Block G – Restoration

Trends

Restoration work is increasing as original masonry in Canada has reached the age where repairs are necessary. Large restoration projects have been initiated on historical buildings across Canada. The use of lasers for cleaning surfaces is being introduced into restoration projects.

Related Components (including, but not limited to)

Stone, brick, concrete, mortars, sealants, aggregate sand, lime, cement, epoxies, acrylics, dyes, colouring agents, grouts, steel angles, ties (anchors), structural steel, flashing, sheet metal, weepers, vents, insulation, membranes, lumber, fibreglass reinforcing, injection systems.

Tools and Equipment

See Appendix A.

Task 18 Rebuilds masonry work.

Context

This task describes the process of removing and reinstalling selected masonry work ranging from small areas to entire assemblies. It involves using proper equipment, support and bracing, as well as matching the existing structure.

Required Knowledge

• K 1 historical and current masonry construction techniques
• K 2 masonry load patterns
• K 3 types and colours of mortars
• K 4 types of anchoring systems
• K 5 effect of natural, mechanical or chemical processes on the materials
• K 6 site, personnel and public safety measures
• K 7 rigging and hoisting
• K 8 storage practices for salvaged units
• K 9 documentation methods for rebuilding such as tagging and photography

Sub-task G-18.01 Disassembles unit masonry.

Key Competencies

• G-18.01.01 determine plan of action based on assessed cause of deterioration and safe approach
• G-18.01.02 shore surrounding masonry to prevent collapse or further damage during disassembly and reassembly
• G-18.01.03 record placement of units using methods such as photography, tagging and sketches to ensure accuracy of future placement
• G-18.01.04 remove mortar and units using tools according to method of disassembly selected
• G-18.01.05 clean salvaged masonry units for reassembly using tools and cleaning agents according to specifications
• G-18.01.06 store salvaged masonry units in a secure dry area to protect against damage and theft

Sub-task G-18.02 Prepares restoration work area.

Key Competencies

• G-18.02.01 remove remaining mortar from standing wall and backup wall
• G-18.02.02 clean and restore components such as anchors, ties and shelf angles
• G-18.02.03 repair backup wall and existing membrane according to deficiencies identified

Sub-task G-18.03 Reinstalls masonry and accessories.

Key Competencies

• G-18.03.01 place and secure related components such as flashings, ties, angle irons and electrical boxes
• G-18.03.02 match appearance and composition of new material to existing material
• G-18.03.03 lay new or salvaged masonry units based on recorded placement to match appearance of existing or recently disassembled work

Task 19 Repairs and cleans existing masonry work.

Context

This task describes non-destructive methods of restoring masonry work, including repointing and repairing of individual units. Repairs may be done in place or after removal and may range from historic fabric to relatively new construction.

Bricklayers clean existing masonry surfaces as part of restoration or after restoration work has been performed so that the surfaces are returned to their original appearance.

Required Knowledge

• K 1 mechanical repair techniques such as stitching, pinning or dowelling, using spiral ties and dispersed hydrated lime (DHL) injections
• K 2 non-mechanical repair techniques such as composite repair, Dutchman repair, cutting and refacing
• K 3 types of components such as bricks, stones and terracotta
• K 4 loss of moisture from mortar due to evaporation and absorption in the masonry (curing)
• K 5 types and bonding properties of mortar
• K 6 preparation techniques of mortar
• K 7 admixtures such as colouring, air entrainment agents, waterproofing and bonding agents
• K 8 historic and conventional construction methods
• K 9 types of materials used for refacing such as epoxies and acrylics
• K 10 epoxy anchoring systems
• K 11 masonry materials that may be affected by the cleaning, sealing or waterproofing/dampproofing processes
• K 12 abrasive materials such as sand, water, nut shells, baking soda and glass
• K 13 cleaning methods to avoid damage
• K 14 operating procedures for cleaning equipment
• K 15 restoration cleaning agents such as acids and non-acid stain removers
• K 16 safety practices when cleaning surfaces and handling products or equipment
• K 17 waterproofing/dampproofing materials such as silicone and solvent-based
• K 18 application methods to clean such as brushing, rolling and spraying
• K 19 practices to protect surrounding materials or assemblies during and after cleaning and waterproofing/dampproofing
• K 20 types of soiling and stains
• K 21 environmental regulations

Sub-task G-19.01 Removes deteriorated components.

Key Competencies

• G-19.01.01 determine and follow plan of action based on assessed cause of deterioration and safe approach
• G-19.01.02 shore surrounding masonry to prevent collapse or further damage during removal and re-installation
• G-19.01.03 record placement of units using methods such as photography and sketching to ensure accuracy of future placement
• G-19.01.04 document shape, size and finished face of non-salvageable units to create templates
• G-19.01.05 remove mortar, entire unit or damaged portion of a unit, using tools according to method of removal selected
• G-19.01.06 document failures in material such as hairline cracks, spalling and delamination for record keeping
• G-19.01.07 clean salvaged masonry units for re-installation according to specifications using tools and cleaning agents
• G-19.01.08 store salvaged masonry units in a secure dry area to protect against damage

Sub-task G-19.02 Repoints joints.

Key Competencies

• G-19.02.01 remove deteriorated mortar from existing joints
• G-19.02.02 clean void after removal of defective mortar using water or air pressure
• G-19.02.03 pre-moisten area to be repointed to ensure adhesion of new mortar
• G-19.02.04 fill, compress and tool joints following established procedures to ensure integrity of new joints
• G-19.02.05 mist joints or cover them with wet burlap to prevent joint failure
• G-19.02.06 protect surfaces from environmental conditions such as rain, wind and sun

Sub-task G-19.03 Repairs masonry units.

Key Competencies

• G-19.03.01 determine and follow plan of action based on assessed cause of deterioration
• G-19.03.02 drill masonry for pinning and stitching
• G-19.03.03 mix repair compound according to manufacturers’ specifications
• G-19.03.04 fill voids, rebuild portions of existing material, or mould units to match original features of the units
• G-19.03.05 rejoin severed or cracked units using materials such as dowels, threaded pins or epoxies
• G-19.03.06 reattach units to backup wall
• G-19.03.07 replace deteriorated unit face with newly cut face using mortar or adhesives
• G-19.03.08 support refaced units using wedges until initial set

Sub-task G-19.04 Reinstalls masonry units and accessories.

Key Competencies

• G-19.04.01 match appearance and composition of existing mortar
• G-19.04.02 pre-moisten adjacent surfaces to ensure correct adhesion of new mortar
• G-19.04.03 lay repaired masonry units based on recorded placement to match appearance of existing or recently disassembled work
• G-19.04.04 apply mortar to unit and adjacent surfaces to ensure total joint integrity
• G-19.04.05 compress and tool joints to match original
• G-19.04.06 mist joints or cover them with wet burlap to prevent joint failure

Sub-task G-19.05 Cleans existing masonry surfaces.

Key Competencies

• G-19.05.01 determine cleaning method according to surface condition
• G-19.05.02 test cleaning method on a small area
• G-19.05.03 mix and apply cleaning agents according to manufacturers’ specifications and in compliance with environmental regulations
• G-19.05.04 pre-soak area to prevent absorption of the cleaning agent
• G-19.05.05 use micro-abrasive cleaners such as soda, sand, water and nutshells according to material to avoid damage
• G-19.05.06 rinse cleaned area with water to eliminate any traces of cleaning agents