ᐅ Ceiling Insulation – Gaps and Seams …

Good evening,

First of all, a warm hello to everyone. I’m new to the forum and this is my first post, or rather my first question.

I’m currently working on insulating my basement ceilings. I decided to use stone wool insulation boards with a one-sided light mineral fleece facing. This makes the boards easy to paint later on. The 100 x 60 cm (39 x 24 inches) boards are being installed using adhesive.

Now I have the problem that, due to uneven walls, ceiling brackets for pipes, and so on, gaps and joints have appeared in some places. I’m wondering which suitable material can be used to seal these gaps and joints.

I’ve been searching online for hours/days and can only find statements like “blah blah blah … the boards can be installed without gaps and joints.” In my older house, that’s simply impossible...

How can I close/seal these joints properly? Have you had similar experiences? What materials have you used? PU foam, acrylic, adhesive, or… I’m not sure.

Any advice would be greatly appreciated. Thanks in advance.

Best regards,
Dellmo

I used to live in an apartment owned by a housing association. The basement and attic were retrofitted with insulation by a professional company. In the basement, panels were glued to the ceiling, and gaps were filled with a type of construction foam. I’m not sure exactly what it was, but it definitely wasn’t acrylic or adhesive. It was supposed to provide some level of thermal insulation.

There is also insulation foam used between the expanded polystyrene (EPS) external thermal insulation composite system (ETICS) panels. Now that you have stone wool boards, can’t you simply fill the gaps with stone wool and then plaster over them?

Thank you for your answers. Yesterday, I also had the opportunity to talk again with a plasterer, and he said that the cracks and joints are normal and that it wouldn’t get any better with this material. He also recommended using foam sealant / PU foam. So, I will probably do that as well...

Fill the joints with foam, carefully cut away any excess material after drying, skim the surface, and then paint.