Explore the Onion Ridge Vent by Geometric Steels. This guide covers how this continuous passive dome-type ventilator works, its industrial applications, and how to choose the right 300-600mm throat width.
Word Count: ~2,500 words | Reading Time: ~10 minutes
What Is the Onion Ridge Vent?
The Onion Ridge Vent is a continuous passive ridge ventilation product manufactured by Geometric Steels, named for its rounded, dome-like cross-sectional profile — visually distinct from the flatter hat-type cavity profile used in our Hat-Top Ridge Vent range. It is designed to run continuously along a roof ridge, providing passive exhaust ventilation without electricity or moving parts, and is available in throat widths of 300mm, 450mm, and 600mm.
This guide explains what the Onion Ridge Vent is, where it is typically specified within an industrial facility, how to select the correct throat width, and what to verify before including it in a project specification.
Onion Ridge Vent is a product name and profile description used by Geometric Steels for our specific ridge ventilation product. We do not represent the general ‘onion’ or dome-type ridge vent profile as patented or exclusive to Geometric Steels — similar profile shapes exist under other names from other manufacturers in the Indian market. All specifications in this guide are general and indicative; project-specific data is confirmed at the quotation stage.
How the Onion Ridge Vent Works
Like other continuous passive ridge vents in the Geometric Steels range, the Onion Ridge Vent operates on the combination of thermal buoyancy (hot air rising and exiting through the ridge opening) and wind pressure differential (a natural low-pressure zone that typically forms at a roof ridge, assisting exhaust airflow). It has no motor, no impeller, and no electrical connection — it functions passively for as long as there is a usable temperature differential between the building’s interior and the outside air, which is the case for the great majority of operating hours in most industrial buildings.
The rounded, dome-type profile is described by Geometric Steels as having self-cleaning characteristics — meaning the curved geometry is intended to reduce the accumulation of dust and light debris on the vent’s external surface compared to a flatter profile, allowing rain and wind to more readily clear material from the dome surface. The specific self-cleaning performance depends on your site’s particulate environment and should be discussed with our technical team if this is a significant consideration for your project — we do not present this as a guarantee of zero maintenance under all conditions, though the product is designed to minimise routine upkeep.
Selecting the Right Throat Width: 300mm, 450mm, or 600mm
The Onion Ridge Vent is available in three throat widths. The correct width for your project depends on the ventilation load calculation for your specific building — the same general principle that applies to any passive ridge vent selection — rather than a fixed rule tied to building size alone.
| Throat Width | General Application Guidance | Typical Structure Type |
| 300mm | Smaller secondary structures with modest heat load and shorter ridge runs — subject to your project’s ventilation load calculation | Small stores, workshops |
| 450mm | Medium-sized secondary structures — subject to your project’s ventilation load calculation | Bagasse stores, medium workshops |
| 600mm | Larger secondary structures or those with higher internal heat or moisture load — subject to your project’s ventilation load calculation | Larger stores, secondary sheds |
Note: Throat width guidance above is general and indicative, not a substitute for a proper ventilation load calculation for your specific building. The correct throat width depends on your building’s heat load, ridge length, roof height, and occupancy — request a project-specific calculation from our technical team using your actual building dimensions before finalising your specification. Figures and characterisations can vary according to client requirements and location.
Onion Ridge Vent vs Hat-Top Ridge Vent vs Monitor Ridge Vent: Which One for Which Application
Geometric Steels manufactures three continuous passive ridge vent profiles. They share the same basic operating principle but are generally positioned for different application contexts within a facility.
| Factor | Onion Ridge Vent | Hat-Top Ridge Vent | Monitor Ridge Vent |
| Profile shape | Rounded, dome-type cross-section | Flatter, dual-louvered hat-type cavity | Raised monitor-type section |
| Typical positioning | Secondary structures, stores, workshops | Primary/main production sheds, new-build | Retrofit on existing roofs |
| New-build vs retrofit | Primarily new-build | New-build / open-ridge sheeting | Purpose-built for retrofit over existing roofs |
| Moving parts | None | None | None |
| Available throat widths | 300 / 450 / 600mm | 300 / 450 / 600mm | 300 / 450 / 600mm |
Note: This comparison describes the general, typical positioning of each GS ridge vent product and is not a rigid rule — any of these products may be suitable for a given application depending on your building’s specific structural and ventilation requirements. Confirm the correct product for your specific building with our technical team, using your actual roof geometry and heat load data. Figures and characterisations can vary according to client requirements and location.
Typical Onion Ridge Vent Applications
- Bagasse and raw material storage sheds in sugar and agro-processing facilities
- Workshop and maintenance buildings within a larger industrial complex
- Secondary warehouse and storage structures
- Ancillary buildings where continuous passive ventilation is required but the primary product’s larger throat width is not needed
- Retrofit and new-build projects for smaller-footprint industrial and agricultural structures
Construction and Materials
| Parameter | Onion Ridge Vent — Geometric Steels |
| Vent type | Continuous passive ridge ventilator — rounded dome-type profile |
| Throat widths | 300mm / 450mm / 600mm |
| Construction material | PPGI / PPGL construction — confirm specific coating specification at enquiry stage |
| Moving parts | None — fully passive |
| Operating power required | None |
| Standard lengths | Confirm available standard and custom mill-cut lengths at enquiry stage |
| Rain exclusion design intent | Designed with rain exclusion in mind — request specific test data if available for your project’s wind-driven rain exposure |
| Wind load design basis | Confirm design wind speed and terrain category basis with our technical team for your project location |
| Quality certification | ISO 9001:2015 (IAF MLA accredited) |
Note: The parameters above describe the general nature of the Onion Ridge Vent product and are indicative only. Specific dimensions, coating specification, lengths, and wind load design data for your project must be confirmed directly with Geometric Steels at the quotation stage. All figures are subject to change according to client requirements, project location, and current manufacturing capability.
Applicable Standards
IS 875 Part 3:2015 — Wind Loads on Buildings and Structures
Governs the wind loading the vent and its fixing must be designed to withstand. Confirm the applicable wind zone and terrain category for your project location and request the corresponding design data from our technical team.
Factories Act 1948, Section 13 — Ventilation and Temperature
Where the Onion Ridge Vent is specified for a factory secondary structure, it contributes to the building’s overall ventilation provision relevant to the general obligations under Section 13 and applicable state factory rules. The specific compliance assessment for your building should be confirmed with reference to your state’s factory rules and, where needed, professional advice.
National Building Code of India 2016 — Part 8, Section 1
Provides general guidance on natural ventilation opening area for buildings, relevant background when assessing whether the specified throat width and ridge length provide adequate ventilation opening for your structure’s floor area.
ISO 9001:2015
The Onion Ridge Vent is manufactured under ISO 9001:2015 quality management, accredited under the IAF Multilateral Recognition Arrangement.
What to Request Before Specifying
- A ventilation load calculation for your specific secondary structure, to confirm the correct throat width (300/450/600mm).
- Wind load design data for your project’s wind zone and terrain category.
- Confirmation of available standard and custom lengths for your ridge run.
- Coating specification confirmation appropriate to your site’s environmental exposure — particularly relevant for bagasse stores and other agro-processing secondary structures with potential dust or moisture exposure.
- ISO 9001:2015 certification documentation.
Frequently Asked Questions
Q1: What does ‘self-cleaning’ mean for the Onion Ridge Vent?
The rounded dome-type profile is designed so that rain and wind can more readily clear dust and light debris from its external surface, compared to a flatter profile shape, reducing the routine cleaning and maintenance generally associated with surface debris accumulation. This is a design intent rather than a guarantee of zero maintenance under all site conditions — actual performance depends on your site’s specific particulate environment. We recommend discussing your site conditions with our technical team if dust or debris accumulation is a significant concern for your project.
Q2: Which throat width should I choose — 300mm, 450mm, or 600mm?
This depends on your specific building’s heat load, ridge length, and roof height — there is no universal rule based on building type alone. We recommend requesting a ventilation load calculation from our technical team using your actual building dimensions, rather than selecting a throat width based on a general size assumption.
Q3: Can the Onion Ridge Vent be used on a main production shed, or only on secondary structures?
While it is typically positioned for secondary structures, stores, and workshop buildings in general industry practice, the correct product for any specific structure depends on your building’s ventilation load and roof geometry. If you are considering the Onion Ridge Vent for a primary production shed, discuss your specific requirements with our technical team, who can confirm whether it or an alternative product such as the Hat-Top Ridge Vent is more appropriate.
Q4: Is the Onion Ridge Vent suitable for a sugar factory bagasse store?
The Onion Ridge Vent is commonly specified for bagasse and raw material storage applications, but the correct coating specification and throat width should be confirmed with our technical team based on your specific store’s dimensions and environmental exposure, including bagasse dust and humidity conditions typical of sugar processing facilities.
Q5: What is the price of an Onion Ridge Vent in India?
Pricing depends on throat width, length, coating specification, and project quantity. Geometric Steels does not publish catalogue prices for industrial B2B products — contact our team with your project dimensions and requirements for a project-specific quotation within 48 hours.
Request a Ventilation Recommendation for Your Secondary Structure
Send us your store or workshop building’s dimensions, roof height, and general use (storage, workshop, etc.). We will confirm the appropriate Onion Ridge Vent throat width, provide wind load design data, and prepare a project-specific quotation.
Every enquiry to Geometric Steels receives:
For More Visit here: https://geometricsteels.com/factory-ventilation-systems/
- A throat width recommendation (300/450/600mm) based on your building’s dimensions
- Wind load design data for your project’s wind zone
- Coating specification recommendation for your site’s environmental exposure
- ISO 9001:2015 (IAF MLA) certification documentation
- A project-specific quotation and delivery timeline
Contact Geometric Steels Roll Forming Pvt. Ltd.
Phone: +91 8550995556 | geometricsteels.com
Manufacturing: Kurkumbh MIDC, Pune, Maharashtra
ISO 9001:2015 (IAF MLA) | CE Marked (applicable products) | Established 2006
India Builds Under Our Roof. | 20 Years · 64 Products · ISO · CE · IAF Certified