| Treated lumber is used to preserve
the wood and should be used where the wood touches the concrete as in
the picture above.
Chromated copper arsenate (CCA) is a wood preservative used for
timber treatment, in use since the mid-1930's. It is a mix of copper,
chromium, and arsenic formulated as oxides or salts. It preserves the
wood from decay fungi, wood attacking insects, including termites, and
marine borers. It also improves the weather-resistance of treated timber
and may assist paint adherence in the long term.
Timber or lumber that is treated with a preservative generally have
it applied through vacuum and/or pressure treatment. The preservatives
used to pressure-treat timber are classified as pesticides. Treating
timber provides long-term resistance to organisms that cause
deterioration. If it is applied correctly, it extends the productive
life of timber by five to ten times. If left untreated, wood that is
exposed to moisture or soil for sustained periods of time will become
weakened by various types of fungi, bacteria or insects.
CCA is known by many trade names, including the world-wide brand
Tanalith. The chromium acts as a chemical fixing agent and has little or
no preserving properties; it helps the other chemicals to fix in the
timber, binding them through chemical complexes to the wood's cellulose
and lignin. The copper acts primarily to protect the wood against decay
fungi and bacteria, while the arsenic is the main insecticidal component
of CCA.
Stair Ledger Damage
Stair Maintenance
Stair Tread Water Problem
Structural Crack in Concrete Stairs
Water Problem at Stair Landing
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