C33 Wallcovering Installation and Preparation 4 — Questions and Answers
Question 1: When installing wallcovering on a surface that has been previously painted with oil-based paint, what is the most critical preparation step?
- Apply wallcovering directly over the oil-based paint
- Lightly sand the surface and apply a shellac-based primer (Correct answer)
- Wet the surface with water before hanging
- Apply sizing directly over the oil-based paint without priming
Correct answer: Lightly sand the surface and apply a shellac-based primer
Oil-based paint must be lightly sanded and sealed with a shellac-based primer to ensure proper adhesion and prevent bleed-through.
Question 2: What is the recommended overlap when seaming two strips of non-woven wallcovering?
- 1/2 inch overlap, then trim through both layers
- Butt seam with edges touching but not overlapping (Correct answer)
- 1 inch overlap without trimming
- 2 inch overlap folded under
Correct answer: Butt seam with edges touching but not overlapping
Non-woven wallcovering is installed using butt seams where edges meet precisely without overlapping.
Question 3: A contractor is installing grasscloth wallcovering in a bathroom with high humidity. Which precaution is most important?
- Use extra paste and double-paste all strips
- Advise the client that natural fiber wallcoverings are not suitable for high-humidity areas (Correct answer)
- Install a vapor barrier behind the wallcovering
- Apply two coats of sizing before hanging
Correct answer: Advise the client that natural fiber wallcoverings are not suitable for high-humidity areas
Natural fiber wallcoverings like grasscloth are not moisture-resistant and should not be installed in high-humidity areas like bathrooms.
Question 4: When installing wallcovering around an electrical outlet, what is the correct procedure?
- Cut out the outlet shape before hanging the strip
- Hang the strip over the outlet and cut an X from corner to corner, then trim the flaps (Correct answer)
- Leave a 1-inch gap around all electrical boxes
- Remove the outlet entirely before wallcovering
Correct answer: Hang the strip over the outlet and cut an X from corner to corner, then trim the flaps
Hanging over the outlet then cutting an X and trimming the flaps ensures a clean fit around electrical boxes.
Question 5: What does 'booking' wallcovering mean?
- Scheduling installation appointments
- Folding pasted wallcovering paste-side-to-paste-side without creasing edges (Correct answer)
- Numbering strips in installation order
- Pre-soaking dry-paste wallcovering in water
Correct answer: Folding pasted wallcovering paste-side-to-paste-side without creasing edges
Booking is the process of folding pasted wallcovering paste-to-paste to allow the material to relax and the paste to activate without drying out.
Question 6: Which tool is used to press wallcovering seams flat and ensure good adhesion without stretching the material?
- Wide putty knife
- Seam roller (Correct answer)
- Wallcovering brush
- Plastic squeegee
Correct answer: Seam roller
A seam roller is the correct tool to press seams flat and ensure adhesion without distorting the wallcovering.
Question 7: When calculating wallcovering needed for a room, which areas are typically deducted from the total square footage?
- Only doors are deducted
- Windows and doors that are larger than 50% of a single strip width
- All windows, doors, and fireplace openings (Correct answer)
- No deductions are made; always order the full wall area
Correct answer: All windows, doors, and fireplace openings
Standard practice is to deduct full openings such as windows, doors, and fireplace openings from total square footage before calculating rolls needed.
C33 Wallcovering Installation and Preparation 4
When installing wallcovering on a surface that has been previously painted with oil-based paint, what is the most critical preparation step?