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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    I'm about to build a 60x35' steel framed building to be used as a studio workshop, split into 4 rooms. The roof will be 120mm insulated composite steel panels and be installed with the steel frame. I'm considering the most cost effective wall system at the moment.

    Currently, the options seem to be blockwork with insulated plasterboard glued to the block or 2x6 studwork on 60cm centers filled with either mineral wood, celotex or spray foam and with gyproc on the inside.

    Blockwork is quick and fairly cheap but the insulated plasterboard is expensive. studwork is cheap but celotex infill is a lot of work and expensive and time consuming. Mineral is cheap but fiddly. Sprayfoam such as icynene is fast but expensive, so I need to weight those up.

    Does anyone have experience using icynene for walls like this or have any thoughts on my other options?
    • CommentAuthortony
    • CommentTimeMar 29th 2014
    straw bales are cheap!
    • CommentTimeMar 29th 2014
    They spray steel boat hulls and they seem to work.
    • CommentAuthormarkocosic
    • CommentTimeMar 29th 2014
    More sandwich panels? Long-span stuff will do floor to ceiling in one hit with no additional supports; probably portal frame to portal frame. If you're happy with seconds (slightly 'off' on insulation thickness etc) then ~17+VAT per square meter for an internally finished, externally finished, fully insulated wall is tough to beat.

    I'm looking at similar for a 10 x 6 metre (30' by 18') flat roofed garage under PD. The standing-seam-lookalike roof panels come in 140 mm insulation thickness, span 3 metres between portal frames with ease/no purlins, and are rated for a 1.5 degree pitch. Then use secret-fix architectural wall panels for the walls. Supplier here:


    This is the standard roof stuff:

    They also do the "standing seam" version that's officially supported down to 1.5 degrees pitch:

    Architectural wall panels are the same price (except louvre and curve walls that nobody wants which are £12+VAT)

    Over-clad with a timber of your choice if you don't like the colours/style available. If fitted horizontally, the wall panels give a lot of racking stiffness to the portal frames. If you're splitting the building up along the ridgeline then your steels will be very slender indeed; lots and lots of headroom.
    What's the quoted U value for the roof? 120mm of Pu does not sound that exciting - perhaps *just* a scrape-through on Bldg Regs.
    I shall be using Icynene 350mm thick in my portal timber I-beam frame. A friend had her timber frame studio sprayed with Icynene and was very satisfied.
    Peter any link to Icycene installers
    • CommentAuthormarkocosic
    • CommentTimeMar 29th 2014
    120 mm PU is a just scrape through option Nick.

    Consider the danish farmer passivhaus approach: sandwich panels for the weathertight/airtight/partial insulation layer; batten and infill internal insulation at a later date. Also cheap:

    James, I received a quote from Airseal Insulation who are the company my friend used for her Icynene. This was a few years ago though.
    markocosic thanks for that, those look very interesting. with the panels vertical and only a max of 20' between the steel uprights, that might be a very good option. The problem is how to batten for the exterior cladding and also how to finish the interior, those panels don't look as though you can screw things to them.

    I'd probably still have to stud and plasterboard the interior as, being a workshop, stuff with be hung on the walls. If I'm doing that, it might be better to just do 2x6 stud and sprayfoam, you get the strength of wall and insulation.

    If I did that, I don't know if I can batten and board straight onto the studwork with a housewrap layer around the studwork. Not sure if icynene would work like that, will have to make some enquiries.
    • CommentAuthormarkocosic
    • CommentTimeMar 30th 2014
    When you TEK screw the sheets to the steel frame, sandwich a vertical timber batten in there so that you have something to attached horizontal timber cladding to. Or use a polyurethane (sikaflex) to bond straight to the steel surface. Good enough for car windscreens subject to some fairly serious cyclical loading. Not easy to find construction workers with the attention to detail to use adhesives properly (cleanliness, application of correct amount etc) but if it is just you sticking non structural fence panels to the outside of a steel shed... ;-)

    Internally you are more limited. Personally I think it is a good thing. Sockets etc can be run with surface boxes/trunking and self tapping screws and/or sikaflex bonded straight to the (finish painted) steel skin. Hang airlines and heavy gear off the steel portal frame. Avoid hanging anything else from the walls like the plague though - kills flexibility/utility of the space unless your needs are very very routine.

    Instead use mobile "carts" that roll around on the concrete floor, with each cart having a "back board" that all the tools etc hang from. See the "Whalen" stuff that Costco sells for inspiration. The 48"x18"x6' steel framed/250kg per shelf "Whalen" shelves at Costco for 48 quid a set are difficult to beat for storage. Use ALCs (attached lidded crates) for bulkier less frequently used items. The 600x400x320 ones are a one man lift and a tenner or so new. The 78 litre ones designed for office moves are a two man lift. They stack safely as high as you can lift them and wheeled dollies are available for moving the stacks around. 35 litre "really useful boxes" work best on the Whalen shelves; 3 per shelf; pay around 7 quid each inc VAT for clear ones.

    For smaller jobs fit rolling toolboxes with worktops and vices, and take the toolbox to the job rather than the job to the tools nailed in an awkward place on the wall. Over-centre catches mounted on the steel portal frame, or rails bolted to the floor that take T-nuts like a milling machine (or the wheelchair restraints for minibuses/rigging mountings for boats/pickup truck bed attachments) can be used to secure stuff to the floor in various locations if you *really* need to lean on something hard. These can also be used for movable walls. Keep say a "+" of all at the centre of the building to reduce roof loads etc, but have the other walls as lightweight studwork panels that can be rolled along the steelwork at eaves/apes and secured to the floor in any position along the building to maximise flexibility of the space.

    If you don't want expensive rails, cut a "bowtie" into a piece of box section steel. Looks like: =0= as a hole. You embed this in the concrete slab at intervals (welding to the rebar is good) with a small sponge stuck inside the hole to stop it filling up with concrete. Drill it out/pull out the sponge when the slab has set and you can drop a "T" shaped tool in there (a piece of stud with a bar welded across the end) in order to anchor things to it at a later date. Keep sponges or caps of some description handy to reduce the amount of muck that blocks these. No good if washing the area down regularly but could be handy in some circumstances. Pukka recessed rails are nicer. Can go fancy and embed a threaded thing in the concrete but these usually fill with muck.
    • CommentTimeMar 30th 2014
    tony quoth: "straw bales are cheap!"


    but I don't suppose that URL will point at the Cropredy build for very long. Perhaps they'll make a more permanent one?
    If you used the kingspan insulated (closed cell spray foam) panels you would not need any other trades at all on those walls (depending on finish requirements).

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