fitter and i have come across this alot from bad window fitters where they screw into the cill and seal the outside of the window(which means the water has to go inwards or through the walls and remember water will take the easiest routedown) all windows have a condensation channel on wood and alu its visible at the back of your window board and on pvc its inside the window but all windows condensate alot specially when a house is new build as the drying concrete and plaseter release moisture int atmos and land on the coldest spot usually the window no matter how high the grade of window but if the window people did screw through the window the moisture will travel down the screw into the cill and cause a leak in the cill and the dpc normally having been trimmed by plasterers will cause leaks under the cill
just thought id voice an opinion on it as everyone seems to be blaming the cill and not the window which could have loads of faults i have even seen pvc windows and doors fitted with the drainage hole inside the house lol it can happen and more than you would think hope this helps

mchammer · 24-01-2011 10:12am

just wondering if you sorted this out as I have a similar problem where the water pools up in the DPC around the sill especially behind it and then seeps out slowly causing damp spots. I found this out by removing the internal window sill and inspecting the DPC at the back of the sill in the cavity.
Not sure how the bloody water is getting there though.. I am definitely taking the sill out and going to replace the dpc with lead tray which I hope will solve it

Poor Uncle Tom · 24-01-2011 11:32am

mchammer wrote: »

just wondering if you sorted this out as I have a similar problem where the water pools up in the DPC around the sill especially behind it and then seeps out slowly causing damp spots. I found this out by removing the internal window sill and inspecting the DPC at the back of the sill in the cavity.
Not sure how the bloody water is getting there though.. I am definitely taking the sill out and going to replace the dpc with lead tray which I hope will solve it

ICF (insulated concrete formwork) is a different type of costruction to a cavity wall build.

davymc31 · 30-01-2011 1:09pm

hi all im fitting windows 25 years and still come across cowboy blocklayers that still dont wrap dpc up on end of cills to make sure water does not flow back in and use too small dpc that wont fold up high enough on inside of window to break bridge from inside to outside.the worst i come across is houses with stone to outside its like nobody know how to do blockwork to windows or the way the dpc should be done ive pointed this out to a lot of house owners and builders (so called) but to no avail,the worst are self builds where nobody checks work ,ive went to measure windows to find out and see dpc cut same length as cill with no fold up and told house owner but was never sorted and they hope theyll have no problems ,,,,,,,but some people wont listen.........if you have a leaking problem go to your engineer and make him responceable as he wasto check all workmanship...but to all ye with leaks im can say 100% it your dpc not done right

galwaytt · 30-01-2011 10:41pm

lebuck wrote: »

...We certainly think the area beneath the cill is a very susceptible point even when it is siliconed.

Say a prayer for us!!

Can I just say a thing about silicone: do not rely on it for keeping water out. Even if it works at the start, it will dry out over time, shrink, and become less-than-useless. Anyone who has a bathroom any more than a few years old will be familiar with this phenomenon.

The key to waterproofing is more than the materials - it's the details. The water/damp egress detail is the first line of defence, and the sealant, second, for incidental or extraordinary circumstance sealing.

Use a non-setting polyurethane sealant.

I did a quick google for ICF window cill detail, but failed miserably - anyone got a link to a good diagram ?

TysonICF · 02-01-2015 2:35pm

Hi Lebuck,
I know its a few years since you put in a post about leaks around the windows of an ICF build. Did you get it fixed? I have the same problem & would appreciate your advice. Thanks

Festwaukee · 18-03-2023 1:37pm

Hi All,

Did any of ye fix your leaks? I have a similar issue except the dpc is cracked in spots at the back of the sill. I hope ye fixed them with out having to take out the sills

rednoggin · 01-05-2023 6:44pm

https://www.boards.ie/discussion/comment/120372678#Comment_120372678

Was it your DPC that Failed festwaukee?

I've water coming out of DPC thats punctured. Only issue is that I have several windows leaking at floor level of ICF, right under them. House is rendered, sealed with silicone around cill and water is still getting in. Real head scratcher.

Festwaukee · 25-06-2023 5:48pm

It seems to be coming in on the reveal where the sill is and going the wrong side of the dpc. Are you in your house?

pipes85 · 14-07-2023 6:46pm

Another new icf house with cill issues. I went with aluminium cills from the window provider and have had torture sealing them. There’s a couple that have me bamboozled, I’ve tried everything at this stage.

Kilough · 22-07-2023 10:19pm

Screenshot_20230722_231602_Adobe Acrobat.jpg

Starting my own ICF in a couple of months and hoping I don't run into same issues! See detail attached, may be of use. There is a ICF ireland page on FB with plenty of useful information and knowledgeable folks who might be able to offer advice too

10-10-20 · 23-07-2023 3:25pm

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 · 24-07-2023 9:48am

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

Would you mind sharing the details of the manufacturer please?

10-10-20 · 24-07-2023 10:06am

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

Passive Sills in Cork.

Scoopsire · 24-07-2023 10:28am

Thanks!

sydthebeat · 24-07-2023 11:11am

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 · 24-07-2023 12:19pm

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

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

rednoggin · 17-10-2023 9:45am

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 · 17-10-2023 10:03am

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 · 06-11-2023 8:06pm

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 · 11-12-2023 6:47pm

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 · 12-12-2023 10:51am

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 · 12-12-2023 11:20am

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 · 13-12-2023 9:38am

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 · 13-12-2023 12:10pm

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 · 13-12-2023 12:24pm

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 · 13-12-2023 1:11pm

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 · 14-12-2023 11:16am

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 · 15-12-2023 11:35am

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 · 19-12-2023 11:42am

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 · 19-12-2023 7:44pm

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.

ICF window sill water leakage

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