Q: In an article on restoring a Victorian, you mentioned exterior painting using three coats: a coat of primer, a second coat of one-half primer and one-half coat of finish paint, and a final coat of finish paint. Is this your suggestion for all exterior painting?
A: Yes, especially on older wood homes. We also recommend the three-coat approach when painting trouble spots — such as windowsills — that are subject to the ravages of sun, wind and rain.
Wood siding on Victorian houses in the San Francisco Bay Area is usually clear heart redwood. A century ago, when the siding was applied, building paper and insulation were unknown. As a result, the wood dried from both sides. Even if the house was painted regularly, today the siding is as dry as a bone. A paint job on this type of house has to be done right to get the longest possible life from the new paint. It’s time consuming if you do it yourself or very expensive if done by a professional.
From time to time we’ve described the painting process in varying levels of detail. Now it’s time to go through it step by step. The painting process can be broken down into three basic steps: preparation, priming (including caulking and filling voids) and finish painting.
A paint job is only as good as the preparation. Prep is a boring process, but if you invest the time and effort, a good prep job will pay lasting dividends. Usually, the first step is to clean the surface to be painted by pressure washing. However, sometimes an older home’s buildup of multiple layers of paint requires stripping the paint to the bare wood. If this is the case, use a propane torch or electric heat gun to strip the old paint before pressure washing.
If you use a propane torch, also use extreme caution. Dry wood and open flame do not get along well. Kevin spent a month or so burning the paint off one side of his Alameda Victorian. Good thing he did, too; the paint lasted at least 10 years before the new owners needed to repaint.
Let the building dry out a full week after pressure washing to ensure that any excess water evaporates. The next step is to use a disc or belt sander to feather the edges of the remaining paint. This way the transition from paint to bare wood is less noticeable. Be certain to dust away any residue after sanding.
Now it’s time to paint. To spray or not to spray? An airless sprayer gets the material on quickly but is susceptible to leaving thin spots and to overspray. There’s nothing quite as tacky as overspray on a roof. But brushes and rollers are slow. We’ve always compromised. We use the sprayer to get the material on the siding, then back brush or roll to ensure an even coat. This method works for all three coats of paint.
Whatever application method you choose, the next step is to apply the primer coat. Use a high-quality primer. We’ve always used an oil-based primer for exterior work. We recommend that you purchase the paint at a paint store rather than at one of the big box stores. Salespeople at paint stores cater to the trade and generally are very knowledgeable and ready with helpful tips. Ask about adding extra linseed oil to the primer to replace some of the moisture lost in the wood over the years. Also ask them to tint the primer toward the finish color for a finish that fully hides the undercoats.
Allow the primer to dry thoroughly. Then caulk and fill all voids in the building. This is critical. The better the caulking, the less chance of moisture penetration and of the paint failing. Joints should be caulked using an acrylic latex caulk. Nail holes and small divots in the siding should be filled with a good-quality exterior Spackle. For more extensive repairs, Bondo works well.
The split coat is next. Back in the day, when all paint was oil-based, painters mixed equal parts primer and finish material to get the “split” coat. Today, if the primer and the finish are compatible (oil and oil or water and water), this is the way to go. If not, apply a second coat of primer and have the paint store tint it a shade lighter than the finish coat.
The primary purposes of the split coat are to add an extra coat of protection and to eliminate “holidays” visible in the final coat. Depending on the color, even a full finish coat can show impressions through a white primer. After the split coat dries, inspect the job for any defects. Now is the time to fix them. Perhaps a little more caulk is required or a nail hole needs to be touched up.
Finally, apply a full finish coat. Follow these steps and you should have a handsome and long-lasting paint job.