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.




Building Regulations and Standards: Exposed glulam posts and beams - fire regulations

Bottom of Page

1 to 11 of 11

  1.  
    • CommentAuthorEd Davies
    • CommentTimeOct 29th 2013 edited
     
    Currently my house sketches have a fairly hefty post-and-beam structure exposed internally. (http://edavies.me.uk/2013/09/roof-rethink/) Further re-thinking makes me consider using glulam in this role - e.g., sketches of posts made up of 3 off 44 × 225 mm in a sort of pi shape and beams of 2 off same in L and T form in different places.

    Wondering, though, if that's likely to be a problem from the fire-exposure point of view, not having the depth to quietly char the way a solid beam would. Anybody know if it's likely going to be a problem or likely not, or do I have to dig into the building standards a bit deeper?

    Single storey (+ loft), Scotland.

    (BTW, seems to me that C16 is about £360/m³ whereas the glulam supplier I got a price sheet from seems to work on £850/m³.)
    • CommentAuthortony
    • CommentTimeOct 29th 2013
     
    Intumescent clear finish? Stinks bad while being applied. Or a sprinkler system may be
    •  
      CommentAuthorfostertom
    • CommentTimeOct 29th 2013
     
    Got a friendly Stuct Eng? He'd tell you the principle - can't quite remember myself but quite a slow char rate per half hour to all exposed surfaces, and then the safety factors that are usually applied are reduced to almost nothing to calc remaining strength. It's generally surprisingly tolerant - but makes you use fatter sections rather than tall thin ones.

    Forget intumescents - just beef up a bit.

    Glulam won't be using C16 surely - better than C24 I'da thought. Unless they cut all the imperfections out of C16 and finger-joint them together - but that'll cost much more than C24.
    • CommentAuthorEd Davies
    • CommentTimeOct 29th 2013 edited
     
    Posted By: fostertomGot a friendly Stuct Eng?
    Sort of, house designer with associated structural engineering resources lined up but he's busy with other projects for a little while so doodling before serious thought. Could ask him, I suppose, but thought I'd try here first.

    It's generally surprisingly tolerant…
    Good news, thanks. I'll persist with sketches and see what he says. Worst case would be to encase in plasterboard or something but seems a pity - would like the appearance.

    Glulam won't be using C16 surely
    Indeed not - I was just comparing prices. They give all the numbers for Eurocode but say for BS to treat as C27 (“conservatively”).

    Hmm, double checking that I now notice they say a charring rate 0.66 mm per minute. If I understand correctly a single storey house would need 30 min protection (does that sound right?) so if both sides of a 44 mm beam were exposed that'd not leave much (5 mm) left.

    My assumption was that considerably less glulam would be needed than standard timber which would go some way to compensating for the extra cost. Combining that with the better appearance and regularity might swing things towards glulam. Fire protection seems to point the other way.
    •  
      CommentAuthorfostertom
    • CommentTimeOct 29th 2013 edited
     
    That's right, remember now, 20mm charring in 30mins.

    What wd normally be reqd col size say 75x100, after applying normal safety factors, might do at 35x50 without safety factors (holding up just long enough to allow escape). 20mm off ea face of the 75x100 wd give 35x60 - ample! But 75 really is the minimum thickness if exposed to fire both faces.

    Looks better a bit fatter anyway - 44w isn't meant to be seen!
    • CommentAuthorEd Davies
    • CommentTimeOct 29th 2013 edited
     
    Thanks for the confirmation Tom. Re-rethink required.

    But any particular reason why not intumescents?
    •  
      CommentAuthorfostertom
    • CommentTimeOct 30th 2013 edited
     
    Thick gloopy coating if 'clear', can be OK if opaque; expense; yet more 'chemicals'; avoidable maybe in this case. In a row of Listed Almshouses, we did Kitchen/stair partitions of 1" T&G & bead moulded planks exposed both faces - v nice - only poss in that case thanks to intumescent paint.
    • CommentAuthorEd Davies
    • CommentTimeOct 30th 2013 edited
     
    Yep, they all sound like good reasons why not. Ta.

    Were those partitions “structural” then or was it to protect an escape route?
    •  
      CommentAuthorfostertom
    • CommentTimeOct 30th 2013 edited
     
    Structural in Bldg Regs (fire) terms, which includes all walls as far as I remember; also to improve escape from bedrm upstairs other than coming down into the kitchen; from foot of stair, escape either thro Liv Rm or Kitchen (the job included similarly boarded door into Kit and another from Kit to cellar steps).

    Brings it all back! Excellent standard of incremental improvements over the yrs. Latest is new garden path, curvy with steel/oak handrail and mid-garden sitting out area, awaiting tenders, £12k + VAT! Unfortunately, the LB Officer, having negotiated the path/handrail detail, decided LB Consent not needed, just Planning, so not only did the Trustees have pay an application fee, but we don't get zero VAT as alteration to a LB (now scrapped, but under the transitory arrangements).
    •  
      CommentAuthorfostertom
    • CommentTimeOct 30th 2013 edited
     
    Lively old dears - almost moved in myself, when I was single for a bit!
    •  
      CommentAuthordjh
    • CommentTimeOct 30th 2013
     
    Posted By: Ed DaviesCurrently my house sketches have a fairly hefty post-and-beam structure exposed internally. (http://edavies.me.uk/2013/09/roof-rethink/" >http://edavies.me.uk/2013/09/roof-rethink/) Further re-thinking makes me consider using glulam in this role - e.g., sketches of posts made up of 3 off 44 × 225 mm in a sort of pi shape and beams of 2 off same in L and T form in different places.

    FWIW, the engineer on our house has used glulam for the horizontal beams and C24 for the posts. Ours will be hidden in the internal walls behind plasterboard though, so no fire problem.

1 to 11 of 11

  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