loft

Discussion in 'Builders' Talk' started by Bcountry, Dec 14, 2006.

  1. Bcountry

    Bcountry New Member

    Our loft is full of old stuff SHE cant bear to throw out. Consequently I am thinking of installing some stronger joists up there and boarding properly so to make a nice storage space which doesnt mean our ceilings sag like her baps.
    The span each side of the loft is 3.6mtrs to the central supporting wall so I plan to put in 195x47mm trees supported 20mm off the ceiling below.
    I plan to cut the beam at an angle where it sits on top of the outside wall / under the roof to get it in. The roof comes straight down on top of the wall so the angle is quite acute. With the packing piece to hold it off the ceiling this means I will only have about 25mm of joist before the angle kicks in.
    Will this effect the strengh of the joists?
     
  2. Bcountry

    Bcountry New Member

  3. Bcountry

    Bcountry New Member

    Please can someone tell me if what I am planning is OK!!
    :)
     
  4. devil's advocate

    devil's advocate New Member

    Hi Bcountry.

    The pros will be along in a minute (I think I can hear the horses pulling up outside...), but I believe what you are proposing is quite normal. Obviously, try and cut the angles as neatly as possible to fit the shape of the roofline, but the loss of strength is minimal.

    Can't comment on size of joist 'cos I'm not an expert - ok, I'm a cowboy :(
     
  5. Bcountry

    Bcountry New Member

    Yeeeeehhhh haw

    Thanks DA

    I will be onto the ordering of timbers tomorrow. If it goes wrong I will blame you!! ;)

    I expected at least HandyAndy to have answered by now - He must be xmas shopping. Any input into my selection of joist size would be great. Remember im only using it for storage and not intending on using it as an office in the future ;)
    Oh, and under no circumstances will running a new ring from the fuse board for the electrics ;)
    That would of course be very dangerous!!
     
  6. devil's advocate

    devil's advocate New Member

    Cowboys! Cowboys! Where are you?!

    Er, I mean 'Builders!' 'Builders!'

    This man needs confirmation of joists sizes for his conversi.. I mean storage space.

    (FWIW, 8x2's sound ok to me for a 3.6m span, but I'm only saying that from picturing myself in my head jumping up and down on them, and none have broken yet. That's quite a nice bit of useful space you'll have there, by the way, but mind your head on that purlin behind you...)
     
  7. Controlled Magic

    Controlled Magic New Member

    By the old Part A tables, 8x2 are more than man enough for a 3.6m span (at 400c/c). Make your centres closer where the existing ceiling joists compromise that c/c dimension.
     
  8. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    Hey, you know I'm not a pro. But eight inches always sounds good to me ;)

    As said, cutting the angles off the top at the ends is minimal loss in strength. Are the original joists like this ?

    Just wondering where and how you are going to fix these joists ?

    Also wondering why you have chosen to raise them 25mm off the ceiling. I would have said they would not encroach/flex any more than the existing joist level(though I suspect you might run some wiring under there)

    And just to add, have you tried the new height for size ?
    195mm + your flooring + your gap - your existing joist height = 140mm approximately extra height.

    I guess you have worked out the loft hatch conversion you will make- extra height on ladder(probably intruding the door aperture more)for example. All these things ?


    'part from that, sounds good to me.




    Mr. HandyAndy - really
     
  9. ChaserRenos

    ChaserRenos New Member

    No it shouldnt as long as they are securely mounted. I would glue and nail them to the exsisting joists for added strength.
     
  10. devil's advocate

    devil's advocate New Member

    Always good to have them completely independent fromt he original joists, and the 25mm gap (probably could be slightly less if you want) is also recommended.

    Doing this will greatly reduce sound transfer, and also eliminate risk of damage to ceiling below; clunking large items of furniture and beds (er, of course, not in this case...) will soon loosen the plasterboard nails :(
     
  11. Mr GrimNasty

    Mr GrimNasty Active Member

    So does that leave room for a full-size snooker table with adequate cueing?
     
  12. yorkshireboy

    yorkshireboy Member

    It is not good to have them independent from the original ceiling joists.The original ones will be supported by hangers to the roof,you will need to remove these to put the floor joists in so the old joists need to be fixed to the new ones
     
  13. devil's advocate

    devil's advocate New Member

    Hi yorkshireboy.

    I don't understand :(

    Why do the original hangers (or skew nails) need to be removed? Why can't the new joists simply be independent (as it was on our recent loft conversion)? Surely sound transfer is geatly reduced this way?
     
  14. yorkshireboy

    yorkshireboy Member

    Evening devils.
    The hangers are vertical timbers hanging the ceiling from the purlins.
    Imagine you are spanning 3.6 m with a 3 or 4x2 ceiling joist.To stop it sagging in the middle you fix a binder/runner at the middle at 90 degrees to the joists and hang this binder from the roof.This method is used in any traditional roof unless the ceiling joists have a very short span.To put new joists above you need to remove the binder which leaves the ceiling unsupported
     
  15. ChaserRenos

    ChaserRenos New Member

    Sound transfer wont be a problem in this case as Bcountry has already stated the area is to be used for storage only.
     
  16. devil's advocate

    devil's advocate New Member

    ChaserRenos, storage space ma botty...


    Hi Yorkie. Oops, I didn't even know what a 'hanger' was (tho' I should have since I've just watched our loft being converted :()

    These hangers usually indicate where the loft-room walls (ashlare - see, I know something :)) are located; can't they simply remain where they are on the original joists and the new floor joists fitted in between?

    I think Bc is looking for as straight-forward a conversion as possible.
     
  17. ChaserRenos

    ChaserRenos New Member

    Lmao forgot about his emotioncons in his post....

    I still say fasten the new to the old, there will be lots of strength there and if they are glued there will be little movement to cause noise. if a soild flooring in laid and new insulation all the better.
     
  18. yorkshireboy

    yorkshireboy Member

    Devils ,the hangers are fixed to a binder which is fixed to the top of the ceiling joists at 90 degrees ie, a 4x2 nailed to each joist.You can,t put any new joist next to the old ones without cutting through this
     
  19. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    Devils ,the hangers are fixed to a binder which is
    fixed to the top of the ceiling joists at 90 degrees
    ie, a 4x2 nailed to each joist.You can,t put any new
    joist next to the old ones without cutting through
    this



    Do you know, I thought these were to help support the roof, not support the ceiling.

    Or is it a bit of both, yorkshireman ?




    Mr. HandyAndy - really
     
  20. devil's advocate

    devil's advocate New Member

    Ah! Thanks for that Yorkie - I see what you mean.

    Mr Ha, the term 'hanger' certainly suggests that it's the ceiling joists that are supported. The uprights which support the roof rafters - and which, I guess, must come of load bearing walls/structures below are called ashlare - I think...:(
     

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