ICF How much more expensive ?

[Dave Jones]

how much more expensive than traditional brick/block is ICF ?

 

2, 3 4 x more ?

 

A site has come up locally which we may buy to help kids build a starter home. Render isn't an option due to planning so will have to be brick/slip external skin but all other options are on the table. Rules out timber frame as too expensive, if ICF comes in cheaper than brick and block would take a look. 

 

I guess the immediate savings are insulation, lintels and time ?

[Conor]

I worked it out as 1.25 times more for walls of  U 0.12. The higher the insualtion spec you are going for, the less of a difference.

 

BUT openings are so much simpler and faster. And you don't have to worry about gaps in insulation boards, or damp/airtight detailing.

[JohnMo]

Really all depends on how you compare.

 

ICF, can be put in just about any weather, block work has limitations.

You can easily do it yourself, or are you paying for a squad to do it for you?

You need to do a couple of concrete pours, do you have access for the concrete lorry and the concrete pump lorry and boom, depending ICF system, you may need to factor in support props for the pour. Block work you need access for a cement mixer, and somewhere to drop of blocks.

 

Really depends on a number of factors. I did ICF and there is a post I did a while ago that details all our costs, it wasn't that expensive. But I did all the work myself with a paid guy to assist me. The walls were completed in Dec 2020 and me 4 weeks to complete, 70m perimeter by an average of just over 3m tall.

[nod]

I think you will be somewhere in between Solid and TF We looked at ICF as an option It was only the material price hikes that stopped us 

TF costs are now ridiculous 

[Dave Jones]

1 hour ago, JohnMo said:

Really all depends on how you compare.

 

ICF, can be put in just about any weather, block work has limitations.

You can easily do it yourself, or are you paying for a squad to do it for you?

You need to do a couple of concrete pours, do you have access for the concrete lorry and the concrete pump lorry and boom, depending ICF system, you may need to factor in support props for the pour. Block work you need access for a cement mixer, and somewhere to drop of blocks.

 

Really depends on a number of factors. I did ICF and there is a post I did a while ago that details all our costs, it wasn't that expensive. But I did all the work myself with a paid guy to assist me. The walls were completed in Dec 2020 and me 4 weeks to complete, 70m perimeter by an average of just over 3m tall.

 

How did you face the blocks externally ?

[Dave Jones]

recticel with 150mm cav is 0.13U which looks very good.

[JohnMo]

32 minutes ago, Dave Jones said:

How did you face the blocks externally

I used Durisol, half the the house is clad in stone slips, these are attached directly with flexible outdoor tile cement, the other half is wood clad, used breather membrane, wooden battens directly screwed into the woodcrete.  All pretty simple.

[Iceverge]

Nothing came close to the cost of a wide cavity block wall for us in 2019/20 except the crappiest PIR filled TF. 

 

 

[Nickfromwales]

With an EPS based ICF block you will become water-tight almost immediately, and getting a crazy-good AT score is almost guaranteed, even for a novice. There's enough support on here to get you through this, if you want to completely DIY it, but you will 100% need to prop or the walls will go to shit when you pour. Suppliers will offer training, and iirc you can hire the props etc.

Getting a masonry build AT is easier if you DIY, with a bit of basic understanding of course, but almost impossible if you employ a general builder and "pop in every now and then" to check how "things are going".

[JohnMo]

1 hour ago, Nickfromwales said:

but almost impossible if you employ a general builder and

Someone did that near us, company rep went to site, just before first pour and  told them to take the whole lot down, as blocks had not been consistently stacked sometimes the thick insulation was inside and then outside, inside corners had been butchered to use as outside corners etc...

 

Edited April 30, 2023 by JohnMo
Spelling

[Dave Jones]

3 hours ago, Nickfromwales said:

With an EPS based ICF block you will become water-tight almost immediately, and getting a crazy-good AT score is almost guaranteed, even for a novice. There's enough support on here to get you through this, if you want to completely DIY it, but you will 100% need to prop or the walls will go to shit when you pour. Suppliers will offer training, and iirc you can hire the props etc.

Getting a masonry build AT is easier if you DIY, with a bit of basic understanding of course, but almost impossible if you employ a general builder and "pop in every now and then" to check how "things are going".

 

the mega rush to weathertight is pointless unless you planning a 3 month build. Same as a timber frame waste of ££££££

[Nickfromwales]

3 hours ago, Dave Jones said:

 

the mega rush to weathertight is pointless unless you planning a 3 month build. Same as a timber frame waste of ££££££

We will never see eye-to-eye on that theory. Being dry on the inside stops the building from being saturated, and the effects of that saturation cause issues for MONTHS after the externals are rain / weather tight. If you're building through the summer then not so much of a prob, but during and after winter it is an absolutely royal PITA, just like prince Andrew, lol.

[Dave Jones]

looks to me that ICF is just over double the cost of traditional build which is a shame. A little cheaper for rendered/clad but those options are a poor downgrade from facebrick both for value/appearance and ongoing maintenance.

 

I'd still like to try it out at some point, maybe a garage or garden room.  Timber prices are also still far too high to use SIP panels as well which is really annoying as a more carbon neutral build is always good to aim for.

 

So back to brick and block for the foreseeable future where costs are the overriding factor.

[Dave Jones]

22 hours ago, JohnMo said:

I used Durisol, half the the house is clad in stone slips, these are attached directly with flexible outdoor tile cement, the other half is wood clad, used breather membrane, wooden battens directly screwed into the woodcrete.  All pretty simple.

 

could you post a photo of the brickwork. Did you use a tiler or a brickkie ?

[Jenki]

I've switched plans from stick build timber frame to Polysteel ICF.

I've got 40 linear m of external wall single storey.

My budget is beyond tight, some would say no chance.

When looking at the cost of timber, OSB (two layers for racking),  additional structural support due to location ( 3 off steel sheer walls). 

The inflated cost of fibre insulation, costs of air barriers and tapes.etc ICF is working out a couple of grand more expensive. It's totally DIY.

My location is also causing expense for delivery, so the idea of one delivery cost for the walls / foundation is offering a saving.

My location is windy, so again getting this built once, and the insulation/ airtightness is all in one is a great positive. I just need to worry about airtightness at ceiling level and obviously doors and windows.

Blocks are ordered and shuttering for the footings start in two weeks. Time will tell, but I'm quite confident, as the costs for the walls  are fixed now.

[saveasteading]

44 minutes ago, Jenki said:

3 off steel sheer walls

That always seemed excessive to me. Timber and plywood woild have been my choice, costwise.

I like timber because things can be adapted to fit, and fixings are easy.

 

But i can see the attraction. You will have a heavier structure that won't budge in the wind, or creak. Not only that but you will sleep easier.

 

A small building in a windy place can suffer extreme wind loads. If I remember rightly, an extreme wind gust is typovcally about 15m wide, engulfing and tugging at your dinky home.

 

What will the roof be made of? Wind at edges and especially corners  can be very destructive, and yours is mostly edges.

[Jenki]

36 minutes ago, saveasteading said:

That always seemed excessive to me. Timber and plywood would have been my choice, costwise.

I like timber because things can be adapted to fit, and fixings are easy.

I agree, but the certificate of design in Scotland, which I think is a good thing, restricts changes on the fly, and the structural guy wanted those sheer walls, and two layers of OSB and some internal racking walls. All adding to costs.

The gables are being timber framed and fink trusses, this was a cost decision, as eliminated another pour for the gables.

In keeping with the highland vernacular, there is minimal soffit / overhang.

The change to insulation at ceiling level ( cold loft) was also a cost decision. I'll have a nice service cavity at the ceiling to minimise penetrations into the airtight membrane, and I'm running hot and cold water in conduit in the slab insulation with manifolds to eliminate any joints. 

 

[Iceverge]

I wonder if there a novelty factor with ICF that folks like.

 

I remember being enthralled by it when I first saw it. I can build my own house I thought, just like Lego. Then I saw the cost of the blocks and nearly fell over. 

 

The trouble is that it's soft on the outside and crunchy on the inside. The wrong way around in my opinion. 

 

Much of the lovely "Legoness" goes out the window when you see all the bracing needed and the rebar. The cost of the silicone render made me fall over again.

 

The U Values out of the box aren't often anything special and need a bit extra added. What really puts me off is the risk of needing another 2 blocks and having to wait for them to come from the moon or that awful situation like Insulhub where people lost all the money by needing to pay lots of cash upfront. 

 

For now, sticks of timber or blocks/bricks still have lots going for them unless you're building below ground, really need the speed, or have some onerous requirements that necessitate poured concrete.   

Edited May 1, 2023 by Iceverge

[SteamyTea]

1 hour ago, Iceverge said:

I can build my own house I thought, just like Lego

Yes.

I had Lego, and Meccano sets as a kid.

There was never enough to make anything interesting.

To make something required also buying the next kit up.

 

I never understood why people don't build a stick build shed, them make TF modules in it.

But then I am always amazed that people think spending 100 quid making a flat, 8 by 4 table is a waste of money and prefer to scrabble around in the mud, with a hand saw.

[FM2015]

If you actually do a fair, like for like comparison, there is little difference for a good spec of building.

 

Geography plays a part, for example in some areas, block layers aren't getting up for less than £2/ block.

 

Timber frame might go up to wall plate quickly but to get to the same stage as an ICF gives you at wall plate, there another half dozen stages.

 

ICF should be quicker to fit out, plasterboard etc with much less waste.

 

Pound for pound the end product is better.

 

So is it cheaper?  Is it expensive?  Is it quicker?  Depends on where you are, what you're building, who's building it, are the follow on trades experienced, and critically do you want a Bentley made by BMW or Reliant.  The Bentley is going to fall on the expensive side but who makes it determines the value for money.

 

 

[Jenki]

1 hour ago, Iceverge said:

I wonder if here a novelty factor with ICF that folks like.

 

I remember being enthralled by it when I first saw it. I can build my own house I thought, just like Lego. Then I saw the cost of the blocks and nearly fell over. 

 

The trouble is that it's soft on the outside and crunchy on the inside. The wrong way around in my opinion. 

 

Much of the lovely "Legoness" goes out the window when you see all the bracing needed and the rebar. The cost of the silicone render made me fall over again.

 

The U Values out of the box aren't often anything special and need a bit extra added. What really puts me off is the risk of needing another 2 blocks and having to wait for them to come from the moon or that awful situation like Insulhub where people lost all the money by needing to pay lots of cash upfront. 

 

For now sticks of timber or blocks/bricks still have lots going for them unless you're building below ground, really need the speed, or have some onerous requirements that necessitate poured concrete.   

I've built 2 cabins on my site, and this is the first time I've built in a windy area,( built a fair few large extensions but never where wind was a constant thought during the build.)

It was a lightbulb moment building the cabins and the reality of trying to get good levels of airtightness was more of a concern. I'm sat here now and we've got a constant 20mph, with the odd 30 gust. 

I was surprised when at stick built stage how the wind was trying to push down the frame, when the OSB went on everything became more stable, but the wind blowing through any gap was surprising.

All of the above can be designed around, and detailed away, but all this comes at a financial and time cost.  The ICF route for me gives me a bit more security, it would be cheaper to build with block, but again the detailing if very important and most definitely not free.

We're cladding the building, brick facade is not a choice in this locality. It's wet dash, render or cladding.

It is definitely not stick it together and off you go, as you say the added rebar, and propping is required, but with stick built I would also have to prop during construction. But the benefit of putting it together, and once it's poured it's solid will give me a shorter time exposed to the elements. Time will tell, but that's the great (scary)  thing about self build.  🤣

[Dave Jones]

1 hour ago, Iceverge said:

I wonder if there a novelty factor with ICF that folks like.

 

I remember being enthralled by it when I first saw it. I can build my own house I thought, just like Lego. Then I saw the cost of the blocks and nearly fell over. 

 

The trouble is that it's soft on the outside and crunchy on the inside. The wrong way around in my opinion. 

 

Much of the lovely "Legoness" goes out the window when you see all the bracing needed and the rebar. The cost of the silicone render made me fall over again.

 

The U Values out of the box aren't often anything special and need a bit extra added. What really puts me off is the risk of needing another 2 blocks and having to wait for them to come from the moon or that awful situation like Insulhub where people lost all the money by needing to pay lots of cash upfront. 

 

For now, sticks of timber or blocks/bricks still have lots going for them unless you're building below ground, really need the speed, or have some onerous requirements that necessitate poured concrete.   

 

im off the same conclusion, ICF kits need to be less than the price of celcons per m2  to be viable in anything but niche builds. Even then they will still be double/treble the cost as you need rebar, conc and an external finish.

 

I cant see an upside to them currently.

 

[SteamyTea]

18 minutes ago, Dave Jones said:

I cant see an upside to them currently.

Airtightness and continuity of insulation.

[Dave Jones]

Just now, SteamyTea said:

Airtightness and continuity of insulation.

 

can still be done with timber frame/traditional at fractions of the cost.

[SteamyTea]

2 minutes ago, Dave Jones said:

 

can still be done with timber frame/traditional at fractions of the cost.

depends on how good the fitters are.