What Are Plinth Blocks And Rosette Blocks?

What are plinth blocks?

A plinth block is a small rectangular piece of MDF or timber that sits at the base of a door frame, one on each side. It occupies the junction where the skirting board ends and the architrave begins, creating a clean visual break between the two.

Plinth blocks are always slightly taller than the skirting and thicker than both the skirting and architrave. This stepped profile is the whole point: the skirting butts up against one side, the architrave sits on top, and both pieces meet the block with simple straight cuts rather than awkward joints.

Plinth blocks have been around for centuries. They were originally structural, supporting heavy stone columns. That load-bearing function has long since disappeared, but the decorative and practical role they play around doorways has kept them relevant, particularly in period properties and, increasingly, in modern homes looking to add a bit of character.

What are rosette blocks?

Rosette blocks sit at the opposite end of the architrave, at the top corners of a door frame. A standard door has two rosettes: one in each upper corner, where the vertical architrave legs meet the horizontal head piece.

Like plinth blocks, rosettes are thicker than the architrave so they sit slightly proud. This allows the architrave to butt up against the rosette with a straight cut rather than a 45-degree mitre. The result is a framed, boxed-in look around the top of the doorway.

Rosettes are square, since they need to accommodate architrave coming in from two directions. Historically, they often featured carved floral patterns, which is where the name comes from. Modern rosettes tend to be simpler, with chamfered or bevelled edges rather than ornate carvings.

Plinth blocks and rosettes are often used together, which gives a door frame a complete, symmetrical border from floor to ceiling. But there is no rule that says you must use both. Some homeowners use only plinth blocks at the base, some use only rosettes at the top, and some use the full set.

Why use plinth blocks and rosettes?

There is a practical side to these mouldings that goes beyond looks. Here are the most common reasons people use them.

They simplify installation

Without plinth blocks, the point where skirting meets architrave requires either a scribe cut or a mitre. If the profiles are different shapes or thicknesses, getting a clean joint becomes fiddly. With a plinth block, both the skirting and architrave simply butt up against the block's flat edges with straight cuts. No mitring, no scribing.

The same applies to rosettes. Instead of cutting precise 45-degree mitres where the top and side architrave pieces meet, each piece butts against the rosette. This is especially helpful for anyone doing the job themselves, as mitre joints are one of the trickiest parts of fitting architrave.

They cover gaps and imperfections

Variations in floor levels, imperfect cuts, carpet removal, and material contraction can all leave gaps where the architrave meets the floor. Unlike skirting boards, architrave cannot simply be lowered to close the gap without creating a new problem at the top. A plinth block sits over the bottom of the architrave and bridges the gap to the floor, hiding the issue entirely.

They solve the skirting board cover problem

Skirting board covers fit over existing skirting, which means they are thicker than the originals. If you install covers but leave the original architrave in place, the skirting will protrude past the architrave and look odd. A plinth block, being thicker than both, provides a clean transition between the two different thicknesses.

They help with uneven walls in older homes

In older properties, walls are rarely perfectly flush. This can cause alignment issues when trying to finish skirting boards neatly against architrave, or vice versa. Plinth blocks are thicker than both, so they give you more tolerance. The skirting and architrave can sit slightly differently on the wall and still meet the plinth block cleanly.

Without plinth blocks, the typical solution is to use thicker architrave. But if you would rather keep the same architrave thickness as the skirting, plinth blocks offer an alternative way to achieve a flush finish.

They protect vulnerable corners

The base of a door frame takes a lot of punishment: vacuum cleaner bumps, shoes, furniture being moved through doorways. A plinth block absorbs these knocks instead of the architrave or skirting. And if the block does get damaged, replacing a single small block is far cheaper and easier than replacing an entire length of architrave.

Do you actually need plinth blocks and rosettes?

The honest answer: probably not, strictly speaking. The vast majority of homes in the UK manage perfectly well with skirting boards and architrave alone. Plinth blocks and rosettes are not a structural necessity in modern construction.

That said, there are situations where they go from "nice to have" to genuinely useful.

In modern homes with straight, flush walls and matching skirting and architrave thicknesses, plinth blocks are a purely aesthetic choice. There is nothing wrong with that. They are increasingly popular as a way to make otherwise plain doorways a bit more considered.

How many do you need?

The quantities depend on how many doorways you are fitting and whether each doorway is accessible from one side or both.

So for a typical house with, say, 8 internal doors that need fitting on both sides, you would need 32 plinth blocks and 32 rosettes if using the full set. If you are only using plinth blocks, that would be 32 plinth blocks.

Choosing the right size

Sizing plinth blocks and rosettes is straightforward once you know the rule: the block should be larger than your skirting and architrave in every dimension. This creates the stepped profile that makes the whole thing work.

Plinth block sizing

There are three dimensions to consider: height, thickness, and width. For each one, choose the next size up from your skirting or architrave.

If you need a size between the standard options, we charge at the next size up. For instance, if you need 230mm tall plinth blocks, you would be charged for the 250mm option with no additional cost. For anything taller than 400mm or wider than 120mm, get in touch and we can price it up.

Rosette block sizing

Rosettes are simpler to size because they are square. The width of the rosette should be wider than your architrave, and the thickness should be greater than your architrave thickness.

For wider architrave, we can produce rosettes at any width needed. Just get in touch for a quote.

The exception to the "bigger in every way" rule

The plinth block must be thicker than the skirting and architrave. That is non-negotiable, as it is the whole point of having one. However, the height and width are more flexible. If you want the top of the plinth block level with the top of the skirting, or the sides level with the sides of the architrave, that is perfectly fine. Some people prefer a subtler look where the block does not project beyond the other mouldings, acting more as a visual break than a feature piece.

Which design to choose

We offer two plinth block designs and one rosette design. Both plinth designs are deliberately simple so they complement rather than compete with whatever skirting and architrave profiles you are using.

Plinth Block P1

Features a small bevelled edge on the top, left, and right front edges. This is our most popular plinth block and works well with both modern and traditional interiors, though it leans slightly more contemporary.

Best for: most setups, particularly modern homes

Plinth Block P2

Even simpler than the P1, featuring just a single chamfered face. Its minimal profile lets the skirting and architrave take centre stage. Works well with both traditional and modern designs.

Best for: understated setups, period properties, and modern alike

There is no wrong choice here. Both designs are intentionally restrained because the plinth block's job is to create a clean transition, not to become the focal point. Choose whichever you prefer the look of, or whichever better matches the edge detail on your skirting and architrave.

Our Rosette Block P1 follows the same design philosophy as the plinth blocks, with a matching profile that keeps the full set cohesive.

Primed vs unprimed

When ordering, you will choose between a primed or unprimed finish. This applies to both plinth blocks and rosettes.

How to install plinth blocks and rosettes

Fitting plinth blocks and rosettes is one of the easier parts of a skirting and architrave job. The key is getting the order right: always fit the blocks first, then the skirting and architrave around them.

Fitting plinth blocks

Fitting rosette blocks

Fitting the architrave between blocks

Once your plinth blocks and rosettes are in place, the architrave fits between them. Measure the distance between the top edge of the plinth block and the bottom edge of the rosette carefully. Each architrave leg slots between its plinth block and rosette with straight cuts at each end, no mitres needed.

The head piece (top length of architrave) runs between the two rosettes in the same way. Accuracy matters here since you are fitting between two fixed points, so measure twice. For a more detailed walkthrough of the architrave itself, see our guide on how to fit architrave.

Finally, fit your skirting boards, butting them straight into the side of each plinth block.

Video guide

For a visual walkthrough of plinth blocks and rosettes, including sizing and installation, have a watch of our video below.

Other uses for plinth blocks and rosettes

Doorways are the primary use, but these blocks turn up in other places too.

Window frames

Rosettes can be used at the corners of window architrave, creating the same framed effect you see around doors. This works particularly well if you are already using rosettes on your doors and want the detailing to carry through the room.

External wall corners

Some people use plinth blocks at external wall corners as decorative features. This creates a period-appropriate look and eliminates the need for mitre cuts where skirting boards meet at external corners. It is a technique you will sometimes see in Victorian and Edwardian properties.

Furniture and wardrobes

Adding a plinth block or rosette detail to freestanding furniture such as wardrobes or drawers can tie them in visually with the room's existing mouldings. It is also a way to refresh an older piece of furniture without replacing it entirely.