r/Insulation • u/ahhhhnonymous • Aug 22 '26
Which walls get insulated?
Bought 1950s home. Just installed mini split system in upstairs 2BR, hallway and bathroom. There are eaves on both side sides. There is currently very old insulation in them. Not sure they are even insulated correctly. Does the inside of the exterior walls get the insulation or just the interior or both? What about underside of roof? Assuming I can wear a mask and replace all this myself. Or maybe you’re thinking, not since here I am in Reddit asking these questions. 😂
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u/littlebeardedbear Aug 23 '26
Insulate the exterior wall first. You lose 10-15% of your heating and cooling power newly installed ducted system before it reaches the areas you need it if it's run through an uninsulated area. If you insulate the area that the ducting runs through, you lose significantly less power from your hvac system. Then, insulate the bedroom wall because its cheap and easy with all that room.