Piers, Slabs Or Runners - Which One To Choose?

Vacant lot preparation is a big deal when filling vacant lots – it can cost as much as 1/3 of the total home in some states. HUD controls the lot preparation requirements in some markets and, while the purpose is to minimize home movement from frost heave, the reality is that it’s a terrible financial burden for the homeowner and a pain in the neck for park owners to perform. But if you have to do expensive lot preparation, what are the options and which should you choose?

What do the codes say?

Lot preparation is not really your choice – HUD has already decided that for you with a set of strict requirements. If they say that you must pour a slab under the home, then a slab it must be. Of course, it’s also not up to you to interpret what the requirements are as that is the realm of the home installer, who is licensed and bonded. However, it is up to you to write the check, so you need to be an active participant in at least knowing the options and their respective cost.

What is the state inspector’s opinion?

Another important player is the state inspector that approves the installations. His opinion obviously carries a lot of weight. So any choice you make on lot preparation would have to be totally to his satisfaction. He’s like the NFL referee – no matter what you think all that matters is what he thinks.

Which is cheapest?

If you have options, then here’s the basic difference in cost:

  • Concrete slab. Essentially, a solid rectangle of concrete that sits under the entire home. Figure on about $10,000 for these in most markets (although a really good shopper might get it done for $6,000 if they put in a ton of bidding effort and concrete demand is slow).
  • Piers. These are concrete structures that sit underneath the blocks that the home sits on (as shown in the photo above). Figure on a cost of about $6,000.
  • Runners. These are two parallel lines of concrete that fit under the blocks that hold the home up. These cost around $4,000 to install.

Weather restrictions

You can only pour concrete normally when the temperature is over around 40 degrees. While that may not be a big deal in Houston, it’s a really big issue in northern Michigan. As a result, if you have to put in expensive lot preparation you will have to do it during the warmer months. Without this advance preparation you may not be able to bring in any homes at all during winter in northern markets.

Can you escape the preparation requirements with used homes?

One loophole you should always watch for in some states is the ability to avoid expensive lot preparation on used homes only. Some states have two different site preparation rules: one for new homes and one for used. In that case, you may be able to save $5,000 or $10,000 by buying a 1990s repo over that new factory home. Don’t be afraid to ask the question and see if this is an option in your state.


Site preparation is extremely complicated and foreign to most park owners. The good news is that the installer knows the rules. But you have to watch over your options and know the prices before you proceed so that you can save time and cost. After all, it’s your money.

Frank Rolfe
Frank Rolfe has been an investor in mobile home parks for almost 30 years, and has owned and operated hundreds of mobile home parks during that time. He is currently ranked, with his partner Dave Reynolds, as the 5th largest mobile home park owner in the U.S., with around 20,000 lots spread out over 25 states. Along the way, Frank began writing about the industry, and his books, coupled with those of his partner Dave Reynolds, evolved into a course and boot camp on mobile home park investing that has become the leader in this niche of commercial real estate.