ICF Question for SAS and others

Lazybones

Hello All,

I have been following posts in relation to ICF (Insulated Concrete Formwork) and I was just looking for some feedback from those who had gone down the route.

In particular SAS, I know that you had put alot of research into the topic in terms of trying to get as low a U value solution as possible.

Have you decided to go down the ICF route or have you gone for another alternative?

For people who have gone down the ICF route is there any practical advice that you would now give to a newbie considering this option based on your experiences / frustrations and / or happiness with the method.

All input is welcome!

sas

Well its about damn time I got some respect around here

I haven't picked a build system yet. Based around lots of little reasons not least of which was that we made some changes to the design of the house that required resubmitting for planning which we did last week.

U-value for u-value I believe ICF to be one of the most expensive available build options. (All prices below include VAT)

SIPs are the most expensive hands down. A quote for a 0.16 u-value system I got was 165k. This included a SIP roof though.

A 0.15 u-value ICF system I got a quote for came in at 65k.

The biggest issue I have with ICF is the price of the render which runs to approx 50 Euros per square metre. That would add approx. 20K to my ICF quote.

The Passive House Institute has approved several ICF systems so fundamentally it must be good.

I have only found 2 ICF system suppliers available in this country that go below a u-value of 0.2.

External insulated block walls appear to be better value. Still waiting on a quote though so I'm not going to comment on it yet.

I got a real shock today though when I got from a timberframe company. The new design is approx. 4200 sq ft. For a 140mm external wall, easi-joist first floor, roof up felted and lathed for 48k including vat. This is an NSAI approved TF company and I've had a recommendation from a builder who built his own house with them and had nothing but praise for them. I thought that was great.

For details on company names you can PM me, forum rules prevent posting of company names.

Slig

External insulation was designed to be used on Poroton, an insulation in itself. When used with blockwork it creates cold bridges.

Whats SIP (Side impact protection?)

sydthebeat

Slig wrote: »

External insulation was designed to be used on Poroton, an insulation in itself. When used with blockwork it creates cold bridges.

Whats SIP (Side impact protection?)

Structurally Insulated Panels

see Kingspan TEK

sas

Slig wrote: »

External insulation was designed to be used on Poroton, an insulation in itself. When used with blockwork it creates cold bridges.

The thermal conductivity of poroton is equivalent to certain offset blocks such as quinnlite B3 or perinsul SL blocks which are used to mitigate this bridging.

Also, It depends on your foundation system. If you use www.isoquick.de for example then this won't be an issue.

The first certified passive house in this country was built with 215 mm single leaf externally insulated with EPS. They offset the bridge between the floor insulation and the external insulation by using a layer of quinnlite blocks that the floor insulation butts up against and reduces the bridge. See www.mosart.ie. I can't speak to it's effectiveness but it is certified by the PHI so I assume it does work.

Apart from at the ground floor wall junction I don't believe it introduces any other bridges.

Poroton can't be used below the dpc (qinnlites and perinsul can) so you still have this bridge to deal with, just to a lesser extent.

Lazybones

Lazybones wrote: »

For people who have gone down the ICF route is there any practical advice that you would now give to a newbie considering this option based on your experiences / frustrations and / or happiness with the method.

All input is welcome!

I built using an ICF system, (see blog below) and have found that the house is warm and low energy.
I got a system that gave a U value of about 0.18 in the panels alone, I actually specified the enhanced version of the system which gave me 50mm EPS on the inside leaf & 150 on the outside.

I did consider sticking another 100mm or so to the external panels to bring the U value down to 0.1 but dedcided that it was too far into dimimishing returns territory.

For me it was a DIY project! lots of minor hassles that an experienced builder wouldn't have.

muffler

sas wrote: »

Well its about damn time I got some respect around here

Ah sure you know rightly that we all love and respect you :cool: