Pressure Washing Commercial Buildings

25th October 2022 General

When pressure washing commercial buildings you need to know what type of pressure washer to use. You need to ask yourself why you are needing to pressure wash your building’s exterior surfaces.

How long has it been since the last time you pressure washed the exterior areas of the buildings? Do they have a large amount of organic growth? Are you needing to tidy up after “messy” builders have left splashes of mortar etc.

There are different types of pressure washers and different attachments suitable for different tasks and different building materials. There may also be alternative cleaning methods more suitable for the project.

Vertical Surfaces (Walls)

Firstly you have the standard cold water pressure washer. This is your most cost effective machine for pressure washing commercial buildings exteriors. If you have non-porous surfaces such as UPVC window frames, fascias and soffits and cladding, the cold water pressure washer is ideal as you can maintain these areas yourself and regular cleaning will not erode the surface. You do need to be careful of how high you have your pressure, how close you hold your wand and your technique to ensure you do not scar or “tiger-stripe” the surface. Cold water pressure washing is also good for fibre cement cladding, metal cladding on warehouses etc. Again, when pressure washing these exterior surfaces be aware of technique. Even on non-porous surfaces it will be difficult to get into every nook and cranny and wash off all organic matter so you ought to think about some sort of biocidal treatment spray.

If you are looking to pressure wash commercial buildings made of bricks or stone, you may want to look into investing in a hot-water pressure washer. Bricks and stone are porous and absorb water. As such a lot of organic growth can live inside the surface. Hot water will be better for killing these spores or regrowth will occur sooner. You also do need to be very aware that pressurised water is erosive and if you pressure wash your bricks or stone too often you will damage the mortar. This is why you need the longest term solution so that you do not need to maintain it too often. Alongside the hot water pressure washer you may want to consider spraying on a biocide of some sort to extend the period between pressure washing treatments. Better still than hot water pressure would be steam treatment where the pressure is very low as it will be steam hitting your building rather than pressurised water and will not damage the mortar. Steam cleaners are not, however, recommended for untrained people and are best left in the hands of a reputable and well-trained professional company. Doff steam cleaners are well designed and capable for steam cleaning buildings.

If you are looking to pressure wash commercial buildings which have hanging tile cladding please be aware of the type of tile. Many hung tiles are coated concrete tiles. Pressure washing this sort of tile almost always erodes away the surface coating and leaves your tile scarred and it loses its colour leaving behind the colour of the concrete beneath the coating. Also hanging tiles are almost always on the upper level of a building. Pressure washing should never be done from a ladder. You should only pressure wash your buildings exterior surfaces from ground level or with a suitable form of access such as fixed scaffolding, scaffold tower, or mechanical lift. In most cases when cleaning the upper level(s) of a building it should be undertaken by a qualified professional with the right training and certifications for working at height.

If you are planning to pressure wash the exterior of your building because of builder’s mess such as sloppily applied mortar you should be aware that you will be unlikely to have much success and will probably cause damage to the building material and have little impact on the problem area. In such cases the recommendation would be to engage a company experienced with TORC cleaning  (ice blasting, sand basting etc)

Pressure washing commercial buildings with render. Render should never really be pressure washed. Best practice for render is either steam cleaning or chemical soft washing. Pressure washing render scars it, blasts pieces from the surface and in some cases makes it break away from the building entirely. Render is also highly porous and cold water pressure washing will only blast the spores more deeply into the surface ripe for regrowth. It will grow back each time faster and faster and be more widespread. Even if you have been lucky and pressure washed your render without damage in the past, it is not a form of cleaning you want to risk too often and cold water pressure washing is a very short-term solution for render. Ideally, if you can budget for it, render should be cleaned and sanitized by a professional company who has a lot of render experience.

Wood – Wood cladding, fences, wooden buildings and structures. Wood is highly porous and when organic matter infests wood it has a contrary effect of rotting it and drying it out/cracking it. Pressure washing wood surfaces is at best a short term solution and is not recommended. It scars the wood without targeting anything but the surface layer of matter. Not only should wood be treated with either steam or softwash but it should then be treated with a penetrative agent which will protect it and moisturize the fibres to extend the life of the wood.

Horizontal surfaces (courtyards, carparks, warehouse floors, driveways, patios)

When pressure washing commercial buildings flat surfaces areas it is recommended to use a flat surface cleaner attachment in all cases. The standard wand is too direct and takes longer without achieving the full coverage of the area. The flat surface attachment has a rotating head within it  and so spreads the pressure which means it will erode the surface less, especially any areas of mortar.

Tarmac is best cleaned with cold water pressure washers (with flat surface attachment) as heat/steam can melt it and chemicals can discolour it. It is still advised to lay down a light spray of biocide or other sanitizing chemicals for longer results.

Resin-bond driveways, walkways, courtyards. Resin bond is very susceptible to damage from moss and should always be kept clean. It is an expensive surface to install and when moss attacks the glue-bond it can result in some very high priced gravel! Cold water pressure is fine with a flat surface cleaner for regular maintenance but it is recommended at least every three years (preferably more) to have a proper sanitizing service on this type of material. Steam and hot-water pressure washers should not be used on resin-bond surfaces as the heat will melt the glue. The ideal treatment for resin-bond surfaces is soft washing which will keep it clean and more importantly free of damaging infestation.

You can easily pressure wash commercial buildings concrete areas, whether slab tiles or poured concrete paths etc. For this you can use either hot or cold pressure washers. Be aware of the atmospheric conditions in the area of your building as pressure washing too regularly will slowly erode the top surface and over time more and more of the aggregate will begin to show on the surface. If you are needing to pressure wash commercial buildings concrete areas too regularly you ought to consider a longer term solution such as soft washing to lengthen the lifespan of your concrete.

Brick and stone surfaces. Both of these are also very easily maintained by pressure washing with flat surface cleaner attachment and if kept fresh from new can be easily maintained by the in-house building cleaning crew. However brick and especially stone such as sandstone, limestone, or York stone are very porous and when you start getting areas of black lichen need to be targeted by a suitable biocidal or soft washing solution as when black lichen dwells too long it can dye the stone itself and then the staining can become permanent even if the infestation is killed 100%. Prevention is better than cure and regular pressure washing and occasional soft washing will be ideal for the long-term look and health of the stone.

Tiles – Ceramic tiles are not porous and can be pressure washed with flat surface cleaner attachment. Be careful not to stay too long in one area as the pressure can then cause damage. An overlapping figure of eight motion is best to keep from potential damage. Terracotta tiles are slightly but not highly porous and can be maintained by pressure washing but, again, once in a while should receive chemical or steam treatment for a deeper clean. Coated concrete tiles should not be pressure washed as the surface colour will be washed away leaving the bare concrete colour.

Gravel – pressure washing gravel….. are you joking? (can still be soft washed)

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