Home > Companies > Manthorpe Building Products Ltd > Thermal Cavity Closer

Manthorpes' profiled thermal cavity closer suits standard vertical cavity and sill details. It provides an economical solution to cold bridging problems and is available in a range of sizes to suit varying cavity widths and can easily be installed with no special fixings. It not only provides a thermal break to the cavity, but also acts as an effective vertical DPC barrier.

Manthorpe cavity closers meet all Building Regulations and achieve the required 'U' value at the reveal of door and window openings when the frames are fixed to allow a 15 mm overlap (which can be reduced depending on the surrounding construction) into the cavity - refer BRE Information Paper IP17.

Standard product features


White UPVC extrusion and yellow CFC and HCFC free, rigid extruded polystyrene insulation.

K value:

0.029 W/mK.


Size (all closers are 2440 mm long x 27 mm wide):

  • G241/50: Approximately 50 mm depth of insulation.
  • G241/65: Approximately 65 mm depth of insulation.
  • G241/75: Approximately 75 mm depth of insulation.
  • G241/90: Approximately 90 mm depth of insulation.
  • G241/100: Approximately 100 mm depth of insulation.
  • G241M: Multi width - allows site cutting to accommodate 50/ 65/ 75/ 85 and 100 mm cavity widths.

NBS Specification

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This product is associated with the following NBS Create clause:
45-25-20/455 Plastics cavity closers

NBS Specification

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This product is associated with the following NBS clauses:

Product specification

An important note about specifying



Manthorpe Building Products Ltd


+44 (0)1773 514200

Product reference



[G245 fixing clip and G246 right angle fixing clip]

Manufacturer details

Manthorpe House,
Brittain Drive,
Codnor Gate Business Park,
Derbyshire, DE5 3ND
Tel +44 (0)1773 514200
Fax +44 (0)1773 514261
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