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?