Shelving on Concrete: LA and Miami Condos

In a house, a concrete wall is a wall you chose. In a tower it is the only wall you have.

Concrete in a converted warehouse is a decision somebody made. Concrete in a condo tower is just the building. That difference sounds small and it changes almost everything about how you approach the wall.

If your exposed brick or cast concrete is a feature you like and want to keep looking at, that is a different post and it is already written — the case for shelving with no back panel, the choice between mortar joint and brick face, and the fact that the wall is the finish. Everything in it applies here.

This one is about the situation underneath that: a wall you did not choose, in a building with rules, where the drilling is permanent and you may not be allowed to do it at all. Three questions in order, and none of them is about shelving.

1. What is this wall, actually?

The single most common mistake in a condo is assuming the wall is what the building is made of. Towers are concrete; the surfaces inside a unit frequently are not.

Four cases, and you need to know which one you have before you buy a fastener:

Exposed cast concrete. What it looks like. Hard, cold, rings solid, no give anywhere. Fixings go anywhere you like, subject to the building's rules and to section 3.

Concrete furred out with drywall. Extremely common, and the one that catches people. A grid of timber or metal furring is fixed to the concrete and drywall is screwed to that, which leaves a shallow cavity — often under an inch — between the plasterboard and the structure. It looks and sounds exactly like an ordinary partition wall for the first three-quarters of an inch. Drill a test hole and you will hit concrete almost immediately, which is the tell, and it means your fixing has to pass through the drywall and the cavity and still get proper embedment in the concrete behind. A drywall anchor here is doing nothing, and a fixing sized for solid concrete may be an inch too short.

Metal stud partition. Interior walls in newer buildings are usually light-gauge steel studs rather than timber. A magnet finds them instantly — much more easily than it finds a timber stud — and they take screws, but not the same screws, and not with the same expectations. Fixings into light-gauge steel are a manufacturer's-values question and they behave nothing like a fixing into a 2×4.

Concrete block or poured shear wall. Solid, and usually structural in a way that timber framing is not. See section 3 before you drill it.

How to find out in five minutes: tap along the wall and listen for the change; run a magnet along it and see whether you get a regular grid; then drill one small pilot hole somewhere invisible — inside a closet, behind where the shelving will go — and pay attention to what comes out. Grey dust is concrete. White dust is gypsum. Curled metal swarf is steel framing.

2. Ask the building before you buy anything

This is the section nobody writes and it is the one that will actually stop you.

Many condo and HOA buildings have rules about drilling into structure, and some are strict. There are good reasons for that, and they are not all bureaucratic:

• Shear walls and structural walls are doing a job for the whole building, not just your unit. What you are allowed to put into one — and how deep — is not your decision alone.
• Post-tensioned slabs. In a great many towers the floor and ceiling slabs contain steel tendons under very high tension. Drilling into one without knowing where they run is genuinely dangerous and expensive, which is why buildings that have them usually say so loudly. This is a slab issue rather than a wall issue in most construction, but it is the reason your building may have a blanket drilling policy, and it is the reason to read the policy rather than assume it is about noise.
• Rented units have a second layer: the owner's permission on top of the building's rules.

None of this is a reason not to shelve a concrete wall. It is a reason to find out first, in writing, because the alternative is discovering the policy after there are anchors in a structural wall. It also frequently comes back as a yes with conditions — a maximum embedment, an approved fixing, a requirement to make good on exit — all of which are things you can design around before you spend anything.

3. On concrete, the track count is the number that matters

Now the shelving decision that is specific to this wall.

The Hangtrack is one track per bay — its length is the width of the bay it carries, 24 in or 36 in. On a stud wall nobody thinks about that, because drilling is quick and revisable. On concrete, every track is a separate hammer-drill operation with its own dust, its own anchors and its own permanent holes, so the count is a real number in the plan:

A 12 ft wall of 36 in bays = four tracks. One row, one height, four short lengths of steel.

Two consequences worth planning around.

Decide the whole layout before the first hole. On drywall, moving a bay 6 in along is filler and paint. On concrete it is a plugged hole that will be visible for as long as the building stands. Draw the full run — every bay, both ends — before the drill comes out, and check it against the obstructions and the outlets. This is the wall where measuring twice is not a proverb.

Choose the anchor spacing for the load, then stop. The track is drilled on a 1 in pitch along its whole length, which on a solid wall means every inch is an available fixing position rather than a hunt for framing. The temptation is to use all of them. Don't — past a certain density extra anchors stop adding useful capacity and start adding permanent holes to a wall you cannot patch, and each one is another few minutes with a hammer drill. The fastener's own published values for your substrate decide the spacing. We publish the gauge of our steel because we bought it and loaded it; we have never seen your wall.

And one thing you get back for the trouble: because the columns hang off the track rather than screwing to the wall, the layout above that single row of holes is still free. Bays slide, shelves move on a 1.25 in pitch, and the wall you were so careful about is not consulted again. On a wall this unforgiving, doing the irreversible part once is the whole argument.

4. Two things about towers specifically

The wall stays visible, and in a condo that is worth more than it sounds. There are no side panels, no back and no carcass — the vertical structure is a slender standard at each bay edge, an inch or so of steel every two or three feet depending on the shelf width, and between them the wall is simply still there. In a unit where the concrete is the architecture, and where you have probably paid for a view and a finish rather than for square footage, not covering the wall is the point.

Coastal air is a coating question, not a steel question. In Miami, in any beachfront building, and in any unit where the balcony door is open more than it is shut, the relevant fact is that this is powder-coated steel: intact, the coating is what faces the room; chipped, there is carbon steel under it, and salt air is unkind to exposed steel in a way that inland air is not. Keep the parts sound, use a damaged one somewhere dry, and do not put open steel shelving outside on a balcony and expect it to behave like it does indoors. We do not publish a marine or exterior rating and you should not infer one.

And in Los Angeles, the seismic question is real — but it is the same question a bookcase asks, and we have written about that where it belongs.

What this costs

Concrete is more work to drill than it is to hold. A hammer drill, dust everywhere, the right anchors, and an afternoon proportional to the run. The holding is trivial. The drilling is the job, and in a building with quiet hours it may also be a scheduling problem.

The holes are permanent and you should price that in. Not in money — in the fact that this layout is the layout. The system stays adjustable above the track line forever; the track line itself is a one-time decision on this wall in a way it is not on drywall.

One track per bay is more tracks than some systems ask for. A continuous rail spanning the whole wall would be fewer drilling sessions. What you get in exchange is that each bay's track is independent, so you can do the wall in stages, and a bay added next year does not mean touching the ones already up.

And the building may simply say no. In which case none of the rest of this applies, and it is much better to find that out on a Tuesday by email than on a Saturday with a drill in your hand.

Before you drill a condo wall

1. Identify the wall. Tap, magnet, one pilot hole in a hidden spot. Grey dust, white dust or metal swarf — that is your answer and it changes the fastener.
2. Read the building's rules, and ask if they are unclear. Get the answer before you buy anchors, not after. If you rent, the owner is a second yes you need.
3. Draw the entire run first. Every bay, both ends, against the real obstructions. On this wall the layout is decided once.
4. Let the fastener manufacturer set the anchor spacing, by substrate, then use the fewest that meets it. Fewer permanent holes is a design goal here, not a shortcut.
5. Keep the top band shallow. Depths of 8, 12 and 16 in mix on one wall, and putting the shallow shelves high leaves more of the concrete in view at the height you actually look at it.

The parts this post describes: the Hangtrack at $35 for 24 in and $39 for 36 in — 12-gauge, drilled on a 1 in pitch, one per bay and the only part fixed to your wall; the Shelf Standards at $49 that hang from it; and the Shelves from $84.99 in 24 in and 36 in widths and 8, 12 and 16 in depths, adjustable on a 1.25 in pitch without tools — which is how a wall you can only drill once stays a wall you can rearrange. Desh Home ships from Atlanta.