We have a house from 1972 and we're wondering whether we should do external insulation or maybe go with internal insulation instead. The heating costs in winter are really brutal and we want to make a change. What would you guys recommend?
For houses from the 70s, external insulation is pretty much always the better choice if it's possible. I know several people who've done it, and the savings are really significant - plus there are way fewer problems with mold and moisture damage. External insulation protects the building fabric itself, whereas internal insulation destroys the heat storage capacity of the walls and condensation problems can develop at the interface. If your house is from 1972, it probably doesn't have proper insulation and the walls are still relatively solid - exactly right for external insulation.
You really only need internal insulation if you can't access the outside - so if the house is listed or the facade is just too valuable to touch. Otherwise you're just losing living space and the effect is never as good. With external insulation, you should go for a good system (polystyrene, mineral wool, or wood fiber all work), but above all make sure you get proper workmanship - that's where hiring a specialist is worth it.
The costs aren't cheap, sure, but given what heating costs look like these days, it should pay for itself in under 20 years. Plus if you ever sell or rent it out, a house like that is way more attractive. I'd prioritize it if I were you, if you can swing it financially.
External insulation is actually usually more efficient, but with houses from 1972 you should check beforehand whether your facade can actually handle it - old brickwork or render can sometimes be problematic and costs can quickly spiral out of control. Internal insulation is more expensive to run and you lose living space, but if the outside is hard to access or under historic preservation, you often don't have any other option. What's the current state of your facade anyway, and have you already gotten a quote for external insulation?
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