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 Introduction

 Brickwork Design

 Walls

  Loadbearing

  Non-Loadbearing

  Lintels & Openings

  Reinforced Brickwork

  Brick Rod

  Mortar & Joints  Control Joints

  Weather Resistance

  Thermal Performance

  Acoustic & Fire

 Case Studies

 Bibliography

 Appendices

Non-Loadbearing Walls

Why non-loadbearing walls

The base of the walls in large nineteenth-century buildings were quite thick (up to a

metre or more), because of the heavy loads to be carried and, before the use of cement mortar, the low strength of the joints. Modern masonry walls can be made to

carry considerable loads by the use of high-strength bricks and mortar, but often a

framed structure allows more freedom in the design of the facade as well as in the

 planning of the interior.

A structural frame of reinforced concrete or steel can support the loads of the floors

and roof, and also of the non-loadbearing walls. The external walls then perform all

the 'enclosure' f unctions. Each wall panel also carries its own weight and resists wind

and seismic loads, but only those that act on the panel itself.

These images of the loadbearing Monadnock Building and the framed Reliance building (both Burnham and Root, Architects, Chicago 1890) illustrate some of the

freedom that a frame allows on the facade.

 

Monadnock building, Chicago

 

Reliance building, Chicago

 

Arrangement of supports

There is a choice to be made about the appearance of a non-loadbearing external

wall. It may completely enclose the structure, or expose the columns, or the floors,

or both. Each of these alternatives will require different details in plan and in section.

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It is usual, but not always necessary, to support the wall at each floor level. By

exposing every second floor slab, a different scale and proportion can be achieved in

the elevation.

The method of supporting the external leaf on the floors depends on whether the

edge of the floor is exposed or not.

The wall can sit on top of the floor slab.

 

The full depth of the slab (and beam, if any) is exposed. This detail should preferably

 be modified with a recess in the edge of the slab, so that any water penetrating under 

the flashing does not enter the building, in the same way that the edge of a domestic

raft slab is recessed. If there is no recess (especially when the wall sits on a slab

which is too thin to accommodate a recess), then the flashing can be turned down at

the outer edge of the beam.

 

The wall can sit on a concrete nib projecting from the bottom of an edge

 beam, (or possibly partway up the face of the beam).

The nib must be designed and reinforced to take the weight of the wall.

Consideration will need to be given to how the exposed concrete will be finished and

 

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how it will weather. It would be better if the concrete was either flush with, or set

 back from, the face of the brickwork. To prevent water from tracking in on the

underside of the beam, either a drip groove is formed in the concrete, or a drip angle

is fixed with a mastic seal to the underside at the cavity location. Where an opening

occurs directly under the beam, a similar drip groove or lug is needed to minimise

staining from dirt laden water flowing from the brick surface above.

 

The wall can be supported on a shelf angle, at the bottom or any other 

 position on the face of the slab or edge beam.

 

This provides a continuous brick facade without showing the slab. The angle is of 

either galvanised or stainless steel.

 Note: The flashings shown in these illustrations are further discussed inFlashings at

floor level.

Some textbooks show thin pieces of brick, known as "brick slips" or "biscuits", as afacing to allow both leaves to be supported on the slab without showing concrete on

the face. This detail is not recommended, as there is a danger of the small pieces

 being dislodged due to loading or differential movement. The outer leaf is also likely

to be supported eccentrically, to a greater extent than with a shelf angle.

Stability of non-loadbearing walls

The additional load imposed on loadbearing walls helps to prevent tension

developing, and therefore helps to prevent overturning. In addition, the fact that all

the walls are connected together at each floor level, and at the roof, helps to make

them all act together to support each other. Non-loadbearing walls lack these

 benefits.

When a brick wall is supported on a concrete beam or a shelf angle at each floor 

 

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eve , care mus e a en a e ower wa oes no acc en a y p c up oa rom

the floor above. A "soft joint" (a joint filled with compressible material and sealed

with mastic) is used at the top of each wall. (See Horizontal Soft Joints.) This not

only prevents the transfer of vertical loads, but it also removes the restraining effect

of the upper floor. The wall panel is virtually freestanding from its base.

If the wall is built as an infill between columns, it also loses support at the sides of the

columns.

To overcome these problems, a variety of special ties have been developed. They

are all based on the principle of allowing movement in one direction but restraining it

in the other directions, basically by sliding one flattened tube inside a larger one. (See

Wall Anchors under Lintels and Openings.) A cavity wall in this situation has the

advantage of greater stiffness than a single-leaf wall, but nevertheless usually requires

support back to the structural frame. Reinforcing the brickwork may also provide

additional support.

 

Brick veneer walls

An external brick wall provides all the advantages of appearance and durability,

whether it is a full cavity wall or a brick veneer over a framed internal leaf. In

commercial buildings, it is common to use plasterboard on steel studs for the internal

walls, and brickwork for the external leaf of the perimeter walls. In this case, the

 brickwork is stabilised by means of wall ties to the steel studs.

A brick veneer wall also allows the inclusion of thermal insulation between the studs,

which is easier than insulating a cavity brick wall. The durability of the internal walls

may be less than if they were all of brickwork.

 

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