How Should Door Sub-Frames Be Installed in Villas Still Under Construction?

The sub-frame is the preliminary frame fixed to the wall before the door itself. The job looks simple, but it's one of the most commonly mishandled steps in construction — and the cost of getting it wrong falls not on the door afterward, but on the wall and the marble.

When should it go in?

The correct sequence is: shell construction finishes, the walls are built, and the sub-frame is fitted before plastering. Plaster is then pulled level against the sub-frame, giving a straight, plumb surface around the door. A sub-frame fitted after plastering requires cutting and patching around it, and that area is never quite as neat as it would have been on day one.

Don't skip the measurement chain

The sentence we hear most often on site is "we left the opening at 100×220." What needs asking is which measurement that actually is. The sequence runs:

• Clear passage dimension — the actual opening left once the door is open
• Leaf + frame dimension — the door's outer dimension
• Sub-frame outer dimension — the frame that sits against the wall
• Wall opening — the sub-frame dimension plus fitting tolerance

Mix these four up, and either the door doesn't fit or you're left with gaps around it that are hard to close. We laid out this chain with a diagram on our measurement page.

Wondering what your own door needs? Send a photo of your door and entrance via WhatsApp to 0532 689 21 46. In most cases we can tell just by looking; a site survey, if needed, is free.

Level and plumb: a two-minute check

Once the sub-frame is in place, three checks are needed: are both uprights plumb, is the top header level, and are the diagonals equal. The diagonal check is the most skipped but the most informative — if the two diagonals differ by more than a few millimetres, the frame is a parallelogram rather than a rectangle, and no amount of door adjustment will seat it properly.

Fixing method by wall type

How the sub-frame gets fixed depends on the wall it's going into:

Wall	Fixing	Watch for
Reinforced concrete	Steel anchor	Avoid hitting rebar
Perforated brick	Chemical anchor or mesh	Standard plugs loosen over time
AAC block	AAC anchor + load-spreading plate	Loosens under a heavy leaf if load isn't spread

On heavy villa leaves, this choice is critical: no matter how good the hinge is, if the frame is poorly anchored to the wall, the load bends the frame and the door looks like it's sagging.

Protection on site

The sub-frame sits on site for months. During that time, the area takes impacts, gets splashed with mortar and paint, and sometimes has scaffolding leaned against it. Fitting a temporary support batten inside the frame and wrapping the uprights in foam or cardboard costs far less than the repair work that follows otherwise. It's also the first thing the installation crew checks when they arrive.

Don't confuse the sub-frame with the main frame

Two parts often get mixed up on site: the sub-frame is the hidden preliminary frame embedded in the wall; the main frame is the visible profile that comes with the door itself, where the gasket sits and the hinges attach. The sub-frame isn't a structural support for the door — its job is to give the plaster a clean edge and prepare a solid seating surface for the main frame.

In practice this means: if the sub-frame goes in crooked, the main frame sits crooked too, and no adjustment fixes the door. That's why our installation crew checks the sub-frame's level before bringing the door in; if correction is needed, it happens before the door arrives.

Frequently Asked Questions

Is a sub-frame mandatory?

Not mandatory, but it has a clear advantage in a building still under construction: plaster and marble finish flush against the door, and installation is quicker. On a finished building where a door is being replaced, installation without a sub-frame is normal.

Who provides the sub-frame dimensions?

The company producing the door should. Frame depth and tolerance vary by model, so a dimension given independently of the manufacturer may not hold up later. If you have a project drawing, we can also work out the dimensions from it.

Can the dimension change after the sub-frame is fitted?

If the plaster ends up thicker than expected, the clear passage can narrow. That's why we prefer to take a verification measurement once plastering is finished, before starting production on the door.

Let's plan your project from the start

If you're at the construction stage, now is exactly the right time: getting the sub-frame dimension right eliminates a lot of downstream work. Send your project drawing or photos of the opening to 0532 689 21 46.