Spawn objects with different widths one after another without overlapping

I need to generate background of buildings (I have an array of 5 sprites) and want to spawn each one right after the last one.

This is my current code.

    for (int i = 0; i < 5; i++) {

         Sprite sprite = BuildingsSprites[Random.Range(0, 5)];
         float currentWidth = sprite.bounds.size.x;

         GameObject Background = (GameObject)Instantiate(BuildingObjectPrefab, nextPos, Quaternion.identity);

         Background.GetComponent<SpriteRenderer>().sprite = sprite;

         nextPos += new Vector3(currentWidth / 2, 0, 0);

         Sprite nextSprite = BuildingsSprites[Random.Range(0, 5)];
         float nextWidth = nextSprite.bounds.size.x;


         GameObject Background2 = (GameObject)Instantiate(BuildingObjectPrefab, nextPos,         Quaternion.identity);

         Background2.GetComponent<SpriteRenderer>().sprite = nextSprite;

         nextPos += new Vector3(nextWidth / 2, 0, 0);
   }

I cant seem to fix the problem which is in the last line, nextPos is set to nextWidth but when the loop goes to the top It may choose different sprite with different width and its placed not where it was supposed to.