You do not mention whether you wooden wall will be painted or stained wood. Either way, there paint products you can use to properly seal and protect the wood either way. You should visit your local paint store and tell them what you are trying to do and see what products they recommend.

Paint ceiling with white color Have perpherial false ceiling , install strip LED lights , this way you can have indirect day light .

Hello Sir, I do not understand- what do you mean by "changing the wall Designs." For coloring/wall papers/textured painting it is better to have finished wall. For wall cladding/tiling it is OK to have a non finished wall as well as they require a rough surface. For changing the tiles, its quite a messy, and wasteful expense. Rather, you can give the tiles of your choice to builder to install on the first go itself. Some builders don't allow such requests but others would happily do so. Some others may even offer a discount for not using their tiles. Same thing with paint as well you can give your colors to them to paint if you are not happy with white. Thanks, Nitin CORNERSTONE DESIGNS Bangalore.

Hello Jagriti, For internal walls , you may want to identify and fix the source of dampness to avoid recurrence. You may then treat the wall with 1 coat of Asian paints damp guard or Dr Fix it damp-proof solution and then with putty mix of same material followed with 2 coats of this paint again. Follow the instructions as given on respective products. Thanks, Nitin CORNERSTONE DESIGNS Bangalore.