Pictured above: a two-tier steel rack frame along the outside wall of a shed, under a roof but open to the yard, in a red-oxide finish, with the slab in front still wet. Frames standing in this kind of place are the reason the finish is worth deciding on purpose.

Most racking quotes name the load class, the beam length and the number of bays. Very few make the buyer stop and ask what the steel is wearing. Yet the finish is the one part of a racking installation you cannot change later. Beam levels can be moved in an afternoon. A frame that has been installed and loaded cannot be sent back for a different coating.

This article is about choosing between the standard powder-coat finish and a galvanised or more durable protective finish for a warehouse in Singapore, where "indoors" is not always dry. It sets out what the standard finish is, where it is a good choice, where it stops being one, and what to ask for in writing before an order is placed. It prices nothing: finish is one of the things that moves the price of a bay, and any figure follows a site survey.

What the standard finish actually is

The standard finish on our racking is powder-coat in Wong Lye red and yellow, with other RAL colours on request. Underneath it, cold-rolled sections are zinc-plated before the powder-coat goes on, and hot-rolled sections in the Super Heavy-Duty tier are shot-blasted and primed before the topcoat. Boltless shelving is powder-coated too.

That is a specification written for an ordinary, dry, ambient warehouse, and in that setting it does its job. Our racking page is plain that when racking is properly specified, installed and maintained, 20 to 25 years is normal, and that the limiting factor is usually forklift impact damage, not corrosion. So for a dry warehouse the finish is rarely what ends a rack's life, and nobody needs to pay for more than the standard.

Where powder-coat is weakest

Powder-coat is a film on top of the steel. It is at its weakest exactly where the steel has been worked: cut edges, punched slots, bolt holes and weld points. In a dry building that makes no practical difference. Where steel is wetted repeatedly, water works in at those points, and corrosion can then spread sideways underneath a coating that still looks intact from a metre away. By the time it shows, a beam-end connector may already be compromised.

A galvanised finish works differently. Galvanising is not a film sitting on the surface: the zinc layer is bonded into the steel, so it protects the cut edges instead of stopping short of them. That is why, for wet and outdoor conditions, we name a more durable protective finish or galvanised components rather than the standard one.

Five situations, five answers

The useful question is not "which finish is better" but "which of these rooms is mine". Be honest about it when you brief a supplier, because the quote follows the answer.

• Dry, ambient warehouse. Standard powder-coat. This is the case the standard finish was written for. Spend the money on beam rating, floor fixing and protection against impact instead.
• Indoors, but humid, with open loading bays. Many warehouses have an open dock end where humid air and blown rain reach the first few bays. The standard finish is still the starting point, but tell the supplier which bays sit near the opening, and ask whether those runs should be treated differently from the rest.
• Food warehouse that is washed down. Washing wets the frames far more often than weather does, and it wets them at the base of every upright, where the water collects. In an ambient food warehouse that is washed periodically, galvanising is a sensible margin. The full list of what else changes for a food store, including decking, is in racking in a food warehouse.
• Chiller or cold room. A chiller is wet: warm humid air comes in each time the door opens and condenses on cold steel, where it stays. Surfaces carry condensation permanently rather than occasionally, and corrosion starts at cut edges, welds, connector holes and anywhere a pallet has chipped the finish. Standard powder-coat is made for a dry room, so in a chiller the choice is a more durable protective finish or galvanised components. A freezer is dry once it is down to temperature, and its worries are frost and the floor. See cold room and chiller racking and our cold room racking page.
• Covered yard or outdoors. A roof keeps off sun and vertical rain, not blown rain, splash from the slab or overnight humidity. Our racking page lists a galvanised option against cantilever racking, marked for indoor or outdoor use. For any other system outdoors, the finish is a quotation question, so get it named in the quote. The rest of that checklist is in outdoor and covered-yard racking.

The bottom metre matters most

Wherever the finish is going to fail first, it is near the floor. The foot of an upright sits in whatever is on the slab: washdown water, condensate, rain splash, a spilt drum. It is also where forklifts clip frames and chip the coating. If you can spend extra on only part of the structure, think about the base of the uprights and the base plates before the top beams.

That is also a reason to treat column guards and barriers as part of the finish decision. A guard that stops a chip is protecting the finish as much as the steel.

What to ask for in writing

1. Which of the five situations the quote assumes. If the quote does not say, it has assumed a dry room.
2. The finish for every component by name: uprights, beams, bracing, base plates and fixings. "Galvanised" on the front page of a quote does not tell you whether it covers the fixings.
3. How cut, drilled and welded edges are treated on site. Any steel cut or drilled after coating has bare edges. A good answer explains the treatment. A vague one is worth writing down.
4. Where the wet points are. Tell the supplier where the washdown, the dock opening or the condensing door is, and ask how those bays are specified.
5. What the real-world rating allows for. We design to a real-world rating of 70 to 80 per cent of the catalogue figure, to allow for impact damage, off-centre loading and corrosion. Ask any supplier what theirs allows for, and whether corrosion is in it.
6. When the first inspection is booked. Our rack inspection looks at uprights and bracing for bend, split or corrosion. Ask for the first inspection to be booked when the racking is handed over and keep the report.

If the racking is already up

You cannot re-finish an installed frame, but you can find out what condition it is in. Look at three places: the bottom of each upright and its base plate, the ends of the beams where they meet the upright, and any spot where the coating has been chipped down to bare steel. Photograph what you find and note where it is. A chip that exposes steel is the point where a powder-coat film is weakest, and it belongs on the list for the next inspection rather than being painted over and forgotten. Our rack inspection service looks at uprights and bracing for bend, split or corrosion, and reports findings green, amber or red.

If the chipping is a result of impact, the cause is the forklift, not the coating, and the more useful fix is protection and a conversation with the driver. That is the more common story, and it is why we say the limit on life is usually impact.

The short version

Powder-coat is the right answer for a dry warehouse and a poor answer for a wet one. The decision has to be made before the order, because it cannot be made after it. Name the room, name the finish for every component, ask how the edges are treated, and put the first inspection in the diary.

Talk it through

If you are planning racking for a washed-down, humid, chilled or outdoor space, message us on WhatsApp with the site location, where the wet or open areas are, what you store and roughly how many bays. We will tell you which finish we would quote against, and the quote follows a site survey. The systems we build are on our pallet racking page.

Related reading: outdoor and covered-yard racking · racking in a food warehouse · cold room and chiller racking