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Cut rebate in door frame for intumescent strips?

Discussion in 'Wood / Woodwork / Carpentry' started by Kmurphy, 25 Oct 2015.

  1. Kmurphy

    Kmurphy

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    Can anyone suggest the best way to cut these into an existing door frame?

    For fd30 door does the threshold need a intumescent strip of any sort anyone know?
     
  2. JobAndKnock

    JobAndKnock

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    Intumescent strips are only ever fitted to the sides and top of a door opening or door, never to the bottom.

    For "fire stripping" retro-fits it is normal to take the door off, support it on two trestles and rout the intumescent strip groove using a router and one of these cutters. They come in 10, 15 and 20mm widths to match your intumescent strip and the bearing ensures that your depth of cut is correct. The router is run on the surface of the door so it will be necessary to remove any obstactles to its' path such as kick plates, Perko closers, hinges, etc. Work the sides first then do the top to reduce spelching. Attempting to retro-fit an intumescent strip into an already-installed door frame or casing is a complete waste of time and effort IMHO, and I doubt you'd ever see a tradesman attempt it
     
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  3. Kmurphy

    Kmurphy

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    Fair enough. The only issue there I think is that the certification details are on the top and the instructions say not to trim the top...

    Seems rebating the top edge won't work?
     
  4. JobAndKnock

    JobAndKnock

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    Yes. And this is where practical expediency and reality overtake theory. Doors are fire tested in BS standard frames to obtain the rating. If you are retro-fitting a fire door into an existing casing/frame which has not got intumescent grooves already in it, then the door and casing/frame simply cannot meet the fire regulations because the casing/frame won't be to BS. spec. either. In reality it is normally accepted that without ripping out the door casings/frames and replacing them the nearest you'll get to a fire-rated door opening in practice is by adopting the procedure I've detailed above, i.e. grooving the door. One university, four large hotels and gawd knows how many schools, shops, pubs and restaurants over the last 15 years and the same technique has been accepted by the main contractor and the client insurers as the only practicable approach for the majority of door openings each and every time. If on the other hand you have a specific fire requirement where the door integrity is cruitical, then you'll need to replace the casing/frame as well, in which case the casing/frame will have the appropriate groove or grooves

    Rebating????? The groove runs down the middle of the door edge. It is not a rebate
     
  5. Kmurphy

    Kmurphy

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    Well... I have unpacked the first door I ordered and found the BWF certificate is on the bottom edge of the door... Going to be a bit tricky for the building inspector to check it...
     
  6. gregers

    gregers

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    just keep the receipts in a safe place.should have enough details on it.
     
  7. ladylola

    ladylola

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    I must have been unlucky in my career or have been unlucky with clients or architects because I've retro fitted into frames and linings on many many occasions , the most recent one being only a few weeks ago. To be honest it's really not that awkward a job. Most of it is done with a router and the last few inches with a Stanley knife and chisel.
     
  8. JobAndKnock

    JobAndKnock

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    Count yourself lucky - with heavy Victorian mouldings, especially if overpainted numerous times, there is no way to run a router on the casing. In addition the time penalty of chopping into the casing when you are tasked with 500 or more casings is considerable. just saying.....
     
  9. ladylola

    ladylola

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    Wouldn't disagree it can be time consuming , perhaps the flip side of those architects is that luckily time wasn't the most pressing of considerations . With regards to the presence of mouldings I've found that some times it was best to build out the sole of the router with a couple of strips of timber and use the frame rebate as a guide.
    All in all as you say so much easier to do the door.
     
  10. DIYnot Local

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