Author: J. Miller (CTP Consulting Engineers)
1st May 2016
First published: 1st May 2016
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J. Miller (CTP Consulting Engineers)
The term “filler joist” is a generic one used for certain types of building floors dating in particular from the late Victorian era to World War II. These may commonly have embedded iron or steel joists. Those of earlier date, from the 19th century, can have wrought iron sections, or even cast iron tees in early floors. They span one way between beams or bearings, and are encased in concrete made with coke-breeze, clinker, broken brick or conventional aggregates.
The filler-joist floor was – at the time – a very important structural development, now long superseded by other systems, such as flat slabs and composite decks. It grew out of an enthusiastic age of Victorian invention that had created a wide range of proprietary, patented make-ups that all worked in a roughly similar way. Filler joists are encountered frequently in the alteration and remodelling of large office and institutional buildings.
This article is the first of two which will discuss the problem of corrosion of steel
frames behind masonry elevations. It aims to provide an introduction to this form of
construction and to consider the ways in which lack of maintenance can lead to corrosion of the steel frame, before setting out how remedial work should be
Cantilever stone staircases have been used in all sorts of buildings for more than 350 years.
Unfortunately, when surveying buildings we can be so intent on getting from floor
to floor that we forget to look at the stairs on the way. Like all structures, stairs need regular inspection and maintenance; without which, collapses can ultimately occur.
In conservation work and like-for-like repair on older masonry, lime mortar is the only recommended material. The thick, plain or lightly punctured walls that make up most historic buildings have few concentrations of load. Calculations of stress in such cases are often needless and, subject perhaps to the check of any critical element, we can generally lay aside our concerns about mortar strength.
In contrast, the need to maintain a balance of moisture and flexibility in the body of an old wall is essential. Ignoring this will lead to the classic error of repointing old structures in brittle, impermeable Portland cement
(OPC) mortar. The mortar provides the route for evaporation from the core and should be more permeable than the brick or stone. To reverse this by sealing the joints with a hard finish can only lead to trouble.