Hey all!
I made a house and tested it. on the third floor there are some walls and some areas of the ground which are invisible although they are textured and have noc "caulk double" inside...
The cruel thing is that those brushes are each out of one part, but not all is invisible, just some parts. Also my hands and gun are black...
I made everything as usual...

Knows anybody help? I would much apreciate!

Hmm; caulk when rendered in-game is invisble. Also anything that it passes through or touches will also not be rendered.

As for black viewmodels, hands, wep etc; this could be caused by no worldspawn.

Just a added thing here ..I have ran in to this prob, before my self ,
Some times when you copy things ,for some reason some times it makes them this way.
So best thing to do is go back and make new walls and floors where this has happened.
Make sure you use caulk first then use your texture .

There are 'test' textures that are just grid's showing the dimensions if you don't want to texture detail yet.