Ontario's Plain-English Guide to Custom Home Buildingπ 705-533-1633 | βοΈ 1-866-868-6606 | βοΈ info@icfhome.ca
Visible Drywall Seams After Painting: Photographing, Flashing, Ridging and Banding, What Each Looks Like, Who Caused It and What Fixes It
Drywall, Taping & Painting
The Seams Show After Painting: Five Different Problems That Look the Same From the Doorway, and Which Trade Owns Each One
The walls looked perfect the day the taper left. Then the painter finished and every joint in the great room is a 12-in. stripe you can see from the kitchen. Both trades are standing in the room pointing at each other. This happens on good jobs, and it happens for five different reasons that need five different fixes, and only two of them are the taper’s fault. Here is how to tell them apart with a flashlight, and what to do about each.
The five problems
| What you see | Name | Cause | Whose | Fix |
|---|---|---|---|---|
| Joints look duller or shinier than the wall between them, visible at an angle, not head on. Surface is flat to the touch. | Flashing | Compound and paper absorb paint differently. No primer, a bad primer, or paint-and-primer-in-one over new drywall. | Painter, usually. Taper if the surface was oversanded and the paper fuzzed. | One coat of proper drywall primer over the whole wall, then repaint. If the paint has sheen, a high-build primer or a skim coat. |
| Joints show as a change in texture: smoother or rougher than the field of the sheet. Visible in raking light. | Photographing | Sanded compound is smoother than board paper; the paint shows the difference, worse with sheen. | Nobody’s, exactly. It is what Level 4 does under critical light. | Level 5 skim coat, or a high-build surfacer. Or flat paint. |
| A raised line down the centre of the joint you can feel with a hand. | Ridging | Board edges pushed together under stress, framing shrinkage, or tape coated too thick and too fast in a cold house. | Taper, or the house. Common in the first winter. | Sand the ridge, feather a wide coat over it, prime, paint. Wait until the house has had a heating season. |
| A hump at a joint, 18 to 24 in. wide, you can see from across the room with a light on it. | Bad butt joint | Butt joints have no tapered edge; the taper has to float a hump 2 ft wide to hide it. Done with a 6-in. knife it is a 6-in. hump. | Taper. Or the hanger, for creating butt joints where 12-ft board would have had none. | Wider feathering, two more coats, sand, prime, paint. Sometimes a skim coat over the wall. |
| Under pot lights or along a window wall, every joint shows as a band of light and shade. | Banding | Raking light on a Level 4 surface. Any of the above, made visible. | Design. Level 4 under pot lights is the wrong specification. | Level 5. There is no paint that fixes raking light. |
The flashlight test
Take a bright flashlight or a work light and hold it flat against the wall, pointing along the surface, in a dark room. Everything shows: ridges, humps, sanding scratches, bubbles, screw dimples. Now look at the same wall from across the room with the room lights on. If the defects you found with the light are invisible from across the room under the lighting the room will actually have, the wall is acceptable at Level 4, and the standard says so: finish levels are judged under the intended lighting, not under a torch held against the surface. If you can see them from across the room, they are defects.
The second half of the test is sheen. Look at the joints at an angle with a window behind you. If the joints are flat to the touch but look duller or shinier than the field, it is flashing, and that is a primer problem, not a taping problem. Run your hand over it with your eyes closed: ridges and humps are taping; a flat wall with stripes is paint.
Doing this before the primer goes on is the whole point of the inspection checklist. The taper fixes ridges and humps while he is still on the job; the painter primes properly because somebody checked. After paint, the same defects cost three times as much to fix because every one is a repaint.
Where homeowners go wrong
- Letting the painter prime with paint-and-primer-in-one. It is paint. New drywall flashes under it. The primer.
- Putting satin or semi-gloss on a Level 4 wall. You will photograph every joint. Level 4 vs 5.
- Inspecting with a torch and rejecting a wall that is fine under room light. The standard is intended lighting. A Level 4 wall is allowed to show under a torch; it is not allowed to show from the couch.
- Paying the taper in full before primer. The primer is the inspection. Hold 10%. Who fixes what.
- Touching up a joint with paint. Now you have a flashing patch over a flashing joint. Prime the wall, paint the wall.
Questions people ask
Why can I see the drywall seams through the paint?
Most often flashing: the compound over the joint absorbs paint differently from the paper, and without a real drywall primer the joint shows as a dull or shiny stripe. Second most often, Level 4 taping under raking light or sheen paint, which needs Level 5. Less often, actual ridges or humps in the taping.
Will a second coat of paint hide drywall seams?
No. Flashing is a difference in absorption and it persists through coats. One coat of proper primer and then paint hides it. Texture differences and humps need compound, not paint.
Are visible seams normal in a new house?
Under a torch, some texture difference at Level 4 is within the standard. Visible from across the room under the room’s own lighting, no, and Tarion’s year-one warranty covers taping defects that show under normal light.
Who is responsible for drywall seams showing after painting?
Ridges, humps and bubbles are the taper’s. Flashing from no primer or the wrong primer is the painter’s. Banding under pot lights on a Level 4 ceiling is whoever specified Level 4. The inspection before primer sorts it out before it costs anyone money.
Stop it before the paint
The finishing inspection checklist is the walk with the light, in order, with what to write down. If the paint is already on and the seams are showing, the $99 review can look at your photos and tell you which of the five it is before you argue with anyone.
Sources and further reading
- Gypsum Association GA-214, Levels of Finish: the standard every “Level 4” and “Level 5” on a quote is supposed to mean. Free summary on the Gypsum Association site.
- Benjamin Moore Canada: product data sheets for the primers and paints named on these pages: coverage per gallon, recoat times and the right primer for new drywall.
- Tarion warranty coverage: what a new-home warranty covers for drywall cracks, nail pops and paint in year one and year two, and what it does not.
