Snecked RubbleIntroduction for Stonemasons Stonemasonry Department 2012
Introduction “(Snecked Rubble)...is a method of building an incredibly strong masonry wall with differently sized, (and even very loosely squared), stones, in either ashlar or rubble work, with a pattern that is both handsome and, at the higher levels of workmanship, artistic.” Bobby Watt
Stone Identification Riser Leveller Sneck There are three stones used to construct snecked rubble. These areknown as the riser, the leveller and the sneck. The combined height of the leveller and sneck must equal the height of the riser and the bed height of each stone is constant.
Dimension Ratios Riser: Height must equal the combined heights of leveller and sneck plus the thickness of the bed. Length is approximately twice the height. Leveller: Height is approximately two thirds of the riser. The length is approximately three times the height. Sneck: Height equals the difference between the height of the riser and the height of the leveller less the thickness of the bed. Length is about three times the height.
Bonding Pattern The three stones are constructed in a bonding pattern which is governed by a set of strict rules. = Foundation = Sneck = Riser = Leveller
Bonding Pattern The wall is started by building a riser followed by three levellers. This combination is repeated for the full length of the wall. = Foundation = Sneck = Riser = Leveller
Bonding Pattern The gaps between the risers are filled with a sneck, then a riser, then two levellers. = Foundation = Sneck = Riser = Leveller
Bonding Pattern The gaps between the new risers are also filled with a sneck, a riser, and two levellers. = Foundation = Sneck = Riser = Leveller
Bonding Pattern This pattern is repeated until the wall reaches its finished height. = Foundation = Sneck = Riser = Leveller
Heads to a Joint There are a maximum of three heads to one joint.
Riser Formation The risers should be positioned to form a rough diamond pattern throughout the wall. = Foundation = Sneck = Riser = Leveller
Maximum Bed Length The horizontal bed should not exceed the combined lengths of two levellers, one riser and one sneck = Foundation = Sneck = Riser = Leveller
Alternative Patterns It should be noted that there are alternative bonding patterns forsnecked rubble. Provided the pattern follows the rules, it is acceptable. = Foundation = Sneck = Riser = Leveller
Common Construction Methods Cavity Wall Construction This form of construction generally has anouter leaf of stone and an inner leaf of brick or concrete block separated by a cavity (airspace) of approximately 50mm. Wall ties are placed in a diamond pattern with five ties per square metre to hold the leafs together.
Common Construction Methods Solid Wall ConstructionThis form of construction has stone on both sides of the wall and uses through stones (one every square metre) to bond the wall.This is a very stable method of construction but is more expensive than other common methods due to the increased quantity of stone required.
Common Construction Methods Solid Composite Wall Construction This form of construction consists of an outer facing of stone and an inner backing of brick, block or concrete. The wall is bonded by the incorporation of bonder stones positioned at least one per square metre.
Image References The image on the “Introduction” slide of this presentation was sourced from http://www.rjwstonemasons.com/documents/pictures.htm The image on the “Introduction” slide of this presentation was sourced from http://www.rjwstonemasons.com/documents/pictures.htm
Developed by The Stonemasonry Department City of Glasgow College 2012