Support steel structures on roofs for engineering systems

Why support steel structures are needed on roofs

Engineering systems on the roof — ventilation units, outdoor air conditioning units, solar panels — create significant loads on the building structure. To place this equipment safely and predictably, support steel structures are used: frames, trusses, posts, beam systems.

For an HVAC designer and a developer this solves several tasks:

• transferring loads to the building’s load-bearing elements rather than to the roof build-up;
• fixing the equipment in the design position (angle, height, orientation to the sun/air flows);
• ensuring access for maintenance (walkways, stairs, guardrails if necessary);
• minimizing interference with the roof waterproofing.

Unlike “standard” equipment brackets, support steel structures are designed for a specific facility, climate, and layout scheme, and therefore require an individual calculation based on the technical specification.

Types of loads from engineering systems: ventilation, air conditioning, PV

When designing supports, it is important to understand what loads each system creates.

Ventilation units and air ducts

• Permanent mass of the equipment and filled air ducts.
• Dynamic loads from fan vibration.
• Wind impact on large housings and shafts.
• Snow loads (moderate for Tashkent, but considered in the overall scheme).

For such systems, spatial frames and trusses are often used to distribute the load over several support points.

Air conditioning systems (VRF, chillers, rooftop units)

• Concentrated load from heavy units on a limited area.
• Vibration from compressors and fans.
• Need for maintenance: clear access routes, possibility of dismantling.

Support steel structures for air conditioning usually include frames with anti-vibration mounts, height-adjustable supports, sometimes with integrated stairs and platforms.

Solar panels (PV systems)

• Distributed load over the roof area.
• Significant wind loads on inclined panels.
• Change in load over time when the plant is expanded.

Special mounting rails and support systems are used for PV: frames with a fixed angle, ballasted structures, combined solutions with fastening to the roof’s load-bearing elements.

Main types of support structures and installation schemes

Support steel structures on roofs can be roughly divided by support method and purpose.

By support method

1. Supports transferring load to load-bearing elements

   • posts tied to beams/girders via embedded parts;
   • frame structures resting on parapets or load-bearing walls.
   • plus: minimal load on the roof build-up;
   • minus: requires coordination with the building structure and often additional embedded parts.

2. Supports distributing load over the roof build-up

   • support frames on base plates/ballast;
   • systems on adjustable supports with distribution plates.
   • plus: less interference with load-bearing structures;
   • minus: higher requirements for calculating pressure on the roof and for waterproofing protection.

3. Combined systems

   • part of the load is transferred to load-bearing elements, part is distributed over the roof;
   • used for complex layouts or constraints related to existing structures.

By purpose

1. Support frames for units

   • chillers, rooftop air conditioners, ventilation units;
   • adjustable height, integration of vibration isolators.

2. Trusses and beam systems

   • for spans over existing structures, bypassing skylights, shafts;
   • allow placing equipment “in the air” without loading the roof over the entire area.

3. Frames and mounting rails for PV

   • linear rail systems;
   • spatial frames for a specified tilt angle.

4. Service structures

   • stairs, walkways, maintenance platforms;
   • guardrails around hazardous areas.

Many projects combine several types: for example, a truss for a span and a service platform for access to equipment.

Materials and manufacturing technologies: from box section to stainless steel

The choice of material depends on the purpose, operating environment, and service life requirements.

Main materials

• Carbon steel (black steel)

  • the most common solution for support frames, trusses, and posts;
  • combines sufficient load-bearing capacity and cost-effectiveness.

• Galvanized steel

  • used where increased corrosion resistance is important;
  • options: hot-dip galvanizing of finished structures or use of galvanized rolled products with subsequent treatment.

• Stainless steel

  • used in areas with aggressive environments (humidity, chemical emissions, coastal zones) or with increased requirements for durability and appearance;
  • advisable for individual joints and fasteners rather than for the entire frame.

Manufacturing technologies

Standard processes for steel structures are used in production:

• Laser cutting — precise preparation of parts, holes, slots, which simplifies on-site assembly;
• Metal bending — manufacturing of complex-shaped elements, stiffeners, brackets;
• Welding — assembly of frames, trusses, support joints with geometry control;
• Machining and CNC — for critical connecting parts;
• Powder coating — protective and decorative coating that increases corrosion resistance and UV resistance.

The combination of materials and technologies is selected according to the specific technical specification: load, climatic conditions, appearance requirements, and budget.

Specifics of calculation based on the technical specification for facilities in Tashkent

For correct calculation of support steel structures, the contractor needs to receive a detailed technical specification from the client or HVAC designer.

Key initial data

• roof plan with reference to load-bearing elements (beams, girders, walls);
• type of roof build-up (insulation, waterproofing, presence of screed);
• equipment characteristics: weight, dimensions, support points;
• equipment layout and required clearances for maintenance;
• installation height requirements (above roof level);
• climatic loads adopted in the project (wind, snow);
• corrosion resistance and coating requirements;
• installation constraints (crane, elevator capacity, roof access).

What is considered in the calculation

• load-bearing capacity of the existing building structures;
• distribution of loads over support points;
• wind impact on equipment and frames (relevant for PV and tall installations);
• possible vibrations and the need for damping;
• thermal deformations of long rail systems.

Calculation based on the technical specification allows optimization of steel consumption: avoiding both underdesigned and excessively heavy structures that increase project cost and complicate installation.

What affects the cost of support steel structures

The cost of roof support systems is formed from several groups of factors. Below is a summary table.

Therefore, an accurate price can only be given after analyzing the technical specification and initial data for the facility.

Coordination of supports with the HVAC design, architecture, and roof build-up

Support steel structures on the roof are the intersection of several project disciplines.

Coordination with HVAC

• location of units and air ducts;
• required clearances for maintenance and equipment replacement;
• directions of air discharge/intake so that supports do not create obstructions.

Coordination with architecture

• equipment height relative to the parapet and visibility from the ground;
• possible requirements for the color scheme of steel structures;
• placement in zones that do not conflict with architectural elements.

Coordination with roof build-up and structural design

• inadmissibility of point loads on a soft roof without distribution elements;
• minimizing penetrations through waterproofing;
• selection of support locations considering the position of beams and floor slabs.

The optimal option is when the calculation of support steel structures is carried out in parallel with the development of HVAC and structural sections, rather than “catching up” with an already completed design.

Production organization: laser cutting, bending, welding, painting

For the developer and designer, it is important to understand what affects the timelines and predictability of implementation.

Production stages

1. Design and issue of KM/KMD

   • development of a 3D model of the structures;
   • issue of drawings for the workshop and installers.

2. Preparation stage

   • cutting of profiles (including laser cutting of sheet parts);
   • metal bending for stiffeners, brackets, base plates.

3. Assembly and welding

   • assembly of frames, trusses, joints using jigs;
   • geometry control, joint inspection.

4. Cleaning and coating

   • surface preparation;
   • priming and/or powder coating;
   • galvanizing if necessary.

5. Kitting and shipment

   • marking of elements for easy installation;
   • packaging of fasteners and installation accessories.

Having in-house equipment (laser cutting, metal bending, welding stations, powder coating booth) reduces lead times and lowers the risk of disruptions at the interface between multiple contractors.

Typical mistakes in designing and installing roof supports

Below is a list of common mistakes to avoid when working with support steel structures.

1. No calculation based on actual loads

   • Use of “typical” frames without considering the weight of specific equipment and wind loads.

2. Ignoring the roof build-up

   • Supporting heavy structures on a soft roof without distribution plates and waterproofing protection.

3. Supports that are too low

   • No access for maintenance, risk of equipment damage by snow, ice, or water.

4. Poorly thought-out installation logistics

   • Structures that cannot be lifted onto the roof or assembled under existing conditions.

5. Lack of anti-vibration isolation

   • Transmission of vibrations from units to the building structure, noise in premises.

6. Insufficient corrosion protection

   • Saving on coating in open-roof conditions leads to accelerated wear and additional repair costs.

7. Unaccounted expansion prospects

   • Frames for PV or HVAC without reserve in load capacity and space for future equipment.

Working with a contractor who can comprehensively assess the facility (HVAC, structure, roof) and offers calculation based on the technical specification helps avoid most of these problems.

Lead times for fabrication and installation: from sketch to handover

Timelines depend on the scope and complexity of the project, but the sequence of stages is roughly the same.

1. Collection of initial data and technical specification

   • transfer of plans, equipment specifications, placement requirements;
   • clarifying questions, site visit if necessary.

2. Preliminary calculation and concept

   • selection of the support scheme (to load-bearing elements or roof build-up);
   • assessment of steel consumption and timelines.

3. Design and issue of working documentation

   • 3D models, drawings, specifications;
   • coordination with the client and related disciplines.

4. Manufacturing

   • preparation, welding, painting;
   • quality control and kitting.

5. On-site installation

   • delivery of structures to the roof;
   • installation, alignment, fixing, and, if necessary, participation in equipment installation.

The earlier the steel structures contractor is involved in the project, the easier it is to meet deadlines and avoid on-site rework.

FAQ on roof support steel structures

1. Can standard supports be used without individual calculation?
For small and light units, typical solutions are sometimes used, but for commercial facilities with heavy equipment and PV systems, individual calculation based on the technical specification significantly reduces risks.

2. Is it mandatory to fasten supports to the building’s load-bearing structures?
Not always. Ballasted and combined schemes are possible. The choice depends on loads, roof type, and operating requirements.

3. What materials are most often used on roofs in Tashkent?
The most common are supports made of carbon steel with protective coating (primer + powder coating or galvanizing). Stainless steel is used selectively — in joints and fasteners.

4. Can existing supports be modified for new equipment?
Sometimes yes, but a verification calculation and inspection of existing structures are required. In some cases, it is safer to manufacture new supports.

5. How to account for equipment vibration?
At the calculation stage, anti-vibration mounts are included, the frame is reinforced, and the load transfer scheme to the building is carefully designed.

6. What if there is no accurate information on the roof’s load-bearing structures?
Options: request data from the original designer, carry out a survey, or use solutions with minimal impact on the structure (ballasted systems) with conservative assumptions.

7. Is it possible to combine supports for ventilation, air conditioning, and PV?
Yes, with competent design it is possible to combine them into a single support system, but this requires careful analysis of loads and maintenance convenience.

8. At what project stage is it best to involve the steel structures contractor?
Ideally at the stage of developing HVAC and structural sections, before the equipment layout is finalized.

How to order a calculation: what data are needed and how to submit the technical specification

To obtain an accurate calculation of cost and lead times for support steel structures for roof engineering systems, prepare the initial data.

For calculation it is desirable to provide:

• city and address of the facility (to understand climatic and logistics conditions);
• roof plan with dimensions and reference to load-bearing elements;
• section of the roof build-up indicating materials and thicknesses;
• list of equipment with weight and dimensions (ventilation units, chillers, outdoor units, solar panels);
• equipment layout (if available) or placement preferences;
• requirements for installation height and orientation (for PV — angle and direction);
• requirements for material and coating (black steel, galvanizing, stainless steel, powder coating);
• installation constraints (equipment access, facility operating mode, deadlines);
• contact details of the responsible specialist (HVAC designer, client’s engineer).

Based on this, an engineering calculation can be performed, an optimal support scheme proposed, and fabrication and installation timelines estimated.

The next step is to submit the technical specification and drawings and receive a proposal.

Submit a request for calculation

Specify in the request:

• type of facility (business center, shopping mall, warehouse, production building, etc.);
• purpose of supports (ventilation, air conditioning, PV or combined solution);
• approximate deadlines when the finished structures are needed;
• whether there is an existing design or design assistance is required.

This will allow a quick transition from idea to working solution and implementation of the project within the specified timeframes.