Painting Latex On Wet Siding: A Viable Option?

Painting the exterior of a building is a great way to refresh its look, but there are many factors to consider, such as weather conditions, paint type, and surface preparation. One common question is whether you can paint latex paint on wet house cement siding. The answer is no – rainy days and wet surfaces pose problems for painting as the paint won't be absorbed and will wash away. Before painting, surfaces must be cleaned and dried, and a primer is recommended for the best results. Latex paint is a good choice for indoor concrete but not high-traffic areas, and it takes a few hours to dry. For outdoor concrete, an epoxy paint finish is more durable and can withstand harsh elements.

Preparing the surface of the siding

Clean the Surface:

Start by thoroughly cleaning the siding to remove any dirt, dust, pollen, or mildew. You can use a power washer or a garden hose with gentle water pressure. If there is stubborn dirt or mildew, use a mild cleaning solution, such as a mixture of bleach and water, and apply it with a pump sprayer before rinsing. Ensure that you clean from the top down, following the grain of the siding. Once you're done cleaning, allow the siding to dry completely before moving on to the next step.

Scrape Off Flaking Paint:

Use a wire brush or a putty knife to lightly scrape away any loose or flaking paint. This step ensures that you create a smooth base for the new paint to adhere to. Be gentle to avoid damaging the siding.

Sand the Surface:

After scraping, use medium-grit sandpaper or sanding pads to lightly sand the scraped areas. Sanding will help create a "key" for the paint to adhere to and smooth out any edges left by scraping. Be sure to wear a NIOSH-approved dust mask to protect yourself from dust and debris. After sanding, wipe down the surface with a damp rag to remove any remaining dust or debris.

Repair and Prime:

Inspect the siding for any cracks, splits, or holes, and repair them using a cementitious patching compound. Allow the compound to dry completely. Also, look for any exposed nail heads and use a rust reformer to remove rust before counter-sinking and spot priming. Once the repairs are dry, apply a primer designed for cement surfaces. The primer will help the paint adhere better and add a protective layer. If there are areas of bare siding exposed, be sure to prime those as well. Depending on the colour change, you may need to prime the entire surface.

By following these steps, you will ensure that your siding is properly prepared for painting. A well-prepared surface will not only enhance the final appearance but also improve the durability of the paint job.

The best type of paint to use

Painting the exterior of a building is a great way to give your home a new look and express your personality, style, and taste. However, the type of paint you use will have a long-term impact on the durability of your paint job.

For fiber cement siding, the best type of paint to use is 100% acrylic paint or acrylic latex paint. These paints are breathable, allowing moisture to escape and helping to prevent peeling and blistering. They also adhere well to most surfaces, are flexible, and offer superior durability, flexibility, and colour retention.

When it comes to specific brands, Sherwin-Williams, Benjamin Moore, and Dunn-Edwards sell acrylic paint that is compatible with cement board siding and can be found at most local home improvement stores.

If you are using latex paint, you will need a minimum of two hours of direct sunlight before any rain comes. The paint may feel dry to the touch after an hour, but it will still wash away. For optimal durability, five days of normal weather is ideal.

If you are painting over a previously painted surface, it is best to stick with the same type of paint for compatibility and adhesion.

In terms of preparation, it is important to clean the surface thoroughly, repair any damage, and prime when necessary. Paint adheres best to clean, dry surfaces, so be sure to let the surface dry completely before painting.

How long to wait before painting

Painting the exterior of a building is heavily dependent on the weather conditions. Temperature changes and moisture can alter the outcome of your paint job. It is crucial to avoid rainy days as the rain will wash wet paint off the surface, and paint won't be absorbed into a wet surface.

If you are using latex paint, you need a minimum of two hours of direct sunlight before the rain comes. Paint may feel dry to the touch after an hour but it will still wash away. After two hours, light rain will not completely ruin your work but you may still have to repaint some of it when it is dry.

For the paint to dry completely, it takes six hours of sunlight. However, if you want it to be its most durable, five days of normal weather is ideal.

The time you have to wait before painting also depends on the surface you plan to paint. If the surface is dry to the touch, you can generally use acrylic paint because it will allow any remaining moisture to evaporate through the coating. However, you must have a perfectly dry surface to use oil paint. You will probably have to wait for a few dry days before painting with this type of paint.

If you are painting cedar siding, it is recommended to wait at least 60 days but no longer than that, as the top surface of the wood will start to turn colour and flake off.

Before painting cement siding, you must wash the siding and let it dry completely. Then, apply a primer made for cement and let it dry.

The time it takes for the cement siding to dry will depend on the weather conditions.

The number of coats needed

Painting cement siding is a great way to give your home a new look. However, the process requires careful preparation and the right choice of paint to achieve the best results.

When it comes to the number of coats needed, the general rule is to apply two coats of paint for full coverage. Cement tends to absorb paint, so two coats ensure a rich and even finish. This is especially important if you are using a lighter colour paint over a darker one, as the base colour may bleed through with just one coat.

However, there are some exceptions to the two-coat rule. If you are simply repainting your siding with the same colour, one coat is usually sufficient. Additionally, if your siding is made of a smooth material, such as aluminium or vinyl, one coat may be enough.

On the other hand, if your siding is damaged or peeling, you will need to address the underlying issues and then apply two coats of paint for a long-lasting finish. Similarly, if you are painting over a dark colour with a lighter one, you may need up to four coats to prevent the base colour from showing through.

It is also worth noting that a primer can reduce the number of paint coats needed. A tinted primer can block the existing colour from showing through, and in some cases, a 2-in-1 primer-and-paint combination may be sufficient with just one coat.

For the best results, it is recommended to consult a professional painter, as they can guide you on the specific number of coats needed based on the condition of your siding and your desired finish.

Whether to hire a professional painter

Painting a house is not as extensive as plumbing or working with the foundation, but there are still several scenarios to consider before deciding to hire a professional painter.

Cost

One of the first things to consider is the cost. It is often assumed that painting yourself would be cheaper than hiring a professional, given that labour costs can account for almost 85% of the price of a paint job. However, when you consider the cost of buying all the necessary painting supplies (brushes, rollers, primer, paint cans, dishes, and possibly tools to repair the walls), the prices can quickly add up.

Size of the job

If you are painting the whole house, you should also consider the amount of time you'll spend labouring. If it's going to take up most of your free time, it may be worth hiring a professional. Painting the outside of a two- or three-story house also requires tall ladders and special equipment to reach high spots, which a professional will have.

Complexity of the job

If your walls are in need of repair or have intricate woodwork, a professional will be better equipped to handle the job. They can also more easily match colours if you are trying to replace old wood siding. If you are painting a room with wide baseboards, elaborate window casings, and cornice moulding, a professional can handle the brushwork with ease.

Time and patience

If you have the time and patience for a basic room paint job, you can save money by doing it yourself. However, painting an entire house will require significantly more effort and planning. Failure to plan the job properly can result in wasted money and time. A skilled painting contractor can complete the job much more efficiently and will know the best way to approach the job to minimise inconvenience to the occupants.

Previous experience

Take a look at painting projects you've tackled in the past. Are you happy with the results? If you want first-rate results that may be difficult and time-consuming to achieve by yourself, hire a good contractor.

Frequently asked questions