June 5, 2014
Damp-Proofing, Watter Repellents & Sealants
“Damp-proofing” is the common term describing the various coatings and membranes used to control construction moisture and ground water. Proper attention to damp proofing procedures in Indiana Limestone construction will eliminate many cosmetic problems during and immediately after construction.
A continuing supply of water or moisture will not harm or discolor Indiana Limestone unless it carries with it a high alkalinity or soluble salts. Portland cement, concrete blocks and other cement products contain such alkalinity. It is important to isolate the stone from sources of alkaline solutions such as wash from concrete pours, untopped concrete block walls, unglazed window openings and the like.
Where Indiana Limestone is used at grade, or where supported on concrete ledges or haunches, or on continuous angles, a back-coating of either cementitious waterproof stone-backing or bituminous stone-backing should be used. This material may be placed on the stone prior to setting; however, the cementitious material must cure to become effective. The bituminous coatings often are difficult to apply cleanly, and will retard mortar adherence.
The stone-backing material should be applied to all unexposed surfaces of the stone up to 1_-0_ above grade including joints. In those cases where stone is carried below grade, the covered portion of the face should also be coated. Below-grade mortar joints should be similarly treated.
Although coating the support surfaces is generally less effective, the same materials may be used on angles, concrete ledges and other bearing surfaces.
Stain resulting from alkalinity will usually disappear within a few months after completion of construction, when sources of moisture may be expected to dry up. Ground moisture usually may be expected to continue for the life of the building, and any stain from that source is likely to be long-lasting.
Exterior water repellents intended for application to vertical, above-grade, masonry walls are, generally, clear liquids of low viscosity. Their chemical makeup allows them to be absorbed by masonry substrates, leaving the surface essentially unchanged in color or texture. The active ingredients in water repellents are intended to be deposited in the pores of the substrate while not closing or blocking them, so that moisture vapor can pass from within the wall, but liquid moisture is not absorbed at the surface. Water repellents should reduce the adherence of dirt to building walls because they render the wall less absorptive. They should reduce or eliminate a “wet look” in rainy weather. They should reduce humidity in cavity walls. An effective water repellent will create these effects without altering the color of the substrate, and without creating a shine, or sheen.
In common usage, water repellents are sometimes called sealers, or waterproofers, or damp proofers These misnomers are confusing; worse, they tend to instill a false sense of security in users. Water repellents will not render a wall waterproof, nor will they “seal” it. Waterproofers or sealers are by definition coat formers; they change the color and texture of the substrate. Ideally, a masonry wall treated with a water repellent should not differ in appearance, during dry weather, from a similar, untreated wall.
Water repellents are not waterproof. They will not bridge gaps in mortar or sealant joints. Their use is not a failsafe for poor mortar practice, nor a substitute for damp proofing. Water repellents have been suspected of contributing to surface scaling in some cases. It is possible that a water repellent allowing vapor transmission may reduce the rate of transmission compared to identical, untreated, substrates.
Water repellents should be applied only on completed walls, with mortar or sealant joints in place. They should not be applied over wet or stained stones, nor to stone backs, nor stones under grade.
Good workmanship is essential in the application of water repellents. As a class, the materials tend to be labor-sensitive; substrate condition, weather condition, application tool, flow rate, etc., should all be in accordance with manufacturers’ instructions.
Product types including silicones, stearates, acrylics, silanes, and siloxanes have all been used with apparent success on Indiana Limestone. ICS does recommend that (1) stone samples be treated on only one-half their surface for initial evaluation; (2) manufacturers provide statements on both vapor transmission and guarantee; and (3) applier and manufacturer agree on the condition of the wall and the weather prior to application.
An understanding of probable retreatment costs, probable length of time until retreatment may be needed, and alternatives to retreatment should be part of the consideration of water repellents.
Graffiti materials include pencil, lipstick, felt-tip pen, spray paints, enamels, and lacquers. Each requires its own type of removal process and materials. The only general rule is that prompt cleanup will be the most successful. Specific recommendations for removal are given in other ILI publications.
Graffiti-proof coatings should not be confused with water repellent materials mentioned earlier. Successful coatings tend to be slick or shiny. They offer no “tooth” to which graffiti materials may cling. The coatings also tend to retard the wall’s ability to breathe. Therefore, their use should be limited to those areas subject to graffiti—generally within about eight feet of grade.
These coatings may change the color of the stone by altering the refractive qualities of its surface; thus, they may become a design consideration. Application should be terminated at joints or other natural stops. Some coatings are fragile and easily scratched when damp.
Indiana Cut Stone is now an authorized dealer for Bonstone Materials based out of Mukwanago, Wisconsin. Bonstone has been manufacturing epoxy adhesives for stone projects and concrete repair for over 50 years. Their stone and concrete repair products are developed and tested for handling the most severe conditions on stone and the bonded area. Bonstone has experience developing high performance products for concrete crack repair, anchoring, fabrication, injection and repair of limestone, sandstone, granite and marble.
Call us today for pricing!!! 812-275-0264
Our featured project this month is the Joint Force Services Headquarters located at Stout Field in Indianapolis, Indiana. Currently under construction, the mason on the project is Bronger Masonry based out of Lebanon, IN. This addition is a 77,000 sq ft addition to the existing structure and will house the communications center.
Our office & mill will be close at the end of the business day on Friday, Dec. 20th and reopen on Thursday, Jan 2nd at 7AM. All of us ICS would like to extend our best wishes to you and your families for a Merry Christmas and a prosperous 2014.