Home  5  Books  5  GBEzine  5  News  5  HelpDesk  5  Register  5  GreenBuilding.co.uk
Not signed in (Sign In)

Categories



Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.
Buy individually or both books together. Delivery is free!


powered by Surfing Waves




Vanilla 1.0.3 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to new Forum Visitors
 Join the forum now and benefit from discussions with thousands of other green building fans and discounts on Green Building Press publications: Apply now.




General: S I units

Bottom of Page

1 to 26 of 26

  1.  
    • CommentAuthortony
    • CommentTimeOct 6th 2007
     
    I get wound up extraordinarily by the awful use made of units in general and we should be getting "with it".

    In the 1970's the UK adopted 'SI' (system international) units

    We should only talk about meters, kilograms and seconds and combinations with factors of a thousand allowable

    Thus centimeters are not SI units, meters or millimeters or kilometers are.

    Feet and inches are definitely out, as well as inches only which are more so, as are fractions of inches.

    BTU's no way --- Watts (W or kW) etc are the ones to talk in terms of

    Kilogrammes, degrees Celsius or may be Kelvin too

    Should we clean up our act on here? What do we think.
  2.  
    Yes, we should, any written spec must be in SI units. The trouble is anyone who has ever cut a piece of 4 by 2 will always slip into calling it just that, rather than the longwinded 100mm x50mm. I hate cm.
  3.  
    Dead right tony, laudable sentiment... but never gonna happen! :wink:, ...even metricly (is that a word) measured building materials are really only multiples of 6 inches pretending to be metric!

    J
  4.  
    Well I'm not just off for a litre or two, no way.
    • CommentAuthorTerry
    • CommentTimeOct 7th 2007
     
    Would a swift half help the metric cause ?
    • CommentAuthortony
    • CommentTimeOct 7th 2007
     
    No 0.5 !! and you may get short measured if it is half a litre
    •  
      CommentAuthorfostertom
    • CommentTimeOct 8th 2007
     
    Posted By: Mike George100mm x50mm
    Actually 95x47, if you're lucky
    •  
      CommentAuthorOlly
    • CommentTimeOct 8th 2007
     
    I'm not too fussed by the use of centimetres, you only need move a decimal point if you want to convert to the metre base unit, but mixing metric and imperial units, such as a 3 metre long 2-by-4 does seem rather strange.

    One other examnple is car tyres, E.g. "225/40 R17"
    That's 225mm (width), 40% (tyre wall height as a percentage of tyre width), 17 inches (wheel diameter)

    And just to be pedantic, I think it should be "metre" rather than "meter" Tony, unless you happen to be American? :wink:
    •  
      CommentAuthorfostertom
    • CommentTimeOct 8th 2007
     
    Model railways - long time ago, honest - 0-gauge was 7mm=1ft, 00 was 4mm=1ft, I went for TT-gauge 3mm=1ft. Was only years later I realised that 3mm=1ft is 1:100, near enough. Also, model cars - Dinkys etc - 1:43 scale, wierd till you work out what 7mm=1ft is.
  10.  
    Aye, keep it metric.
    • CommentAuthorhowdytom
    • CommentTimeOct 8th 2007
     
    can you get tt gauge trains fostertom ?. my sons just gone 'n' gauge, 11mm i think. anyway whats wrong with feet for building, I found out years ago that my boots are 12", fantastic for rough layouts on the ground. now try that using 300mm .... say 3,900 x 5,700 !!! that 13steps by 19steps. and fractions are impossable !!.
    I leared both systems and they both have there uses. When it come to cad drawings then I say use mm.
    tom
    •  
      CommentAuthorfostertom
    • CommentTimeOct 8th 2007
     
    N gauge - bit new fangled for me. I once saw a geeky list of all the model railway standards in the world - hundreds! I do recognise that architecture is just adult model railwaying.
  13.  
    Posted By: fostertom
    Posted By: Mike George100mm x50mm
    Actually 95x47, if you're lucky


    I thought a European standard "2x4" was 89x38mm and had to be specifically defined so that 2x4 wood would be legal!

    Over here in Canada, we're nominally metric (distances are in km, temperature in C, stuff in the food shops in litres and kg) but all construction material is in imperial - probably due to the dinosaur to the south of us - where the imperial measures aren't even the same as the UK ones in some cases - pints of beer being a particular area of short change!

    Paul in Montreal.
    • CommentAuthorbiffvernon
    • CommentTimeOct 9th 2007 edited
     
    Posted By: Paul in Montreal
    I thought a European standard "2x4" was 89x38mm


    No, that's 4x2. Quite different deflection properties under load.
  15.  
    NZ laser frame timber is multiples of 45mm.

    45x90, 45x135,45x180 and so on.
    • CommentAuthorLizM
    • CommentTimeOct 9th 2007
     
    If we're talking S I units do we also use ^-1 instead of / eg W.m^-2 instead of W/m^2?
    •  
      CommentAuthorfostertom
    • CommentTimeOct 9th 2007
     
    Isn't 89x38 Canadian planed-all-round wimpy stuff? Hate it - 33% of the section gone in shavings - I specify regularised sawn - i.e. nom 100x50 with the 100 dim reduced to 95 by a regularising machine (coarse planer) so top and bottom become reasonably straight even if the sides remain wavy. In the words of Bldg Regs old span tables, 'sizes are either regularised from BS4471 basic sawn sizes ..... or CLS/ALS sizes with BS4471 tolerances'
  18.  
    Posted By: fostertomIsn't 89x38 Canadian planed-all-round wimpy stuff? Hate it - 33% of the section gone in shavings -


    2x4 wood in Canada seems to be exactly the same dimensions as the 2x4 wood I used in England back in the 90s. A 2x4 seems to be more like 1.5x3.5 (inches). I don't ever recall seeing anything that was really 2inches by 4 inches in my lifetime. In my old house, the framing wood is 4inches by 3inches actual size with the joists 2inches by 12 inches on 14" centres. I've never seen rough sawn lumber used in construction here - it's all "dimensioned" and I presume the 89x38 European designation was to recognize the fact that 2x4 dimensional lumber is that actual size in mm. Last time I was in the UK, the local B&Q was selling it as "89x38".

    I presume that Biff was joking earlier when he said a 4x2 has different strength characteristics than a 2x4 (as I had used 89x38 as the metric equivalent of 2x4 - when, of course, I should have said 38x89).

    All that said, we used 2x6 framing on the new house we built - which is really 1.5x5.5" :smile:

    Paul in Montreal
    •  
      CommentAuthorfostertom
    • CommentTimeOct 9th 2007
     
    UK builders - what do you say - what real size is nom 100x50 sawn (before shrinkage, before regularisation)? Couple of mm off nom i.e 98x47? - that's 4mm blade width off 4"x2" (102x51).
  20.  
    Posted By: fostertomN gauge - bit new fangled for me. I once saw a geeky list of all the model railway standards in the world - hundreds! I do recognise that architecture is just adult model railwaying.


    Oh Christ... you might be right... have always gently ridiculed Dad's 00 guage hobby... but now you mention it... ...I suppose if you take away the trains...

    ...what your left with is an architectural model...! :cry:

    J
  21.  
    I find timber sizes vary, a rough sawn piece of say 50mm x 100mm can be exactly that if it is ungraded. If you go for C16 or C24 it can be a little less [but I think it depends upon the mill]. PSE is different again, as is CLS. The latest addition at my local Builders Merchant is termed 'Standardised and Regularised' which is almost as good in its finish as PSE, though it is graded. It is genearally 5mm less than its sawn equivelent, IE 95mm x 45mm - luvly stuff to use, and they no longer stock rough sawn, other than treated timber
  22.  
    No discussion of Whitworth?
    • CommentAuthorbiffvernon
    • CommentTimeOct 9th 2007 edited
     
    Posted By: Paul in Montreal
    I presume that Biff was joking earlier when he said a 4x2 has different strength characteristics than a 2x4 (as I had used 89x38 as the metric equivalent of 2x4 - when, of course, I should have said 38x89).


    Never cracked a joke in my life. And I didn't mention 'strength'. I said "different deflection properties ". Jump on a 4x2 and a 2x4 and feel the difference.

    Anyway, this all goes to show why Imperial is better than metric in some circumstances. I mean, who'd ever say "Pass that eighty-nine by thirty-eight, mate."
  24.  
    Biff,

    a 4x2 on its side is a 2x4 isn't it? 89x38 becomes 38x89 when rotated through 90 degrees :)

    Over here, the nominal sizes of construction lumber are the same as the square edged stuff (that's used for trim and the like). The construction lumber has rounded corners so you don't get your hands cut when handling it :smile:

    Paul in Montreal
    •  
      CommentAuthorfostertom
    • CommentTimeOct 10th 2007
     
    Posted By: Paul in Montrealso you don't get your hands cut when handling it
    like I said
    Posted By: fostertomCanadian planed-all-round wimpy stuff
    (No offence meant!)

    I always scrupulously put the section height first - 100x50 if on edge, 50x100 if laid flat. Don't know if anyone appreciates the info thereby imparted but it keeps my mind tidy!
    •  
      CommentAuthorfostertom
    • CommentTimeOct 10th 2007 edited
     
    Posted By: Paul in Montrealso you don't get your hands cut when handling it
    like I said
    Posted By: fostertomCanadian planed-all-round wimpy stuff
    (No offence meant!)

    I always scrupulously put the section height first - 100x50 if on edge, 50x100 if laid flat. Don't know if anyone appreciates the info thereby imparted but it keeps my mind tidy!

    What about Whitworth, anyway - anything to do with Royal Enfield?

1 to 26 of 26

  1.  
Add your comments

    Username Password
  • Format comments as
 
Back to Discussions Top of Page
   
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   
Logout    

© Green Building Press