Steel Tube Greenhouse Calculator
About Steel Tube Greenhouse Calculation
This calculator calculates the geometry of a steel tube greenhouse with an arched shape and returns the main areas, volume, arc length, and total length of frame members. The calculation is suitable for preliminary sizing, estimating tubing and sheet covering quantities, and preparing a dimensioned drawing before fabrication.
The greenhouse model is treated as a body with a constant cross section along its full length. This makes it possible to unambiguously calculate the floor area, end wall area, shell area, internal volume, and approximate length of tubing for frames and sections.
Reference points and recommendations
Geometric model
Cross section shape. The calculator treats the front view as a combination of a lower rectangular part and an upper arched part. The input dimensions are greenhouse length A in mm, width B in mm, total height H1 in mm, and straight wall height H2 in mm. The height of the arched part is taken as h = H1 - H2.
Arch. The upper part of the front view is calculated as a circular arc passing through the top points of the straight side walls. For this arc, the radius is first determined from the width B and the arch rise h.
R = B2 / (8h) + h / 2
Central angle of the arc. After the radius is found, the angle corresponding to the arched part is calculated. This angle is then used both for arc length and for the segment area.
θ = 2 arsin(B / (2R))
Area, volume, and outer shell
Greenhouse area. The base area is calculated as a rectangle in plan view. This value shows the footprint occupied by the greenhouse on the site.
S = A x B
Area of one end wall. One end wall is made up of a rectangle with width B and height H2 and a circular segment with height h. The segment area is determined using radius R and angle θ.
Sseg = R2 x (θ - sinθ) / 2
Sfacade = B x H2 + Sseg
Greenhouse volume. Since the cross section does not change along the length, the internal volume is calculated by multiplying the area of one end wall by the greenhouse length.
V = Sfacade x A
Roof and side surface area. For an arched greenhouse, the outer longitudinal shell is calculated as greenhouse length A multiplied by the arc length of one cross section. This result includes the roof and both curved side surfaces, without the end walls.
Larc = R x θ
Sroof = A x Larc
End wall area. The total area of both end walls is equal to twice the area of one end wall.
Sfacades = 2 x Sfacade
Total area. The total outer covering area is obtained by adding the area of the longitudinal shell and the area of both end walls.
Sfull = Sroof + Sfacades
Perimeters and arc length
Plan perimeter. The perimeter value refers to the base of the greenhouse and is calculated as the perimeter of a rectangle with length A and width B. It is useful for a preliminary estimate of the base frame, foundation outline, or total edge length along the contour.
P = 2 x (A + B)
Section perimeter. The value called "section perimeter" corresponds to the length of one transverse greenhouse arch. In practice, this is the tubing length required to make one arched frame without internal bracing members.
Frame calculation logic
Transverse sections. The number of transverse frames is determined by dividing the greenhouse length into side sections. The more sections there are along the length, the smaller the frame spacing and the greater the total number of transverse arches and longitudinal members.
End walls. For the end walls, the calculator takes into account the outer contour of each end wall, the door opening, and the internal members based on the specified number of horizontal and vertical sections. Both end walls are treated as identical in geometry.
Side walls. For each longitudinal side, the calculator sums the longitudinal members along the greenhouse length and the vertical posts according to the specified number of sections. The result is then doubled because there are two side walls.
Total frame material length. The total tubing length is obtained by summing the lengths of the transverse frames, end wall members, side members, and door framing. This is the length measured along the member centerlines, so when purchasing material it is common to add a fabrication allowance for cutting, fitting, and waste. In practice, a reserve of about 5% is often used for simple cutting and about 10% when there are many joints and trimmed pieces.
What is not included in the calculation
Structural verification. The calculator does not size the tubing section for snow, wind, or erection loads and does not check frame stability. It calculates geometry, areas, volume, and member lengths, not the load-bearing capacity of the structure.
Tubing size. The tubing size in mm is used for the drawing and visual representation of the members, but it does not replace a full structural calculation of the metal frame. For a real structure with cladding and actual loads, the section must be checked separately.
Normative references. For design verification of a steel greenhouse frame in Europe, it is common to refer to EN 1993-1-1 Eurocode 3. Design of steel structures. Part 1-1. General rules and rules for buildings, EN 1090-2 Execution of steel structures and aluminium structures. Part 2. Technical requirements for steel structures, and for greenhouse structures also EN 13031-1 Greenhouses. Design and construction. Part 1. Commercial production greenhouses. These documents are used to verify strength, stability, serviceability, and fabrication requirements, while this calculator performs a geometric and quantity calculation.
FAQs
Why is arc length important for a greenhouse made from rectangular steel tubing?
Arc length is needed for two tasks at once: calculating one transverse frame and determining the area of the outer shell. It helps estimate both the tubing length for one arch and the covering quantity for the arched surface.
What is the difference between greenhouse area and total area?
Greenhouse area is the base area in plan view, which is length multiplied by width. Total area is the full outer surface that must be covered with material: the arched shell plus the two end walls.
Can this calculation be used directly to buy rectangular steel tubing?
The calculator gives a good preliminary estimate of the total tubing length, but it is better to add a reserve for cutting and joints before purchasing. If the structure will be made from standard stock lengths, it is also useful to check the cutting layout for the individual members.
Does the calculator take the greenhouse door into account?
Yes, the total frame length includes the door framing according to the specified door dimensions. At the same time, the calculation remains geometric and does not evaluate separate reinforcements, hinges, diagonal bracing, or the exact type of door assembly.
Is this calculator suitable for checking greenhouse reliability under snow and wind loads?
No, this calculator does not replace a structural capacity check. Snow loads, wind loads, tubing wall thickness selection, and stability verification require a separate engineering calculation according to European standards for steel structures and greenhouses.