Portable Cabins for City Sites: Fitting Office and Welfare on a Tight Plot

On a city-centre job, the compound is usually whatever space is left once the building, hoarding line, scaffold and loading bay are drawn in. Portable cabins for city sites therefore have to do more per square metre than on an open plot: the site office, toilet, washing point and mess room may need to share one or two units, and those units often have to come down a busy street and be lifted over a hoarding. This guide is for contractors and site managers planning that compound.

What the welfare rules ask for on a construction site

In England, Scotland and Wales, Schedule 2 of the Construction (Design and Management) Regulations 2015 (CDM 2015) sets the minimum welfare facilities for construction sites. Northern Ireland has its own Construction (Design and Management) Regulations (Northern Ireland) 2016; check HSENI guidance there. HSE guidance says contractors must provide the right welfare for workers under their control, and the principal contractor must make sure it is in place from the start of the project until it finishes.

Schedule 2 does not set a number of toilets or a floor area. HSE says the type and number of facilities depends on the size and type of work, so your project's welfare plan decides how many units you need. On a small plot, what matters is how each requirement fits into a compact unit:

Facility	What it asks for, in summary	What it means for a compact unit
Toilets	Suitable and sufficient toilets at readily accessible places, lit, ventilated and kept clean so far as reasonably practicable. Separate rooms for men and women, unless each toilet is in its own room with a door that locks from the inside.	A WC in its own room with a door that locks from the inside can be shared by men and women, so you avoid two toilet rooms. Check the WC door lock on the layout drawing before production.
Washing	Washing facilities next to every toilet and near any changing room, with hot and cold or warm water (running where reasonably practicable), soap and towels or another way to dry. Showers where the work or health reasons require them.	Put the basin in or beside the WC. HSE gives cement, lead and micro-organisms as examples where extra facilities such as showers may be needed.
Drinking water	An adequate supply of wholesome drinking water at readily accessible places, with cups unless it comes from a drinking jet.	Decide where the drinking water point goes, and how it is supplied, before services are planned.
Changing rooms and lockers	Changing rooms where workers wear special clothing and cannot be expected to change elsewhere, with seating, a way to dry clothing where necessary and lockable storage where necessary.	A second room with its own entrance can work as a changing and drying room.
Rest facilities	Rest rooms or areas with enough tables and seats with backs, facilities to prepare and eat meals, a means of boiling water and an appropriate temperature. Where necessary, somewhere for pregnant workers or nursing mothers to lie down.	A kitchenette and heating matter more than desk space. Size the rest area for the most people on a break at once.

Using facilities nearby

HSE guidance also allows existing facilities nearby to be used, such as a café, public toilets or an occupied building, which helps where the plot is very tight. The conditions are that you have a proper agreement with the owner, the facilities are available all the time workers are on site, and there are arrangements to keep them clean and stocked. Check that the arrangement still covers the hours your crew starts and finishes.

Combining the office and welfare in one Karmod unit

Karmod's container layouts come in four footprints: 2.30m × 6.00m, 3.00m × 5.00m, 3.00m × 6.00m and 3.00m × 7.00m. On a narrow plot the 2.30m-wide unit leaves more room alongside for a walkway or a materials bay, and the 3.00m × 5.00m unit is the shortest. Product images show the 3.00m × 7.00m model; on smaller footprints the rooms are scaled to fit, and we confirm the final layout on a drawing before production.

Your situation	Layout	What is inside	From (2.30m × 6.00m)
One unit has to be the office, toilet and tea point	K2004 Site Office with WC & Kitchenette	Open office, WC cubicle with toilet and basin, kitchenette with sink	£7,440 + VAT
An office and a separate mess or drying room	K3003 Site Welfare Unit	Two rooms with their own entrances, central core with WC and kitchenette	£7,440 + VAT
Two teams sharing one toilet	K3002 Twin Office with Central WC	Two offices off a central hall with a WC and basin	£5,965 + VAT

Other WC and shower layouts are compared on our welfare and WC units page.

The trade-off with a single combined unit is floor space. In K2004 the WC and kitchenette take one end and the open office is what remains, so breaks and paperwork share one room. For a larger crew it usually works better to split the roles: an office unit from our site office range, plus a separate welfare unit or a mess room from the canteen and break room layouts.

Going up instead of out

When the ground area is not there, stacking is the other option. Karmod's projects include a two-storey container office block with an external staircase, which doubles the office space on the same unit footprint. The staircase needs ground space of its own beside the block, and a two-storey arrangement is not one of the online layouts, so raise it when you first ask for a quote; we confirm the final layout on a drawing before production. Our page on modular buildings covers multi-unit and two-storey arrangements.

Delivering portable cabins to a city-centre plot

Karmod units are built in the factory and delivered ready to place on a prepared base, so the day's work is offloading and setting down, not assembly in the street. Offloading needs equipment such as a HIAB, crane or forklift, and before we send a formal quote we check the drawing, the delivery route and the offload equipment. Useful details to send:

• where the lorry can stand, and for how long;
• the hoarding height, and any gate or gap the unit must pass through: container layouts are 5.00m to 7.00m long and 2.30m or 3.00m wide;
• anything overhead: cables, trees, scaffold, canopies or a tower crane jib;
• how far the unit travels from the lorry to its base, and what it must clear;
• any delivery time windows set by the client, the council or neighbours.

If a crane or lorry-mounted crane has to stand on the road or pavement, lift from it or swing a load over it, many councils in England require a crane licence or permit before work starts, and a road closure needs its own permission with a longer lead time. Requirements vary, so wherever the site is, contact the local highway or roads authority before you fix a delivery date.

A base that suits a hard urban plot

City plots often already have an old slab or tarmac. It may not be level, and it may sit over basements, cellars, drains or live services, so have it checked before you treat it as the firm, level base each unit needs. We advise on the base when we prepare the quote.

The base is not the only ground a unit takes. Raised units need steps or a ramp at each door, and layouts with a WC, basin or kitchenette need water, drainage and power runs to reach them, so mark both on your site sketch before the base is set out.

Before you ask for a quote

1. Peak headcount on site, and how many people take a break at the same time.
2. Which welfare facilities go inside the hoarding, and any nearby facilities you have an agreement to use.
3. The space available, with the hoarding line, gate and no-go areas marked on a sketch.
4. The delivery details listed above, and any permits you expect to need.
5. The base you plan and the services you can bring to it.
6. The layout and footprint you have in mind, and any electrics, heating or air conditioning.

Send those details through our contact page or call 0116 403 0143. We confirm the layout on a drawing, and the formal quote confirms delivery to your postcode and the offload equipment needed. Website prices exclude VAT, delivery and offloading.