Panel restraints

Witches hats

Witches hats are an efficient solution for restraining panels, ideal for fixing to the underside of the slab.

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Witches hat 3D model
Witches hat real render
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Applications and features


  • Provides lateral restraint to precast panels.
  • Typically fixed to the underside of the slab.


  • It can be placed close to the top of the precast panel.
  • Good adjustment for cavity variations.
  • Lightweight and easy to install.
  • A cost-effective way of providing lateral restraint for panels.

Product variants

Product variants
Load classDimensions
Profile sizeLoad range [kN]
Load capacity group
Design load [kN]
Dowel [-]Depth [mm]L1 [mm]
Embedded length
Load group [T]D [mm]
Metric thread
M [mm]
Metric thread
L [mm]
x [mm]
y [mm]
L2 [mm]
Ø D1 [mm]
Ø D2 [mm]
Ø D3 [mm]
L [mm]
c [mm] Rd [mm]
e [mm]
j [mm]
Hole width
a1 [mm]
Gap between holes
∠ Angle [°]
Angle in degrees
C [mm]
Hole to edge distance
Matching profile
Compatible part
hp [mm]
Profiling depth
Weight [kg/m]
e1 [mm]
Max supported height [mm]B [mm]
Box width
Load group [T]Max lateral load [kN]

Attachment type

Witches hats can be manufactured in two different variants based on the attachment type used for the installation.

Variant A

The standard hole version is for applications with a cast-in channel.

Witches hat 3D model with no holes

Variant B

Variant B is the slotted version used for post-fix with FAZ anchors, to allow some tolerance if they hit rebar.

Witches hat slotted variant


TypeThreaded bar diameterAttachment typeLength of the threaded bar
WHM16 A100

WH-M16-Attachment type-Length of the threaded bar


  • WH-M16-A-100

Witches hat to be used with M16 bar 100mm long, using channel attachment to the concrete structure.

The precast cast-in part (cast-in channel) needs to include captive lock-in plate in order to be compatible with this product. These can be bought separately but it is important to make sure the correct fixing was chosen.

Assembly note

The assembly consists of:

  • Witches hat
  • Cast-in channel in precast panel (this varies based on panel thickness, please see accessories)
  • Captive locking plate
  • Threaded bar (DIN976)
  • 3x full nut (DIN934)

Based on the variant of attachment:

  • Cast-in channel and 2xT-bolts to suit
  • 2x Postfix FAZ Anchors

We can advise you based on your requirements and preferences.

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