Adding a toilet under the stairs is one of the smartest uses of dead space in an Irish home. A standard under-stairs cloakroom in Dublin starts from €2,500 – €5,000 fully fitted, takes around 8 to 12 days to install, and adds both everyday convenience and genuine resale value without eating into any of your living space. This guide covers the design options that actually work in tight spaces, the two plumbing approaches you need to understand before you start, what the job involves from beginning to end, and what to watch out for.
Is There Enough Space Under Your Stairs?
This is the first question everyone asks, and the honest answer is that most Irish semi-detached and terraced homes have enough space, though it takes a proper assessment to confirm it.
The practical minimum for a functional toilet and small basin is roughly 80cm wide by 140cm deep, with a minimum head height of around 180cm at the front where you stand, dropping to around 140cm at the back near the cistern. The sloped ceiling that makes under-stairs space look awkward actually works in your favour here. It means you can position the toilet pan at the highest point, directly under the stairs where there is most headroom, with the cistern tucked back into the slope where height matters less.
The internal width of a standard Irish staircase is typically 70cm to 80cm, which is tight but workable with the right fixtures. Wall-hung toilets with concealed cisterns, compact back-to-wall WCs, and 40cm or 45cm-wide cloakroom basins are all designed specifically for this kind of space, and they work well in it. The key is choosing fixtures built for small rooms rather than trying to squeeze standard ones in.
If you are unsure whether your under-stairs space is large enough, the quickest way to check is to measure the internal dimensions and compare them against a couple of compact WC unit specifications from a bathroom supplier.
The Two Plumbing Options: Gravity-Fed vs Macerator
This decision shapes the cost, the complexity, and the long-term practicality of the whole project, so it is worth understanding before you get any quotes.
Gravity-fed drainage is the traditional approach. Waste flows by gravity through standard 100mm soil pipe to the external drainage system. It is the most reliable, lowest maintenance option, and the one any plumber will prefer. The challenge is that it requires the soil pipe to have a continuous downward fall from the toilet to the external drain. In some Dublin homes, particularly older terraces and semis where the soil stack is at the back of the house and the staircase is at the front, achieving that fall through the floor slab can be difficult or expensive, sometimes requiring the concrete floor to be broken up and excavated.
A macerator – also called an upflush toilet or Saniflo system – grinds waste into a fine slurry and pumps it through a small-bore 22mm or 32mm pipe to the existing soil stack. The pipe runs inside walls or along skirting boards rather than under the floor, so there is no excavation needed and the installation is significantly less disruptive. A macerator unit like the Saniflo Saniaccess range can pump waste up to 4 metres vertically and 50 metres horizontally, which gives real flexibility on where the toilet can be positioned relative to the nearest soil stack.
The trade-off with a macerator is ongoing maintenance. The unit requires periodic descaling (especially in Dublin’s hard water areas), must only be used with toilet paper, and relies on an electrical connection to operate. It will eventually need to be replaced, typically after 10 to 15 years with regular maintenance. It is also slightly noisier than a gravity system when flushing. That said, for many under-stairs installations in Irish homes, particularly where breaking the floor is not practical, a macerator is the right call and performs reliably for years.
The plumber you appoint should assess both options and give you an honest recommendation based on your specific house layout. If they quote for a macerator without checking whether gravity drainage is achievable, ask them to look again.
Under Stairs Toilet Ideas That Work
The challenge with under-stairs toilets is that every dimension matters. A fitting that is 5cm too deep can make the door almost impossible to use. These are the design approaches we consistently see working well in Irish homes.
Wall-hung toilet with concealed cistern. This is the most popular choice for under-stairs installations, and for good reason. A wall-hung WC sits off the floor with the cistern hidden inside a slim duct frame built against the wall. It opens up floor space visually, makes the room easier to clean, and reduces the projection into the room compared to a close-coupled pan. Short-projection wall-hung pans are available with projections as low as 480mm, which in a tight space makes a meaningful difference.
Back-to-wall WC with hidden cistern furniture. A good alternative if you want the cistern hidden but prefer a floor-standing toilet. The cistern is concealed inside a slim furniture unit or boxing behind the pan. Slightly more depth is needed than a wall-hung installation, but it avoids the need for a full wall duct frame, which can be an advantage in a very narrow space.
Combined basin and toilet units. These all-in-one units integrate a small basin directly on top of the cistern lid. When you wash your hands, the grey water flows into the cistern and is used for the next flush. They are compact, clever, and designed exactly for this application. The projection from wall to front of unit is typically around 680mm to 700mm, which works well in standard under-stairs depths.
Corner basins. In spaces where width is the limiting factor, fitting the basin diagonally into a corner can recover 10 to 15cm of usable floor width. Combined with a narrow cloakroom WC, a corner basin arrangement can make a very tight space feel workable rather than cramped.
Pocket door or sliding door. A standard inward-opening door eats into the usable floor space of a small toilet room and can make the experience of using it genuinely awkward. A pocket door that slides into the wall cavity, or a sliding barn-style door that runs on a wall-mounted track outside the room, solves this immediately. If a pocket door is not possible because of what is in the wall, a door that opens outward into the hall is another option, though it needs clear space in the hallway to swing without obstruction.
Bold decoration. Because you spend very little time in a downstairs toilet, this is one room in the house where you can afford to be brave with design. Dark paint colours and dramatic wallpaper actually work better here than in a larger room, because the small footprint means bold choices look deliberate rather than overwhelming. A single striking tile on the back wall, tongue and groove half-height panelling in a deep colour, dark metro tiles with contrasting grout, mosaic tiles on the sloping ceiling section – these are all approaches that look genuinely impressive in well-executed under-stairs cloakrooms across Dublin.
Sensor lighting and automated ventilation. Because there is almost never a window in an under-stairs toilet, getting the lighting and extraction right is not optional. A motion-sensor light that switches on automatically when the door opens is the most practical solution. An RECI-registered electrician will connect the extraction fan to a timer or humidity sensor rather than a manual switch, which keeps the room fresh without any thought required.
What the Installation Actually Involves
Understanding the sequence of work helps you plan around the disruption, which for most families is the more pressing concern than the cost itself. The job typically runs over 8 to 12 working days, though not all of those will involve tradespeople on site.
Stage 1: Strip-Out and Preparation (Days 1 to 2)
Removing any existing cupboard furniture, assessing the existing floor and wall structure, and confirming drainage routing. If a gravity-fed system is being installed and floor excavation is required, this is the most disruptive phase, typically one or two days of concrete breaking and digging before the new soil pipe can be laid and the floor made good.
Stage 2: First Fix Plumbing and Electrical (Days 3 to 5)
Running the new waste pipe (whether gravity or macerator), bringing a cold water supply to the new toilet and basin, running electrical cable for the extraction fan and lighting, and building any new stud walls needed to define the space and conceal pipework.
Stage 3: Waterproofing and Tiling (Days 6 to 7)
Once first fix is signed off and walls are dried out, the tiler comes in. Waterproofing around the floor and wet wall areas is done before tiling begins, not after. An under-stairs toilet in Irish homes typically uses ceramic or porcelain tile on floors and walls, which is the most practical and durable choice for a damp environment. Allow a day or two for tiling and another day for the grout and adhesive to fully cure before the plumber returns.
Stage 4: Second Fix and Final Finish (Days 8 to 12)
The plumber connects and installs the WC, basin, taps, and waste fittings. The electrician returns to fit the extraction fan unit, light fitting, and switches. The joiner hangs the door and fits any skirting and architrave. The room is then painted and handed over.
What Does a Toilet Under Stairs Cost in Ireland?
A standard under-stairs toilet installation in Dublin costs €2,500 to €5,000 depending on the complexity of the drainage, the quality of fixtures chosen, and the finish of the room (OS Holding, 2025). Dublin prices run 15 to 20% above the national average due to higher labour costs, so the same job in Cork or Galway might come in at €2,000 to €4,000.
| Item | Typical Cost |
|---|---|
| Labour – plumber, electrician, tiler, carpenter | €1,200 to €2,500 |
| Groundwork and drainage (gravity system) | €450 to €800 |
| Macerator unit (if gravity not possible) | €400 to €700 |
| WC, basin, taps, and sanitaryware | €400 to €900 |
| Tiles, adhesive, grout | €200 to €500 |
| Door, architrave, skirting | €200 to €400 |
| Extraction fan and lighting | €150 to €300 |
The biggest cost variable is drainage. If the under-stairs space sits close to an existing soil stack and gravity drainage is straightforward, the plumbing element of the job is relatively modest. If the floor needs to be broken and excavated to achieve a fall to the drain, or if the soil stack is at the far end of the house requiring significant pipe routing, that cost increases considerably. A macerator avoids floor excavation but adds the cost of the unit and a dedicated electrical connection.
The second major variable is finish. Standard mid-market sanitaryware and ceramic tiles sit at the lower end of the cost range. Designer wall-hung fittings, large-format porcelain tiles, custom boxing and joinery, and a concealed cistern frame system add cost but produce a noticeably better result in a space that guests use every day.
Do You Need Planning Permission?
In most cases, no. Installing a toilet under the stairs in an existing home is an internal alteration that does not require planning permission under Irish planning law. Citizens Information has a clear guide to what qualifies as exempted development if you want to verify the position for your specific property.
However, if the installation involves any structural changes to the staircase itself, or if your home is a protected structure or in a conservation area, you should check with your local authority before starting any work. And while planning permission is not usually required, a Commencement Notice may be needed if the works constitute a material alteration under the Building Control Acts. The Dublin City Council building control page sets out exactly when a notice is required and how to submit one online for €30.
All plumbing work must be carried out by an RGI-registered plumber and all electrical work by an RECI-registered electrician. Both are legal requirements in Ireland.
Does a Toilet Under the Stairs Add Value?
It does, reliably. Estate agents consistently list a downstairs WC as one of the features buyers notice and value in Irish family homes, particularly in the three and four-bed semi-detached market that makes up most of Dublin’s housing stock. A well-executed under-stairs toilet adds convenience for everyday family life, reduces pressure on the main bathroom, and is a specific selling point that buyers with children look for. It is not the kind of renovation that pays for itself in added value on the day you sell, but it makes the house more liveable while you are in it and more attractive when you come to sell.
The renovation is worth doing if you plan to stay in the property for a few years. If you are selling shortly, put the money into the kitchen or main bathroom instead, where the return on a good renovation is more immediate.