Opaque stain vs paint on your deck: how to choose?

So your deck is old and doesn’t look so good. Should you use opaque (or solid color stain) or paint? How do they cope comparatively with sunlight, moisture, foot wear, cost and wear mode? Click on to find out.

Look out for Deck Destroyers: Guarding against pests and rot on your deck

Look out for “Deck Destroyers”


The two principal deck destroyers are surface damage (like mold) and deep damage (like rot and pests). Let’s look at them in turn:


Dealing with Surface Mold

There are four types of mold under the deck to look out for:

1. Black mold. This is mildew and can be seen as lots of black spots. It is fairly normal to see this.  Sometimes, if the deck is very wet, the whole bottom of the deck boards is black. A spray of dilute bleach under the deck is a simple treatment to keep this under control.

2. White mold. This is a fungus called Mycelium and it is a sign that the deck is wet and staying wet. Often you see this where water “stands” where deck boards meet the joists. This indicates that a problem will appear in the next ten years. If you can reach it, it is best to pressure wash off the fungus and then kill it with dilute bleach.

3. Green mold. This is the worst rot and needs immediate attention. Usually it is a thin film of green mold, but it can get far worse within a few years. I have seen a deck covered in thick green mold under and on the deck; you could barely walk on it without your feet going through. Best to pressure wash off the green mold and apply chemicals to stop it coming back.


Dealing with Deep Rot and Pests

There are four types of deck board damage to look out for:

1. Dry rot. You will be familiar with this. This is rotting, usually first seen at the ends of deck boards as a softness and brown discoloration, often dampness. Replace the board when the end starts to get springy. Or you can use Copper Green chemical (very toxic, respirator needed).

2. Brown rot. This is quite rare, and is a cubic break-up of the wood. Treat with chemicals or replace the board.

3. Termites. When wood gets damp (such as, when the stain no longer keeps the water from entering the wood), termites can burrow into it. They tend to enter at the ends of boards and munch their way down the grain, then they find another board. Many people think they are like piranha but they are not that fast. Every house has termites; you just don’t realize it. There are different types of termites. Some fly around and then drop their wings and enter the wood. Others can make their own “ladder” and climb vertically upwards towards your deck! Look out for discarded wings, small brown wood particles pushed out of holes in the wood, or distinctive fungus-like vertical tubes under your deck. Treat with “Orange Oil”, tent the deck and house with chemicals for 3 days, or have a pest-destroyer come along with their microwave wand.

4. Beetles. Fairly rare, they leave a single pinprick entry point about 1/32 inch in diameter. Easy to miss. Usually not that destructive. Apply killing chemicals to entry point.


You can find more information and pictures in our handy pdf called “Deck Destroyers” from our website.

Keep It Tight: Fixing Lifting Boards and Wobbly Handrails on your Deck

Keep It Tight


Decks dry out if not looked after and joints start to fail. This can affect safety and I suggest you keep a “weather eye” out for this.


Brace handrails when they become wobbly.

In the old days, handrails were bolted into the fascia below the deck level and in turn the fascia was connected to the deck joists via a few nails banged into their end-grain. Over the years, with all that leverage between the top of the handrail and the bottom where the nails are, the handrails can get a bit wobbly. If it worries you (and if you have a long drop!) then consider bracing handrails in the middle of a long span. (Corners are often much more rigid). We use blocks where the handrail post is bolted into the joist at 90˚ using an intermediate wood block. Or we bolt an extension to the handrail and then use a diagonal brace which connects the bottom of the handrail post to the joist. If the deck is far above the ground and the ground below is slopey, however, it can be very difficult to use this sort of brace, so a diagonal brace through the deck from above has to be used. There are some pictures of these solutions on our website (look under “deck carpentry.”)


Corners of handrails can be a bit “dodgy”. A 90˚ angle brace lag-bolted into both handrail caps on the corner usually makes everything a lot safer.


Insert screws where nails pop up.

If you have boards that are lifting, i.e. the ends are warping upwards, or you have nails that are popping out, then a solution is to bang down the nails and insert a screw between them. Some people have tried to remove nails using a claw hammer and then put a screw down the hole. But the hole has often been widened by the rot and the screw barely holds. Some try banging down the nails, but they always come back out within a month – the reason is that walking on the boards gently pushes the nails back up again as they have lost their friction. The answer is to put a screw between two nails. It makes a new hole so avoids the issue of existing rot. And it holds the boards down so the nails don’t come out. If you are screwing at the end of a board, either pre-drill the hole for every screw (to avoid cracking), or angle the screw and put the screw in an extra half inch from the end. You may need to use a longer screw to get through to some good wood. We recommend powder-coated screws, rather than the usual zinc-plated screws. The former last a lot longer and don’t rust, though they do cost three times the price. Well worth it.


We find it is usually enough to put screws into every board-end and every other joist  – no need for every joist. If your deck is old, you might want to buy a box of 1,000 screws and allocate two afternoons to the job. Oh, and don’t forget to charge up a few cordless batteries before you start (you will need a new one every 20 minutes), and use knee-pads.


Keeping Mold on a Deck Under Control

Keep Mold Under Control


Mold is the harbinger of much more serous damage. It’s best to keep an eye on it. Here are two things you can do.


Spring and Fall scrub.

During the winter, fungus and moss can grow in wet dark corners under trees and in the shade of your house. Sometimes these areas never dry out and they can get slippery. The answer is to put some dilute bleach/deck cleaner onto the deck. I recommend first wetting the deck with a pressure washer or garden hose, then gently applying deck cleaner liquid through a pressure washer on its lower pressure setting and scrubbing it in. Or pour bleach into a 5 gallon bucket and fill up with water then brush on.  I advise against a more concentrated mix than 10%. You want to be careful not to let droplets of concentrated bleach fall on your deck – you will get distinct spots of discoloration.


Scrape between boards before the rains.

Deck boards should be spaced at 3/16” or ¼” spacing when they are new, to allow tree debris to fall through. Contractors in the old days didn’t do this (they prided themselves on tight boards) and many decks today are suffering because of it. What happens in the winter is that the wood swells as it gets wet. Amazingly a 5.5” wide board (the actual size of a standard “2 by 6”) will swell 1/8” each side. If there isn’t a ¼” space then you will gradually get warping and lifting boards. Especially if there is debris stuck in the gap. The answer is to keep those gaps empty before the rains come. The best way we have found to do this, is to use a paint scraper, a hooked handled device you can buy at Home Depot or Ace Hardware. You gently drag it along the gaps and you can pull out the debris, and then blow it off the deck. To avoid hurting your back, most people tape the handle to a broomstick and stand up while using it. I have heard people using a Skilsaw to clear the gap or widen it but this leads to big problems at the end of the cut when you can’t get the saw in, and it is easy to wander off track a bit and end up with very uneven edges.