Preparing your home for exterior painting

Preparing the exterior of your home for a new coat of paint will save you time and money. Many people skip this step because they mistakenly think a new coat of paint will seal and cover the imperfections of the old paint. In fact, without proper paint preparation, new paint can make the situation worse. Bubbles and cracks will appear in your new coat of paint due to loose paint layers, dirt, and chemical reactions. Avoid these and other problems by following these simple paint preparation steps.
Look at your siding.

Before you slap on a new layer of paint, look to see if the previous layer of paint had any problems. If there are spots that bubbled, look to see if water damage was the cause. If paint has cracked, determine if the wood underneath has been damaged by dry rot or insects. This is also the time to decide if you need to replace any siding or trim. Be sure to solve any underlying problems now to ensure your new coat of paint will last for years.
Give your house a bath.
Dirt and chalky layers of old paint will prevent your new paint from adhering to the exterior surface of your home. Dirt can be a particular problem under the eaves where it has avoided being washed away by the rain. You can remove the grim by washing your home down with a solution of TSP or mild detergent. Using a mop or pressure washer will speed the cleaning process. If you choose to use a pressure washer, be careful with the level of pressure you are using. Too much pressure can result in gouges in your home's siding. Also, take care when washing around vent openings and window seals; you do not want water leaking into your house. Give your home a final rinse and allow all surfaces to dry completely. If you paint on a damp surface, expect it will peal in the near future.
Remove loose paint.

After your siding is dry, you will need to remove all loose paint so the new paint will have a surface it can bond to. Even if you have used a pressure washer, there will be bits of loose paint that still need to be removed. There are several methods to remove paint. One method is to use a metal scraper for large areas and a wire brush for small nooks and crannies. Another method is to use a heat gun which blisters paint up that can then be easily scraped off. The advantage to this method is that you do not have toxic paint dust flying around. With either of these methods, you will need to do a final sanding to smooth the surface and give some tooth to the old paint layer. A third option is to use chemical strippers. This type of method was used on the White House to preserve the original wood as much as possible. Be aware that this method can be toxic, and you must follow the manufacture's directions carefully.

Caulk any gaps.

Avoid water damage to your home by caulking gaps in your siding. Caulk areas where two dissimilar materials meet, such as, around your foundation, chimney, and doorways. Also, caulk the gaps between your trim and siding. You will also want to cover nails holes with caulking to prevent rust. Choose a caulking that can be painted, so avoid silicone-based products.

Prime all surfaces.

The final step in your paint preparation process is to prime all surfaces to ensure they will not ruin your new coat of paint. Some old paints can have a chemical reaction with the new paint, and will bubble and crack the new layer. When you choose a primer, pick one that is compatible with your final paint choice. Some latex and oil-based paint products have a problem bonding together, so be sure to check the labels. Also, remember to have your primer tinted to the color of your final paint layer. This will save you having to paint an extra coat.