ᐅ Insulating the Attic – Small Residential House from 1959

Hello,

I have already shared some information about our property in another thread, so I’m particularly interested in your expertise here.

As mentioned above, we have purchased this little house and are currently busy with renovations. Since the electrician will be coming in soon, we want to focus on the attic. We plan to insulate the top floor ceiling, preferably using an all-in-one system, for example, Capaclick or something similar.

In various instructional videos, including the official one by Caparol, no vapor barrier is used. Do you generally recommend using a vapor barrier, or does it depend on the substrate? In one video, they apply Capaclick directly onto the substrate and finish it off with edge insulation strips.

More interesting, however, is the side area of the attic. The sloped sections down to the knee wall can, in theory, be fully filled.

The previous owner had filled about 30% of the slopes with old glass wool insulation, which is now deteriorated. How can this area be effectively and sustainably sealed? I cannot access it from underneath/inside; can I simply push suitable EPS strips in from above, or is a membrane required here? If so, how can I manage that since I only have access through the attic? I want a well-insulating system covering the slopes from the knee wall up to the attic, as well as the attic itself, on all sides.

I hope this makes sense. Do you have any ideas on how to approach retrofitting insulation in an older house?

Thanks and best regards

Peter Silie schrieb:

The previous owner filled about 30% of the sloped ceiling areas with now outdated mineral wool, but it is deteriorated. How can this area be effectively and sustainably sealed? I can’t access it from below/inside. Can I simply slide suitable EPS strips in from above, or do I need to use a membrane here? If so, how can I do that since I only have access via the attic? I just want to have a well-insulating system. Slopes from the knee wall up to the attic, insulate the attic and do this on all sides.

Hello Peter,
why is the mineral wool deteriorated?
If there is a cause (such as water ingress), you should probably address that first.
If you cut strips and push them in, they will be too small and won’t provide proper sealing. Ideally, everything should be tightly fitted without gaps.
You could also consider blowing in loose fill, but if there are holes where the material can escape, that won’t work well either.
It all depends on the condition of the existing construction layers (e.g., the underlay membrane).
Best regards from
Babenhausen