ᐅ Idea for Terrace Flooring on Garage Roof – Roofing Felt

Hey everyone,

So far, we had exposed concrete pavers on our terrace (garage roof). I recently removed them all. The roof is now "bare," meaning just roofing felt. Of course, it’s not perfectly flat but has some waves.

Now we’re considering what surface to use for the terrace. At first, I thought about those 30 x 30cm (12 x 12 inches) wood-look tiles, but since these require a flat substrate, they’re not an option.

Next idea: porcelain stoneware slabs on adjustable pedestals. Question: If I choose 60 x 40cm (24 x 16 inches) porcelain stoneware, how thick do they need to be at minimum so they can be supported by pedestals without breaking?

Or do you have any simple and cost-effective suggestions?

How uneven is the roofing felt exactly? If it’s just “a little bit uneven,” these wooden slatted bases (called Runnen at IKEA, previously known as Platta) might work. They are quite comfortable and low-maintenance, but of course not suitable for very uneven or mountainous ground.

Already a bit wavy.. I will check it with a long wooden batten. We also had the IKEA Runnen in mind. It might not be a bad idea to buy one or two packs and just test them out...

This is what it looks like

Maybe start by leveling the surface first?

Don’t expect too much from those Ikea things. I had them on the balcony, and by the second year they didn’t look new at all anymore.

How do you level something like this without having to replace the entire roof?