I just finished building G.P Sportster 40 and I noticed that I have about 1/16’’ gap between Stab and elevator. Same gap between the ailerons and the wing. So just wondering is that going to cause any problems during flight?

The gap is not really good, and it may or may not cause some flutter, most likely in the ailerons. Turn the wing upside down, flex an aileron so that it hangs down, and lay a 1/2" wide piece of scotch tape down the hinge line, or iron a strip of Monokote in the hinge line. Do the same on the stab hinge line. This will stop the problem. And your ailerons and elevators will be more effective as well.

Clarification: the tape/Monokote is down IN the hinge line, in the shape of a "V". This allows the control surface to flex normally.

Clair

If you only have a 1/16th gap I say , Bravo however, depending on the application even larger gaps are required..... you did good for a 40.......
It is a good idea to develop a good habit, seal the control hinges....... good advice!

Yes, a 1/16" gap is not bad at all. In fact, that's about what you want. It gives your control surfaxes and hinges a little "breathing room".

Sealing the gap is always a good idea. Just do it as Azcat said.

BTW, I see you're from Boynton Beach, do you fly with the WPB Skyhawks?

Thanks for the advices. NO, I'm flying at Bush Pilot.