When working with Limestone tiles, it can be installed nearly anywhere in the home – kitchen countertops, bathroom counters, flooring and other locations. Limestone should be installed by an experienced stone setter. In most cases, all limestone pieces are identified with a unique piece number corresponding with the number on the shop drawings. Interchanging of numbered pieces is not advised.
Temperatures for Installing and Setting Limestone
Prior to starting the installation process, ensure the temperatures are appropriate. In cold weather, the International Masonry Industry All Weather Council recommendation for setting is 40ºF to 20ºF (4ºC to -6ºC), and below 20ºF (-6ºC), all work would need to be done in heated enclosures. If the tiles are being installed outside, or have been outside in cold weather, ensure they contain no ice or frost to avoid complications. If ice and frost is present, allow the tiles to come to room temperature, adding salt or other material to the stone prior to installation is not recommended. As with all tile installations, adequate protection measures should be taken to ensure that exposed surfaces of the stone are to be kept free of mortar at all times. Portland cement with a low-alkali content is recommended.
Cleaning Limestone Prior to Installation
Cut limestone is typically shipped as it comes from the supplier’s plant. It is likely to be covered with dirt or saw dust, especially those pieces which have not been exposed during shipment.
Prior to installation or construction of cut limestone, cleaning is not typically required since the existence of dirt or saw dust does not delay the construction process or the process of application of joint sealants or pointing.
However, it is key to thoroughly clean stones that will be set indoors as well as protect the work once in place from other construction projects.
Among the methods used is washing with a fiber brush and soap powder, followed by a thorough rinsing with clear water. All stone joint surfaces not thoroughly wet are drenched with clear water prior to setting.
Stone should be set in full beds of mortar with all vertical joints packed, unless otherwise recommended. Completely fill all anchor, dowel, and similar holes. All bed and vertical joints should be 3/8″. Plastic setting pads should be placed under heavy stones, column drums, and other similar locations, in the same thickness as the joint, and in sufficient quantity to avoid squeezing mortar out. Heavy stones or projecting courses should not be set until mortar in courses below has hardened sufficiently to avoid squeezing.
While joints can be adjusted after the initial set has occurred, pointing cut stone after setting, rather than full bed setting and finishing in one operation reduces a condition which tends to produce spalling and leakage. It is a good idea to set the stone and rake out the mortar to a depth of ½” to 1½” for pointing with mortar or sealant at a later date.
It is important to securly prop or anchor any projecting stones until the wall above is set. The ends of lugged sills and steps need to be completely embedded in mortar. The remaining portion of the joint should be left open until finally pointed. All cornice, copings, projecting belt courses, other projecting courses, steps, and platforms (in general, all stone areas either partially or totally horizontal) should be set with unfilled vertical joints.
After setting, insert a backup material or backer rod to proper depth, and gun in sealant. Individually set thin tile (nominal 3/8″ thick) on vertical surfaces, exceeding 8′ in height is not recommended.
Whenever possible, all anchor preparations in limestone units should be shop-applied. All anchorage devices and anchor hole/slot fillers should be in accordance with ASTM C1242. Care must be taken to ensure that any holes capable of retaining water are filled after use to prevent water collection and freezing.
Joints requiring sealant are first filled with a closed-cell ethafoam rope backer rod. The backer rod should be installed to a depth that provides an ideal sealant profile after tooling. If recommended by the Sealant Manufacturer, primers should be applied to the substrate surfaces according to the manufacturer’s directions prior to application of the joint sealant.
Joints should be adequate to allow for thermal and structural differential movement. Filler material for these joints should be nonstaining. The Specifying Authority must specify expansion and control joints and show location and details on the drawings. MIA recommends a maximum area of 400 square feet between expansion/control joints for horizontal surfaces. In areas where there are large sections of natural light, this area should be reduced depending on the quantity of natural light entering the area. In glass ceiling atriums, 120 square feet is the maximum area that an expansion/control joint should encamp.
Joints should be pointed with the sealant(s) specified above, after first installing the specified backup material and applying a primer (if required), Follow the instructions by the Sealant manufacturer for the particular sealant you plan to use. All sealants should be tooled to ensure maximum adhesion to the contact surfaces.
Put plastic weep tubes in joints where moisture may accumulate within the wall, such as at the base, angles, etc.