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Best Practices:
What Lurks Above—
Tips for Finishing Ceilings

Wednesday, January 22, 2014

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Back in the day, ceilings were often finished with spray textured surfaces consisting of polymeric binders or modified plaster and aggregate that created a “spatter” effect. This helped hide flaws in the finish that otherwise might be quite visible to the onlooker.

But nowadays, especially in medium- to high-end construction, many owners and architects prefer a flat, smooth drywall ceiling surface.

Drywall ceiling
Photos unless indicated: MPI

The finish may look fine when viewed straight up, but an angled view under work lights may tell a different tale.

We’ve discussed the challenges of obtaining a satisfactory finish with new drywall. They include seams or repairs telegraphing through a three-coat paint system because the filler in the joints is smoother than the surrounding paper texture.

But we find ceilings to be bigger offenders than walls.

If you look straight up at a ceiling, you may not see a defect directly above you. But any area viewed at an angle will show all the tiny shadows from the variations in texture. And the lower the ceiling, the bigger the problem, because the angle is more acute.

Let There Be Light (Or Maybe Not)

Critical lighting conditions caused by natural light from windows or ceiling-mounted fixtures can exacerbate the problem.

It is worth noting that some recessed lighting fixtures (pot lights, for example) can help reduce the visibility of ceiling texture variations.

At the opposite end of the scale (and much to the frustration of the paint inspector), the large halogen portable work lights that typically stand on the floor for new construction projects magnify every shadow from those variations.

An inspector viewing an ASTM Level 4 drywall finish ceiling over these lights is likely to cringe when viewing the finish—which is why the final inspection must occur only after the permanent lighting is in place.

Drywall ceiling with recessed geometrical ornament Decorative drywall ceiling
drywallceilingideas.com

Drywall ceilings offer a variety of design ideas, but there are challenges to achieving an optimal finish.

Industry standards and MPI generally advocate specifying an ASTM Level 5 drywall finish to help assure a satisfactory paint job for a ceiling or wall, especially in critical lighting conditions or when using non-flat finishes.

But there are no guarantees: Many drywall finishers lack the skill or experience to properly apply a Level 5 finish, and most projects don’t budget for the increased expense of Level 5.

The Case of the Mall Ceiling

The paint inspector was called to a very large new mall project with massive 16-foot drywall ceilings.

The painting contractor had applied the sealer and first finish coat. Much to the inspector’s dismay, the ceiling looked awful.

Shadows from the texture variations were magnified by the big halogen lights below, and the seams from each 4x8 sheet of drywall were clearly telegraphing through. No doubt the problem would be exacerbated over the food court area, where glass entranceways brought in substantial natural light.

An ASTM Level 5 drywall finish would have helped solve the problem. But as the GC explained to the inspector, the spec called only for Level 4. What to do?

The inspector has seen too many poorly painted ceilings—not because the painter did a bad job, but because even a flat finish applied perfectly can’t hide ceiling drywall surface flaws.

Fortunately for this project, the ceiling drywall finishing work improved as the job progressed down the aisles and to the food court, to create wider, smoother seams over the joints.

Drywall Ceiling

A painted ceiling lit by work lights shows drywall seams telegraphing through the finish.

When the finish coats were applied and the ceiling was viewed with the recessed pot light fixtures installed, the finish was deemed acceptable.


Getting Better Results

Here are some tips for optimizing your results with drywall ceiling finishes.

  • Consider a specification that requires an ASTM Level 5 drywall finish.
  • Even if the initial finish was sprayed, the spec should require backrolling the ceiling finish. The roller's stipple pattern may help hide the underlying texture variations. A ½ inch/15 mm nap roller may offer the best and most efficient results.
  • Very large ceilings are finished in phases, so it's best to get all the paint from a single batch, as is generally advocated for wall coating work.
  • The spec should also require the painter to “blend back” the finish of each new section by shading the new topcoat back over the previous section with a spray gun. With a flat finish, this can effectively prevent a noticeable difference between sections finished at different dates and/or with material from different batches.

And What if You Had to Live with It?

The paint inspector then turned to a project with equally large repercussions: the expansive new drywall ceiling in the remodeled main floor of his own home sweet home.

After seeing enough ceilings with seams telegraphing through, he considered applying an ASTM Level 5 finish. The drawback? The inspector is a pretty accomplished painter, but when it comes to finishing drywall, he’s a bit slow.

What to do?

ASTM’s Level 5 Drywall finish standard states that “a thin skim coat of joint compound shall be trowel-applied to the entire surface… . As an alternate to a skim coat, a material manufactured especially for this purpose shall be applied.”

But the inspector has not been impressed with the “alternate” spray-on skim coat products he’s seen. They lack adhesion to the drywall; they tend to develop air bubbles when sprayed; and they tend to fall off or crumble when sanded.

So he was mighty skeptical when a local paint store offered him a product he’d not seen before: a fast-drying,sandable, high-solids latex basecoat designed specifically to minimize the surface differences between wallboard facepaper and joint compound.

Drywall Ceiling

Sprayable high-solids latex basecoat over an ASTM Level 4 drywall finish helps achieve a smooth painted ceiling finish.

The inspector decided to test it on a wall section. He mixed and strained the material and, even though it was quite heavy in weight and viscosity, he didn’t want to thin it. The inspector wondered if he’d get a good spray pattern using his Graco 395 airless rig with a 517 tip—not a particularly big machine.

He pulled the manifold and gun filter to allow for better flow of the material and was pleased to find the tip did not plug even once while spraying.

Now I'm a Believer

The resulting wall finish was as advertised: The paper texture was filled, the surface was quite smooth, and the basecoat had excellent adhesion.

Encouraged by the test patch, the inspector sprayed out four gallons of material for his 1,100-square-foot ceiling. After it dried, he scuff-sanded the surface with 120 grit paper on a pole sander.

That's when he learned a valuable lesson: Since the material was quite hard, heavy sanding was difficult, and the best results were obtained where the product was applied in a smooth, consistent pattern.

He then sprayed one coat of a drywall sealer approved under MPI #50 and two coats of a product approved under MPI #53 interior latex, and following the tips above, he back rolled both the sealer as well as the finish coats.

The result? A very smooth, flat ceiling that—even with critical side lighting—showed no sign of underlying paper texture or seams. And because he had backrolled the finish coat, touch-ups were easily done with a small short-pile roller with closely matching nap.

The combination of the high-solids latex basecoat and flat latex finish produced one of the best drywall ceiling finishes the inspector had ever seen.

Which led him to conclude thus: Given the right products and tools, a smooth, flat finish can be attained by painters over a Level 4 drywall finish.

Editor's Note: This article was written by PQA Inspector Dave Lick and is reprinted with permission from the MPI (Master Painters Institute) newsletter. MPI content describes best practices for commercial, institutional, and light industrial painting.

   

Tagged categories: Ceilings; Coating failure; Coating inspection; Drywall; Master Painters Institute (MPI); Paint defects; Painting Contractors

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