Private Villa

ETFE single layer, Khobar Saudi Arabia

Area500 m²

FabricETFE

CityKhobar

Year2023

SectorResidential

Project overview

This private villa in Al Khobar has a courtyard roof of clear, un-printed single-layer ETFE covering more than 500 m². TMSI's scope was design, supply and installation, and the project is dated 2023.

The clear foil was chosen to bring as much daylight as possible into the enclosed courtyard. The membrane sits on curved tubular steel arches that were rolled and welded in the TMSI factory, and a stainless steel cable net runs with the curvature to control deflection under wind uplift. An integrated aluminium perimeter clamping system holds the foil and provides a continuous water seal.

Because it is a single-layer system, the roof has no mechanical plant and no power requirement — a passive, low-maintenance installation. The roof geometry was set by form-finding and analysed for wind, uplift and thermal load; panels were then patterned, thermally welded and inspected in the Dammam factory before being installed, tensioned, sealed and water-tested on site, with curvature checked so that no ponding can occur.

Project photos

Private villa — clear single-layer ETFE courtyard roof, Khobar — photo 1

Private villa — clear single-layer ETFE courtyard roof, Khobar — photo 2

Private villa — clear single-layer ETFE courtyard roof, Khobar — photo 3

Private villa — clear single-layer ETFE courtyard roof, Khobar — photo 4

Private villa — clear single-layer ETFE courtyard roof, Khobar — photo 5

Private villa — clear single-layer ETFE courtyard roof, Khobar — photo 6

Private villa — clear single-layer ETFE courtyard roof, Khobar — photo 7

Private villa — clear single-layer ETFE courtyard roof, Khobar — photo 8

Private villa — clear single-layer ETFE courtyard roof, Khobar — photo 9

Private villa — clear single-layer ETFE courtyard roof, Khobar — photo 10

Private villa — clear single-layer ETFE courtyard roof, Khobar — photo 11

Private villa — clear single-layer ETFE courtyard roof, Khobar — photo 12

Private villa — clear single-layer ETFE courtyard roof, Khobar — photo 13

Private villa — clear single-layer ETFE courtyard roof, Khobar — photo 14

Private villa — clear single-layer ETFE courtyard roof, Khobar — photo 15

PROJECT 01

ETFE Single Layer — Clear · Al Khobar, Saudi Arabia

Project data

Project data
Project	Private Villa
Location	Al Khobar, Saudi Arabia
System	ETFE single layer, clear
Approx. area	500+ m2
Foil finish	Clear, un-printed
Restraint	Stainless steel cable net
Structure	Curved tubular steel arches
Scope	Design, supply and install

Scope of works

Structural design and form-finding of the courtyard roof
Fabrication of curved tubular steel arches and secondary members
ETFE panel patterning, welding and quality testing
Aluminium perimeter extrusion and cable restraint system
Site erection, membrane installation, tensioning and sealing

System description

01Single skin ETFE welded membrane, clear foil, maximising daylight into the enclosed courtyard.
02Fully integrated aluminium perimeter clamping system with continuous water seal.
03Stainless steel restraint cables running with the curvature to control deflection under wind uplift.
04Curved tubular steel arch structure, rolled and welded in the TMSI factory.
05No mechanical plant and no power requirement — a passive, maintenance-light installation.

Private Villa — Fabrication & Installation

Every panel is engineered, patterned and welded in our Dammam factory, then delivered to site as a finished, numbered assembly. The sequence below follows the actual production and installation route used on this project.

01 Form Finding & AnalysisRoof geometry is generated by form-finding, then analysed for wind, uplift and thermal load. Curvature, cable spacing and pre-stress are fixed here.
02 Steel FabricationTubular sections are rolled to the design radius, welded into arch segments and dimensionally checked against the setting-out drawing.
03 Patterning & CuttingThe curved surface is developed into flat cutting patterns with compensation for foil elongation, then plotted and cut to the panel schedule.
04 Thermal WeldingSeams are thermally welded under controlled temperature and pressure, with a keder edge welded to the perimeter. Every weld is inspected before release.
05 Steel ErectionArches are craned into position, aligned and bolted to the prepared bases, with temporary bracing retained until the frame is closed.
06 Extrusion InstallationSecondary members and the aluminium perimeter extrusion are fixed, levelled and surveyed to confirm the clamping line before any foil is opened.
07 Cable RestraintStainless steel restraint cables are installed and tensioned to the calculated pre-stress, forming the working surface for the membrane.
08 Membrane InstallationPanels are unrolled, the keder edge is fed into the extrusion and the foil is progressively tensioned. Clamping plates are torqued in sequence.
09 Sealing & Water TestPerimeter seals, flashings and rainwater details are completed and water-tested. Curvature is verified so that no ponding can occur.
10 Inspection & HandoverFinal visual and dimensional inspection, cleaning, as-built records and the operation and maintenance manual are issued at handover.

DESIGN & ENGINEERING

Private Villa – Design & Engineering

Brief Description — Structural Concept & Roof Geometry

Structural model of the villa courtyard roof: plan, elevation and isometric views of the two curved arch bays with their supports. — Structural concept and roof geometry

Loadings — Dead, Live & Wind Load (100 km/h, SBC 301)

Analysis model with the live load applied over the whole roof surface, annotated 0.24 kN/m². — Live load case — 0.24 kN/m²

Analysis model with the wind load case applied to the roof, load arrows shown over both bays. — Wind load case — 100 km/h per SBC 301

Support Reactions & Cable Design — Internal Forces

Member internal forces diagram for the cable net, maximum and minimum values of result combinations CO1 to CO26 shown along each cable. — Members internal forces N — result combinations, max and min values

Support forces and support moments — 3 rows

Support forces and support moments
Node No.	LC/CO	Support Forces [kN]			Support Moments [kNm]
P X'	P Y'	P Z'	M X'	M Y'	M Z'
	CO47	0,43	28,23	-6,86	0,00	0,00	0,00
	CO48	-5,13	30,94	-7,40	0,00	0,00	0,00
	CO49	0,43	28,23	-6,86	0,00	0,00	0,00

Cable Design — Member Sizing

Definitions, symbols and values — 28 rows

Definitions, symbols and values
Definitions	Symbol	Unit	Value	Formulation
Cable tension	Nges	[kN]	47,39
Quantity of cables	n	[-]	1
Cable tension in the single cable	Nseil	[kN]	47,39
Design Criteria	LRFD
Load Safety Factor	γf	[-]	1,00
Material Safety Factor	γR	[-]	1,00	(usually 1.0)
Cable Type	1x19
Cable Diameter	d	[mm]	12
Tensile Strength	Rr	[N/mm²]	2160
Youngs Modulus for variable action	EQ	[kN/cm²]	15000
Filling load factor	f	[-]	0,760
Equavalent Diameter Factor	fed	[-]	0,872
Equavalent Diameter (Sap2000)	de	[mm]	10,46	=de*fed
Reduction dirilling	k	[-]	0,880
Self Weight factor	w	[kg/cm²]	0,830
Breaking Load Factor	K	[-]	0,525	= pifk/4
Metallic Cross Sectional Area	Am	[cm²]	0,860
Nominal Metallic Areac Factor	C	[-]	0,600
Stifness Single Cable	EA	[MN]	12,893
Stifness All cables	EAges	[MN]	12,893
Cable Weight	g	[kg/m]	0,71	=Am*w
Minimum Breaking Load Cable	Fmin	[kN]	124,1	= Kd2Rr/1000
Socet Type	Swaged Socket
Loss factor (Due to cable fitting)	ke	[-]	0,90
Characteristic value of the resistance	Fuk	[kN]	121,0	=Fmin*ke
Design Value of the cable tension	FEd	[kN]	47,39	=Nseil*γf
Design value of the cable resistance	Frd	[kN]	80,67	=Fuk/1.5*γR
Verification in the ultimate limit state	Fed/Frd	[-]	0,59	OK

Cables 12 mm stainless steel.

ETFE Foil Design — Material Properties & Warp Direction

This means ideally that the pretension in single layer ETFE foil structures should not exceed 3 MPa (for 250 micron 0.75 kN/m) and permanent high load like snow should be avoided. The breaking strength of ETFE foil is 50 MPa. However the elongation at the tensile strength level (tensile strain at break) is 500%. That’s why the breaking strength can not be used for design. In the design tensile stress at 10 % strain has been taken into account (23 MPa). The thickness of ETFE foil is 0.25 mm (250 micron). For 250 micron foil, the tensile stress at 10 % strain equals to 5.75 kN/m. The safety factor is taken into account as 1.5 for short term load (e.g. wind loading).

Membrane force plot in the warp direction across the ETFE panels, with the colour scale and the note that the maximum stress is 3.58 kN/m. — Warp direction — max n-x 3.58 kN/m, less than 5.75/1.4 = 4.1 kN/m (OK)

ETFE foil — material properties — 17 rows

ETFE foil — material properties
PROPERTY	TEST METHOD	UNIT	MEAN VALUE
General
Specific Gravity	ASTM D 792	g/cm³	1.75
Optical (200 µm film, clear)
Light Transmission	DIN EN 410	%	> 91
Colour Rendering Index	DIN EN 410	-	98.8
Shading Coefficient	DIN EN 410	-	1.063
Solar Heat Gain Coefficient	DIN EN 410	-	0.925
Mechanical
Tensile Strength	DIN EN ISO 527-1 (MD/TD)	MPa	50
Tensile strain at break	DIN EN ISO 527-1 (MD/TD)	%	500
Tensile stress at 10 % strain	DIN EN ISO 527-1 (MD/TD)	MPa	23
Tensile Modulus (0,05-1%)	DIN EN ISO 527-1 (MD/TD)	MPa	1000
Tear resistance	DIN 53363 (MD/TD)	N/mm	400
Thermal
Thermal Service Range		°C	-200 - 150
Melting Point	ASTM D 4591	°C	265
Shrinkage 150 °C/10 min		%	0 - 5