Lead is corrosion-resistant and will not rot. Lead anchors (photo 2, A, B) were developed for use with bolts and screws. Although wood anchors are no longer used in construction, many older buildings were assembled using them, and the condition of any individual wood plug or nailer is usually unknown until it fails. If a nailer that replaced a wythe of brick is exposed to fire, it will burn and create a weak plane in the wall–like the notch we cut in a tree to direct where it falls. If the wood anchor has rot or insect damage, it will loosen and fail quickly. Some of these wood anchors have been in place for more than a hundred years and are still in good condition–if the wood was dry when it was installed, and if it has not been exposed to water or insect damage.

Photo1 shows a piece of rough-sawn 2 × 4 laid up in the wall to replace an entire wythe of bricks and used to attach firring strips for wood lath and plaster and a piece of 1 × 8 laid into the wall to support the window jamb. Sometimes, pieces of wood shingle were laid between bricks in the mortar joints. Sometimes a hole would be drilled in the masonry after the mortar was set (or a hole could be left in a mortar joint) and a wood plug would be whittled to fit and pounded into the hole. Wood was the earliest material used as anchors in masonry, to accept nails, pegs, or screws. The solution developed hundreds of years ago was to fill the hole in the masonry or concrete with a plug of a material that would hold the fastener, and at the same time expand and grip the inside of the hole. Holes must be drilled in these materials for the fasteners, and the materials are hard enough that the fasteners may not grip well. It is not so simple when we need to attach something to concrete, masonry, or even a plastered wall or ceiling.

Hilti anchors zip tight