How To Check for Spaces Beneath a Brick?

In my game, I need to make sure that when a building is placed, there are no crevices or openings beneath the base plate brick of my building models. All of these are named Torso and are set as the primary part of the model. When a player clicks, to place a building, the client sends a request to the server about placing it, and it can go through a simple check: Will the building be on the same plane as where the client put it? If not, remove it. Then it checks for if the player who placed the building is still there and can pay for it (the client has already confirmed that he or she has enough money so I figured ANOTHER check for that would be pointless.)

Since the building is centered on the point where the player clicked, on rough terrain, buildings can end up "dangling" over edges Like in this picture: http://prntscr.com/4inl86

The code below is what I use to check for building placement. I hope someone knows some sort of method, I'm completely lost. Thanks for your help!

game.Workspace.Inputs.ChildAdded:connect(function(c)
	if c.Name == "Building" then
		local bldg = storage[c.Value]:Clone()
		bldg.Team.Value = c.Team.Value
		bldg.Parent = game.Workspace.TestBuild
		bldg:MoveTo(c.Location.Value)
		if math.abs(bldg.Torso.Position.Y-Location.Value.Y) < .2 then
			if something then -- something, implying whatever I have to do to check for uneven terrain.
				local paid = false
				for _,v in pairs(game.Player:getChildren()) do
					if v.TeamColor == c.Team.Value then
						v.Cash.Value = v.Cash.Value-storage[desired].Cost.Value
						paid = true
					end
				end
				if paid then
					if c:findFirstChild(TPTank) then c.TPTank.Value:destroy() end
					bldg.Parent = game.Workspace
				else
					bldg:destroy()
				end
			end
		else
			bldg:destroy()
		end
	end
	c:destroy()
end)