Insulated Concrete Formwork Sill problems

orwellgeorge

Has anyone encountered problems with dampness occurring in ICF houses where traditional concrete sills have been installed? I have recently built a ICF house and water is coming through at the sill level. I would be very interested in hearing from anyone with similar problems.

The probelm is essentially due to using concrete sills which work fine in a double skin construction, ie cavity wall with Damp proof trays at windows etc, in what is a single skin construction, ie ICF.

(see page 69 0f homebond 5th edition for DPC detail at sills)

Even if the sill is wraped in DPC it is highly likely that the DPC will get knocked out of place as the concrete is poured from the top of the wall into the cavity. Even if this dose not happen the concrete will form a bridge over the top of the end of the sill that protrudes into the cavity and so water penetrating the plasterwork at the reveal will seep into the concrete and from there into the house.

Anyone encounter similar problems?

orwellgeorge

dampness due to water ingress at sills.

I built an ICF house but have had no problems, I used concrete "TF" type sills and fitted them after the concrete had been poured.

The sill is sitting outside of the concrete core on brackets (in the external ICF) thus eliminating cold bridging & damp.

orwellgeorge

What are TF type sills? I presume that your windows are sitting over the sill and thus are much nearer to the outside than the inside? Are they outside the line of the concrete? What ICF system did you use?

Many thanks

orwellgeorge

sorry TF = timber Frame

orwellgeorge

orwellgeorge wrote: »

What are TF type sills? I presume that your windows are sitting over the sill and thus are much nearer to the outside than the inside? Are they outside the line of the concrete? What ICF system did you use?

Many thanks

I used Eurozone with 150mm Polystyrene outside & 50mm inside, yes the windows are fitted in the outer leaf of polystyrene in a similar way to timber frame ones.
I wanted to avoid a cold bridge in the concrete surrounding the frame.

orwellgeorge

Was there any DPC used as a second line of water barrier? Was a verticle DPC installed on each side of the Window, or did you rely on the Insulation to act as a DPC?

orwellgeorge

orwellgeorge wrote: »

Was there any DPC used as a second line of water barrier? Was a verticle DPC installed on each side of the Window, or did you rely on the Insulation to act as a DPC?

I have a dpc tray around the sill but just relied on the insulation around the frame, no problems so far, even with driving rain before the house was plastered (a bit of horizontal rain through a gap in one of the gables but that was only temporary).

orwellgeorge

Thanks Dolan Baker

1not24get

orwellgeorge wrote: »

Has anyone encountered problems with dampness occurring in ICF houses where traditional concrete sills have been installed?

Looking at the photo you have posted, it looks like there's water/damp coming in at the DPC at floor level as well...is this right??

muffler

1not24get wrote: »

Looking at the photo you have posted, it looks like there's water/damp coming in at the DPC at floor level as well...is this right??

Thats probably the run off from the sill

1not24get

muffler wrote: »

Thats probably the run off from the sill

I don't know....the ICF has darker patches running from the floor wall junction up the wall and is continuous along the floor wall junction horizontally in either direction passed the window. Orwellgeorge, has this happened anywhere else in the house?

Could that be standing water outside the wall? (didn't see the photo earlier)

orwellgeorge

It's a combination of both but principly from the sills, there are three windows on that wall. The DPC was laid flat on the raft (which did not have a step in it, a big mistake in hindsight) since the concrete is poured in rather dry, it dose not form a watertight seal. However we have eleminated most of the floor dpc problem.

The combination of installing a concrete sill, which is designed for a double skin wall (ie cavity wall) into a single skin structure is leathal. I believe that this problem will show up in many ICF houses in the near future. I'm working on designing a system that will get over this.

For the house which is already construted we are cutting out a neat 8-10mm gap all the way around the sills and windows and filling it with a special silicone from Sika. It is not a perfect solution but it is the best that can be done right now. It will mean monitoring it for years and perhaps replacing it after 20 years or so. The particular product is very impressive, very sticky and sets like a rubber with good adhesion to the render, the PVC and the concrete sill.

orwellgeorge

Dolanbaker, May I enquire what ICF system are you using? We are using Euromac 2.

Did you have a step in the raft just inside the wall? was there any 'waterbar' type system used to prevent water getting in at floor level?

Very much appreciate all the replies from every one.

orwellgeorge

Information. Modern renders, from Weber, Lafarge, Maxit etc. are great produtcs and really are waterproof. However as they are made of different materials to windows and doors, they expand and contract differently. Thus it is necessary to put a line of flexible mastic, or silicon around all window and door edges where the two meet. In cavaity wall construction this was not needed as any dampness that penetrated simply went down the inner face of the outer leaf. Not so with the solid construction of an IFC wall.

The IFC companies say you don't need to do this, the render companies say you don't need to do this( even though thiere manuals say so). I can tell you from first hand experience that it is totally necessary. I feel that over the next few years IFC will wrongly gain a bad name for leaks at window and door reveals and soffits. If you want to prevent these leaks go by the technical manuals of the render companies and apply a specill seal or apply a line of mastic around each window and door where they meet the render.

1not24get

orwellgeorge wrote: »

Thus it is necessary to put a line of flexible mastic, or silicon around all window and door edges where the two meet.

Could you name a brand name of silicon mastic that would definitley work as there are so many to choose from?

orwellgeorge

orwellgeorge wrote: »

Dolanbaker, May I enquire what ICF system are you using? We are using Euromac 2.

Did you have a step in the raft just inside the wall? was there any 'waterbar' type system used to prevent water getting in at floor level?

Very much appreciate all the replies from every one.

I am using the Eurozone ICF system, I've built of a strip foundation plus 600mm rising wall also using ICF.

The whole building is surrounded by gravel, no damp problems at DPC level.

orwellgeorge

1not24get wrote: »

Could you name a brand name of silicon mastic that would definitley work as there are so many to choose from?

Sikaflex Pro 2HP. you have to use special primers, on for the join between the window and sill and another between the render and the PVC

1not24get

orwellgeorge wrote: »

Sikaflex Pro 2HP. you have to use special primers, on for the join between the window and sill and another between the render and the PVC

Thanks

narommy

Deleted User wrote: »

I built an ICF house but have had no problems, I used concrete "TF" type sills and fitted them after the concrete had been poured.

The sill is sitting outside of the concrete core on brackets (in the external ICF) thus eliminating cold bridging & damp.

Hi

What are "TF" sills made from? concrete or aluminium. couldn't tell from blog

could you do a sketch (in paint or something) showing the detail of the above and how they were fixed to walls.

would appreciate as considering ICF and it is the cold bridging, thresholds and sill detail that worries me.

orwellgeorge

Anyone having problems with Insulated Concrete formwork houses should post here. I have quite abit of experience with these, in particular water ingress at various points, such as at the sills. window and door reveals, etc. The solutions are not simple but will last.

orwellgeorge

Anyone having problems with Insulated Concrete Formwork houses should post here. I've been involved with the construction of a large ICF house and can provide some solutions to problems with water ingress at sills and window and door reveals.

muffler

orwellgeorge wrote: »

Anyone having problems with Insulated Concrete Formwork houses should post here. I've been involved with the construction of a large ICF house and can provide some solutions to problems with water ingress at sills and window and door reveals.

You already have a thread on this matter.

Please refrain from starting multiple threads on the same subject.

Moved to existing thread.

orwellgeorge

About 6 weeks ago I posted asking if anyone encountered problems with ICF houses, especially window sills, window/door fitting, etc.,

I'm posting again to raise the question again. So if anyone out there has had problems with ICF houses, post it here and hopefully we will be able to give some advise.

muffler

orwellgeorge wrote: »

About 6 weeks ago I posted asking if anyone encountered problems with ICF houses, especially window sills, window/door fitting, etc.,

I'm posting again to raise the question again. So if anyone out there has had problems with ICF houses, post it here and hopefully we will be able to give some advise.

Have you a link to that post?

Im too lazy to go looking for it.

I've built an ICF house and can't think of any major problems.

I don't understand what you are asking, are you offering solutions to ICF related problems or are you asking for advance warning of things to watch out for.

muffler

orwellgeorge wrote: »

About 6 weeks ago I posted asking if anyone encountered problems with ICF houses, especially window sills, window/door fitting, etc.,

I'm posting again to raise the question again. So if anyone out there has had problems with ICF houses, post it here and hopefully we will be able to give some advise.

First of all I am moving this to the older thread.

Secondly I see that I previously advised you about starting multiple threads on the same topic but the warning appears to have fallen on deaf ears.

Have a weeks holiday.

muffler

Thread locked.