Installation of Interior Piers

[Bina Panchal]

I have 1250 sq ft house in Irving, TX. The entire slab is dipping to one side of the house. Thus the highest point is 2.5" higher than center point and lowest point is 2.5" lower than center point, giving a 5" stretch, paced at a 1" drop every 11 feet. I have had several foundation companies give me a quote. All companies agree there needs to be piers all around one half of the house which is low. Half of the companies say internal piers are required (but vary in a how many and location). The other half believe interior piers are not required because when you lift the foundation, the entire foundation will lift. The slab is 56" wide. I am confused about whether I should go ahead and put in internal piers now, or do so later. I plan on having the house as a long term rental.