The ceiling is insulated with PIR plates, as explained in Roof, insulation, installing vent, fan and solar.
The top of the PIR boards are covered with self-adhesive Armaflex sheets (9mm thick).
With this, the insulation was equal in thickness to the support beams, and the wooden timber which I had previously installed. The Armaflex was already black, the wooden timer and everything else have been spraypainted black to make a rather solid black background.
On top of this, there will be a layer of black fabric. I found a cheap black fabric (2.50 eur / m). This is slightly stretchable, perfect for my purpose. Since this is rather thin, white spots might be seen through the fabric, thats why I made the ceiling black and spraypainted where needed.
Once cut to size, I used thumbtacks to temporary fix the fabric in place.
The final cladding will be made from slats of beech wood, just as the countertops and table. Also painted in the same color. The slats were 4.5cm (1 3/4″) width and 1cm (3/8″) thick, I used a wood planer to remove 4mm and make them 6mm (1/4″) thick (Save weight, gain usuable height).
After that, I’ve sanded them down, and painted them with dark varnish.
Once the slats were finished, I started installing them to the ceiling. The center slat also contained the lights, so I had to cut the appropriate holes first. Once confirmed everything was fine, I nailed them to the wood structure of the ceiling (About each 25cm / 10″), using a pneumatic stapler (which only created very small holes, barely visible).
I used some leftover wood of 12mm (1/2″) as seperator between the slats, exposing the fabric. Used this as spacer for equal with along the slats, nailed them and went to the next one. The fabric gives it a nice smooth backdrop. And once more slats are installed, I removed the thumbtacks, and the fabric is hold into place by the slats.