How to Avoid Deck Deterioration

July 1, 2010

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Decks often face many types of problems depending on their location, function and method of construction.  Because deck structures are commonly made of concrete, deck deterioration often comes from a chemical reaction when concrete isexposed to the environment. 

Below are some signs that decks are deteriorating or facing problems:

1.  Cracking and spalling. Decks may show cracks and rents that indicate severe concrete strain.  The strain may be due to sudden freezing and thawing temperatures.

2.  Laitance formation.  Too much water during concrete mixing can form laitance, which is a thin layer of cement that comes to the surface after the mix is poured. 

3.  Efflorescence.  A white crystalline substance on top of the concrete surface indicates salt residue deposits caused by moisture exposure.  

4.  Incorrectly-cured concrete surface.  Decks should be cured for at least 30 days before deck coatings application; otherwise the high moisture content in the surface can lead to coatings failure.

5.  Corrosion of reinforcing steel.  Decks use reinforcing bars for better structural integrity.  But when steel is corroded, a rust-colored stain appears on the deck surface to indicate that the structural integrity is being threatened.

Deck Repairs and Coating Applications

It is good practice to enlist the aid of professional coatings contractors to assess the severity of deck deterioration.  No amount of deck coatings can fix the problem in cases of severe deck damage.  Coatings specialists can determine and recommend if the deck needs a complete renovation instead.

Damages in concrete decks should be fixed first before applying any deck coatings solutions.  The surface should be carefully inspected for cracks.  If the crack is still spreading, the surface must be completely repaired.  If the reinforcing steel appears corroded, deck rehabilitation should be conducted.

Protective Deck Coatings

Deck coatings products are designed with concrete’s porosity in mind.  These products prevent moisture, or soluble salts from penetrating the surface.  Other products also offer chemical, corrosion and freeze/thaw resistance.  The choice of coatings depends on the specific need of the deck in question.

Protective coatings are commonly thick-film formulations that provide barrier protection.  They may be based from epoxies, vinyl, acrylics, polyurethane and elastomerics.  They offer flexibility and waterproofing benefits to deck structures.  

Surface preparation prior to deck coatings application involves achieving a rougher profile for better coatings adherence. 

Any traces of moisture should be removed from the deck surface before coatings application, to prevent surface blisters.  To assure low to zero moisture content, a moisture test should be conducted.

Water-Repellant Deck Sealers

Sealers have water-repellant abilities that are useful in exterior areas such as parking lots, where the chance of water exposure is greater.

Unlike thick-film deck coatings, thin-film sealers penetrate concrete and fill up every pore in the area, leaving no space left for water to penetrate.  Sealers require a completely clean surface.  Dirt, oil or grease prevents sealers from totally permeating the deck surface.   

Manytypes of deck coatings may be used to repair decks.  But it should always be done using the most appropriate product, with the most careful surface preparation, and by skilled deck coatings specialists.

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