SIPS or ICF

[jimmy_stocks]

Hi all,

 

New to the forum and very much wet behind the ears and so hoping to gain some tidbits of knowledge from you all.

 

I have pre-app granted to build a bungalow at the rear of the largish plot of land we have at the back of our existing house.

 

I want to build a home that ends up having minimal bills and have been researching passiv and other build designs that will help achieve this. (we are not precious on certs, just return from investment)

 

Our bungalow wishlist is a simple 17m x 8m, with a mezzanine floor across 2/3rd's of the build, and full ceiling height for the remaining 1/3, which will be the open plan living/kitchen area. 3/4 beds, 2 bathrooms.  

 

Our budget could stretch to £200k. Hopefully we will live in this house for some years but we also don't want to spend over and for that money to not be reflected in the value of the end property, if that makes sense. The land is worth minimum £150k, if we spent £250k+ then the bungalow is not going to be worth £400k+.

 

Another key detail for us is indoor air quality. Both my other half and me have mild asthma and we also have a 3 year old that we want to have happy healthy air to grow up in. 

 

I have had several quotes back from SIP providers, and it is looking unrealistic for us (between £250k and £400k) or £1800m-£2500m2. We ideally need a turnkey solution as I am not building minded and wouldn't trust myself or wouldn't trust having to deal with separate contractors to the manufacturers, with that kind of investment it seems risky and stressful for one company to not take ownership of the completed build.

 

Are these SIP quotes coming out so much because of the price of Timber? And will these likely drop in the next year or 2, if Timber prices come down? 

 

And if you go with a separate contractor to put the house together, do they offer guarantees that any mistakes etc this will not fall on us in any way financially?

I also had 1 quote for ICF, which was a rough estimate over the phone, and he said around £40-50k but that was just delivery and we would need a builder or somebody experienced to complete the project, which he said he had 2 contacts near to ourselves in Cannock, Staffs. This seemed suspiciously cheap to me but then I'm not sure what the contractor and end costs would be.

 

It is a bit of a minefield and given we are just beginning this journey, I thought wise to join this forum, hoping to gain some advice! 

 

Thanks for reading.  

[FM2015]

An EPS ICF should be below £170/m2, based on external dims and for the sake of it, include all openings in the area calc.  This would be supplied and fit, Inc concrete, rebar, pump, labour, props etc.

 

Render on the outside may reach £50/m2 of wall.

 

Plasterboard and plastering to finish internals, £40/m2. Of wall.

 

Your 17x8 building is going to be in the region of 125m2 of wall so all in,  less than £35k.  Groundworks excluded.

 

Shell is then £277/M2 of footprint.  Or less than  15% of your 1800min budget.

 

ICF over sips: one main advantage is that it doesn't support mould like timber does.

[Bitpipe]

On 03/02/2022 at 17:32, jimmy_stocks said:

Hi all,

 

New to the forum and very much wet behind the ears and so hoping to gain some tidbits of knowledge from you all.

 

I have pre-app granted to build a bungalow at the rear of the largish plot of land we have at the back of our existing house.

 

I want to build a home that ends up having minimal bills and have been researching passiv and other build designs that will help achieve this. (we are not precious on certs, just return from investment)

 

Our bungalow wishlist is a simple 17m x 8m, with a mezzanine floor across 2/3rd's of the build, and full ceiling height for the remaining 1/3, which will be the open plan living/kitchen area. 3/4 beds, 2 bathrooms.  

 

Our budget could stretch to £200k. Hopefully we will live in this house for some years but we also don't want to spend over and for that money to not be reflected in the value of the end property, if that makes sense. The land is worth minimum £150k, if we spent £250k+ then the bungalow is not going to be worth £400k+.

 

Another key detail for us is indoor air quality. Both my other half and me have mild asthma and we also have a 3 year old that we want to have happy healthy air to grow up in. 

 

I have had several quotes back from SIP providers, and it is looking unrealistic for us (between £250k and £400k) or £1800m-£2500m2. We ideally need a turnkey solution as I am not building minded and wouldn't trust myself or wouldn't trust having to deal with separate contractors to the manufacturers, with that kind of investment it seems risky and stressful for one company to not take ownership of the completed build.

 

Are these SIP quotes coming out so much because of the price of Timber? And will these likely drop in the next year or 2, if Timber prices come down? 

 

And if you go with a separate contractor to put the house together, do they offer guarantees that any mistakes etc this will not fall on us in any way financially?

I also had 1 quote for ICF, which was a rough estimate over the phone, and he said around £40-50k but that was just delivery and we would need a builder or somebody experienced to complete the project, which he said he had 2 contacts near to ourselves in Cannock, Staffs. This seemed suspiciously cheap to me but then I'm not sure what the contractor and end costs would be.

 

It is a bit of a minefield and given we are just beginning this journey, I thought wise to join this forum, hoping to gain some advice! 

 

Thanks for reading.  

 

Welcome, lots to unpack there.

 

Firstly passive standard (not certified) will meet many of your design objectives around low energy and improved air quality as they are inherently highly insulated and airtight so you need to use a MVHR system to deliver filtered fresh air to your home and remove stale air from the interior. You can spec different degrees of filtration for your MVHR system also. Important to say that you don't need to go all out on achieving passive standards but they are not that hard to achieve in practice.

 

A key part of the passive standard will be delivered by the building frame/structure and the rest by doors & windows. You spec a heating system that is matched to your requirements (usually a low temp UFH solution) and then figure out to run that and deliver your domestic hot water - either ASHP or gas boiler. Depends on your existing service connections, budget, preferences but ASHP with in slab UFH gives the option of cooling in summer also.

 

What's important is to understand how the house will behave year round - while we are all obsessed with heating, attention is needed to minimise overheating also - which can occur from spring to autumn. The modelling (PHPP)  can be done at the design stage and can influence window placement & sizing, external shading etc. Note this is different from SAP calculation which are required by law but is a bit of a blunter tool.

 

As to one build method over another, again that's a tradeoff in budget. ICF will give you a solid, strong insulated and airtight shell but the roof will need separate consideration as will your internal floor construction (joists etc). SIPs can be used for roofing an all SIP build (or an ICF) and various contractors will erect the shell and provide different degrees of internal fit out (floors, structural walls etc). There is a third way, timber frame, where the bare panels are made off site but once installed, airtightness and insulation are done on site. Some firms (MBC) also offer an insulated passive slab as part of the package. A ICF contractor may be able to do a slab also but SIPs will expect the foundations to be in situ.

 

Once you have your fabric/ shell, the rest is a standard house - follow on trades need to respect the airtightness measures (no random drilling of holes in external walls etc.) but that's about it.

 

So if you decide to use a single main contractor (usually the most expensive option) or arrange follow on trades yourself is up to you. You may find that many general builders are clueless about passive standards or that you pay a significant premium to get one who is experienced but really, once the shell is up and the windows etc are in, the rest is a standard build.

 

For that reason, many of us here contracted to get the passive frame erected directly and then managed the trades (not as hard as it sounds) to complete as that was the best way to control cost and maintain the focus on passive detail. Some may use a project manager to get the same outcome but you will pay them a % of the build cost (10-15).

 

Your frame contractor will offer a standard warranty but that will not cover anything that comes after. Usually these are incorporated into the general building warranty whether that comes from a 3rd party insurance company or your builder or architect.

 

And yes, timber has spiked in price but is coming back down, however SIPs and Timber Frames are always more expensive as you're paying for off site manufacture and a fast erection process that can save you money in the longer run.

 

Hope this all helps!

 

Keep asking the questions.

[Russell griffiths]

I think you need to re evaluate, 

you have a plot of land attached to the house you already own, so doesn’t that make it a free plot??

obviously you could sell it and gain £150. 

If you want to build a house to live in for a good few years then why does it need to add up to the cost you believe it to be worth now. 

And why the £200,000 budget, if you own the house on the front then won’t you sell that to finance the build. 

 

From where im standing you are in a position that many people would give there right arm for. 

If you build something nice to a good standard I bet it’s worth way more than you are estimating, but it will also cost more than £200,000. 

 

Go for it, I’ve never lost a penny on any house I’ve brought. 

[CotswoldDoItUpper]

We had a similar conundrum on a previous project… went with ICF in the end due to access. You often need a bloody big crane to get the SIPS into place!

 

Good luck!

[Chanmenie]

I researched both but decided on ICF,

I’m using Isotex blocks rather than EPS Type as its more DIY friendly 

 

one of the main pluses for me is the thermal mass you get with concrete and it absorbs the noise, won’t go mouldy and hopefully less cracks 

[Happy Valley]

We are doing a very similar thing to yourself in that we are lucky enough to be building in our existing plot having gained planning consent. We live on-site in the older house. 

 

We have never built before whilst I have worked in property it was not in construction so could say that we are very green too. We went ICF (Polysteel Warmerwall) and I am project managing with the help of an excellent builder. 

 

Even so our build costs have escalated mainly due to the increased cost of materials over the last 10 months. We will probably spend about 30% more than anticipated initially - we had factored in a 15% contingency.

 

If this is going to be your home for the next 15 to 30 years I do not think that it matters too much about going over the budget that you mention. 

 

Good luck.

 

Edit: The cost of professional fees alone is likely to be around or in excess of £20000 - architect, ecology survey, soil survey, structural engineer, water survey etc etc

Edited February 7, 2022 by Happy Valley

[Russell griffiths]

28 minutes ago, Chanmenie said:

I researched both but decided on ICF,

I’m using Isotex blocks rather than EPS Type as its more DIY friendly 

 

one of the main pluses for me is the thermal mass you get with concrete and it absorbs the noise, won’t go mouldy and hopefully less cracks 

Why do you say isotex is more diy friendly. 

[Chanmenie]

6 minutes ago, Russell griffiths said:

Why do you say isotex is more diy friendly. 

Good question Russell, it’s my opinion having looked at both

Less bracing required, and the bracing you do need is easier to fit, looks easier to size and make openings.

I could be wrong as I haven’t actually worked with either type yet.

[Adrian Walker]

3 minutes ago, Chanmenie said:

Good question Russell, it’s my opinion having looked at both

Less bracing required, and the bracing you do need is easier to fit, looks easier to size and make openings.

I could be wrong as I haven’t actually worked with either type yet.

 

If you're considering at Isotex, then I would have a look at the Velox ICF system, which also has flooring.

[Russell griffiths]

Just now, Adrian Walker said:

 

If you're considering at Isotex, then I would have a look at the Velox ICF system, which also has flooring.

Oh god, just don’t. 

[Russell griffiths]

6 minutes ago, Chanmenie said:

Good question Russell, it’s my opinion having looked at both

Less bracing required, and the bracing you do need is easier to fit, looks easier to size and make openings.

I could be wrong as I haven’t actually worked with either type yet.

I would re think that a bit then, woodcrete is bloody heavy, hard to cut, the dust is horrendous. 

I could go on and on, but I would start sounding like a salesman for poly type icf. 

[Adrian Walker]

1 minute ago, Russell griffiths said:

Oh god, just don’t. 

 

Just because you had a bad experience, you should  let others do their research, etc.

[Russell griffiths]

2 minutes ago, Adrian Walker said:

 

Just because you had a bad experience, you should  let others do their research, etc.

That’s ok saying that, but they do their research over the internet with a few pictures. 

Nothing like being on a site and watching the troubles unfolding in front of you. And it wasn’t my place, so no financial loss to me, just horrified at the grief it caused to the builder and the financial loss to the home owner. 

 

[saveasteading]

On 03/02/2022 at 17:32, jimmy_stocks said:

Are these SIP quotes coming out so much because of the price of Timber

No, as most of the material cost is the foam fill.

It is simply an expensive product to manufacture, transport and hoist. You are paying for quite a bit of factory time, with all the costs that incurs.

 

I have no experience of building with it, but have researched and had quotes, and it was always easier/cheaper/better another way.

BUT it comes into its own for simply shaped buildings of ideal dimensions, and will be quick on site which has a value to some clients.

Also some people simply like it, and there is reduced scope for build quality problems.

Edited February 7, 2022 by saveasteading

[Ajn]

On 03/02/2022 at 17:32, jimmy_stocks said:

near to ourselves in Cannock, Staffs

We are not too far from you. We used the Durisol ICF blocks clad with brick and timber, very easy for diy, very quick to build, once the foundation is good, if you follow a few simple tips.

One Key point to remember is to ensure all templates for holes through the finished concrete are done before it is poured. Drilling C30  concrete later is not fun.

[Chanmenie]

1 hour ago, Russell griffiths said:

Oh god, just don’t. 

I won’t

[Chanmenie]

1 hour ago, Russell griffiths said:

I would re think that a bit then, woodcrete is bloody heavy, hard to cut, the dust is horrendous. 

I could go on and on, but I would start sounding like a salesman for poly type icf. 

Heavy doesn’t bother me I’m big and strong, and the fact that it’s heavy is why it doesn’t blow out so easily like EPS, I’ve seen some of the disasters with EPS, even the woman on the TV who used Nudura had blow outs and walls buckling.

Any system is only as good as the people building with it. 

[Chanmenie]

1 hour ago, Russell griffiths said:

That’s ok saying that, but they do their research over the internet with a few pictures. 

Nothing like being on a site and watching the troubles unfolding in front of you. And it wasn’t my place, so no financial loss to me, just horrified at the grief it caused to the builder and the financial loss to the home owner. 

 

I did not just rely on internet research 

I do my research properly before making a decision  

[Simplysimon]

go with timber kit i beams and blown celluose insulation, no blow outs and no cutting of woodcrete

[JohnMo]

Another plus from me for woodcrete.  I used Durisol.  All cuts done with reciprocating saw, but an alligator saw is better. Bracing with osb on internal and external corners and over opening.

 

Get a structural engineer used to the material, otherwise they stuff way to much steel rebar into it.

 

Airtightness with an internal parge coat, battens and plasterboard or wet plaster.

[Happy Valley]

5 minutes ago, Simplysimon said:

go with timber kit i beams and blown celluose insulation, no blow outs and no cutting of woodcrete

 

No blow outs with our ICF - I can however point you in the direction of a 20 year old timber framed building that is rotting from the inside out.

 

Every form of construction has it's pros and cons. As long as you are happy with yours that's all that matters.

[Simplysimon]

19 minutes ago, Happy Valley said:

I can however point you in the direction of a 20 year old timber framed building that is rotting from the inside out.

properly constructed house?

 

have fixed a few early timber kits which rotted out but as we've been building with them for quite a few decades now up here we know the reason for this happening. we may be a stubborn bunch up here, however, we're not all stupid and keep building a certain way just because we've doing it that way for a long period of time. if there was an issue with the build method we would change it. yes kits may still rot but as with all builds it's down to the care of those doing the building. done incorrectly all build types will fail somewhere.

 

not pushing one build method over another, everyone has different ideas but giving the OP another option for a warm, airtight, quiet build method and more importantly a build type with a long decrement delay.

[Happy Valley]

8 minutes ago, Simplysimon said:

properly constructed house?

 

 

It's a small building of 3 apartments on a development by a "premium" builder. Clad in stone, there are 18 houses and three more small apartment blocks. It is just one of the buildings which is known to have a problem. 

 

I think if there were more builders using timber frame here where we live we may have considered it. Our chosen builder had little or no experience of it so we ruled it out. 

[Nickfromwales]

43 minutes ago, Happy Valley said:

 

It's a small building of 3 apartments on a development by a "premium" builder

Then it will be a terrible benchmark and not apples for apples. Here people are mostly self / new building for themselves, developers cut any and every corner to make a fast buck. Even the "good" ones are not great. Premium is just the price the buyers paid for dwellings which were likely a load of shart.