Domakihub How to Box In a Staircase: A Step-by-Step Guide
Frame, board, and finish the underside and sides of your staircase for a clean, professional result.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 5 min read
Boxing in a staircase — enclosing the underside, open sides, or structural timbers with a smooth, painted finish — is one of the most effective cosmetic upgrades you can make to a hallway in a home, holiday rental, or boutique hotel. The video above demonstrates the panelling process in detail, while this article breaks down every stage from structural assessment through to final decoration. In Greece's varied building stock, from postwar polykatoikia apartments to island stone houses, staircase arrangements differ widely, but the core technique is the same.
What 'Boxing In a Staircase' Actually Means
The phrase covers two related tasks: enclosing the triangular void beneath a flight of stairs (the understairs soffit), and cladding any exposed side stringers or structural timbers so the staircase looks like a finished architectural element rather than a bare frame. In older Greek construction it is common to find concrete staircases with bare soffits or timber staircases with open sides — both are strong candidates for boxing in.
The result is a flush, paintable surface that can conceal pipes, cables, and insulation while also improving fire safety when the correct board is used. It is a cosmetic and minor-structural job that a competent carpenter or builder can complete without a permit in most cases, though you should always check local planning rules if the staircase is in a listed or protected building.
Materials, Tools, and When to Call a Pro
For a typical timber staircase, you will need: CLS or PAR timber for the stud frame (45 x 70 mm is a standard choice), 12.5 mm plasterboard or 12 mm MDF for the face, joint tape and setting compound or flexible decorator's caulk, screws (50 mm for timber-to-timber, 25 mm drywall screws for board to stud), a spirit level, a mitre saw or jigsaw, a tape measure, and a pencil. If you are boxing in concrete stairs you will additionally need masonry anchors and a hammer drill.
Call a licensed professional — and obtain the relevant permit — before boxing in if: there are gas pipes running through the void (gas work is licensed in Greece and must not be enclosed without certified inspection), if you suspect structural damage to the stair carriage or treads, or if the void is damp with no obvious source. Damp behind a sealed box will cause rapid deterioration of timber and board and can be a serious defect in a rental property.
Fire Safety: A Non-Negotiable Detail
In Greece, as across the EU, the understairs area in a building with more than one occupancy unit is considered a protected escape route. Standard 12.5 mm plasterboard already provides approximately 30 minutes of fire resistance, which satisfies most residential requirements. If the staircase serves more than one apartment, use Type F (fire-rated) plasterboard and intumescent strips around any access hatch. This is not optional — it is both a legal and insurance requirement. Discuss requirements with your local fire safety office (Πυροσβεστική Υπηρεσία) if you are unsure of the classification.
How to Box In a Staircase: 5 Steps
- 1
Assess the structure and plan the frame
Before cutting a single piece of timber, inspect what is already there. On a concrete staircase, check for cracks, spalling, or moisture and resolve these first. On a timber staircase, look at the condition of the carriages (the structural side beams) and the undersides of the treads. Measure the longest diagonal run of the soffit, the height at the tallest point, and any protrusions such as pipes or wiring that will need to be accommodated or rerouted. Sketch a simple plan showing stud positions — aim for centres of 400 mm to 600 mm, which suits standard plasterboard sheet widths and minimises waste. Mark stud positions on the wall and floor with a chalk line before you start cutting.
- 2
Build and fix the stud frame
Cut your timber studs to length, mitreing the ends that follow the rake of the stair at the correct pitch angle — measure this directly from the staircase with a digital angle finder or a sliding bevel. Fix the top plate (the piece running along the underside of the treads or along the wall) first using masonry anchors into concrete or structural screws into timber. Then fix the sole plate to the floor. Drop in the vertical and diagonal noggings, checking each piece is plumb or parallel to the stair rake as appropriate. The frame should be rigid with no flex before you move on — any movement here will cause the finished surface to crack along board joints.
- 3
Cut and fix the facing board
Plasterboard is the most common choice for residential work: it is cheap, fire-resistant, and paintable. MDF gives a crisper edge detail and is preferred for a high-end finish or where mouldings will be applied flush to the surface, but it is heavier and must be primed on all cut edges before fixing to prevent swelling. Cut sheets to fit using a Stanley knife scored across the face and snapped over a straight edge (for plasterboard) or a jigsaw or circular saw (for MDF). Fix to the studs with the appropriate screws, keeping fixings at 150 mm centres at edges and 300 mm centres in the field. Leave a 2–3 mm gap between adjacent sheets to allow for joint compound.
- 4
Tape, fill, and achieve a flat surface
Apply self-adhesive mesh tape or paper tape over all board joints and screw heads. Skim over with two thin coats of finishing compound (or use ready-mixed jointing compound for ease), feathering each coat outward at least 200 mm from the joint. Allow the first coat to fully dry — in the Greek summer this can take as little as 2–3 hours in a ventilated space, but do not rush it. Sand lightly between coats with 120-grit paper and finish with 180-grit. Run a thin bead of flexible decorator's caulk along the junctions with walls, skirting, and the stair treads themselves — these junctions are always the first place paint lines crack, and flexible caulk will prevent that. On MDF, apply a coat of MDF primer before any topcoat.
- 5
Fit an access hatch if there is useful storage beneath
If the understairs void is large enough to be useful — typically anything over 0.6 m in height at the apex — it is worth incorporating a flush access hatch or a hinged door rather than sealing the space permanently. A framed door opening with a pre-hung door blank is the cleanest solution. Alternatively, a flush hatch with magnetic catches gives a seamless look when painted. Mark out the opening before you start boarding, double-frame the rough opening with an extra trimmer stud on each side, and fit a head board above the opening. Finish the hatch reveal with 18 mm MDF architrave to match any other door trims in the hallway.
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FAQ
- Do I need a building permit to box in a staircase in Greece?
- For a straightforward cosmetic boxing-in of an existing staircase in a private residence, no permit is normally required. However, if you are altering the structure of the stair itself, creating a new room or habitable space under the stairs, or working on a building in a protected zone (διατηρητέο κτίριο), you should consult your local planning authority (Πολεοδομία) before starting work.
- Can I use MDF instead of plasterboard for boxing in stairs?
- Yes, and many carpenters prefer MDF for staircases because it takes paint and moulding profiles cleanly without the paper-face tearing that plasterboard can suffer. The trade-off is that MDF has no inherent fire rating, is heavier, and must be sealed on all cut edges. In areas that require fire-rated construction — typically any staircase serving more than one occupancy unit — use fire-rated plasterboard instead, or check with your contractor whether a combined system is acceptable.
- How long does it take to box in the underside of a typical staircase?
- A single flight of stairs in a standard Greek apartment or villa (10–14 steps) typically takes an experienced carpenter and helper about one to two days: half a day for the frame, half a day for boarding, and a further day for taping, filling, and first-coat painting once the compound has dried. Add finishing coats on a third day. DIY first-timers should budget for roughly double that time.