DIY How-To: Proper Surface Preparation Tips for Interior Painting


Some tips for preparing your walls, ceilings and woodwork for a professional do-it-yourself interior painting home improvement project. Walls and wood need to be prepared thoroughly and properly or your paint job is sure to fail sooner than you would like.

interior painting surface preparation of walls and wood

Spackling, wall repair: surface preparation for interior painting.

Perhaps one of the most popular DIY projects is interior painting. It seems simple enough, right? And in a struggling economy, paying a professional to do something you can “easily” do yourself just doesn’t seem like a smart move. Well, it may be do-able, but it’s not as “easy” as you might think: there are big mistakes that are easily made that have devastating and costly results. You can’t just slap some paint on those walls and ceilings – you need to execute thorough preparatory work first. This article will cover just a few important steps you can take to ensure that your DIY job ends up looking and lasting like it was executed by a professional… almost.

Cleaning Dirty Surfaces

The average surfaces in any room – particularly kitchens and baths – are very dirty: grease, mold, mildew, and other contaminants will ultimately cause even the most premium paint to fail (lift, crack, peel, “gator-skin”, etc.). So those surfaces need to be cleaned. Mold and mildew must be cleaned with bleach, rinsed and allowed to dry. If that doesn’t suffice, a high quality oil-primer should be applied. Sanding helps remove many contaminants also, and will help give the existing paint some “tooth” to improve the adhesion of the new paint. However you do it, thorough cleaning is crucial to preparing for a quality paint job.

Repairing Damaged Walls

Got cracks? Holes? Popped drywall nails? You probably want to fix those before you paint. In most cases, application of a medium- to lightweight joint compound will suffice. Just lightly hammer in those popped nails, sand out the holes and cracks, dust them off and fill with compound. It sounds simple, but it really is sort of an art. You can try applying the compound a little heavier than necessary and then, once it sets and is dry, sand it down to a smooth finish.
          ^ If you’re in a rush, try setting-type joint-compound that comes in powder form. It dries in as little as 20 minutes due to a chemical reaction once you mix the powder with water. It has a short workability time-frame – because it dries so quickly – so it should really be reserved for professionals, but you can always give it a shot!

To Prime or Not to Prime

That really is the question. If you’re painting over removed wallpaper you absolutely MUST use an oil primer, no matter how thoroughly you removed the glue it will have absorbed into the pores of the substrate and it needs to be blocked or the paint will certainly fail. Zinsser’s problem-surface product called Gardz is good for this also, as it applies an impermeable seal but since it is a clear product it won’t help with a color change, and we like to use a white oil primer on top of the Gardz to ensure the wallpaper glue is removed from the equation completely. You will also need to apply a primer if you’re using a latex- or water-based topcoat over oil paint, because the topcoat won’t adhere otherwise. Additionally, a tinted primer is effective if you’re making a drastic color change. Paint-and-primer-in-one products are becoming increasingly popular. Benjamin Moore’s Regal Select line of paints is a good product for the money, and Sherwin Williams offers some excellent products in this category also. You should always spot-prime spackled areas with a latex primer to prevent “flashing” (being able to see the spackled areas even after 2 coats of paint).

Sand Everything Thoroughly

Sand before you clean, after you clean, after you spackle. Sand before coats and between coats of both primer and paint. This not only helps smooth the surface, but it applies “tooth” to the primer/paint to allow for improved adhesion. Use a fine-grit (220) sandpaper and sand, sand, sand. Except for the final topcoat. Obviously don’t sand that.

Caulk and Putty

Gaps in trim and molding need to be caulked or you’ll certainly notice it when you observe the finished product. We recommend DAP brand ‘Alex Plus’ latex caulk with silicone. Easy to work with and guaranteed for decades, it comes in many colors to help with paint coverage. Sherwin Williams also offers some excellent caulking products. Cut the nozzle at a 45 degree angle to the desired width and apply a bead of caulk where the trim/molding/casing meets the wall. Even if there is no gap – it will prevent gaps in the future. Even if there is such a small gap that the wet paint fills it – apply the caulk beforehand. When the paint dries it will shrink, and that annoying gap will be back. Also, fresh-milled lumber usually has some moisture content and as it dries it will pull away from the walls. If you have installed new trim, apply the caulk liberally (though it still may require a round #2 in a few weeks). Once your bead of caulk is applied, simply run your finger along it to smooth it out and push it into the gap. Remember: caulk is not sandable, so be neat and make sure the only caulk left is cleanly placed inside the gap. Wait for it to dry before you paint or prime or your brush is sure to ruin your smoothed caulk bead. Finally, apply putty (DAP brand Painter’s Putty or their window glazing compound “33”, or Sherwin Williams’ “66” glazing compound all work great) to nail holes and smooth it out with your finger. The putty will need to be primed depending on the product you choose, according to the label – but we have found that this is not always the case.

Our Humble Opinion on Paint Quality: Use Sherwin Williams or Benjamin Moore paints. Department store paints just don’t provide the quality of these two brands. Someone once said “nothing is more expensive than cheap paint”, meaning if you use discount paint you’ll just have to do the job over again sooner than you’d like when that lower quality paint begins to fail. Spending the extra few dollars per gallon is worth it. That’s why you don’t see a lot of respectable professional painting contractors getting their paint from big-box home department stores.


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