Home > Companies > Manthorpe Building Products Ltd > G961 Vertical Extension Sleeve

The G961 Vertical Extension Sleeve is designed for use with the G960 Telescopic Under Floor Void Ventilator. Each extension sleeve enables a further two course brick adjustment vertically. Alternatively the sleeve can also be clipped to the base of the G960 to provide horizontal extension through larger cavities or wider internal blockwork: each unit extends the under floor ventilator a further 150 mm vertically or 185 mm horizontally and additional units can be added to achieve ventilation over any number of courses.

The G961 should be used in conjunction with other Manthorpe products to provide a complete through wall ventilation system.

Standard product features



Size (l x w x h):

208.5 x 242 x 51.5 mm.

Free airflow:

7000 mm².

NBS Specification

NBS Create logo
This product is associated with the following NBS Create clause:
45-80-50/394 Ventilation ducts

NBS Specification

NBS Buliding logo
This product is associated with the following NBS clauses:

Product specification

An important note about specifying



Manthorpe Building Products Ltd


+44 (0)1773 303000

Product reference

G961 Vertical Extension Sleeve

Manufacturer details

Manthorpe House,
Brittain Drive,
Codnor Gate Business Park,
Derbyshire, DE5 3ND
Tel +44 (0)1773 303000
Fax +44 (0)1773 303300
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