How to Paint Your House's Exterior
Although siding is certainly the largest area to paint of you're painting your house, the work goes surprisingly fast, even if you're using a brush. And with a sprayer, you move so fast that you have to be careful not to bump into yourself! This is your reward for doing such a good prep job.
Consider a few tips for painting wood siding:
New or untreated wood siding: Coat new wood siding as soon after installation as possible. Untreated wood requires a primer and two topcoats if painting, or two coats of stain. Previously untreated or bare redwood and cedar may bleed tannin through a paint finish unless you seal the surface with an alkyd primer-sealer (preferably two coats) before applying a 100-percent latex topcoat.
Rough lumber: Airless spraying works best for painting or staining rough surfaces, but be sure to brush the finish as you apply it. Backbrushing, as this technique is called, gets paint into areas that the roller or sprayer misses and works the finish into the surface. Brushing also results in a more uniformly stained surface and gives you the chance to brush out drips and runs.
New, smooth wood: Some new siding that's installed with the smooth side out doesn't accept stain well and sometimes is even too shiny for paint or solid-color stain, which is like thin paint. If you plan to use stain, you can have professionals install the wood siding with the rough side out. The smooth, sometimes shiny, planed surface (called mill glaze) doesn't provide enough "tooth" for paint or solid-color stain to grab onto. Sand off the mill glaze with 100-grit paper and then stain or paint. If you plan to use a penetrating stain, you can let the siding weather for six months to a year and save yourself the sanding work.
Of course home exteriors aren't all wood. Here are some other surface considerations:
Painting hardboard siding: You can topcoat previously painted hardboard siding if the finish is clean and in excellent condition. The American Hardboard Association recommends using an alkyd primer if you're painting over the original factory finish or if you're unable to determine when the existing finish was applied. After cleaning and making any repairs, use an alkyd primer to spot-prime any areas where you removed the existing finish.
Painting aluminum siding: People usually think of aluminum siding as maintenance-free, but the finish eventually fades and ages. If you're happy with the color but the finish looks dull, try cleaning the siding with a wood-cleaning product designed to renew wood decks. Another approach that works wonders is to apply a coat of Penetrol, a paint conditioner. Buy a pint and test it in an inconspicuous spot. Often, it will renew the luster so that you don't need to repaint. If Penetrol does the trick, apply it with a sponge or paint pad over the entire surface. If you decide to paint after all, Penetrol provides an excellent base.
If you've made repairs that expose bare metal, you must spot-prime those areas with a primer formulated for aluminum or galvanized metal.
Painting brick, stucco, and concrete: Generally speaking, you can paint brick, stucco, concrete, or concrete block with exterior latex paint after you clean the surface to remove accumulated grime. Use a finish with a satin sheen to make cleaning easier the next time.
Think twice before you tamper with unpainted brick, because removing paint from brick is nearly impossible. Instead, use a water-repellent sealer or stain, both of which offer some weather protection but don't peel.
Ask a paint dealer or stucco contractor about painting stucco in your area. Typically, you can paint stucco with an acrylic latex product. You need to seal some masonry, especially highly alkaline surfaces such as stucco, with an alkali-resistant masonry primer. Moisture from the ground and from the house's interior rises to the exposed portion of the foundation and escapes harmlessly when the foundation is unpainted. If you paint it, make sure that you use a water-based product that allows moisture vapor to pass through. Use a sprayer, long-nap roller, or rough-surface painting pad/brush to paint a masonry surface.