Bleach cleaning your deck, a recipe for disaster!

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Decks, fences, pergolas, even composite structures attract mold and mildew like any other non-porous surface. The problem here however is wood is not a non-porous surface and therefore should be treated as such. Lets break this down in Layman’s terms and keep it very simple.  Porous surfaces are areas covered with highly porous material that allow water from precipitation to pass through, yet are strong and durable enough to support vehicular or pedestrian traffic (i.e. wood). Non-porous surfaces are mainly smooth surfaces which the latent print resides on the surface. Examples of non-porous surfaces include glass, plastics, metals, and varnished wood. When we think of these types of surfaces we automatically use a bleach cleaner to clean and disinfect these surfaces so we would automatically think to use it on anything where mold or mildew is present. That is simply not the case and for very good reason.

The use of bleach as a mold disinfectant is best left to kitchen and bathroom countertops, tubs and shower glass, etc. The properties of chlorine bleach prevent it from “soaking into” wood-based building materials to get at the deeply embedded mycelia (roots) of mold. The object to killing mold is to kill its “roots”. Reputable mold remediation contractors use appropriate products that effectively disinfect properly scrubbed and cleaned salvageable mold infected wood products. Beware of any mold inspector, mold remediation contractor or other individual that recommends or uses chlorine bleach for mold clean up on wood-based building materials. OSHA is the first federal agency to announce a departure from the use of chlorine bleach in mold remediation. In time, other federal, state and other public safety agencies are expected to follow OSHA’s lead.  The public should be aware, however, that a chlorine bleach solution is an effective sanitizing product that kills mold on hard non-porous surfaces and neutralizes indoor mold allergens that trigger allergies. Mold and mildew is a vegetative growth, and NOT a type of dirt to be cleaned. It is produced by a tiny plant of the fungus family. It can sprout on most surfaces especially if a food source is present for the minifungus to thrive on, especially on paper and wood. Additionally, mildew can grow on the dirt and soil on them, especially in dampness. Mold spores (seeds) exist everywhere and will grow when the conditions are right. Like a weed growing on your front lawn, mold and mildew must be killed by an effective, acknowledged, E.P.A. registered disinfectant cleaner making mold and mildew claims.

The affects of bleach on decks/fences

Bleach is the old standard used for years. The chlorine kills algae, moss and mildew. BUT – chlorine breaks down the lignin that holds the wood together, causing excessive damage to otherwise healthy wood. Chlorine is dangerous, environmentally unsound, and likely to cause damage to surrounding greenery. The corrosive effects of chlorine bleach on wood decks are cumulative and are more numerous than you might imagine. Not only does chlorine bleach break down wood fibers and alter the color of wood, it also corrodes metal fasteners – including the screws and nails holding your deck together. Bleach literally bleaches the wood, resulting in a lightening of wood’s natural coloration. This bleaching effect may provide initially pleasing results, but over a period of several months the wood begins to take on a lighter appearance. The natural pH of wood is just slightly acidic, and bleach is a basic solution. As a result, use of bleach on wood shifts the pH from wood’s natural, near neutral, pH to a basic pH which will damage the cellular structure. As a cleaner, bleach provides minimal results. The natural bleaching action creates the impression of a cleaner surface which, in reality, is only bleached but still needs cleaning. Cleaning with bleach does kill mold and mildew which may be on the deck, but does not eliminate the spores from which mold and mildew grow.

Safer more effective alternative to using bleach

Sodium Percarbonate (Oxygen Bleach) is an excellent detergent and bleaching agent based on hydrogen peroxide. It is a good cleaning and bleaching agent at normal temperature, and has strong fungicide effect. (Fruits and vegetables treated with sodium percarbonate can be kept fresh, and be stored for a long time. In medicine, it can kill staphy lococcus, and colon bacillus). This product is a white particle powder, non-toxic no contamination, non-flammable, non-explosive, easy to get damp, and soluble in water. It is efficient, safe and economical. It is environmentally safe, biodegradable, leaves no harmful by-products or residues which can harm the environment. Except for industrial-strength cleaning or stripping jobs, sodium percarbonate is, hands-down, the choice for most average wood preparation jobs. Your first line of attack is undiluted hydrogen peroxide which is an oxidizing agent (JUST LIKE CHLORINE BLEACH) and should kill the mildew on contact within several minutes. However, hydrogen peroxide is a far safer substitute. Its chemical formulation is H2O2. As the excess molecule of oxygen is released during the oxidizing process, H2O (water) remains as its residue. Oxalic or citralic acid (deck brightener) must be applied after the Sodium Percarbonate has been used in the cleaning process. The deck brightener will restore the wood to its natural pH and neutralize the Sodium Percarbonate cleaner. This will provide for a beautiful finish when applying the final stain.

You paid a lot of money for that deck, why not keep it looking healthy and new for as long as you own your home!

Ready to hire a contractor to re-finish your deck? Make sure you understand what you’re getting!

By | Tips

Beware of the ridiculously low priced specials you may find advertised. These deals are volume based meaning, the goal for that contractor is to get as many jobs scheduled and completed as quickly as possible to make up for those crazy low priced deals. They may also try to up-sell you other services to help offset that special low price.

To prevent unnecessary repairs, your deck should only be trusted to a professional wood cleaning contractor – a contractor that professionally cleans or strips your deck’s existing finish, uses cleaners that are safe around your plants and landscaping, properly neutralizes and brightens your deck, and applies a sealer that will be effective in preventing future deterioration. And most importantly, take the time it needs to ensure its done right!

Here are a few tips to keep in mind before having the work done:

Paints and solid color stains are generally not suitable for horizontal substrates subject to the weather, such as exposed deck and porches. The film-forming properties of these paints and coatings work against them in these situations. Penetrating semitransparent stains and water repellent finishes, on the other hand, do not generally peel or blister as they age. They fade and erode off the surfaces as they weather, making re-coating a much easier task. Wood is a dynamic substrate. Since these penetrating semi-transparent stains do not form discreet films, they are better able to move and breathe with the wood during the weathering cycles. One thing to remember, the goal of keeping your deck maintained is to ensure the re-finishing process does not cost you an arm and leg when its time to have it re-done. Solid stain or paints can not be stripped without professionally sanding the surfaces to remove the old coating. This absolutely has to be done before applying a new sealant. If not, the sealant or stain will not penetrate deep into the wood and will only sit on top of the surface having zero affect of protection and peel off within months. Not to mention trap the old mold and mildew under the original stain causing further damage. Stay with an oil-based semi-transparent or if need be a semi-solid stain. These are much easier to remove, look very nice and provide the best protection.

When used on decks, bleach-based products can do more harm the good. Not only are they ineffective in removing dirt, surface deposit, gray and UV-damaged fibers – they can leave the deck with a whitish’ unnatural tone due to the bleaching out of components in the wood. Treatment with hypochlorite-based products can also result in premature graying of the wood.

The most common unprofessional method by the low priced contractor is to blast high pressure 4 inches away from your woods surface using no cleaning solution in order to save money.  Do not allow this to happen! If this is the method they plan on using than you know right away to steer clear of that contractor.

After the cleaning process a neutralizer or wood brightener should be applied and rinsed. This will provide for a more professional looking finish when the stain is applied and bring the wood back to its natural PH balance. You will not get this process performed with the cheap deals because its an added cost in supplies and labor.

Finally, make sure you know and educate yourself on the best type of oil-based stains to use when sealing your deck. Stay away from the store bought water based stains you find at Home Depot or Lowes. If you absolutely had to use one, only use Olympic stains and sealers for semi-transparents & semi-solids. They are considered a hybrid oil & water combination.

Picture 1: This is what happens when a previous stain is not stripped/removed and a new seal applied over top. Mold and mildew are trapped under the original stain.

Picture 2: This shows both layers of stain removed prior to re-applying a new sealant by PlanetGreen PowerWash.

Another rule of thumb to remember is no stain will last longer than 3 years max. No matter what the can states. It may still look nice cosmetically but the truth is, mother nature has already taken over and has begun to wreck havoc on the surface. Have your deck re-sealed every 3 years if possible and never go past 4. Look for wood preservative sealers like TWP or Armstrong-Clark.