Steam & Hot-Water Cleaning (DOFF & ThermaTech)

Steam cleaning is the method most people are surprised by. The instinct with a dirty building is to reach for more pressure, and on a hard, modern surface that often works. On anything older or softer, pressure is exactly what you don't want — it drives water into the substrate, opens up mortar joints and can strip the weathered face off soft stone in seconds. That damage doesn't wash off.

Superheated steam takes the opposite approach. Instead of blasting the contaminant off with force, it uses heat to break the bond between the dirt and the surface, then lifts it away with a gentle flow of water. The systems we use — the DOFF and ThermaTech families of equipment — run at around 150°C at the nozzle but at a pressure low enough that you can hold your hand in the flow a short distance away. That combination is what makes it safe on surfaces that pressure washing would ruin.

How superheated steam actually works

Water is heated well past boiling point inside the unit and delivered as a wet steam through a nozzle held a few inches from the surface. Three things happen at once. The heat softens whatever is stuck to the surface — organic growth, atmospheric carbon, gum, some paint binders. The moisture penetrates the contaminant and releases it from the pores of the substrate. And the small volume of water carries the loosened material away without flooding the wall.

The low water volume matters more than people expect. A pressure washer can put out well over ten litres a minute; a steam system uses a fraction of that. On an occupied building that means less run-off to manage, less risk of water finding its way through a window reveal or an air brick, and a wall that dries out in hours rather than days.

The temperature does a second job on organic growth. Moss, algae and lichen spores are killed by the heat, not just washed off the surface. A pressure wash removes what you can see and leaves the root system in the pores of the stone, which is why jetted paths often green up again within a season. Steam-cleaned surfaces stay clean noticeably longer, particularly when we follow up with a biocide.

Where we use it around Manchester

The North West's building stock plays to this method's strengths. Manchester and the surrounding boroughs are full of Victorian sandstone and red brick, mill buildings, stone churches, war memorials and civic frontages — all materials where a careless pressure wash does permanent damage. Add the region's rainfall and a lot of north-facing, shaded elevations, and organic growth is the single most common thing we're asked to remove.

We also reach for steam on render and pebbledash, which is everywhere on housing association stock across Salford, Oldham and Rochdale. Render is deceptively fragile: a jet lance held too close blows the top coat clean off and leaves a patch that is more obvious than the dirt was. Steam cleans it evenly with no scarring.

• Heritage and civic stonework — town halls, memorials, listed frontages, churchyard walls
• Render and pebbledash on housing stock, where pressure would break the surface
• Chewing gum on paving and precinct surfaces — heat softens gum in seconds
• Graffiti on porous brick and stone, usually alongside a solvent-based remover
• Shaded elevations and paths carrying heavy moss, algae and lichen

Steam, hot water or pressure — how we choose

These aren't competing products, they're settings on a spectrum, and most real jobs use more than one. We assess the surface first: what it's made of, how weathered it is, what condition the mortar and any coatings are in, and what's actually sitting on it. Only then do we pick the method.

As a rough guide, the harder and more modern the surface, the more pressure it will safely take. The softer, older or more decorative it is, the more we lean on heat and chemistry instead of force. A single elevation might get jetted at low level on the concrete plinth, steamed across the stone above it, and spot-treated with a poultice where somebody has sprayed a tag into the porous face.

• Superheated steam — soft stone, lime mortar, render, heritage brick, organic growth
• Hot water at moderate pressure — sound modern brick, concrete, street furniture, gum
• High-pressure jetting — hard standing, block paving, car park decks, service yards
• Chemicals and poultices — anything the above three won't shift on its own

What a steam clean involves on site

The units are fully self-contained. We arrive with our own water, our own power and our own containment, so we don't need a tap, a socket or a key to a cupboard — which is why this method suits occupied buildings, live retail frontages and school sites out of hours.

We always test a small, discreet area first and let you see the result before we work across a whole elevation. That test panel tells us the right temperature, the right stand-off distance and whether the surface needs any pre-treatment. It also gives you a genuine before-and-after to compare, rather than a promise.

Set-up is quick, there's very little noise beyond the generator, and because water volumes are low the working area stays walkable. On a public frontage we'll usually cone off a small zone that moves along with the operative rather than closing the whole footway for the day.

What you get afterwards

Every job finishes with photographs — before, after, and the test panel — so whoever signs it off has a record without visiting site. For councils, housing associations and FM providers that paperwork is often as important as the clean itself, because it's what closes the job on their system.

Where organic growth was the problem we'll normally recommend a biocide wash as the final step. It costs very little on top of a clean that's already happening and it buys a considerable amount of time before regrowth. On graffiti-prone surfaces we'll talk to you about an anti-graffiti coating instead, so the next tag comes off with cold water.