Hello, this may be just a crazy idea but has anyone built there own icf house, without the use of pre formed blocks?

i`m currently drawn to the woodcrete blocks like Isotex, mainly due to finishing up with a timber interior surface for fitting kitchen units etc.  I`m currently waiting on a quotation from the supplier, but i am expecting it to come in around 45K for the supply of the blocks, it then occurred to me, is it possible to build my own using a 150mm kingspan sheet bolted with spacers to an 18mm OSB board leaving a suitable cavity for concrete. The finished product would then simulate a sips build on the outside with a concrete thermal mass on the inside! My build is a dormer bungalow with gables, so assuming i build adequate bracing to prevent blow out & have the structural engineer calculate the rebar required, materials would come in at less than half the cost of preformed blocks!

just a thought!

Woodcrete is not sufficient for screwing things like kitchen units to. You can install strips of plywood, and put lots of screws through that, into the woodcrete and over a much bigger footprint, but not directly afaic. 

It has pockets where there is great purchase for fixings, and then voids with naff all, same as the Velox build I’m on atm. 

Yes, it would be crazy. Do not underestimate the amount of force and pressure even a 1.2m concrete pour exerts on formwork. Youll need a lot of extra support and bracing. It would also take much, much longer, defeating one of the big selling points of ICF. Look in to Amvic, Nudura and Integraspec as well for a full range of options and prices.

2 hours ago, Glen said:

Hello, this may be just a crazy idea ...

 

Yes, it is crazy.

But to know the difference between crazy and sensible the question needs to be asked. All credit to you, therefore, for asking it.

 

If the idea were sensible, everyone would be doing it. If this board  demonstrates one thing it's the creativity and drive that self-builders have. And at the planning stage all sorts of ideas bubble up. Some need tempering with experience.

If you can, get permission to view a pour on an ICF house. The forces exerted are huge.

 

As I know to my cost: cost as in I'd be able to change my car now if ..... ahhhh, never mind just look at my posts about ICF

1 hour ago, Conor said:

Yes, it would be crazy. Do not underestimate the amount of force and pressure even a 1.2m concrete pour exerts on formwork. Youll need a lot of extra support and bracing. It would also take much, much longer, defeating one of the big selling points of ICF. Look in to Amvic, Nudura and Integraspec as well for a full range of options and prices.

Thanks for that Conor, yes i`ll look into the alternative suppliers as i`m keen to follow this method of construction. As for the DIY approach i`m aware of the lateral forces of wet concrete, i was just wondering if anyone on the forum had done this before. I was basing the idea on similar constructions i had seen witnessed in Germany. Thanks again for your imput.

2 hours ago, Nickfromwales said:

Woodcrete is not sufficient for screwing things like kitchen units to. You can install strips of plywood, and put lots of screws through that, into the woodcrete and over a much bigger footprint, but not directly afaic. 

It has pockets where there is great purchase for fixings, and then voids with naff all, same as the Velox build I’m on atm. 

Thanks Nick, good advice

6 minutes ago, Glen said:

.... I was basing the idea on similar constructions i had seen witnessed in Germany. Thanks again for your imput.

 

You've got me hooked.

Where? Do you have a link to examples?

2 hours ago, Glen said:

Hello, this may be just a crazy idea but has anyone built there own icf house, without the use of pre formed blocks?

i`m currently drawn to the woodcrete blocks like Isotex, mainly due to finishing up with a timber interior surface for fitting kitchen units etc.  I`m currently waiting on a quotation from the supplier, but i am expecting it to come in around 45K for the supply of the blocks, it then occurred to me, is it possible to build my own using a 150mm kingspan sheet bolted with spacers to an 18mm OSB board leaving a suitable cavity for concrete. The finished product would then simulate a sips build on the outside with a concrete thermal mass on the inside! My build is a dormer bungalow with gables, so assuming i build adequate bracing to prevent blow out & have the structural engineer calculate the rebar required, materials would come in at less than half the cost of preformed blocks!

just a thought!

 

 

You could, but you would have to use supports and shuttering that they use on civil construction. There is a table on BH somewhere that gives a cost per sqm of ICF systems external walls including concrete.  I think that Isotex is about £70 per sqm, so £45K is a very big bungalow.

Edited November 23, 20223 yr by Adrian Walker

I've just had the following costs from Econekt

300mm Elements, 150mm concrete core - 0.19W/m2K 112 m2 £ 58.95 £ 6,602.40

Upgrade from Prince to King and a u value of 0.15W/m2K would be £15.34/m2 so circa £2,040 up.

Upgrade from Prince to Super King and a u value of 0.11W/m2K would be £25.06/m2 so circa £3,332 up.

Problem with these was delivery charge to my location.....

 

My 190sqm Chalet bungalow with Isotex blocks is a lot less than £45k 

As far as fixings are concerned, with heavy items like kitchen units and windows / doors you fix through the woodcrete into the concrete 

Same with me for Durisol approx. 190m2 plus 3m tall, less than half that price delivered to NE Scotland.

@JohnMo, are Durisol-UK still trading?  I thought they were (are?) in receivership. 

From what I heard a month or so ago, they have been taken over, not certain if they are back trading yet

The big thing about Durisol UK (for an intending user ) would be the lead time for supply and - worse- re-supply.

No reason it couldn't be done but you'll need conventional shuttering pans I would have thought. 

 

You could forgo the OSB. 

 

Shuttering concrete is very fast. I had an agri job done last year. 117m2 in 3 days. No openings in that however.