What Makes us

We stand behind our work. We are a family-owned business with integrity and values. Getting a great price doesn't mean a lack of quality. Our buildings are manufactured to the highest industry standards. Our design, detailing and engineering staff guarantees your new building will be built accurately and cost effectively. Our design staff has the flexibility and control to build to your special needs and requirements.

Building Systems of Illinois has developed a reputation for constructing and designing the highest quality buildings at very affordable prices. We have constructed commercial, municipal, recreational, agricultural, and industrial buildings for virtually every type of business and use throughout Illinois.

Our company history.

John Mackling Started In 1989…

John and three others had an opportunity to buy a pre-engineered steel building franchise in 1989. They primarily just sold metal buildings as Building Systems of Decatur.

John buys out Partners

John bought out his partners out one at a time, and by 1992 he was the sole owner of the business.

Building Systems old logo

Incorporated in 1995

John Mackling incorporated as Building Systems of Illinois as an S Corp in 1995.

Greg Mackling Joins BSI

John's son, Greg Mackling joined BSI as an estimator and project manager in 1997.

In 1998, BSI started moving away from metal buildings, and towards more brick and mortar commercial projects, such as multi-family and restaurants.

Liberty Village - Clinton, IL

First Project For Liberty Village

BSI completes our first project for Liberty Village, and we've completed 6 other large projects for them since.

DQ Grill & Chill

Built the largest DQ Grill & Chill

In 2010 we built the largest DQ Grill & Chill in North America, in Bloomington, Illinois.

DG Market remodel


In 2012 we built our first Rainstorm Carwash, and have built 10 total so far.

In 2014 we built our first Dunkin project, and have built 8 total so far.

In 2017 we built our first Dollar General in Bethany, IL.

In 2019 we built our first out of state projects in IA, followed by IN and MO late in the year.

Naf Naf Grille

Naf Naf Grille

In 2021 we built the first franchise-owned Naf Naf Grille in Champaign, IL.

Dollar General


We will be starting our 49th Dollar General store in spring 2023.

Trusted by our clients

From car washes to restaurants to retail to industrial, we've worked on all types of projects, with many clients becoming repeat customers.

"Building Systems of Illinois, Inc has completed over 50 commercial retail projects for our company across four states. They have a proven track record of completing projects on time with great quality and an outstanding safety record."

R.B. Grisham

The Overland Group

"During the past 10 years Building Systems of Illinois, Inc. has completed several projects for the Decatur Housing Authority. The company offers high quality service, and their staff will go above and beyond to make sure the work is completed in a professional manner. They manage their subcontractors well and hold them to the same standards. You will not regret hiring BSI for your building and construction needs. I look forward to their participation on my future projects."

Diane Hackert

Decatur Housing Authority

"Best contractors in the Midwest. John, Greg, Brian athe best and most knowledgeable people I have ever dealt with. You will not be disappointed in any of their work or service from the top on down. Last thing if their bid is a little higher still go with them because they don't cut corners for quality. Their name depends on it, good ain't cheap and cheap ain't good. Thanks Gang will be using you all again."

Eldon Berg


"Great company to work with. Highly recommended."

Don Shimkus

 United Glass and Door