Purchasing internal fire doors

[curium]

Hi All,

I'm purchasing some internal fire doors after having the loft converted. We've decided we want to replace all the doors to a similar style so I need some advice on measuring up for ordering as I don't want to call a chippie until the doors are on-site as lead times during the conversion caused a bit of stress.

So is it simply a case of measuring the inside of the existing door-frames and then ordering a door to the nearest size going a little larger to allow the chippie to trim as required for a good fit allowing for the flooring?

Any tips on what to look for when buying doors?

Thanks in advance!

 

[Deleted member 174758]

Many fire door manufacturers now state that fire doors must not be trimmed to size and therefore must be ordered to the exact size required. Bear in mind that the maximum gapping round three sides is 2 to 4mm, with a maximum of 3 or 4mm at the bottom dependent on the individusl manufacturer's specification (note that different manufacturers may have differing specifications on the bottom gapping). You can exceed that bottom gap, with a maximum gap of 10mm if a drop seal is fitted which meets the 3mm requirement. All measurements are when the door is closed

Firstly make sure you have a decent quality tape measure - there are a lot of cheap, nasty, inconsistently marked, inaccurate carp tapes out there and you don't want or need a tape measure which is out by 2 or 3mm at 600mm or which has a damaged end. Personslly I've found three brands to be fairly consistent - Stanley FatMax, Bahco and Hultafors which all seem to read consistently when placed side to side, so I trust them.

Take the measurement across the top of the casing as your width of opening, then take the height in both the corners and give the shorter of the two as your opening height. Clearly state that this is the opening size (NOT the door size) in any correspondence.

I'd also check the legs of the casing with a 6ft level to see if the jambs are straight and parallel. If they aren't the door will need to be hung, the architraves removed and the jambs adjusted to get the correct gapping between the door and casing.

If the gap across the bottom of the door is more than 3mm (or whatever the door manufacturer specifies) a drop seal or a floor threshold will be required. Either way the gap beneath the door cannot exceed 10mm at any point

A lot of joiners still want to shoot doors in by planing them to fit, however that is now considered to breach the fire integrity of a door, so unless a door manufacturer specifically states this can be done the joiner should not be allowed to do this and instead he will need to make the casing fit the door (Grenfell has changed a lot of things). This can be an awkward job to do, and nobody likes doing it as it can take an hour or two extra per casing (over hanging the door), if they are really bad