You know you overbuilt your rocket when...

[Fr8monkey]

You need LV-T45 engines to maneuver the ship 'cause RCS thrusters aren't enough.

When using MechJeb to move your ship, you get an error message saying "Awww hell no!".

[Technical Ben]

...when your space station becomes a Duna mission.

When all your space stations become "Jool" missions... then you decide to install the "solar systems" mods to send them even further!

(It's at least in the plans, just waiting for the last 20 or so ships to reach Jool. )

[Slam_Jones]

When your rocket is gaining dV during it's ascent. And you're not even using LV-Ns.

[InterCity]

When you use the same assembly you used for your first mun landing to land at and return from eve... With about 5000 Delta-V remaining when you land at KSC.

Also: You know that you've overbuild your rocket when you can hear your CPU scream "I CONFESS! I CAN ACTUALLY MAKE YOU PLAY CRYSIS 3 AT 60 FPS! JUST PLEASE STOP PLAYING KSP! AAAAAARGH! NOOOO! NOOOOOO!"

Edited December 16, 2014 by InterCity

[Depth]

When Rockomax's new Eve satellite still has the lifter attached

[Hello moto]

When your PC uninstalls KSP and adds it to your 'virus vault'

[Alewx]

In addition to boosters for separators!

[edit]

Beaten by worir4, so a new one...

... when your Jool transfer craft is so big, you decide to just send the engine block on it's own, leaving the main stage as a fuel depot, as that's all you really needed to get there!

http://benart.www.idnet.com/giant2.jpg

What the hell, how many parts does it have? what is your fps?

[Theoderich]

...when you mount your engines radially on IR rotatrons since that makes rendezvous and docking so much easier then turning the whole craft around.

...when you need to send life support package including electricity to the mun and use a 2.5m fission reactor from interstellar for that.

A landing attempt with LV-Ns is always the sign of an over-engineered rocket.

Hey, nothing wrong with that. They make great mun landers, once you get your landing gear placed in a way that compensates for their length.

[Janos1986]

When your ship's mass starts deforbiting nearby asteroids.

[temporalExile]

When you get it into kerbin orbit...

And kerbin is orbiting around your ship.

[Kesa]

When you use kerbal engineer to build your NERAV powered transfer stage for your Laythe station...

And forgot you have clicked the 'atmospheric stats' button.

[djnattyd]

When your ascent stage becomes your transfer, insertion, landing, return and powered landing stage.

[DMSP]

When you get to the mun, land, return to kerbin, and then stage.

[Guest]

...when the ingnition of first stage vaporizes Kerbin.

...when your landing lights are stars.

[Fr8monkey]

When you get to the mun, land, return to kerbin, and then stage.

What do you mean... I can just climb my ship to the Mun without launching.

[Aragosnat]

When your lvl 1 launch pad cannot support the part count, mass, size or all 3. But, you still think it looks cool and that it needs moar parts on it.

[tetryds]

When your lvl 3 launch pad cannot support the part count, mass, size or all 3. But, you still think it looks cool and that it needs moar parts on it.

Fixed, haha.

[Rakaydos]

When your suborbital science rocket accidently gets a Mun encounter.

(Explore Mun before Orbit? really? I needed that contract!)

[Alchemist]

When your small station turns into a huge refueling outpost. Because it still has half of the launcher attached.

[mordin86]

When the launchpad collapses and explodes under my rocket...

[Fleb]

When the launchpad collapses and explodes under my rocket...

This! That happened to the runway with one of my spaceplanes. :/

[Grover]

- the kraken cant eat your entire craft before it gets full

[ShadowZone]

... you just want to bring a 82t payload via shuttle into orbit, never make it the first few times and then create such a giant booster stage that not only can you deliver the payload into orbit, but after that have 2000 m/s of Delta V left, so you make a sightseeing trip to Mun and Minmus and then return to Kerbin.

[Yukon0009]

when just one half of the fairing falls onto the launch pad and blows it up.......

[Reactordrone]

When the small satellite launcher you made for Kerbin satellite contracts can also do Eve satellite contracts.