Grand design on a budget

[K78]

I just stumbled across this http://www.nacsba.org.uk/selfbuildonashoestring/12-shoestring/39-shoestring2013top16

 

Some of the designs are interesting. But the listed prices seem optimistic.

 

I’ve always wondered why more people don’t use steel frame like in the winning design. It really minimises foundation costs. 

[nod]

Some great ideas 

 

As you say they costings seem way off

[PeterW]

Most have zero labour cost for anything other than electrical systems. 

[Triassic]

I built this  7.5 x 5 metre home for £30k

 

Edited May 20, 2018 by Triassic
Typo

[Tennentslager]

Ahem...45 sq/m for £10k???

[recoveringbuilder]

3 hours ago, Triassic said:

I built this  7.5 x 5 metre home for £30k

 

 

[recoveringbuilder]

Just now, Christine Walker said:

 

Wow @Triassic,this I am interested in, this is our next plan, we have two building plots for sale and this is our pension fund, we are hoping to build something along this line to use as a holiday home and holiday rental, looking to buy a plot up north and build a three bed log cabin, what size is yours?

[ProDave]

If you want a cheap holiday home size property, look at the "caravan" regulations.  You can build a single storey building a shade over 100 square metres as long as you stick to a few maximum dimensions, and by making it "portable" in sections it can legally be claified as a "caravan" and be exempt from building control.  It does NOT need to be on wheels to be a "caravan" and lifting by crane onto a low loader is sufficiently portable.

 

Where are you going to be building this?

[K78]

4 hours ago, Tennentslager said:

Ahem...45 sq/m for £10k???

 

Cool. Makes garden studios look ridiculously expensive. 

[caliwag]

Or Explore 'theweehousecompany.co.uk mentioned in an earlier blog...very elegant little traditional rural houses. 

[K78]

I don’t understand why steel frame isn’t more widely used on self builds? Look how simple the foundation is. 

 

I imagine a agricultural building company cound errect that frame with foundation for a similar cost to a insulated slab? 

[Jeremy Harris]

Thermal bridging may be an issue, as all the insulation would have to go outside the structure and would inevitably increase the overall wall and roof thickness.   The thickness could be kept down by using a high performance insulation, but then the decrement delay would be short, which may well lead to comfort problems in terms of maintaining a stable internal temperature.

 

Lots of potential labour time and cost savings to be made by using a prefabricated steel portal frame, though, but whether they would be greater than the time and cost savings from a prefabricated timber frame I'm not so sure. 

[K78]

2 hours ago, JSHarris said:

Thermal bridging may be an issue, as all the insulation would have to go outside the structure and would inevitably increase the overall wall and roof thickness.   The thickness could be kept down by using a high performance insulation, but then the decrement delay would be short, which may well lead to comfort problems in terms of maintaining a stable internal temperature.

 

Lots of potential labour time and cost savings to be made by using a prefabricated steel portal frame, though, but whether they would be greater than the time and cost savings from a prefabricated timber frame I'm not so sure. 

 

I was thinking it could work well with 200mm MgO SIPs. 

 

I’ve just had a reasonable quote for the sips. I was wondering if a erected steel portal frame would be cheaper than the insulated slab quotes I’ve had? 

 

The area I’m building in is semi rural so I’m thinking I could probably get a good deal. My groundworkers are local farmers. 

 

http://www.nacsba.org.uk/images/shoestring/18_shoestring13_ed-green.pdf

 

http://www.pentan.co.uk/project/barnhaus/

Edited May 20, 2018 by K78

[recoveringbuilder]

@ProDavethis is a long term plan for when we eventually sell the plots we have on the market just now, not wanting to get the money for them and squander it as it’s our only pension pot we thought we’d buy a plot in the highlands , build a storey and a half log cabin and rent out as a holiday home when we weren’t using it ourselves.We have seen a log cabin suitable for this priced at 30k for the kit and reckon another 30 would have it up. As I say long term plan, need to get the current house up first ?

[Jeremy Harris]

3 hours ago, K78 said:

 

I was thinking it could work well with 200mm MgO SIPs. 

 

I’ve just had a reasonable quote for the sips. I was wondering if a erected steel portal frame would be cheaper than the insulated slab quotes I’ve had? 

 

The area I’m building in is semi rural so I’m thinking I could probably get a good deal. My groundworkers are local farmers. 

 

http://www.nacsba.org.uk/images/shoestring/18_shoestring13_ed-green.pdf

 

http://www.pentan.co.uk/project/barnhaus/

 

With SIPs you don't need any structural frame - the first "S" stands for "Structural".  The main issue with SIPs, is getting the wall/foundation interface details right - it's critical in terms of eliminating the thermal bridge and reducing the interstitial condensation risk in the sole plate.  There are details around that sort this out, though.

 

 

[Crofter]

My own little build has worked out at just a fraction over £40k for a 43m2 (net) single storey house, price includes all services, fees, access, interior fit out, but it was about 99% DIY labour which obviously kept the cost down. Creating the access and installing the sewerage and other services took almost half of that budget. On a flat site with mains drainage the project would have been significantly cheaper. I could also have cut back on the spec, e.g. no alu clad 3G windows, no plaster skim, budget kitchen, and saved a few thousand that way.

[K78]

1 hour ago, JSHarris said:

 

With SIPs you don't need any structural frame - the first "S" stands for "Structural".  The main issue with SIPs, is getting the wall/foundation interface details right - it's critical in terms of eliminating the thermal bridge and reducing the interstitial condensation risk in the sole plate.  There are details around that sort this out, though.

 

 

 I am aware of that.. I’ve just had another sip quote. The foundation detail put me off sips initially as did OSB skin. MgO is waterproof and can be rendered/plastered straight onto. Prices have also dropped considerably.

 

I just like the simple foundation of the steel frame and I think it would be possibly cheaper than a traditional foundation. Sip and steel usually only go together above 3 storey height.

 

I been quoted around £6k-£7k for a 16m x 6m steel frame erected including foundations. I appreciate sips would be expensive to use as cladding and insulation and there are cheaper options that would make more sense. I beams attached to the steel coloumns then clad seems to be the cheapest route. 

[PeterW]

What would you use as a floor though if not a ground slab ..? Surely any cost saving in the portal frame would be reduced as you will still need some sort of foundations to retain the floor and support the walls..,

[DavidFrancis]

What I don't understand is why no one appears to have built a whole house with a lightweight steel frame and sandwich panels, as Roger440 did with his old garage.  (I asked both Kingspan and Tata if they had any examples back in 2015 and Kingspan couldn't come up with any examples and Tata's one example was actually a SIPs house.)

 

As far I can see this would do away with the need for VCLs, breather memranes and loads of OSB, and when I looked at the Kingspan site (back in 2015) some of their panels seemed to come with battens on the exterior so you could add whatever cladding you liked.

 

One of the downsides would be a poor decrement delay, but you could perhaps improve this with some extra high-density mineral wool somewhere.

 

What other problems would there be? Any one looked into the cost?  Roger's garage seemed to be pretty good value as far as I can remember.

[Jeremy Harris]

I think there's no real merit in using SIPs, even MgO clad ones, as you're paying a lot extra for structural strength and certification that isn't needed, as the portal frame is bearing the loads.  If you are OK with the wall thickness build up, then you could just clad the steel portal frame with insulation and then use a cement board outer skin, which could be rendered, clad or have brick slips fitted. 

 

I'm not convinced it would be cost effective though, as others have tried to bring the advantages of a steel frame to domestic scale buildings without much success.  There was a chap on Grand Designs who ran a steel fabrication company who opted to build a modular steel prefabricated house, which looked like a good idea in principle, but it was clear that his design had thermal bridging through the steel and AFAIK the idea never really took off.  I think that, in part, that may have been because modular, fast assembly, timber frame panel houses are cheaper and just as quick to erect on site, and most of any possible cost saving came from the speed of on site assembly. 

 

Labour is far and away the biggest variable cost in a build, and is a cost that is impacted by our weather, very much so for the early stages, before the house is up and watertight.  Anything that speeds up the foundation and house erection to the watertight stage is potentially good, as long as it doesn't introduce compromises.  With a steel portal frame there would be a lot of details to get right, including how to stop the foundations for the steel frame becoming big thermal bridges to the ground beneath.  Putting the steel frame outside the insulated envelope would get around that problem, but then you add another problem, which is how to stop the structural penetrations that come through the shell to the steel frame becoming thermal bridges, which would also require some careful detailing.

 

All in I think it would be getting the details right that would be the challenge, and could well absorb a lot of design time to get right, plus, I suspect, more than a little aggravation from everyone from building control, through contractors working on the build to insurance and warranty companies over the non-standard construction.

[SteamyTea]

On 21/05/2018 at 08:12, DavidFrancis said:

What I don't understand is why no one appears to have built a whole house with a lightweight steel frame and sandwich panels

They did

https://en.wikipedia.org/wiki/BISF_house

 

There was someone over at the otter place that had one.

http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=9214&page=1#Item_20

[DavidFrancis]

@SteamyTea A BISF-style house is not what I was suggesting.  I was thinking of a lightweight steel frame (not a portal-style frame) clad on the outside with modern steel-faced insulated panels such as these

 

Tata panels

 

Could be used with an insulated raft foundation.