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solving geometric challenges in timber for more than 25 years...
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  • GRP Faced
  • Scottish Birch Strips
  • Double Curved SIP
  • Aluminium Faced
  • Reverse Curved Birch Plywood
  • Thermowood Cross Laminated


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Curved Panels

We have the moulds, 5 axis CNC machining and analytical skills to press multiple curved panels in plywood, OSB or other suitable wood based sheets, (Birch faces are popular). They can provide structural infill for cones, domes and unique shapes.

Custom Built
The panels are individually detailed for each project. Specifications can be varied to suit particular needs.
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Outer Skin - 3 x 6mm OSB4

  • For external applications many metal or membrane coverings require 18mm for fixing purposes. Three layers of 6mm grade 4 Oriented Strand Board provide an economic structural solution.
  • Alternatives include WBP plywood and/or reduction to two layers when bonded to insulation.

Inner Skin – 2 x 6mm Birch plywood

  • The light even colour of this fine grained plywood can be maintained or varied with subtle or deep stain.
  • Class 1/0 flamespread protection can be provided.
  • Alternatives include coniferous plywood which has more pronounced grain or MDF for a painted finish.

Insulation – Platinum EPS

  • Expanded polystyrene with a graphite additive e.g: 170mm overall thick in combination with the 18mm & 12mm board combinations provides a ‘U’ value of 0.20 w/m²°C and contributes to the stiffness of the panel.
  • Alternatives include injected/sprayed foam for more challenging shapes or mineral quilt/sheep’s wool which require ventilation.

Available individually or in combination

Panel Size
Current production is based on standard 1200 x 2400 sheets which may be cut to smaller rectangles or triangles for pressing tighter radii.
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Two features combine to provide efficient structures:-

  • The double curvature is substantially more stiff than equivalent flat sheets – as with motor bodies.
  • The double skin, when bonded to the core insulation, also creates a stiff form. (Structural Insulated Panel)

This means that curved single panels need less framing – say 1200ccs rather than 400 or 600ccs and that some panels can work without framing.


‘Standard’ construction panels can be curved to 1200mm radius in one direction or 1800mm radius double curved but with a size limit of radius/2.

Tighter radii can be achieved with thinner sheets, especially where the challenge is mainly in one axis. Cones and cylinders can be very tight for nosings and fascias.


The ’standard’ construction comprises:

  • Outer skin
3 x 6mm OSB4 = 13kg/m²
  • Insulation
125mm EPS = 3kg/m²
  • Inner skin
2 x 6mm Birch Ply = 9kg/m²
  • Sub Total
= 25kg/m²
  • Add for sundry trim/connections, say
= 5kg/m²



Panel to panel

A pair of plywood tongues are effective and economic.

A more substantial framing member can be designed to fit within the panel depth where needed for greater forces.

Panel to frame

Outer skins are extended to meet on the frame.

For composite panels, insulation and lining would need no further fixing but careful sealing is essential.

For ventilated roofs and/or where the lining is required to cover the frame it would be supplied separately.

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See Also...

Shell Structures

birmingham   cleavesalt   COTF
interbuild   LSE   napier
strawfields   peckham   winerack
cambs   maggies   zahahadid


Cowley timberwork is a trading name of timber engineering connections ltd