> You’re describing my situation. How do you de-leakify a house?

Do a blower door test and see where the air is coming in/out:

* https://www.energy.gov/energysaver/blower-door-tests

* https://www.youtube.com/watch?v=msZ_E-4GFs8

* https://www.youtube.com/watch?v=Q5vHxgq7GKo

Then plug the holes.

Aero barrier and/or spray foam for an existing home should work well. But they are not long lasting and are often not environmentally friendly. You can also look into exterior insulation.

If possible and if you have the funds, try to do a retrofit: https://ekobuilt.com/2019/04/24/retrofitting-an-older-home-t...

https://www.buildwithrise.com/stories/passive-house-retrofit...

You don't have to do all the the things to improve performance -- you can pick and choose.

I would start by blowing insulation into the exterior walls (assuming they don’t have any), and insulating the attic. Also, upgrade the windows to double paned or better.

Fixing unintended holes in exterior walls is probably also reasonably safe.

However, randomly plugging intended leaks without understanding how the house is supposed to breathe can lead to condensation issues (mold and rot), carbon monoxide poisoning (if you have natural gas) and radon poisoning (if that is a thing where you live).

If you want to do more than I mentioned above, consider hiring an architect, or reading up on house ventilation designs.

Some home energy companies will do a free audit, in my case it's Mass Save. My in-laws on a limited income even got new windows and insulation for free.

AeroBarrier does the spray insulation strategy all at once for a whole home. Could look into something like that.

- spray foam around/behind outlets on exterior walls (major leak point) which can be done often by just removing the outlet covers

- spray foam around windows (requires removing trim)

- caulk joints/spray foam rim joist in basement/crawl space

- spray foam around any attic can lights/duct work

- make sure ducts and air returns are sealed properly

The easiest is honestly to remove the siding and roof, and wrap the entire building in insulation.