Dirty loft - no roof underlay

Discussion in 'Other Trades Talk' started by xifwercs, May 14, 2017.

  1. xifwercs

    xifwercs Member

    Hi,
    I've looked in my 'new' house's loft as i want to board it for storage, its pretty dusty as you can see from the photos.
    Ill be binning all the old dirty insulation, adding loft legs, new insulation and loft boards, to keep the place relatively cleaner i'm thinking of stapling inside a breathable membrane like Tyvek or similar from the rafters at the top to the 2nd rafter down.

    Any issues with condensation from this or should it be ok?
    Ill leave below the bottom rafter 'open' for airflow.
    roof is slate and approx 120 years old so no underlay.

    Thanks for any advice offered :D

    . 20170514_163834.jpg 20170514_163945.jpg 20170514_164048.jpg 20170514_164102.jpg 20170514_164112.jpg
     
  2. xifwercs

    xifwercs Member

    edit- staple membrane to the underside of the rafters from the top to the 2nd purling down, leave the rafters open from the bottom purling for airflow
     
  3. Wayners

    Wayners Screwfix Select

    As above. Seen some use that plastic floor cover from b and q, the cheep black stuff but better to use roof felt. Also seen companies come in and spray foam to the underside of tiles.
     
  4. xifwercs

    xifwercs Member

    Thanks for the reply, im not keen on plastic, any moisture id assume would condense and run onto my rafters.
    Same with the spray, also replacing a tile would be a pig.
    Membrane seems like a viable option, fairly cheap too!
     
  5. Phil the Paver

    Phil the Paver Screwfix Select

  6. Dr Bodgit

    Dr Bodgit Super Member

    Could use Airtec double under the rafters, would also act as a vapour control layer?
     
  7. xifwercs

    xifwercs Member

    just to be clear, the roof is slate with no underlay,im not removing the slate to put membrane between the batons and slate, im looking to staple membrane below the rafters.... would the vapour control and air tech not create a moisture barrier for condensation to accumulate and drip onto said rafters?
     
  8. sospan

    sospan Screwfix Select

    Its a good idea to replace the old insulation with a new modern equivalent. Be careful with the new heigh not to block any vents at the soffit area. It is also a good time to check out the wiring the loft as quite often there will be issues with older cables, connectors and the usual bodges.

    Because of the lack of roofing felt water is probably entering between some of the gaps of the slate but isn't a problem because of the airflow in the attic. Fitting a breather membrane across the faces of the rafters will still allow air to move through but prevent larger particles of grit and dust to come through.

    However a lot of dust within the attic is internal from the house and attic itself and is brought down by the internal air flow. A lot residual dirt would be from the original coal fires that used to leak into the attic space. However, whilst these may not be in use, small cracks in the chimney still emit old debris as the chimney air circulates.

    Whilst it can be easily fixed with a staple gun, because of the angle of the roof and size of the roll, it can be a real swine to fix by yourself. If I was doing it I would install the new insulation and boards and then monitor beyond the initial settling, how dusty it is in the attic before fitting a vapour barrier. If the dust is minimal ou could get away with covering the items with a protective sheet rather than wrestling with a membrane
     
  9. xifwercs

    xifwercs Member

    Hi thanks for the replies, i've been into the attic today to size up, the floor beams are only 2x3" with 30cm separation holding up a plaster lathe ceeling below, x13 either side of a central staircase. 2 walls support the beams in the centre (central staircase). these 2x3" beams run from the centre for about 5m to the outerwalls on either side. I'm a bit conscious of using loft legs incase they arn't strong enough to hold weight, would laying and securing new 2x3 beams at right angles to the existing 2x3 beams strengthen the loft floor this so i could put loft legs ontop(to meet insulation reccomendation? bit of a loss how to proceed at the moment, thanks for any help.
     
  10. sospan

    sospan Screwfix Select

    You are probably better off fitting a ledger beam to the pine ends and then use joist hangers to fit new joists using metal hangers. This will give you the additional strength and depth for the insulation.
     
  11. xifwercs

    xifwercs Member

    loft.jpg
    Ive made a crude drawing of the loft, as above would running 2x3 perpendicular to these beams adds strength to the current 2x3 for loft legs the boarding the central portion?
     
  12. xifwercs

    xifwercs Member

    i'm wary of space to get large beams into the loft to make a new floor, its also only for storage also, i wont be making regular trips into the loft, was thinking of the least id be able to get this project done as I still have another 2 floors to renovate.
     
  13. Dr Bodgit

    Dr Bodgit Super Member

    I had similar 2x3 joists and 350mm centres give or take. Screwed 2x2 on top to strengthen them.
     
  14. xifwercs

    xifwercs Member

    was the below diagram ive found similar to what you've done? to support every beam i'm looking at x26 - 4.8 m lengths of 2x3"

    many thanks
     

    Attached Files:

  15. sospan

    sospan Screwfix Select

    You don't need them full length, you can use shorter lengths and then join them together over the the stair well walls which will support them.

    You can glue and screw timber on the top of the existing 2x3 but it does depend on the quality of the timber joists and can be a really tedious job. The other problem is supporting the ends of the beams because you have added more weight on a small bearing
     
  16. xifwercs

    xifwercs Member

    thanks for the help sospan, the rooms below will need joists about 5m in length to reach from outer wall to centre staircase supporting wall, on either side, id have to cut the joists in 2 to take them into the attic, thinner timber would be a much easier option to haul into the attic. i was wondrering about the strain on the ends but hoping as im only boarding the centre portion with about a 2m overlap into the rooms( from center) it will have a large part with the boarding supported by the brick staircase directly below.
    Ive walked on the existing 2x3 beams directly into the centre of the 4.6 x 4.5m room, I weigh about 15 stones and i didn't feel any flex whatsoever, they were solid walking about. hoping that maybe good enough? loft legs may add cross beam support further with screwed boards ontop?
     
  17. Jord86

    Jord86 Screwfix Select

    Unless I'm missing something, screw 3x2 timber hangers down from the rafters and screw to the sides of the joists, you'll have to cut your flooring around the hangers but you don't want to do Sospans suggestion I'd say this is your next best bet.
     
  18. Dr Bodgit

    Dr Bodgit Super Member

    Yes but not glued just screwed. I don't have large unsupported spans though.
     
  19. xifwercs

    xifwercs Member

    Many thanks for the guide, I'm well underway in the project already. Here's a few pics. Needs the 10cm celotex between the new joists then boards. New loft hatch is in also.
     

    Attached Files:

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