Composite

Mildew on composite decking?

February 13th, 2010 | by admin |

We built a deck (2 1/2 years ago) primarily out of "Choice Deck" composite decking (spindles are wood). Last year we noticed black mildew on the floor and pressure washed it w/a soap specifically for pressure washing decks, mildew, etc. This year, it looks real bad, with mildew spots all over the floor decking. we love having composite, but thougt it would fairly maintenence free, aside form regular cleaning. It gets full sun, so never has standing water on it.

What is the best way to clean it AND how can we prevent this from continuing to happen? I’m afraid bleach will ruin the color.
The retailer didn’t talk us into it. We have built wood decks before and chose composite this time because many of our friends and family memebers have had compostie decks for years and love them. None of them have this problem, or we would have reconsidered.

We don’t mind hard work and do maintain our home. That’s why we want it to look nice and CLEAN. I know decks need to be cleaned, we don’t mind doing that. I know that some mildewing is normal, but this mildewing is excessive, so we want to make sure we are cleaning it properly to avoid additional staining.

Honestly, it gets full sun all day from the back…there are no trees near our house.

Maybe we got a bad batch…

To help prevent mold and mildew, sweep the deck regularly to keep

gaps between planks free from debris.

• Keep your gutters clean. Overflow from a leaf-clogged gutter above a

deck is a potential source of food for mold and mildew growth.

• Keep the underdeck area well ventilated and free of materials that

retain moisture.

• Particularly for decks near ground level, a high-quality landscape fabric

should be placed under the deck and covered with washed stone or

pea gravel, to prevent weed growth.

• To help prevent cooking stains, we suggest that grills be placed on a

large mat to reduce the deck’s exposure to staining.

• Plants should be placed in large flower pots or planters and swept beneath

periodically to prevent mold or mildew from soil runoff and trapped moisture.

• When using any deck cleaner, household plastic or rubber gloves

are recommended. Be sure to follow the manufacturer’s instructions

regarding safety, proper use and disposal

General Stains and Cleaning Remedies

All exterior building materials require some degree of maintenance and

cleaning. Composite Decking and Railing is no exception.

Most stains are caused naturally or environmentally and do not constitute

a manufacturing defect. Just like wood, composite decking is not

impervious to grease, mud or stains resulting from normal use and

environmental conditions. The best preventive maintenance for any deck

is to sweep it often. Power-washing is also effective in removing surface

blemishes. Sanding with a very fine grit sandpaper is also effective. For

general cleaning, we have found these products to be effective:

• Olympic® Deck Wash

• Thompson’s® Water SealTM Deck Wash

• Pittsburgh Paints® Ultra Deck Cleaner

If just a portion of the deck is cleaned, there may be a slight difference in

surface appearance between treated and untreated parts of the deck. This

difference will fade over time.

Tannin Stains

Extractive bleeding, also called “tannin staining,” may cause stains on

a deck surface. It frequently happens when objects such as wrought iron

furniture, flowerpots, grills and other items are placed directly on the deck

surface. These stains may also be the result of becoming wet

during storage. Tannin stains occur with decking products made with

wood fibers. contains oak and/or maple, and certain woods,

including oak, contain natural tannins that will “bleed” for a short time

after installation. These stains are temporary and should disappear after

several rain and sun cycles and not reappear. Use the general cleaners

recommended above to remove the stains immediately.

Mold and Mildew

Mold and mildew are part of the environment. They form on virtually any

horizontal surface, and on virtually any material, such as wood, stone,

steel, brass, and composite

decking and railing products.

Mold and mildew will not

damage Composite

Decking and Railing.

Maintaining proper gap

widths, seeing that gaps are

not clogged, and regular

cleaning of the

deck should inhibit the

growth of mold and mildew.

Removing Mold and Mildew

from your Deck

Regular cleaning of Boardwalk Composite Lumber will remove most

mold and mildew growth. The general cleaners recommended below

are effective in removing mold and mildew:

• Olympic® Deck Wash

• Thompson’s® Water Seal Deck Wash

• Pittsburgh Paints® Ultra Deck Cleaner

First, sweep the deck thoroughly, cleaning out any clogged gaps between

planks. Be sure to follow all manufacturer’s instructions regarding safety,

proper use and disposal. For best results, apply cleaner to dry deck with a

broom. Wait 10 to 15 minutes and then rinse with a garden hose or powerwasher

set to low pressure. Should an additional cleaning be necessary, let

the deck dry completely and repeat these steps. The following prepared

solution is also effective:

- 1/3 cup laundry detergent (e.g. Tide®)

- 2/3 cup trisodium phosphate (e.g. TSP or Soilax®)

- 1 quart 5% sodium hypochlorite

(e.g. Clorox® or other liquid chlorine laundry bleach)

- 3 quarts water

Use of household plastic or rubber gloves with any deck cleaner is

recommended. As with other commercial cleaners, be sure to take

precautions to protect plants, surroundings, clothing and exposed skin.

CAUTION: Greater concentration may cause discoloration. Do not mix

other cleaners with the deck wash solution Good Luck !