How to keep the brick in place during a brick size increasing?

I created this script inside a brick called Part the script says

Part = script.Parent

while true do 
	Part.Size = Part.Size + Vector3.new(0,.1,0)
	wait(0.05)
end 

It is growing the brick but it keeps going out of position. It ends up somewhere else when it sizes up. Also I want the brick to only increase on one side of the brick not both ways. I do not know how to do that?

Changing size should not change position unless the part is touching something, then I guess it's inevitable. To only size one side, look into this: http://wiki.roblox.com/index.php?title=API:Class/BasePart/Resize