Perpend
The term ‘perpend’ (perp or cross joint) refers to the vertical joints between blocks or bricks that have been laid in a horizontal course to form a wall. Perpends are normally filled and sealed with mortar. The horizontal mortar joint in a wall construction is typically referred to as the bed joint.
Rather than being filled with mortar, perpends may also be left open to form weep holes or cavity ventilators. These provide openings that allow the drainage of moisture from within a wall construction and allow ventilating air to the back of a wall to help prevent mildew, dry rot and damp. They are generally formed by plastic inserts into the perpends, as these form a more uniform opening compared to simply leaving a void. See weep holes for more information.
A perpend stone is a long stone that extends between the inner and outer layers of a stone wall, tying the two layers together. The stone is ‘dressed’ at both ends.
The term ‘perpend’ may also be used more generally to refer to any brick or stone the longest dimension of which is perpendicular to the face of the wall. See bond stone.
The expression “keeping the perpends” is a term used to describe what happens when cross joints or transverse joints in brickwork are maintained in a perpendicular line.
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
Design and construction industry podcasts
Professional development, practice, the pandemic, platforms and podcasts. Have we missed anything?
C20 Society; Buildings at Risk List 2025
10 more buildings published with updates on the past decade of buildings featured.
Boiler Upgrade Scheme and certifications consultation
Summary of government consultation, closing 11 June 2025.
Deputy editor of AT, Tim Fraser, discusses the newly formed society with its current chair, Chris Halligan MCIAT.
Barratt Lo-E passivhaus standard homes planned enmasse
With an initial 728 Lo-E homes across two sites and many more planned for the future.
Government urged to uphold Warm Homes commitment
ECA and industry bodies write to Government concerning its 13.2 billion Warm Homes manifesto commitment.
From project managers to rising stars, sustainability pioneers and more.
Places of Worship in Britain and Ireland, 1929-1990. Book review.
The emancipation of women in art.
Call for independent National Grenfell oversight mechanism
MHCLG share findings of Building Safety Inquiry in letter to Secretary of State and Minister for Building Safety.
The Architectural Technology Awards
AT Awards now open for this the sixth decade of CIAT.
50th Golden anniversary ECA Edmundson awards
Deadline for submissions Friday 30 May 2025.
The benefits of precast, off-site foundation systems
Top ten benefits of this notable innovation.
Encouraging individuals to take action saving water at home, work, and in their communities.
Takes a community to support mental health and wellbeing
The why of becoming a Mental Health Instructor explained.
Mental health awareness week 13-18 May
The theme is communities, they can provide a sense of belonging, safety, support in hard times, and a sense purpose.
Mental health support on the rise but workers still struggling
CIOB Understanding Mental Health in the Built Environment 2025 shows.
Design and construction material libraries
Material, sample, product or detail libraries a key component of any architectural design practice.