ᐅ What type of insulation is recommended for a 50-year-old house?

My 85-year-old father is determined to insulate his 50-year-old single-family house (double-wall masonry) using blown-in insulation. It is a double-wall masonry construction. I believe that the 50-year-old plastic windows with double glazing, as well as the front door, should also be replaced. He considers that unnecessary, saying the windows are still in good condition and that they would only install double glazing again anyway. He doesn’t see an energy efficiency improvement there. The house is a detached single-family home with just under 100 m² (1,076 sq ft) of living space. The attic is unfinished, and apart from the glass wool insulation commonly used in the past, there is no insulation in the ceiling between floors. Under the roof tiles, there is a roofing membrane that was typically installed in the mid-1970s.

What do you think? And what happens if the walls are fully blown with insulation now and new windows are installed later, or if a patio door is installed instead of a window? Will the insulation then fall out again?

To be honest, I wouldn’t recommend guessing what to implement here. It’s best to involve a real expert (I believe in this case an energy consultant) to visit the property on site. They can then provide the best advice on which measures will achieve which improvements and how these relate to the blown-in insulation if that is insisted upon.

[QUOTE="Heidi1965, post: 654453, member: 11461"]
My 85-year-old father was determined to have it done,
he feels more satisfied since then and has contributed to the environment, and it doesn’t harm the house.

Heidi1965 schrieb:

My 85-year-old father has decided to insulate his 50-year-old detached house (double-layer masonry) using blown-in insulation.

This is one of the most cost-effective energy measures you can take. Kudos to you and your father.

Heidi1965 schrieb:

The attic is unfinished, and the ceiling of the top floor is not insulated at all, except for the commonly used glass wool insulation from earlier times.

Now here comes the great son with a brilliant idea to make his dad happy. Go to the home improvement store and buy insulation batts by the roll, then simply lay two layers of 12 cm (5 inches) insulation (such as friction-fit batts) on the top floor ceiling. Very affordable and highly effective. Given the age of the house, I assume there is adequate ventilation in the roof space.

There are different materials for blown-in insulation. One option is to blow in flakes, usually made of stone wool. These tend to interlock well and even during window replacement, they only cause minimal shedding. However, a minimum air layer thickness of 4 cm (1.5 inches) is required for this.
Alternatively, granules, often EPS beads, can be blown in. These have a slightly better insulation value and the air layer thickness can be smaller. On the other hand, they tend to shed significantly more during window replacement.
Overall, the mentioned options for blown-in insulation and ceiling insulation are reasonable.
Replacing windows also leads to energy savings. New double-glazed windows are significantly better than the 50-year-old ones, but ideally, triple-glazed windows would be installed in any case (especially in combination with blown-in insulation).

If advice is needed, I would recommend commissioning an ISFP (Individual Renovation Plan) from an energy consultant. The cost, after subsidies, should be between €300 and €500. Blown-in insulation, window replacement, and ceiling insulation could then be subsidized with 20% (up to €60,000 per calendar year with an ISFP). Without an ISFP, the subsidy is still 15% / €30,000.

If only blown-in insulation and ceiling insulation (DIY) are planned, it is better to skip the ISFP and subsidy, as it is not worthwhile for this scope.

jens.knoedel schrieb:

From an energy-efficiency perspective, this is one of the measures with the best cost-benefit ratio. Congratulations on having such a father.

And now comes the great son with a brilliant idea that makes his dad happy. Go to the hardware store and buy insulation by the roll. Then simply lay 2x12 cm (2x5 inches) of insulation (e.g. friction-fit mineral wool) on top of the upper floor ceiling. Very inexpensive and highly effective. I assume that, given the age of the house, there is sufficient ventilation in the roof.

The wonderful daughter, who is already 59 and definitely won’t crawl around doing insulation herself. I’ve been told that new windows would make more sense at first. That probably won’t happen because he doesn’t like any disturbance.