Metal cornices are commonly installed at the front historic building facades in Washington DC. Metal cornices, like aperture headers and sill, ornate doors and casing, and detailed brickwork are part of the architectural accents which make the historic DC neighborhoods unique and classically beautiful.
The image below shows an upclose view of a metal cornice, almost in profile position.
A lot of our clients do not understand the true material makeup and nature of the metal cornices. In most cases they are made from paint coated ferrous metals.
The picture below shows an up close view of a zinc galvanized metal cornice at the top of a front building facade in Capitol hill Washington DC. (Painting zinc presents unique challenges related to coating cohesion and bond.)
Many historic building owners do not understand the exact nature of the metal cornices. From the ground it’s hard to distinguish a metal cornice like this from a wooden or cement type of cornice. In the picture below you can see, up close, where a portion of the metal cornice was removed. The space behind the cornice is an open void. In most cases the metal cornice is attached By small nails. Today, in modern times, we would use stainless steel (or metal types compatible with the substrate.)
Sheet metal is generally cold formed. The cold form nature means that the metal is produced in sheets. The sheets are relatively thin. Today’s metal is thinner than metal of the past. In today’s industry’s, aluminum is one of the most common materials for inexpensive and highly weather resistant metal on exterior building facades. Other metals though are still used such as galvanized or zinc coated steels, copper, and on occasion for specialty installations stainless steel may be used. Sheet metals have a high degree of flexibility, by nature, and can bend and easily be formed with permanent deformation. Once a sheet metal is bent lengthwise, it is difficult to bend again across the strength axis which follows the linear run of the bend. It By comparison, hot formed metals (depending on the exact context, also referred to as: hot rolled) built with more than one planer plane are generally stronger to resist bending and deformation.