911Stone Masonry Walls

911.01 Description.

This work includes providing wet stone masonry walls of standard designs at the required locations.

911.02 Materials.

General.

911.03 Construction Methods.

Weather Limitations. Ensure that the temperature and weather conditions for stone masonry wall construction conform to Subsection 807.03.1. Mixing of Mortar. Ensure that the mixing of mortar conforms to Subsection 807.03.2. Selecting and Storing Stone. Keep a sufficient stock of the approved stone on site to permit adequate selection and blending of stones by the masons. Keep the stones free from dirt, oil, or any other injurious material that may prevent the proper adhesion of the mortar or detract from the appearance of the exposed surfaces. Shaping and Dressing Stones. Use selected stone, roughly squared and pitched to line, at all angles and wall ends. Perform all shaping and dressing of stone before the stone is laid in the wall . Do not use any dressing or hammering that will loosen the stone after it is placed. If a stone is loosened after the mortar is set, remove the stone, clean the mortar, and relay the stone in fresh mortar. Laying Stone. Lay the wall compactly with all vertical joints in the interior of the wall completely filled with suitable stones or spalls thoroughly bedded in mortar. Clean and wet each stone to be set in mortar before being set in a full bed of fresh mortar. Ensure that t he stones are settled in place before the mortar has set. Remove any mortar in which initial set has commenced from the mixing boards or receptacles; do not reuse the mortar in the work. Do not retemper any mortar. When laying is interrupted, leave the top courses unplastered.

Part 900 — Incidental Construction and Services August 2025

SECTION 911 — STONE MASONRY WALLS 900-35 Lay the masonry to line and in the required pattern. Lay the stone with bearing beds parallel to the natural bed of the material. Restrict the use of chinking stones in the face to a minimum , which will be permitted only in the horizontal joints to provide firm bearing of stones. Do not chink vertical joints in the face. Prevent the bunching of small stones or stones of similar size. When weathered or colored stones, or stones of varying textures are being used, distribute the various kinds of stones uniformly throughout the exposed faces of the work. Ensure that the foundation (base) of the wall is composed of large stones (stones that are distinctly larger than the majority of the stones in the wall) that are laid to form a relatively flat surface upon which the succeeding courses may be placed. Use large stones for the bottom courses and, in general, decrease these stones in size from the bottom to the top of the work. Ensure that at least one -fourth of the stones in the face are headers (a stone laid with its end toward the face of the wall) and evenly distribute these stones. Extend headers not less than 12 in. into the core (or the stones that make up the center) of the wall. Ensure that headers are uniform in height and width throughout their length. Extend headers in walls 2 ft or less in thickness entirely through the wall. Lay all stones to break joints and to thoroughly bond the work. Place stones to form bonds with the stones of adjoining courses of not less than 12 in. ashlar (squared and dressed stone) and split face masonry and not less than 6 in. rubble masonry. Place headers over stretchers (stones laid with their length parallel to the face of the wall) and, in general, ensure that the headers of each course equally divide the spaces between the headers of adjoining courses. Do not place any header over a joint and do not make any joint over a header. Place headers in each course, which must have a width of not less than 1½ times their thickness and must be spaced no further than 8 ft apart, center to center. Ensure that stretchers have a length of bed not less than 2 times nor more than 3½ times their thickness and not less than 3 ft. Finish the tops of walls flat. Ensure that c apstones, if required, are flat on the upward side and are not less than 6 in. in thickness for ashlar and split face masonry and 3 in. in thickness for rubble masonry. Ensure that at least one-fourth of the stones used on the top of the wall are tie stones and extend entirely across the top. Ensure that the remaining stones used in constructing the top course are of a size that allows the top course to be constructed by the placement of no more than two stones across the width of the wall and that are no less than 8 in. in width. Joints. Finish joints requiring pointing so that the mortared joint is filled to the face line of the wall. Finish the mortar so that it is pitched downward and away from the center of the wall. Ensure that joints on the top of the wall are pointed flush with the top of the wall and are slightly pitched to direct water off of the wall. When possible, e nsure that joints are properly pointed before the mortar becomes set. For joints that cannot be pointed, prepare these for subsequent pointing by raking the mortar out to a depth of 2 in. before the mortar has set. Wet joints that are not pointed at the time the stones are laid with clean water, and fill the joints with mortar. Ensure that the mortar is well driven into the joints and finished with a pointing tool. Ensure that t he maximum widths of joints in the faces and tops of stone masonry walls are as follows:

Part 900 — Incidental Construction and Services August 2025

900-36 SECTION 911 — STONE MASONRY WALLS Ashlar Split Face Rubble Face ½ in. 1 in. 1 in. Top ½ in. ¾ in. 1 in. Weep Holes. Furnish and install drainage holes and weep holes as detailed and at the required locations. Excavation. Perform any excavation below the designated slope or subgrade and subsequent backfilling according to SECTION 203. Backfilling. Perform the backfilling with approved pervious materials placed in layers of not more than 6 in. in thickness. Compact each layer before the succeeding layer is placed. Cleaning. After the mortar has set, clean the wall and leave the wall in a neat and workmanlike condition.