Filling a board with tiles, with separation

I'm creating a basic prototype of something I have in mind, a sort of board game. Here's a picture if you're interested: http://i.imgur.com/WVck6MY.png

Each of these tiles is a separate game object right now just to show the setup. I know I can use two for-loops to place a single tile multiple times onto the board instead of having tons of identical separate game objects, but I have trouble wrapping my head around how to create 'gaps' between each tile so they're not all squished together (check my picture and you'll see there is a noticeable gap between each tile). Any help on how to generate this via code is appreciated.

I have a GameManager empty object with the following script:

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 public class GameManager : MonoBehaviour {
 
     public GameObject TilePrefab;
     List <List<Tile>> board = new List <List<Tile>>();
 
     public int maxRows = 4;
     public int maxCols = 5;
 
     // Use this for initialization
     void Start () {
         generateBoard ();
     }
 
     // Update is called once per frame
     void Update () {
 
     }
 
     void generateBoard ()
     {
         board = new List<List<Tile>> ();
 
         for (int i = 0; i < maxRows; i++)
         {
             List <Tile> row = new List<Tile>();
             for (int j = 0; j < maxCols; j++)
             {
                 Tile tile = ((GameObject)Instantiate(TilePrefab, 
                               new Vector3(i - Mathf.Floor(maxRows/2),0, -j + Mathf.Floor (maxCols/2)), 
                               new Quaternion(new Vector3()))).GetComponent<Tile>();
                 tile.boardPosition = Vector2(i,j);
                 row.Add (tile);
             }
             board.Add (row);
         }
     }
 }

The tile class is basically empty, except for the default statements Unity provides and this line:

 public Vector2 boardPosition = Vector2.zero;