[modo_mario]

How does that happen tho? I'm thinking about the gaps in my own that's only slightly younger and the only gaps i can think of are at the door and maybe there's a gap at one corner of the roof but i can easily fix. Nothing gets trough that brick and mortar.

[whafro]

First, there are many gaps in pretty much every home. Junctions between drywall/plaster joints, windows and window frames, every electrical switch/outlet box, details in the attic and roof, the rim joists and sill plates, and yes, even any exposed masonry.

Secondly, exposed masonry does often warrant being air sealed:

https://www.greenbuildingadvisor.com/article/insulating-old-...

https://www.jlconline.com/how-to/insulation/air-sealing-a-br...