How Submittal Drawings Simplify RTU Replacements

Purpose of Curb Adapter Submittal Drawings

The submittal drawings are a necessary part of ordering a curb adapter. We are not asking the contractor to check “our work” – we are asking them to verify the “unknowns”. The installing contractor is generally the only individual who has actually been on the roof and has seen the original curb or any obstacles surrounding the existing unit. This makes them the best person to compare our submittal drawings to the actual field conditions.

The installing contractor should verify that the existing curb, matches the bottom drawing we provide. The old RTU’s are hard to recognize and often the data plates are missing or corroded to the point they are unreadable. Even the owner of the building often unknowingly provides incorrect information.

We design the curb adapter to accommodate the supply and return ducts and to provide adequate support for the new RTU. In numerous cases this causes the new RTU to overhang one or more sides of the existing curb. Using the submittal drawing on a field inspection is the best way the installing contractor can determine whether or not the physical RTU or it’s access panels will be too close to other units, fans, walls, vent pipes, etc.

We can change any of the adapters to accommodate almost any circumstance; however, the installing contractor has to use the submittal as a tool to ensure that his installation will go smoothly with no surprises.

If you don’t have time to do it right, when will you have time to do it over? – John Wooden

How to Read Submittal Drawings

Our current Submittal drawing is a Plan View of the old and new unit curbs.

We start with the old or existing unit curb dimensions. We take the outside diameter (O.D.) of the old curb and add grow it 2”. This is to allow for tar and other roofing buildup around the unit. The dimensions at the top and down the left side of the drawing are the O.D. of the Adapter Bottom that will be sitting on the old curb. The outline of the Adapter Bottom is a solid line. The existing duct openings are solid lines, with the EXISTING SUPPLY and EXISTING RETURN in the appropriate square or rectangle with their dimensions.

A double line with slashes in-between represents the Adapter Top (the new unit curb). The dimensions immediately to the right and on the bottom of the drawing are the Inside Diameter (I.D.) of the Adapter Top. The duct supports are also shown as double lines filled with slashes. The supply duct is marked with an “X” in dashed line and the return duct is marked with a “/” in dashed line similar to engineering blueprints.

The areas of the old curb that will not be covered by the Curb Adapter (if any) are covered with an 18 gauge galvanized standing seam insulated panel or panels. These panels are not work platforms. ***IMPORTANT*** These areas are shown as lines with a dash dot pattern.

The drawings on the right and bottom of the Plan View show the profiles through the adapter. These views give the details of the transitioning of the air from the new unit down to the old curb and the overhang (if any) there will be beyond the perimeter of the existing curb.

Please feel free to call any time! There are no emergencies while the adapter is still on paper. We can talk you or your contractor/dealer.


Purpose of Submittal Drawings
Reading Submittal Drawings