What is RTU?

Definition of RTU in Construction

Roof top units. The RTU is a piece of mechanical equipment that is designed to heat, cool, ventilate by providing air flow for any combination of the three. The RTU is located on the roof, and is therefore a roof top unit.

The roof top unit is installed on a mechanical curb that is set onto the roof and flashed in by the roofing contractor. The mechanical curb, in most cases sits on an engineered roof support structure that is engineered by the structural engineer for the project. The curb will be supported on al l( 4 ) sides with either built up wood beams, steel angles or even small wide flange beams of steel. The support of the RTU is transferred through the supports that are located in the roof deck. The mechanical curb will transfer the load of the RTU down through the roof top curb and into the support structure installed in the roof framing.

The RTU is a major piece of mechanical equipment for any construction project and must be fully approved by the mechanical engineer, before being ordered and installed on the project. In many instances, the mechanical subcontractor will attempt to provide an alternate to the specification. This alternate submittal is due to the fact that many major mechanical equipment suppliers have their nationally known brand, which is what is usually specified.

However, they will also have their more economical brand that is normally less money, less of a delivery schedule and, according to the sales individuals, will perform identical to the specified product. This is a common issue with major mechanical equipment and it is essential that the general contractor and mechanical subcontractor work together, to ensure that this attempt to provide an alternate supplier does not delay the project. In the majority of cases, the attempt to provide an alternate manufacturer takes a considerable amount of time for the engineer to review, discuss with the owner, and make a decision. All parties must be aware of this delay, and anticipate it, when scheduling the project. In many instances the suggestion, and subsequent approval, of an alternate to a priority specification is only approved upon a savings in money. Usually the offer of money back by the subcontractor to the general contractor eventually making its way into the owners pockets is the catalyst to persuade the owner and engineer to accept the alternate manufacturer.