Most Cost Effective High Performance Build Method
Posted 19 April 2015 - 08:05 AM
Posted 19 April 2015 - 08:18 AM
Just because 'most houses' are built with one method does not make it 'best'.
There are numerous reasons for picking different construction methods.
You had a Morris Minor for many years I believe, is that still the best car there is?
Posted 19 April 2015 - 09:05 AM
Posted 19 April 2015 - 09:27 AM
My personal view is that a single skin block wall with external insulation makes a lot of sense if you (and the planners) are OK with a rendered finish. Instead of fixing the EPS in one 300mm thickness, I think I'd be inclined to look at fixing it in 100mm sheets, with rebates cut in with a hot wire cutter to take battens and counter battens on alternate layers. You bond and mechanically fix the first layer through the battens, then fix the second layer with the sheets at right angles and bond and screw them to the battens in the first layer through counter battens in the second layer, then fix the last layer by bonding and fixing to the counter battens in the second layer, using EWI fixings.
You can get long EWI, large head fixings, but I'm not 100% convinced they are that good a method at this sort of thickness, plus they are fairly expensive. The bond and batten method uses shorter fixings and more or less standard fasteners for the first two layers.
Posted 19 April 2015 - 09:59 AM
Costs can vary greatly in high performance systems. I know when we built 5 years ago, I priced out 3 types of timber frame - standard 140mm timber frame kit with additional insulation to lift U value to my target, closed panel timber frame kit injection filled with PU insulation, and closed panel timber frame filled with cellulose insulation. The standard 140mm timber frame kit came out £2K less than the injection filled closed panel kit, which itself was £30K less than the cellulose filled closed panel (when you added in the cost of windows, plasterboard, timber finishes, doors etc which were included in the timber frame kit and injection filled closed panel kit). I discounted the cellulose system based on cost. I went with the injection filled closed panel, although a little more expensive, as it offered a well insulated and airtight by design system which I thought would be very difficult to achieve with a standard kit (as this involved cutting, fitting and foaming rigid board insulation into the timber frame).
All I think you can really do is price up all the options and be prepared to look at more than one way of building /building system. Prices will vary company to company according to material costs and whether they actually want the work. A company with a full order book and waiting list may well decide to raise its prices to dampen demand rather than having the headache of investing to expand its business.
Posted 19 April 2015 - 10:07 AM
Posted 19 April 2015 - 09:53 PM
I'm swaying towards the insulated reinforced raft for the floor an then.....
An external wall structure that is inherently airtight by design. A 300mm twin stud/I beam filled with cellulose sounds like a great performer but very expensive. This maybe offset by using a cheaper rain screen like a fibre board render system.
Would you have to rely on the internal render of a dense block/EPS system to give you your air tightness? Does anyone have experience in building a single block and EPS system? Could this sit on an insulated slab?
Posted 20 April 2015 - 10:23 AM
For me you buy a factory built box and then put a cheap but effective rain screen around it.
Posted 20 April 2015 - 10:44 AM
If you go block on flat with thick polystrene (which I reckon is best bang for buck at the moment) then forget about timber cladding the outside, use something like Parex Maite adhesive to stick your 200mm EPS onto the wall, then more Maite on the outside for the fibreglass mesh and finish with your chosen style of render. No bridging, very quick and very cheap per m2 and definitely very airtight especially if the inside of the block gets plastered instead of boarded. The two layers of Maite on the outside also serve to stop any air leakage. Do any of our NI contingent have any news on how the 2020 architects were getting on with their builds of this style?
Posted 20 April 2015 - 02:57 PM
Maybe the best option would be an MBC package without a masonry skin, just render on board? Wind and watertight would still be around £90k for a 230 sqm though!
Posted 21 April 2015 - 07:57 PM
Posted 21 April 2015 - 07:58 PM
How is the airtightness achieved though ICF?
Posted 22 April 2015 - 09:05 AM
Edited by notnickclegg, 22 April 2015 - 09:05 AM.
Posted 23 April 2015 - 10:34 AM
Have you looked at any closed panel systems? Just do a general search online and you will come up with several offerings.
Various different systems out there -panels injection filled with PU, filled with bonded EPS bead, mineral wool etc.
Scotframe, who supplied my kit, have a price guide which lets you see the difference between their offerings which range from open panel just meeting build regs to beyond passive house levels of insulation
Posted 24 April 2015 - 05:17 PM
Most of them aren't high performance .
Posted 23 January 2016 - 11:31 AM
If you go block on flat with thick polystyrene (which I reckon is best bang for buck at the moment) then forget about timber cladding the outside ...
Posted 23 January 2016 - 12:06 PM
Thanks so much Neil. I had looked at that when I visited, but hadn't seen it. Thanks indeed. Ian
Posted 23 January 2016 - 12:24 PM
Posted 23 January 2016 - 12:33 PM
Don't need to parge the inside of the cavity. Just check all the beds and perps have no holes in them and give them a brush with a hard brush to seal all the joints.
Posted 23 January 2016 - 12:39 PM