ICF window sill water leakage

lebuck · 09-01-2010 12:28pm #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 3:45pm

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

lebuck · 09-01-2010 9:46pm

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 10:43pm

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 4:01am

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 9:52am

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 5:26pm

Sorry my bad

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

lebuck · 11-01-2010 1:46pm

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 2:59pm

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 3:11pm

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 5:08pm

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 7:11pm

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 8:37pm

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 11:29am

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

onq · 12-01-2010 4:52pm

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 6:56pm

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 3:22am

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 6:51pm

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 11:58pm

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 3:25pm

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 8:07pm

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 11:12am

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 12:32pm

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 2:09pm

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 11:41pm

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 3:35pm

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 2:37pm

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 7:44pm

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 6:48pm

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 7:46pm

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 11:19pm

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

ICF window sill water leakage

Comments