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help loft floor

Discussion in 'Home Cinema Building DIY' started by andya, Jun 7, 2004.

  1. andya

    andya
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    hi im thinking of getting the loft floors reinforced,the loft is 25ft by 11ft and have been told it will cost about £2500.seems a lot of money to me.over time would like to put a projector and screen in,but have got about £4000 to spend.can anyone tell me if this is a bit overpriced
     
  2. aarons

    aarons
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    depends how its being strengthened.steels or timber
     
  3. andya

    andya
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    its timber,im just worried if the job isnt done properly it would be a nightmare.
     
  4. aarons

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    are you putting it through for planning permission if so it would have to have steels.you can do it with timbers no problem.just make sure enough are put in.have you got timbers going across centre of loft halfway up from the floor if so these will have to be taken out.
     
  5. Gary Lightfoot

    Gary Lightfoot
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    To double up the strength of the floor, you could 'sister' the existing joists (4x2s I assume) with wood of the same dimension by laying them up alongside and screwing them directly to the joists. That way you'll end up with the equivalent of 4x4s for example. It'll be easier with plasterboard ceiling rather than lathe and plaster as the plaster protrudes above the lathes and may make locating the new joists difficult. Your existing flooring will be 6 x 2s, so the 4x4 will be stronger.

    You may have another beam running across the existing joists, so that'll prevent you from having a flat floor all the way across unless you run some more beams parallel with it and then board on top of that. That'll allow you to have 8ins of insulation and a little more soundproofing/fireproofing. Lay the second layer of rockwool across the first. If you're keen, use metal netting to hold the first layer in place in case of fire. Another fireproofing suggestion is to add another layer of plasterboard to the ceilings underneath.

    You'll still have to leave the purlin supports in to support the roof, and I doubled up on those for added strength after adding plasterboard to my roof joists. To do that properly, and assuming you have 4x2s there too, use 2" rockwool slabs with 2" clearance behind them for ventilation, fit a vapour barrier (plastic sheeting), and then the plasterboard. I only used a single layer to keep the weight down. The supports don't get in the way, and can't be seen when a movie is playing. Cover them in black material such as speaker grill cloth/felt (cheap) or proper felt or similar light absorbing material.

    If you have a south facing roof, it might be a good idea to use the insulated plasterboard with silver foil backing - this will help reduce heat going into the loft space. I didn't, and it gets 3 degrees warmer up there than on the landing.

    I've some pics on how I converted my loft cheaply in my website. I think the whole thing cost under £1000 or there abouts.

    Gary.
     
  6. DJW

    DJW
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    Gary is spot on with this option, which I did in a 200 year old cottage. Another option was metal plates which run the length of the beam & ar just screwed to the side of the beams at regular intervals. Also if you were to use large sheets of decent chipboard, or posibbly even ply, it would spread the load across the joists, meaning you don't have to do each one.

    Cheers Dave
     

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