Takes less time, but is more expensive?

[GC1]

Hi, 

 

New to the forums. 
 

I’m just about to embark on the very early stages of a new build project and have this question.... If ICF takes next to no time to be installed/concrete poured/etc compared to more traditional build methods - why does it cost more? From what I’ve been reading it’s much less labour intensive and last time I checked polystyrene isn’t that expensive! How would one get the cost down so it falls inline with a traditional structure? 
 

Thanks

[Conor]

I think the cost is comparable - if you compare by performance levels

. I.e. a standard ICF build will outperform a standard block build in terms of insulation, airtightness, strength etc. I.e. so you have to take in to account the extra insulation, airtightness measures, structural elements, cold bridge mitigation etc for a standard build. So don't be comparing a ICF system against a standard block cavity building with 100mm insualtion.

 

[ToughButterCup]

1 minute ago, GC1 said:

...

If ICF takes next to no time to be installed/concrete poured/etc compared to more traditional build methods - why does it cost more?

...

 

Welcome. 

 

Comparing apples and pears isn't a valid comparison. The ICF that I used didn't cost more.

There are many ways to quantify cost - so its difficult (not knowing your assumptions about the costing process) to answer your question as well as you might like. Its common to 'cost' per square meter. I guess that many self builds are coming in at £1500 per square meter  (and that really is a guess). There are some who have it down to less  than £900 ( @nod and one or two others - @ProDave I think) and I am sure there are others who are more expensive that £1500.

 

Be careful with the '... next to no time to be installed/... compared to ...' thought. 

My ICF is produced in one factory  ' far-far-away '  from where we live. The estimator got the quantity wrong, and the builders (it felt like) broke  as many blocks as they used to build - and despite my constant badgering to tell me long before they needed more - decided to tell me at 5:00 on a Friday. It took 7 working days to get more stock.   

 

Brick and block? Pop down the BM with a trailor and get more.

 

21 minutes ago, GC1 said:

...

How would one get the cost down so it falls inline with a traditional structure? 

 

Pick a commonly used costing measure and stick to it.  Price per square meter is as good as any.

[GC1]

1 hour ago, ToughButterCup said:

 

Welcome. 

 

Comparing apples and pears isn't a valid comparison. The ICF that I used didn't cost more.

There are many ways to quantify cost - so its difficult (not knowing your assumptions about the costing process) to answer your question as well as you might like. Its common to 'cost' per square meter. I guess that many self builds are coming in at £1500 per square meter  (and that really is a guess). There are some who have it down to less  than £900 ( @nod and one or two others - @ProDave I think) and I am sure there are others who are more expensive that £1500.

 

Be careful with the '... next to no time to be installed/... compared to ...' thought. 

My ICF is produced in one factory  ' far-far-away '  from where we live. The estimator got the quantity wrong, and the builders (it felt like) broke  as many blocks as they used to build - and despite my constant badgering to tell me long before they needed more - decided to tell me at 5:00 on a Friday. It took 7 working days to get more stock.   

 

Brick and block? Pop down the BM with a trailor and get more.

 

 

Pick a commonly used costing measure and stick to it.  Price per square meter is as good as any.

Thanks for the reply. I’ve been reading and the common theme was that going the ICF route would add 5-8% to the overall cost, it’s a 275 sq/m house so that would add quite a lot to the overall cost. The main thing that stands out for me is the insulation benefit and reduced build time (“Lego for adults” being a common thing I’ve been seeing) - think I’ll be committing to this route and can get cracking with the plans. 

[SteamyTea]

2 hours ago, ToughButterCup said:

Price per square meter is as good as any

Or one of the worse metrics.

 

Insulation levels would be a good one, £/(linear metre.U-Value)

[ToughButterCup]

12 minutes ago, SteamyTea said:

Or one of the worse metrics....

 

Because ... 

[SteamyTea]

Just now, ToughButterCup said:

Because

Geometry.

[ToughButterCup]

1 hour ago, GC1 said:

... the common theme was that going the ICF route would add 5-8% to the overall cost, ...

 

I've never seen that . I would be interested in a simple link to anything that made that argument.

[FM2015]

Coming at this from a contractor perspective, to get the same stage and performance values, we generally came in more expensive than timber frame and on par with masonry subject to geographic area.  That is for supply and fit.  

If you had three houses, one of each build type of which there others but we'll ignore those for a minute, and you ordered all three on the same day, the masonry one would most likely start first and finish last, the ICF one would start second and finish first and the timber frame, in current market conditions, start last and finish second.  Note: accounting for lead times.

 

One school of thought might be that a "superior" end product shouldn't cost less than a lesser alternative.  

 

Wastage is a product of design and inefficiency.  With polystyrene ICFs there should be very little wastage, a couple of dumpy bags maximum. 

 

A lot of ICFs can produce all sorts of savings throughout the build.  As a contractor again, it's our responsibility to share these benefits with follow on trades.

 

If you self build, be involved, understand the product and extract practical(!) Information from the supplier.  And think three steps ahead before you make that cut!  And don't cut corners, figuratively or literally!

[GC1]

22 hours ago, ToughButterCup said:

 

I've never seen that . I would be interested in a simple link to anything that made that argument.

https://www.self-build.co.uk/build-cost-calculator/build-cost-calculator-house-page/
 

Using all the same parameters ICF comes out higher than block work. Doesn’t appear to be taking into account time saved on labour?

[FM2015]

3 hours ago, GC1 said:

https://www.self-build.co.uk/build-cost-calculator/build-cost-calculator-house-page/
 

Using all the same parameters ICF comes out higher than block work. Doesn’t appear to be taking into account time saved on labour?

All rates for follow on trades will be the same irrespective of shell type.  A lot of very broad brush assumptions.  

[AliG]

The more I look into it the more I think ICF is the right way to build. This is especially true as houses get larger and more substantial.

 

So for a modest house in timber frame ICF might be more expensive and offer few benefits.

 

But for a larger house built in block with concrete floors etc, then ICF has many benefits to the finished house in terms of insulation, air tightness, noise and so on. I think many of these benefits will only show up with occupation and this is why ICF isn't more popular.

 

When people price ICF and masonry I am not sure that they price like with like, there are many extra costs in masonry that may be missed in initial forecasts. You will likely need more steel and lintels. Pipe stacks can go inside the ICF walls instead of needing to be boxed in inside rooms. There is a lot less need for air tightness tape, expanding foam etc. I think a lot of the small sundry items add up and often don't make it into initial costs. A lot depends on how complicated the masonry build is. We have a load of steel in our walls supporting concrete upper floors. I suspect this might not have been necessary with ICF.

[IanMcP]

On 07/02/2021 at 13:42, GC1 said:

Hi, 

 

New to the forums. 
 

I’m just about to embark on the very early stages of a new build project and have this question.... If ICF takes next to no time to be installed/concrete poured/etc compared to more traditional build methods - why does it cost more? From what I’ve been reading it’s much less labour intensive and last time I checked polystyrene isn’t that expensive! How would one get the cost down so it falls inline with a traditional structure? 
 

Thanks

Hi 

 

new here and seem to be at your stage in Feb. What did you go with ? How did it go ? 
 

thx 

[JohnMo]

I went Durisol route., Was building wall in November/December last year.  No down time due to weather, can pour concrete at -6 deg I believe.  You don't need as much rebar as other ICF systems.

 

2 of us working 5 days a week, took 4 weeks to build our walls.  70m long, 2.5m high at rear, 3.5 to 4m at front.  Structurally complete and fully insulated.

 

Never done it before, I am not a builder.

 

Stone slips attached straight to Durisol.  Timber cladding external battons screw into Durisol.  Same with internal battons.  Parge coat inside walls for airtightness.

[JohnMo]

Forgot cost all in including a wage for no 2 man, was just under £12k

[IanMcP]

@JohnMo Did you go for large pour or build as you go ?

[JohnMo]

With Durisol, you do 6 rows then pour., So rear of house had 2 pours and front 3.

 

But only had the cement pump twice.  Front of house had lots of fiddly bits, so first pour there was done by bucket.

[FM2015]

On 24/12/2021 at 09:06, JohnMo said:

Forgot cost all in including a wage for no 2 man, was just under £12k

Be fascinated to see the actual details to deliver 200+M2 shell for less than 12k.

Take out pumps and 2nd man and I'm down to 7k.

 

Probably 20m3 concrete, another £2000 based in a 4" cavity.

 

Ancillaries, bracing, scaffolding, poleplates, ledger system, another £1k?

 

So the product cost £4,000, £20/m2.

 

Which less than 50% the cost of nearly all other ICF systems.  20/M2 barely covers the cost of the pir board in woodcrete.

 

You've then got air tightness to achieve on the walls.  £12k is so cheap I think it needs a good deal of clarification so that it is useful as a reference.

 

£60 only just gets you a square m of decent ICF without concrete.

 

 

 

 

 

 

 

[FM2015]

And rebar quantities are proportional to design of the build.  Plenty of engineers will specify lintel steel only; irrespective of ICF product.

3.5 times stronger than a concrete block without joins.

[saveasteading]

On 07/02/2021 at 14:05, ToughButterCup said:

decided to tell me at 5:00 on a Friday

Conversation  me with bricklayer.

 

There's no bricks

 

Did you not realise they were running out?

 

There's no bricks.

 

On 07/02/2021 at 13:42, GC1 said:

If ICF takes next to no time to be installed/concrete poured/etc compared to more traditional build methods - why does it cost more?

 

I have never been able to justify ICF on any projects where it was an option, and I really tried and was being offered very big discounts . 

 

Perhaps this is slightly unfair as none of these was a single house, and it doesn't lend itself to larger spaces.

 

My feeling is that it works best in a self-build scenario, as the blocks are easy to carry and build, without bricklaying skills.

Also perhaps the other factors such as wastage, propping etc are a risk that is discovered later on some projects.

 

I did use a concrete block equivalent though, and was shocked by how much the blocks joggled during concrete filling. Does that happen with polystyrene?

And quality control...is there a risk of voids within the blocks?

 

 

[FM2015]

18 minutes ago, saveasteading said:

Conversation  me with bricklayer.

 

There's no bricks

 

Did you not realise they were running out?

 

There's no bricks.

 

 

I have never been able to justify ICF on any projects where it was an option, and I really tried and was being offered very big discounts . 

 

Perhaps this is slightly unfair as none of these was a single house, and it doesn't lend itself to larger spaces.

 

My feeling is that it works best in a self-build scenario, as the blocks are easy to carry and build, without bricklaying skills.

Also perhaps the other factors such as wastage, propping etc are a risk that is discovered later on some projects.

 

I did use a concrete block equivalent though, and was shocked by how much the blocks joggled during concrete filling. Does that happen with polystyrene?

And quality control...is there a risk of voids within the blocks?

 

 

No substitute for experience.  Experience reduces risk.

 

Cost per performance is on par if not superior.

 

Sounds like you got snagged on a labour only contract thinking it would be cheaper.  

 

Multi unit developments work out cheaper again.

 

Biggest problem with ICF and mass build?  We'd make thousands of brickies jobless.

 

 

[saveasteading]

2 minutes ago, FM2015 said:

Sounds like you got snagged on a labour only contract thinking it would be cheaper.

 

No, I never used it, and don't get snagged. Messed about yes, but not for long.

 

Do any housing developers use ICF?

[Adrian Walker]

26 minutes ago, saveasteading said:

 

Do any housing developers use ICF?

 

Very few because they are not going to live in it

[JohnMo]

1 hour ago, FM2015 said:

Be fascinated to see the actual details to deliver 200+M2 shell for less than 12k.

Take out pumps and 2nd man and I'm down to 7k.

 

Probably 20m3 concrete, another £2000 based in a 4" cavity.

 

Ancillaries, bracing, scaffolding, poleplates, ledger system, another £1k?

 

So the product cost £4,000, £20/m2.

 

Which less than 50% the cost of nearly all other ICF systems.  20/M2 barely covers the cost of the pir board in woodcrete.

 

You've then got air tightness to achieve on the walls.  £12k is so cheap I think it needs a good deal of clarification so that it is useful as a reference.

 

£60 only just gets you a square m of decent ICF without concrete.

 

Durisol walls cost breakdown only, doesn't include internal battons, parge coat or external stone slips or timber finish.

 

Scaffold were mostly installed for the roof so not include in wall cost.

 

£7k to Durisol

Rebar £500

£1160 for cement pump x2

£1500 for wage

2k for concrete

 

Total £1 2160.

 

No idea what poleplates, ledger system are so obviously didn't use them.

 

No support required for concrete pour other than ply on corners, but has been used a few times so no real cost.

 

Airtightness was achieved with a concrete, lime, sand parge coat, which was around £400 in materials.

[FM2015]

13 minutes ago, JohnMo said:

 

Durisol walls cost breakdown only, doesn't include internal battons, parge coat or external stone slips or timber finish.

 

Scaffold were mostly installed for the roof so not include in wall cost.

 

£7k to Durisol

Rebar £500

£1160 for cement pump x2

£1500 for wage

2k for concrete

 

Total £1 2160.

 

No idea what poleplates, ledger system are so obviously didn't use them.

 

No support required for concrete pour other than ply on corners, but has been used a few times so no real cost.

 

Airtightness was achieved with a concrete, lime, sand parge coat, which was around £400 in materials.

Fair enough.  

 

I think the important thing here is that a comparison on headline cost is irrelevant.  And comparison of cost to get to the same stage for a given performance metric is far superior.

 

We could still argue over what you include in your 12k figure when other systems incorporate elements which you haven't listed.  And including all scaffold costs in the roof cost doesn't reflect the requirements of the system being installed.

 

Apples and apples