My guess is that if the gap is large when the door is shut then maybe the flooring is not level and when you open the door to a certain point it is tighter, this is down to the joists not being levelled properly. Only a guess though
A big self generating power wash, lots of brick acid, very long hoses, long reach bolster bars, big lances, lots of PPE, lots of method statements and risk assessments and the ability to be at 3 places at once and then have nothing the week after
Ask whoever is doing the roof, they will be able to do it cheapest as they are doing the reroof, they won't want to provide scaffolding and access/time for someone else to nip up while the roof is off
Sometimes you can knock a row of brick off at the bottom and the internal frame height is still higher than the internal finished floor height, this could gain a bit of leeway especially if the threshold is tall eg. More than 1 brick height, then maybe take some off the head of the frame to...
I have solved this before by cutting a square out of the floor in the area making noise, then noggin out where the square lines are cut to stop the new joints dipping, then glue and screw the trap back down using gorilla glue. While it is up if any metal straps are visible on top of the joists...
Make sure you don't use any gas powered gear like a calorie gas heater! Co poisoning is a silent killer, are you drying clothes in the house? Do you have water under the floor boards? Water rises up sometimes. Do you have extractor fans in kitchen and wet rooms? Do you use them if so
Take the fixings out of the door and cut the sealant off, then wedge the frame up a bit and refix in new holes, if there's not much room to go up then take out the whole door and frame cut 10-15mm off the top then refit higher :mrgreen: