Plastering (Internal/External)

A contractor's guide to cement plastering for interior and exterior walls, covering mix ratios, common cracking problems, and what actually separates a smooth, long-lasting finish from one that fails in two monsoons.

Plastering doesn't get the attention it deserves. Homeowners spend weeks picking tile designs and paint shades, then treat the plaster underneath as an afterthought. Honestly, that's backwards. From our experience, a poor plaster job is the single biggest reason paint peels early, walls develop hairline cracks, and exterior surfaces start looking patchy within a year or two. Get the plastering right first, and everything you put on top of it, paint, texture, tiles, lasts a lot longer.

This guide covers what internal and external plastering actually involves, the difference between the two, common problems we see on job sites across Nepal, and what to expect when you book the work.

What Does Plastering Actually Involve?

At its core, plastering is the process of applying a cement, sand, and water mix (sometimes with additives) over brick or block masonry to create a smooth, even surface. It's not just cosmetic. Plaster protects the masonry underneath from moisture, seals gaps between bricks, and gives you a clean base for painting, texture work, or tiling.

A typical plastering job goes through these stages:

•      Surface preparation (cleaning, wetting the wall, removing loose debris)

•      Applying the base coat (rough plaster)

•      Applying the finish coat (smooth plaster)

•      Curing period with regular water spraying

•      Final inspection for cracks, hollowness, or uneven patches

Here's the thing: skipping or rushing any one of these steps is exactly where problems start. We've walked into homes where the plaster looked fine on day one and started hollowing out within six months, simply because the curing period was cut short to save time.

Internal Plastering vs External Plastering: What's the Difference?

People often assume plastering is plastering, but internal and external walls face very different conditions, so the approach isn't identical.

Internal plastering focuses on a smooth, paint-ready finish. Since interior walls aren't exposed to rain or direct sun, the mix ratio can be lighter, and the priority is a flat, even surface that takes paint or texture well without visible joints or trowel marks.

External plastering has to deal with monsoon rain, UV exposure, and temperature swings. In most projects we've handled, external walls need a richer cement-sand ratio, sometimes with waterproofing additives mixed in, plus a slightly rougher final texture that holds paint better over time. If the external plaster is done with the same light mix used indoors, you'll usually see damp patches and peeling within a couple of years, especially on north or west-facing walls that catch more rain.

Common Plastering Problems We See on Site

A few issues come up again and again on plastering jobs across Kathmandu, Lalitpur, and Bhaktapur:

•      Hairline cracks: Usually from applying plaster too thick in one coat, or curing that was rushed in hot weather.

•      Hollow sounding patches: This means the plaster hasn't bonded properly with the masonry underneath, often from poor surface prep or applying plaster on a dry wall.

•      Dampness on exterior walls: Often traced back to a mix ratio that wasn't dense enough, or missing waterproofing additives on exposed elevations.

•      Uneven surface for texture or paint work: If the finish coat isn't level, it shows up badly once texture and decorative paint goes on, since texture tends to highlight rather than hide surface irregularities.

Honestly, most of these problems trace back to rushing the job or using an unqualified mistry who's cutting corners on mix ratio and curing time.

When Plastering Comes Up in a Renovation or New Build

Plastering isn't just a one-time job for new construction. It comes up constantly during renovation and repair work too:

•      After a wall opening for a new door or window, the surrounding area needs to be replastered to match the existing wall finish.

•      If you're adding a new room partition, the new wall needs plastering on both sides before it's ready for paint.

•      During a kitchen renovation, walls behind old tiling or cabinetry often need patch plastering once fixtures are removed.

•      If electricians cut wall chases for new house wiring, those channels need to be filled and replastered before the wall looks finished again.

These small patch jobs matter more than people think. A poorly matched patch plaster job is one of the most common reasons a wall looks uneven under paint, even when the paint job itself is done well.

Not sure whether your walls need a full replaster or just patch repairs? Our team at constructionsewa can inspect the surface, check for dampness or hollow spots, and walk you through the right approach for your specific walls, whether that's a full internal and external plastering job or targeted repairs in a few problem areas.

Plaster as Prep Work for Other Finishes

A good plaster finish is really the foundation for everything that comes after it. If you're planning:

•      Texture or decorative paint work: The plaster surface needs to be level and free of hollow spots before any texture and decorative paint is applied, since texture products don't hide underlying imperfections, they tend to exaggerate them.

•      Marble or granite cladding: For feature walls or staircases using marble and granite work, the plaster base still needs to be sound even though it'll be covered, otherwise the stone cladding can crack or shift over time.

•      Exterior waterproofing: On terraces and roof edges, external plastering often ties directly into the RCC roof waterproofing scope, since both are addressing the same moisture entry points from different angles.

Trying to save money by rushing the plaster stage almost always costs more later, either in early repainting, patch repairs, or in the worst cases, redoing the plaster entirely.

What to Expect When You Book Plastering Work

The process is straightforward once you book through a marketplace like constructionsewa:

1.    Book a free site visit online or by phone

2.    A contractor inspects the walls and shares a written estimate covering area, mix specification, and timeline

3.    Work is scheduled, usually with milestone-based payments tied to progress

4.    Final quality check and handover, with workmanship warranty terms included

Because pricing is quoted per square foot after an actual site inspection, you're not stuck with a vague estimate that changes halfway through the job.

Frequently Asked Questions

What is included in internal and external plastering service?

It covers professional cement plastering work for both interior and exterior walls, including surface preparation, base coat, finish coat, and curing. Exact scope and materials are confirmed after a site inspection.

Do you provide a written estimate before starting?

Yes. After the site visit, we share a transparent estimate covering labour, materials, and timeline before any work begins.

How long does a plastering job typically take?

This depends on the total wall area, whether it's internal or external work, and weather conditions, since curing time varies with temperature and humidity. Our team gives an expected duration during the site inspection.

Can external plastering be done during the monsoon season?

It's generally best avoided. Rain interferes with curing and can weaken the bond between coats. Most contractors, including our verified partners, will recommend scheduling exterior plaster work outside the heaviest monsoon months where possible.

Do you work outside Kathmandu Valley?

Yes. constructionsewa connects you with verified professionals across Nepal, not just the valley. Share your location when booking and we'll match local contractors.

Is there a warranty on plastering work?

Workmanship warranty terms depend on the scope of the project and are shared in your project agreement after inspection.

Ready to Get Your Walls Plastered Properly?

Whether you're finishing a new build, patching walls after renovation work, or dealing with cracked and damp exterior plaster, it's worth getting a proper site inspection before deciding on the approach. Request a free site visit, get a written quotation based on your actual wall area, and ask our team any questions about mix ratios, timelines, or curing before the work starts. Book an inspection at a time that suits you, there's no obligation to commit on the first visit.

Need Reliable Plastering Work in Nepal?

Cracked, damp, or uneven walls usually trace back to a rushed plastering job. constructionsewa connects you with verified contractors for internal and external plastering across Nepal, from small patch repairs to full house replastering. Book a free site visit today and get a clear, per-square-foot estimate before work begins.