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Historic Preservation - Technical Procedures

Spectitle:

Cleaning Blackened Clay Roofing Tiles

Procedure code:

0732102R

Source:

Gra Research File - Clay Roof Tile

Division:

Thermal And Moisture Protection

Section:

Clay Tiles

Last Modified:

05/28/2014

Details:

Cleaning Blackened Clay Roofing Tiles



CLEANING BLACKENED CLAY ROOFING TILES


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on cleaning blackened
         clay roofing tiles.

    B.   Clay tile may become discolored or blackened due to any
         of the following:

         1.   Dirt build-up from air pollutants

         2.   Organic growths such as lichen, algae or moss

         3.   Industrial pollutants


PART 2---PRODUCTS

2.01 MATERIALS

    A.   Household detergent, household ammonia, weed killer, or
         mixture of zinc or magnesium and water.

    B.   Clean, potable water

2.02 EQUIPMENT

    A.   Stiff bristle brush

    B.   Ladder

    C.   Garden sprayer/garden hose

    D.   Medium or coarse long handled vegetable fiber brushes


PART 3---EXECUTION

3.01 PREPARATION

    A.   Surface Preparation:  

         1.   Sweep down tile to remove dirt and debris.  Use a
              long handle broom or brush with more rigid bristles
              which do not scratch the tile surface.

         2.   Pick up and bag the debris washed from the tile
              such as leaves, dirt, and other litter from the
              gutter and clean gutter at the same time.

3.02 ERECTION, INSTALLATION, APPLICATION

    A.   For Dirt and Pollutant Crusts:  Scrub the tile by hand
         with water and a stiff bristle brush.

    B.   For Organic Growth:

         1.   Remove growth with a stiff bristle brush and clean
              water.

         2.   Apply detergent, household bleach, weed killer or
              use a solution of zinc or magnesium and water.

         3.   Rinse thoroughly with clean, clear water.

    C.   For Industrial Stains:  Clean with a water-based
         household detergent and a stiff bristle brush.

                             END OF SECTION
 


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