extractor fan holesaw

Discussion in 'Electricians' Talk' started by tore81, Oct 8, 2017.

  1. tore81

    tore81 Well-Known Member

    After a bit of advice

    Installing a fan into the ceiling using exsisting cable need to cut a hole in Tand G ceiling. Could I multi tool, holesaw?

    Getting the fan from the host

    What size holesaw will I need? I believe it's 4inch hoping to go through the facia outside what's the best method drilling through there.

    Any advice would be great
  2. Rulland

    Rulland Well-Known Member

    Hi Tore, few ways to make a big hole tbh, hole cutter is my preferred choice, dry wall saw, but multitool will do, I've also been known to chain drill the perimeter and knock out, depends on the material.

    As for the outside, just be aware of asbestos matey.
    KIAB and tore81 like this.
  3. KIAB

    KIAB Well-Known Member

    A 102mm Bi metal hole saw is only £11 in SF.(42986)

    And in Cromwell tools a Starrett one is £13:30p.
    Last edited: Oct 8, 2017
    tore81 likes this.
  4. tore81

    tore81 Well-Known Member


    fascia is plastic and flat roof.

    Think the ceiling downstairs could be so avoiding drilling there. Need to get it checked.
  5. tore81

    tore81 Well-Known Member

    Cheers kiab will check that
  6. tore81

    tore81 Well-Known Member

    Not sure it will fit the the drill bit I have. Think I have the Bosch one, and the host don't do a Bosch one. Milwaukee even Typical lol
  7. KIAB

    KIAB Well-Known Member

    There are two arbors available, one does 14mm -32mm hole saws, other one 32mm- 150mm hole saws(1779H) @£9:95p), cheaper in competitor,(51826) under a fiver.:eek:
    Last edited: Oct 8, 2017
    tore81 likes this.
  8. DIYDave.

    DIYDave. Well-Known Member

    Sounds obvious but check where ur planning to cut through T&G doesn’t coincide with joists, noggins, pipes, cables, etc that may be in the ceiling void. Sounds like you may have access from above to check this out, ie, loft space maybe ?
  9. CGN

    CGN Well-Known Member

    102mm as mentioned. Reasonable from TS. Asbestos shouldn't be an issue. If you're drilling into soffits, there could be asbestos under cladding!
    tore81 likes this.
  10. tore81

    tore81 Well-Known Member

    Have bought the fan from the host and

    The tube on the fan itself looks quite long maybe 5inches.

    Will this be to big for a flat roof asi don't have an attic. Will this be ok? What's the generally size of joists for flat rood. 6x2? Haven't been on one for years.

    Also the fan isn't labelled LEN no clear markings on block. I'll attach a pic!

    Why they can't write LNE near the block is very poor.

    Also I'm going to have to use the holesaw half to cover spotlight, would I need a template to stop the hole saw from wandaring. Cut out of ply etc.

    Thanks for help!
    KIAB likes this.
  11. tore81

    tore81 Well-Known Member

    Pic of fan

    Attached Files:

  12. KIAB

    KIAB Well-Known Member

    Thought green terminal block was usually marked, as for tube, sometimes it's easier with rectangular duct & use rectangular to round adaptor one end or sometimes both ends.

    What fan you using.
  13. tore81

    tore81 Well-Known Member

    Once you open the cover that block is inside then on the back of the cover there is LEN. But then it depends which way you are looking at it silly.

    Which isn't very helpful!

    I got to drill the hole no matter what so I guess I need to just investigate. Sometimes getting parts pre planning is quicker. Then on the other hand you have to take things back as you can't foresee what's there.
    KIAB likes this.
  14. tore81

    tore81 Well-Known Member

    Here is the fan picture explains more

    So thr black pipe at the back of the fan is quite big in depth not sure if that will be ok for a flat roof grr

    Attached Files:

  15. KIAB

    KIAB Well-Known Member

    Why not just go through flat roof, use weather collar, black jack or similar to water proof area & a mushroom vent, a lot easier.
    tore81 likes this.
  16. tore81

    tore81 Well-Known Member

    Its either that or drill out through a tiled wall. Thought the collar would be smaller than that.

    Must be able to get smaller black collar? This is like 5inch I'd rather go through the facia I don't want to mess with the roof. I'm using flexi white bent pipe then to vent through the facia
  17. CGN

    CGN Well-Known Member

    Stick it through the wall.
  18. tore81

    tore81 Well-Known Member

    Won't I chip tiles etc now seems hassle. Bad planning but no cable there. Accessing cable from a downlighter

    I haven't got an SDS or core drill bit I'm presuming.

    If the fan isn't so flush I should have room
  19. tore81

    tore81 Well-Known Member

    Just thought now if I put the fant tight to the ceiling cable will be hidden. No chasing out! And can prob get cable there

    Any diamond bits that don't make a mess of tiles you can reccomend and will it for regular electric drill.

    Thanks for replies.
  20. CGN

    CGN Well-Known Member

    Just about to suggest that :)

    I've retro fitted extractors on tiled walls many times Tore and just go through with my standard core drills. Just go steady.
    Also, if the PB has been dabbed on, then sometimes you can get lucky and get the cable behind the PB :)

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