B08_Solicitation_(Attachment_7_-_Specs_-_Stone_Repointing)_0001.pdf

NICO 311127 6/18/25

Div. 4 V. 2021-10-18 STONE REPOINTING 040140.62 Page | 1

SECTION 040140.62

STONE REPOINTING

PART 1 - GENERAL

1.1 SCOPE OF WORK

A. Project Location: Nicodemus National Historic Site (NICO) Township Hall building

B. Building: 304 Washington Avenue Nicodemus KS 67625. Note Bogue Kansas and Nicodemus Kansas share the same zip code and similar street names. This work is in Nicodemus KS

1.2 SUMMARY

Work will clean approximately 3747SF the exterior stone and brick surface, removing organic growth and dirt by gentlest means possible. Repoint approximately 375SF of loose and cracked mortar of chimney and around windows, doors and the beltline of the building; to the depth of 3-time the joint width and fill void with a matching mortar.

PREINSTALLATION MEETINGS

A. Preinstallation Conference: See Division 1.

1.3 ACTION SUBMITTALS

A. Product Data: For each type of product.

B. Samples: For each exposed product and for each color and texture specified.

C. Approved Mortar Mix Proportion Specification.

1.4 INFORMATIONAL SUBMITTALS

A. Quality-control program.

1.5 QUALITY ASSURANCE

A. Stone Repointing Specialist Qualifications: Engage an experienced stone repointing firm or person to perform work of this Section. Firm/Person shall have completed work similar in material, design, and extent to that indicated for this Project with a record of successful in-service performance. Experience in only installing standard unit masonry or new stone masonry is insufficient experience for stone repointing work.

B. Quality-Control Program: Prepare a written quality-control program for this Project to systematically demonstrate the ability of personnel to properly follow methods and use materials and tools without damaging stonework. Include provisions for supervising performance and preventing damage.

C. Temperature: Maintain wall temperature between 40- and 95-degrees F. To the extent possible, repoint in the shade, away from strong sunlight in order to slow the drying process.

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D. Mockups: Prepare mockups of stone repointing to demonstrate aesthetic effects and to set quality standards for materials and execution.

1. Repointing: Rake out joints in one area approximately 12 inches (300mm) high by 24 inches (600 mm) wide unless otherwise indicated for each type of repointing required and repoint one of the areas. Mortar to be removed to the depth of 3-time the joint width.

Coordinate with COR for approved area on building for Mockups.

2. Remove mortar with hand tools (chisel and hammer) in combination with assistance of power tools as follows:

a. Use of hand-held small pneumatic impact chisels and narrow rotary-grinder drills is allowed if done without damaging the existing stone units.

b. Use of angle grinder with a diamond-impregnated metal blade, for aligned horizontal joints only, is allowed if done without damaging the existing stone units.

Blades shall be half as narrow as the joint, cut made in the center of the joint, and final removal from the sides of the joint by hand.

PART 2 - PRODUCTS

2.1 MORTAR MATERIALS

A. Portland Cement: ASTM C150/C150M, Type I or Type II, white or gray, or both where required for color matching of mortar.

1. Provide cement containing not more than 0.60 percent total alkali when tested according to ASTM C114.

2. Hydrated Lime: ASTM C207, Type S.

B. Mortar Sand: ASTM C144.

1. Match size, texture, and gradation of existing mortar sand as closely as possible. Blend several sands if necessary to achieve suitable match.

2. Color: Natural sand or ground marble, granite, or other sound stone of color necessary to produce required mortar color.

C. Water: Potable.

2.2 MORTAR MIXES

A. Measurement and Mixing: Measure cementitious materials and sand in a dry condition by volume or equivalent weight. Do not measure by shovel; use known measure. Mix materials in a clean, mechanical batch mixer.

1. Mixing Pointing Mortar: Thoroughly mix cementitious materials and sand together before adding any water. Then mix again, adding only enough water to produce a damp, unworkable mix that retains its form when pressed into a ball. Maintain mortar in this dampened condition for 15 to 30 minutes. Add remaining water in small portions until

Div. 4 V. 2021-10-18 STONE REPOINTING 040140.62 Page | 3 mortar reaches desired consistency. Use mortar within one hour of final mixing; do not retemper or use partially hardened material.

2. Pointing Mortar by Type: ASTM C270, Proportion Specification, Type N (750 psi) unless otherwise indicated; with cementitious material limited to Portland cement and lime. Add mortar pigments to produce mortar colors required.

2.3 REPLACEMENT STONE UNITS NA

PART 3 - EXECUTION

3.1 PROTECTION

A. Protect window and doors frame from damage. Provide temporary protective covering for public access to the building during work activities within 20-feet of building entrance. Provide and protect metal flashing and lightening protect device and ground from damage of work activities.

3.2 REPOINTING

A. Rake out and repoint joints to the following extent: Remove approximately 375SF of loose and cracked mortar around doors, windows and below windows as well as the chimney; to the depth of 3-time the joint width and fill void with a matching mortar. Only low-pressure water spray should be used on masonry COR approval need when pressure exceeds 100 PSI.

All joints in areas indicated. around doors, windows and below windows as well as the chimney

B. Rake out joints as follows, according to procedures demonstrated in approved mockup:

1. Remove mortar from joints to depth of 3 times joint width and not less than that required to expose sound, un-weathered mortar. Do not remove unsound mortar more than half the masonry depth; consult COR for direction.

2. Remove mortar from stone surfaces within raked-out joints to provide reveals with square backs and to expose stone for contact with pointing mortar. Brush, vacuum, or flush joints with clean, low pressure water spray to remove dirt and loose debris.

3. Do not spall edges of stone units or widen joints. Replace or patch damaged stone units as directed by COR.

a. Remove mortar from joints that abut area of stone removal to same depth as stone was removed. Remove loose mortar particles and other debris from surfaces to be bonded and surfaces of adjacent stone units that will receive mortar by cleaning with stiff-fiber brush.

b. Cut and trim partial replacement to accurately fit area where material was removed. Fabricate to size required to produce joints between partial replacement and adjacent stone to match joints existing joints.

Set replacement stone with rebuilding (setting) mortar and with completely filled bed, head and collar joints. Butter vertical joints for full width before setting and set

Div. 4 V. 2021-10-18 STONE REPOINTING 040140.62 Page | 4 units in full bed or mortar. If applicable, replace existing anchors with new anchors matching existing configuration.

C. Notify COR of unforeseen detrimental conditions including voids in mortar joints, cracks, loose stone, rotted wood, rusted metal, and other deteriorated items.

D. Pointing with Mortar:

1. Rinse joint surfaces with water to remove dust and mortar particles. Time rinsing application so, at time of pointing, joint surfaces are damp but free of standing water. If rinse water dries, dampen joint surfaces before pointing.

2. Apply pointing mortar first to areas where existing mortar was removed to depths greater than surrounding areas. Apply in layers not greater than 3/8 inch (9 mm) until a uniform depth is formed. Fully compact each layer and allow it to become thumbprint hard before applying next layer.

3. After deep areas have been filled to same depth as remaining joints, point joints by placing mortar in layers not greater than 3/8 inch (9 mm). Fully compact each layer and allow to become thumbprint hard before applying next layer. Where existing stone has worn or rounded edges, slightly recess finished mortar surface below face of stone to avoid widened joint faces. Take care not to spread mortar beyond joint edges onto exposed stone surfaces or to featheredge the mortar.

4. When mortar is thumbprint hard, tool joints to match original appearance of joints as demonstrated in approved mockup. Remove excess mortar from edge of joint by brushing.

5. Cure mortar by maintaining in thoroughly damp condition for at least 72 consecutive hours. Coordinate mortar curing accordingly to avoid weekend and holiday work, unless approved by COR.

6. Hairline cracking within mortar or mortar separation at edge of a joint is unacceptable.

Completely remove such mortar and repoint.

E. Pointing with Sealant: NA

F. Where repointing work precedes cleaning of existing stone, allow mortar to harden at least 30 days before beginning cleaning work.

3.3 FINAL CLEANING OF REPOINTED MORTAR

A. If repointing work is carefully executed, there will be little need for cleaning other than to remove the small amount of mortar from the edge of the joint following tooling.

B. Remove excess repointing mortar from joint edge with a stiff natural bristle or nylon brush after the mortar as dried, but before it is initially set. Do not employ aggressive cleaning methods that could damage masonry surfaces or the mortar.

END OF SECTION