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Is there a minimum width for joining different tiles on a semi bungalow. Neighbours roofer has gone for thin width and can’t find anything online if this is correct.

Hi At my sons flat the front door lock is a era, you can lock it from inside but from outside the key turns nothing left and right and opens the door you can lock the door Is this normal or is the lock broken ?

I have a damp wall in a 1920s cellar which has a lot of efflorescence causing the pointing mortar to crumble in places. I can't afford to tank the cellar right now, but should I get the wall repointed to help protect the structure for now?