The original side door had a lock that required a key inside and outside to close and open the door. The inner closing mechanism didn’t work well and after a couple of days it stopped working entirely. I had to remove the inner door panel to take the door lock apart. While removing the lock, I spotted rotten wood below the lock.
Apparently a woodworm had enjoyed a delicious and long meal. The wood was riddled with holes and full of wooden dust.
After cutting out all the broken parts and sanding the remaining wood, I cut a new piece of wood to size and installed it.
While the wood glue was drying I had a closer look at the door lock.
Unfortunately, the lock cylinder was missing a few tiny springs and screws. The company that had built the cylinder still sold them but they seemed quite expensive. Luckily, I found an entire second hand door lock that matched the dimensions of my broken lock. It didn’t require a key to lock the door from inside and was much cheaper than a new lock cylinder. Win-win!
After fixing the insulation and installing the new lock, I could comfortably look the door again.