cavity wall

"The term ?cavity wall? is applied to a type of masonry wall construction in which a continuous air space or cavity is provided inside the wall. A cavity wall therefore is actually two walls separated by an air space, but joined by means of metal des for structural strength. They are extensively used in European countries, particularly Great Britain, where they have been developed as a means of obtaining protection from penetration of rain through masonry walls. In recent years in North America many important buildings have been constructed with cavity walls." -- from CBD-21. Cavity Walls, 1961

An air gap is placed behind cladding/brick veneer.

There are several functions for the cavity: ingress wall drainage, pressure screen, increase insulation mainly by eliminate thermal bridge.

The cavity can be empty, half filled or fully filled with insulation material.

Brick ties or equivalents are used to connect the inner layer with the outer layer.

array of six performance characteristics: airtightness, U-factor, transient thermal response, hygric and thermal stress and strain, overall moisture balance, and thermal bridging by Hens, H. and Fatin, A.M., 1995, Heat-air-moisture design of masonry cavity walls: theoretical and experimental results and practice

EDRA concluded that: "improved drying of water that penetrates into the stud cavity is not a benefit of the rainscreen design"

Air gap for brick cladding is "to accommodate the large and inescapable differential movement that occurs between these very dissimilar materials."

Tidbits

CBD-21. Cavity Walls

pressure gradient in cavity by wind tunnel

A study of mean pressure gradients, mean cavity pressures, and resulting residual mean pressures across a rainscreen for a representative building, by Skerlj, P.S. and D. Surry, 1994

--------

Cavity pressure in rain screen walls , by Fazio, P. and Kontopidisa, T., 1988

--------

Combined `flow and strength' geometric optimization: internal structure in a vertical insulating wall with air cavities and prescribed strength , by Lorentea, S. and Bejan, A., 2002

rain pentration

Control of rain penetration through pressurized cavity walls, by Kontopidis, T., 1992

cavity ventilation in wood sideing + sheathing

Drying capabilities of wood frame walls with wood siding, by Salonvaara, M. H., Ojanen, T., Kokko, E. and Karagiozis, A. N., 1998

effect of cavity ventilation

Effect of cavity ventilation on moisture in walls and roofs, by TenWolde, A., and C. G. Carll, 1992

field testing, filled-cavity

Field testing of filled-cavity wall systems, by Straube, J.F., and Burnett, E.F.P., 1997

design performance of filled cavity wall

Heat-air-moisture design of masonry cavity walls: theoretical and experimental results and practice, by Hens, H. and Fatin, A.M, 1995

monitoring cavity humidity levels

Monitoring of cavity humidity levels at Canada life building, by Canadian Building Envelope Science and Technology, 1995

--------

Natural convection with unsaturated humid air in vertical cavities , by Mcbaina, G. D., 1997

--------

On the influence of cavity ventilation on moisture content in timber frame walls, by Hansen, M. H., Nicolajsen, A. and Stang, B. D., 2002

--------

Rain penetration control - applying current knowledge (rpc-00), by Lawton, M., Meklin, T., 1999

cavity excitation for rainscreen testing

Testing rainscreen wall and window systems: the cavity excitation method, by CMHC, 1997

zero cavity and DPV wall by CMHC

The Zero-Cavity and DPV Wall Project, by Building Engineering Group, 1996

pressure vents

Vents, ventilation drying, and pressure moderation, by Straube, J. F. and Burnett, E. F. P., 1995