RC Frame/ICF (Single Faced) vs. Steel Frame/Metal Stud

[james ivett]

Hello,

 

We are designing a 4 story carbon neutral, built for purpose office block on stilts (as it is in a flood zone). ICF was originally specified for the walls during planning phase to achieve the best thermal performance, air tightness, security and acoustics outlined in GBS's Sustainability SPD and client brief. This was also backed up by our sustainability consultant.

 

Over the last year of waiting for planning permission, the client has taken a liking to the single faced ICF system (based on aesthetics) and the Architect seem to prefer the more traditional methods with steel frame with light weight metal stud, sheathing, cladding railing system and all the insulation/membranes/tapes/etc.

 

In my opinion, I feel like we will struggle to achieve the above requirements outlined in the SPD with steel frame while the RC frame/ICF will provide these properties inherently. The only negative I can think of for the ICF although will be a heavier build and therefore more piles/thicker caps.

 

If anyone has had any experience achieving almost passive standards with Steel frame/light weight metal stud and possibly also has ICF experience to compare the two, it would be greatly appreciated?

 

Also, I was hoping to see if anyone has had any experience with the 'off the shelf' single faced ICF systems (Nudura/Integraspec) as well as potentially using systems like Quad-Lock that don't offer a single faced solution but could easily adapted to do so. (Fixings 8'x4' ply sheets too the ties at 12" H&V centres). The main reason for trying to "re-invent the wheel", is mainly cost of the material, cost of importing the smaller/expensive sections of pre-drilled wood from Canada and also speed of build. I am however, concerned about how well the wall will hold with pour heights of ~3m.

 

Any suggestions would be appreciated.

 

Many thanks

[saveasteading]

This was what I did for 35 years and the family business continues without me.

 

Therefore i will only give a few points, and you must do as you wish. 

ie this is some of what we would tell you for nothing if discussing a design and build contract.

 

Taking a project from 5 years ago as an example. This was a 4 storey nursing home, so quite like yours in size and scale.

 

It had to have brick facing.

 

I analysed about 6 different ways of building it.

polystyrene

timber

lightweight steel

structural steel

masonry.

mixture of the above

 

We ended up with timber frame, with light steel a close second, the differentiator being the multitude of small, standard rooms.

 

BUT for an office you should have, in my opinion, great open spaces, so I would propose structural steel as the likely favourite.

You can still infill with pod offices if you like, and change them in the future to suit fashions.

 

I have never met a 'sustainability consultant', unless you mean a Breeam consultant.

I sat and passed the exam simply to satisfy clients and planners that I knew of what I spoke,  but didn't agree with most of what they proposed.

 

In fact we have always renegotiated Breeam planning conditions, by pointing out and deleting the crazy bits.

 

You clearly have architects and other consultants, but are asking this Buildhub  community for help...can I ask why?

I don't think many here are likely to advise on how to pour a wall, if your consultants cant help.

 

 

Perhaps that will become clear of you tell us your role for 'your client'.

 

[james ivett]

3 hours ago, saveasteading said:

You clearly have architects and other consultants, but are asking this Buildhub  community for help...can I ask why?

I don't think many here are likely to advise on how to pour a wall, if your consultants cant help.

 

Perhaps that will become clear of you tell us your role for 'your client'.

Thank you for your response,

 

As you say, many here aren’t likely to, but I am looking for the few - like yourself - who have.

 

Just to clarify, I am not looking for anyone to tell me how to pour a wall, just how the single sided ICF systems mentioned above preformed during the pour.

 

The only information I have found on the single sided ICF has been by "Up to Kode" YT channel and this Forum. I have reached out to both.

 

The manufactures and UK suppliers don't seem to do much of it and are also reluctant to share detailed information also.

 

The architect is in his 80's/90's and is also the father of the client so not your typical arrangement and doesn't have experience with high proformance structure in steel frame/stud or ICF. The Sustainability Consultant (or "Independent engineering consultant & researcher" as he references) is into building physics and not physically building, hence why I don't expect him to answer my concerns.

 

The commercial sector is reluctant to change, whereas the self-build community can see beyond the "bottom line cost", appreciate the future benefits and are typical more savvy with alternative methods of construction.

 

I don't see why this is relevant to my question but, I am the currently the designer on the project but will also hopefully build it if it goes down the RC/ICF route. I have designed and built with ICF for the last 8 years, using 5 different systems as well as SIP and traditional prior. I have not used single sided systems; I am looking for user experience and thought this would be a good place to start?

 

Thanks again for your response, James

3 hours ago, saveasteading said:

 

 

[saveasteading]

Thanks. I see what you mean about asking people who look beyond the obvious.

I was a d and b contractor, all  in-house, so there is a synergy.

 

Your role is relevant, because if you are the designer and want to be the builder, then I will pull out of the conversation, on a conflict of interests basis, as my family's business does just that, pure d and b, all in-house.

 

I suggest forget the polystyrene, which is great for amateurs but is not really commercial imho.

 

Good luck with it.

[Mr Punter]

I must say that this seems an unconventional way to procure a building.

[saveasteading]

I don't have difficulty with this method of procurement. The client can do as they like, and presumably gets a fixed price and it is the contractor who takes the financial risk.

 

It looks like a £3M+ job though, and client not short of money if happy to pay for these very complex features, so very nice to get the job.

 

I see that polystyrene houses is what you do.

If your supplier can't answer the question that concerns you I would be very wary.

 

I looked into the polystyrene option very seriously, as there was no shortage of suppliers chasing us,  and costed several jobs in detail against other methods,  but it never proved the winner for me, even on small blocks. 

However that was for office blocks, schools and industry, so it is very different indeed from one-off housing.

Steel is nearly always the right answer for big buildings like this, and all your targets can easily be achieved or exceeded.

 

The trouble with competing construction methods is that usually tenders are between contractors offering the same methods, as instructed by the architect. Then if you suggest there is another way, they tend to get defensive rather than think of the client's budget.

 

Presumably flood plain issues has caused the planning  delay. Another plus for steel is simple columns and beams form your  under-croft, and can be galvanised and painted ready for the big flood.

 

I will be interested to hear of progress if you will allow us.

 

 

[the_r_sole]

It looks a fairly well advanced scheme to change the construction method? Should surely be designed with the method considered...

I'd say as soon as you step away from standard construction methods you're opening a can of worms, you'd want to check first off that it could all be insured/sold etc without hassle, poured concrete also reduces the potential for alterations later which may or may not be a consideration. 

Commercial building are usually built in the most cost effective way possible, look at other office buildings or even blocks of flats, they're not built with inefficient or expensive methods  - at the moment with high prices all round it will be even more of a battle to get funders to build in a more experimental way, especially if they ever get a qs involved (which I'd guess will be happening looking at the scale of it)

Anything commercial  I've seen that's aiming for passivhaus standard is timber kit (or mass timber) - be interesting to hear how you get on with this, you'll want to get a fire engineer on board to look at the proposed wall build ups asap! 

[james ivett]

Thank you for your response.

12 hours ago, the_r_sole said:

It looks a fairly well advanced scheme to change the construction method? Should surely be designed with the method considered...

The proposal has only been issued for planning permission so early days still.

 

As above, the building was designed as RC/ICF to achieve the requirements in the SPD. The architect is now suggesting using steel frame, hence my post regarding its thermal performance and air tightness.

 

A structural engineer was not consulted as there is no guarantee that we will get planning and the client did not want to waste money prior to approval. 

 

The client is building the offices for his company and employees who will be the end users. He is keen to keep future maintenance, running and operational costs to a minimum and see's the benefit of investing in the building fabric as the most effective way of achieving this. He also appreciates that the building fabric has a huge effect on the internal climate/working environment and in turn will have an effect on the working conditions of his employees. He therefore wants the optimum solution, hence my post regarding its thermal performance and air tightness for steel frame as these are typically hot boxes in my experience...

 

RE the building methods, RC is not unconventional for commercial buildings, all building needs to be insulated therefore ICF makes sense as it is simply the formwork system that stays in place and also achieves ~5 other steps in one operation. Alternatively with steel frame, insulation is placed between studs and cladding railing systems as part of a multiple step operation in addition to sheathing, breather membrane, vapour barrier and numerous other air tightness tapes/mastics to get even close to what ICF does inherently.

 

It was proven at Loughborough that the most efficient way to use the thermal mass of a wall is to have the internal face completely exposed. My client also likes the look of exposed concrete. This is why we looked at single sided ICF but again, cannot really find it being us too much in the UK and from my experience don't really like the look of the internal formwork restraint, not to mention the additional labour costs to rip down the forms, drill the required holes and set up the blocks (if we used locally sourced film faced ply as opose to imported ply). The accuracy of this also has the potential to create further issues, hence why I asked this forum as other posts have mentioned it. Regretably, I now realised I should have just commented on that post, but as I have varying concerns, I decided to create my own.

 

Just to clarify, I am mainly concerned about:

 

-The thermal performance of steel frame and all the elements that will go into achieving the required thermal resistance and air tightness.

- How the single sided ICF systems mentioned above preformed during the pour. The only information I have found on the single sided ICF has been by "Up to Kode" YT channel and this Forum. I have reached out to both. The manufactures and UK suppliers don't seem to do much of it and are also reluctant to share detailed information also.

 

21 hours ago, Mr Punter said:

I must say that this seems an unconventional way to procure a building.

I don't think you have read my post, I am not procuring, merely asking for information on single sided ICF as this is one of the few places it has been discussed.

[the_r_sole]

Ok, I get it, your mind is made up - the commercial reality is going to hit hard with this, engage with not just the owner who likes thing, but the people in control of the purse strings who will actually be funding it. I've worked on lots of commercial projects where the owner and end users have great ideas then the board approval for the funding is required and it reverts back to standard construction.

 

good luck with it