“What’s the difference between T37 Concealed & T38 Exposed Grid?”
And honestly, I don’t mind answering it every time. Because getting this wrong is the kind of mistake that costs you time, money and a very uncomfortable conversation with a client who notices that you are not using the correct grid system.
So let’s sort it out once and for all — it’s simpler than it sounds.
Before we compare the two, let’s make sure we’re talking about the same thing. A suspended ceiling grid is a metal framework that hangs from the structural soffit or trusses above, creating a secondary ceiling below. You hang wire from the above structure, attach Main Tees — 3 connection points per Main Tee — lock in Cross Tees, and then drop your ceiling tiles into the grid. Job done — in theory.
The grid does several things simultaneously. It holds the tiles, it hides the pipes, wires and ducting above, it provides acoustic control, and in fire-rated applications, it forms part of the passive fire protection system. This is why choosing the right grid for the right application matters more than most people think.
In South Africa, the two grids you’ll encounter on virtually every ceiling project are the T38 exposed grid and the T37 concealed (screw-up) grid. Same family group, but very different look and installation method.
The T38 is your exposed grid system. “Exposed” means the metal tee runner is visible below the tile once the ceiling is installed. You see the white grid lines running across the ceiling in a regular pattern — 600×600mm or 1200×600mm bays — and the tiles simply drop in from above and rest on the flanges of the tee.
This is the grid you’ll find in virtually every office block, school, clinic, retail shop, government building and shopping centre corridor in South Africa. If you’ve ever looked up at a ceiling and seen a white metal grid with acoustic tiles sitting in it, that’s a T38 system. You’ve seen it a thousand times without probably knowing what it was called.
The name T38 refers to the profile height of the main tee runner — 38mm. That height gives it the structural capacity to span the distances required in commercial suspended ceiling applications, support the weight of the tiles, and accommodate light fittings and air conditioning grilles without deflection.
The T38 is the most widely used exposed ceiling grid system in South Africa, manufactured locally to ISO quality standards. The fire-rated version has been independently tested and achieves a 60-minute fire rating for stability and integrity when used with the correct ceiling tile system — something worth specifying on any commercial or institutional project where the building regulations require it. For commercial and institutional buildings, that fire rating matters, and it’s something we can advise on when you come in to spec your job.
The “click” you hear when you lock a cross tee into a main tee is one of those genuinely satisfying sounds in this industry. It means it’s properly seated. If you’re not getting the click, something’s not right — check your main tee alignment before you start tiling.
Here’s where a lot of people go wrong, and it’s important to get this straight: the T37 is not a tile system. It’s a board system. The T37 concealed grid is specifically designed to support 9mm gypsum plasterboard, which is then skimmed with a 3mm finish coat to produce a completely smooth, seamless plastered ceiling. No visible grid, no tiles, no grid lines — just a clean flat surface ready for paint.
The grid itself consists of a T37-profile main tee and a T32-profile cross tee. It carries a galvanised zinc coating for durability and corrosion resistance — important in the humid environments you get inside freshly plastered spaces. Once the 9mm boards are screwed up from below and the joints are taped and skimmed, you’d never know there was a grid above it at all.
This system is the standard specification for flush plastered ceilings in South African homes, offices and commercial interiors — and it’s also used extensively for bulkheads. Bulkheads are those boxed architectural features that drop below the main ceiling level to conceal beams, pipes, ducting or lighting tracks. The T37 system handles these beautifully because it allows you to create a fully plastered, skimmed bulkhead that matches the finish of the rest of the ceiling perfectly.
The aesthetic result is fundamentally different from a T38 exposed grid ceiling. Where the T38 gives you a commercial, grid-pattern look, the T37 gives you a residential or high-end commercial finish — smooth, flat and completely uninterrupted. When a homeowner says they want a “proper plastered ceiling,” this is the system that delivers it.
| Feature | T38 Exposed Grid | T37 Concealed Grid |
|---|---|---|
| Grid visibility | Grid visible below — white tee lines | Grid fully hidden — seamless finish |
| What goes into it | Acoustic or vinyl ceiling tiles (drop-in) | 9mm gypsum board screwed up from below |
| Tile/board sizes | 600×600mm or 1200×600mm tiles | Standard 9mm gypsum board sheets |
| Tile/board edge | Square edge or revealed edge tiles | Tapered edge board — taped and skimmed |
| Finished look | Commercial grid-pattern ceiling | Smooth flat plastered ceiling |
| Used for bulkheads | Rarely | Yes — standard bulkhead specification |
| Access above ceiling | Lift tile out instantly — no tools | Board is fixed — no easy access |
| Grid profile | T38 main tee + cross tees | T37 main tee + T32 cross tee |
| Fire-rated option | Yes — fire-rated version available | Standard — no specific fire rating |
| Typical applications | Offices, schools, retail, clinics, warehouses | Homes, offices, boardrooms, bulkheads |
The T38 system is faster to install and more forgiving of minor irregularities. Because the tiles simply rest in the grid, small variations in hanger spacing or tee alignment are less visible in the finished ceiling. It’s why large commercial projects spec it almost universally — speed and consistency across large areas are what matter.
The T37 is less forgiving. Because the finished ceiling is a continuous flat surface, any misalignment, sagging, or inconsistent tile fixing becomes immediately visible. You need straight, level main tees and accurate cross tee spacing. I’d strongly recommend that homeowners attempting a DIY T37 ceiling get their layout right before a single screw goes in. Snap chalk lines, check your levels, and dry-fit before you commit. Come back to us and we’ll help you plan the layout from your room dimensions — it takes ten minutes and saves a lot of pain later.
One thing both systems share: the quality of your hanger wire installation determines everything. Sloppy, uneven hangers mean an uneven grid, which means an uneven ceiling, which means an unhappy client. Take the time to get your hanger spacing right — typically 1200mm centres on main tees, with perimeter support at 300mm from the wall.
This is the most important practical point in this entire article, so read it carefully.
T38 (exposed) grid takes ceiling tiles — not boards. Your options are acoustic mineral fibre tiles (the standard porous grey/white commercial tile for sound absorption), or vinyl clad tiles (a gypsum-core tile with a vinyl facing, more durable and wipe-clean). Both come in 600×600mm and 1200×600mm sizes. Tiles are available with either a square edge (sits flat on the tee flange) or a revealed edge (has a stepped rebate that creates a shadow line between tile and grid — a more architectural look). These tiles drop into the grid from above. That’s it. (We covered the differences between vinyl and acoustic tiles in detail in our vinyl vs acoustic ceiling tiles blog.)
T37 (concealed) grid takes 9mm gypsum plasterboard — standard ceiling board. The boards are screwed up from below, joints are taped with fibreglass mesh tape and filled with jointing plaster, and then the entire surface is skimmed with a 3mm finish coat. The result is a smooth, continuous plastered ceiling that looks like traditional plaster but is faster to install and doesn’t crack the way solid plaster does.
These two systems are entirely separate. You cannot use T38 drop-in tiles on a T37 grid, and you would not use the T37 concealed system to hang tiles. Ordering the wrong materials for the wrong system is an expensive mistake — one I’ve seen catch people out more than once. When you come to us, we confirm what you’re building before anything leaves the counter.
The bottom line is that neither system is universally “better” — the right choice is entirely job-dependent. Here’s how I break it down at the counter every day:
When you come in to spec a job, tell me what the space is, what the client expects the ceiling to look like, and whether there are any services above that need to be accessed regularly. From there, the right system picks itself.
We stock the full T38 and T37 grid range at our Edenvale warehouse — main tees, cross tees, wall angles, hanger wire and all associated accessories. We also stock the 9mm gypsum ceiling board for T37 installations and the full range of acoustic and vinyl ceiling tiles for T38 systems. Call us on 011 974 0513, WhatsApp on 082 600 1872, or come in at 61 Terrace Road, Eden Glen, Edenvale.
We’re open Monday to Saturday — and yes, we’ll still answer a sensible question five minutes before closing time. It’s just how we operate.