# Routering fire doors



## CRO (Dec 30, 2010)

HI. CHRIS HERE CAN SOMEONE RECOMMEND THE BEST ROUTER BIT FOR DOOR EDGES.AS I HAVE GOT EIGHT DOORS TO DO .THE DOOR SIZES ARE 35mm THICK.


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## Ralph Barker (Dec 15, 2008)

What is your objective? Trimming the door edge to fit the opening? Installing heavy hinges?

If trimming, a power plane (or, hand plane) may be the better option. 

If you're doing hinge mortises, you might think in terms of a jig that can be moved from door to door, with template sections of the appropriate size.

Also, you don't mention the material and/or treatment. You'll want to make sure that any treatment chemicals are safe to cut or rout before kicking up a toxic cloud.


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## Phil P (Jul 25, 2010)

Hi Chris

35mm seems a bit on the thin side for fire doors, FD30 (the lowest commercial spec in the UK) are normally 40 to 44mm thick. As Ralph says, what do you need to do? Are you trying to plane the doors in, hang them or rout-out for intumescent or brush strips?

Ralph, British certified fire doors normally don't contain toxic retardant chemicals (at least I've never hung one yet, and I have done quiet a few). The fire rating is rather from the choice of filler (e.g. chipboard/particle board), facing and thickness which means the factory can give it an appropriate rating. This is generally FD30 or FD60 for 30 or 60 minute fire rating and is marked by a special sticker on the top edge of the door. The door casing, stop laths/stop rebates, gaps, intumescent seals, hinges, etc all have to conform to Building Regs to make the installed door meet the required fire rating. For example proper fire doors generally need to be on a washered or ball hearing stainless steel, brass or bronze hinge of a minimum thickness (not a cheap stamped "builders special" steel hinge)

Regards

Phil


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## jw2170 (Jan 24, 2008)

G’day Chris

Welcome to the router forum. 

Thank you for joining us


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## CRO (Dec 30, 2010)

HI, CHRIS HERE AGAIN MY DOORS WILL BE A NEW 35mm FIRE DOOR SIZE.I WANT TO ROUTER DOOR EDGES FOR FIRE/SMOKE STRIPS USING A 1\4 DIAMITER BIT SIZE NOT 1\2 INCH.


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## CRO (Dec 30, 2010)

Thanks james ,hi. To you also.


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## Phil P (Jul 25, 2010)

Hi Chris

Intumescent/cold smoke seal strips come in 10mm, 15mm and 20mm widths. My understanding is that new build/new door and casing calls for 20mm on FD60 doors and that the 10mm and 15mm widths are used only on FD30s or for retrofitting to existing doors (if in doubt talk to the Building Control Officer at your local council). A lot of FD30 door makers seem to prefer the 15mm over the 10mm as it is more certain of reaching the required rating. Generally intumescent/cold smoke seal strips have a depth of 4mm (Edit: Yes, there are 2mm, 3mm, 5mm, etc strips out there, but if you walk into a commercial stockist and ask for them you'll generally get 4mm thick ones......). In your case you are hanging new doors so I'd stick to the standard depth, shallower or deeper grooves are often to accommodate fitting to existing doors which have shrunk and fixing to existing doors which are in some way restricted (e.g. as in a listed building) respectively. 

Personally I've never seen a 1/4in shank intumescent strip cutter, although I know that Wealden Tool sell 8mm, 3/8in and 1/2in shank cutters, see here. You could try Trend or Titman, but I think that they're the same. The alternative is to use an appropriate straight cutter and rout on the surface or to use an appropriate slotting cutter and bearing, which will be available in a 1/4in shank. Both techniques are shown in Trend's Knowledge Base article. I used that approach before switching to the special purpose 1/2in shank cutters which are faster to set-up as well as faster in use and more accurate. Using a router with the straight cutter on the edge of the door can be particularly "tippy" so a second fence on the opposite side of the door will help stability. Be careful to get the groove width bang on and the depth dead right or you moght find the strip detaching itself from the door as it is opened and closed because of the wiping motion of the brush strip against the door casing.

Before cutting the intumescent grooves you'll need to shoot the door in all round (to fit the casing), but remember that the depth you can cut into a certified fire door is severly limited (often just 3 to 6mm max) and that you are supposed to leave the fire rating label intact and on the top edge if it's a BWF fire rated door (not always possible, that one) or the marker plugs visibe in the hinge edge (for TRADA doors). For a painted door I'd leave a 3mm gap up both sides and at the head with about 6mm at the bottom. Normally a job for the plane, that.

I'm still concerned that your doors aren't proper fire doors, though. 35mm is the thickness of domestic hollow doors which are not fire rated whilst most BWF Certifire or TRADA Q-Mark (the two ratings in use) are as a rule 44mm thick (FD30) or 54mm (FD60). If they need to be fire rated I suggest you check the top edge (BWF) or hinge edge (TRADA) to ensure that they are correctly certified. If on the other hand you are installing the brush strips merely as a draught excluding method fire rating doesn't come into it

Regards

Phil


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## CRO (Dec 30, 2010)

Hi. Phil a big thankyou for your advice .back to the drawing board for me.
Will keep in keep you informed of my progress. Chris.


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## Phil P (Jul 25, 2010)

Chris

Just a bit of extra info on doors, etc. I was talking to one of my suppliers today and he was convinced that he'd seen 1/4in shank intumescent cutters. He rang me this afternoon to tell me that Trend do do both 10 and 15mm ones in their low-cost Craft-Pro ranges, the reference numbers are C209 and C220 respectively. He also told me that he'd never sold either in 10 years despite being a main stockist, so they'll probably be special order if you need them (24 to 48 hours from Trend)

On the door thickness front, if you were to go with standard thickness FD30 doors replacing non-compliant doors there are two options; with built-up stop laths it is possible to pry off the old laths, clean-up the door casing, hang the new doors then refix the old laths (or replace them with some planed timber) whilst on rebated casings one way to proceed is to remove the architraves on the hinge side, fix packer pieces to build-out the rebate to the correct depth, e.g. to 45mm for a 44mm thick door (the packers ideally need to be the same width as the architraves + about 8mm for a 9.5mm architrave set-back), then refix the architraves and hang the new door. If you find any gaps between the casing and the plasterwork or nasonry this should be filled with either intumescent (fire rated) expanding foam or mineral wool (Rockwool, etc) to form a fire break. I've used both these techniques when upgrading doors in pubs and had no problems getting the work passed by Building Control who seem more bothered about the use of BS.Kitemark stamped fire-rated hinges

Regards

Phil


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## CRO (Dec 30, 2010)

Thanks again for the advice phil have taken note..........


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## bobj3 (Jan 17, 2006)

Hi

Fire doors = ?????,,, you can buy them right out of the rack with the metal door frame, and they will pass the code..with all the hardware that's needed for a fire door.

=========


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## Phil P (Jul 25, 2010)

Bob

We have slightly different regs here in the UK. You can buy pre-hung performance doorsets here, but they generally just come in standard sizes, so for new build, really.

Singletons and short runs you generally have to buy the doors, hinges, intumescent strip, etc separately. Just a different system


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## CRO (Dec 30, 2010)

T hanks for that bj.......


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