Living in a Victorian house where three of the four door linings aren't standardised to fit modern doors. The doors we’re looking at are solid core veneered oak doors that give a trimming tolerance of 5mm (I imagine that’s the depth of the veneer?). What are the consequences of going beyond this 5mm? Is it just a case of there being an exposed raw edge of the core material? The door is going to be painted if that makes a difference. Our sizes vary between 1930-1950 x 730-750. And the closest suppliers sizes are 1981mm x 762mm. Door in mention: https://www.building-supplies-onlin...1Ao2FoATD89Yx3WjoaAjjiEALw_wcB#prod_id=114597
Be a case of trying one. Cut then fit timber down edge. I've done this with hollow doors but not a solid core. Hollow doors timber fits inside but solid doors it may have to sit along edge. Other way is to fit new door lining to correct size but that may not be the best option?
You’ll expose the chipboard core. Not a problem if it’s top and bottom, not a great idea on the sides and additional work to add timber back of course as Wayners has said. Perfectly possible to do though. If you’re painting them anyway you may be better off finding an alternative. You’ll be paying a premium for oak that you’re then going to cover up unless you can only find the style you want in that timber of course.
Buy closest-matching oversize doors. Cut them down to size. Conceal/make good exposed core using hardwood lipping available pretty much anywhere. Make sure your downtrim includes an allowance for the thickness of the lipping. Fix lipping to edges using a decent spread of Titebond II or any other decent wood glue. Use masking tape to hold it tightly in place whilst glue sets. PS - (history lesson of the day) - this is entirely typical of a Victorian house. Back then there were no standard-size doors - these didn't come in until the 1890's when two large companies (one in London, one in West Yorkshire) set up factories producing machine-made doors in what's now considered to be 'standard' sizes.1981 x 762 is 6'6" x 2'6" in old money, a throwback to the imperial measurements of old. The brickies would leave a rough door-sized hole in the brickwork - the local chippy would then come along and build a frame and doors to fit the hole. The brickies would also hammer in oak wedges between horizontal brick courses to give the chippy something to nail the frame into - if you've ever removed a Victorian door frame you'll know exactly what I mean. They also did the same thing between vertical courses for skirtings, picture rails, and dado rails. No Paslodes or grab adhesives back then - everything was done using wedges, cut nails and a big hammer. I've just finished building and installing 18no. 4-panel doors for an 1878 rectory in the Peak District. Every one was a different size ......
PPS - sounds obvious (but just in case it's not) remove 50% of the oversize from one edge, and 50% from opposite. Just thought I'd throw that in there ...
PPPS - ever wondered why joiners set the top hinge at 6" and the bottom one at 8" ??? It's because when these machine-made doors first appeared, they were made using through tenons (no CNC routers back then). The top rail had a 5" tenon and the bottom one had an 7" tenon = the hinges were cut in to avoid these. The tradition has stuck to this day. Oh - and if any chippies south of Watford are reading this - the reason why most of you use 6" + 9" instead of 6" + 8" is that the London company's doors had bottom rails which were an inch higher then the Yorkshire ones. Just thought I'd throw that in there, too.