Solid or hollow core internal doors: which should you fit?

10 September 2026 · The Home Upgrade Co.

Nearly every internal door decision people agonise over is about the finish. The one that actually changes how the door feels every day is the core, which is the part you never see. Here is what separates them.

What is the difference between solid and hollow core?

Hollow core doors have a thin skin over a honeycomb cardboard centre. Solid core doors are filled through, so they weigh far more and feel different.

The outside can look identical. Two white primed shaker doors on a merchant's rack can differ by several kilos and behave completely differently once hung.

Vivid Doors sets out the construction difference in detail in its solid versus hollow core guide, including why the honeycomb centre is what keeps a cheap door light.

Which rooms need a solid core door?

Bedrooms, bathrooms and home offices. Anywhere a closed door is supposed to mean privacy, the core is doing that work rather than the finish.

A hollow core door on a bedroom sounds hollow when it closes, and everyone in the house can hear that it is hollow. It is the single most common regret we hear about doors.

Spare rooms, hot presses and store cupboards are where a lighter door is perfectly sensible, and where the money saved is not felt.

Do solid core doors really block more noise?

Yes, and it is mass that does it. A denser core gives sound less to pass through, which is why the heavier door is the quieter one.

There is no magic to it. Sound insulation between rooms tracks fairly closely with the weight of what is in the way, which is why a semi-solid door lands between the two.

The frame and the gap under the door matter too. A good door hung badly, with daylight under it, loses much of the benefit you paid for.

Is a hollow core door ever the right choice?

Often. On a store cupboard, an attic room or a door nobody closes, a lighter door does the job and costs less to hang.

Doors are usually bought as a house set, and treating every opening as equally important is how a door budget gets spent in the wrong places.

The sensible pattern in most Irish semis is solid or semi-solid on bedrooms and bathrooms, lighter doors on the rest.

Does a heavier door need different hinges?

It does. A solid core door needs three hinges rather than two, properly specified, or it will drop and start catching on the frame within a year.

This is where supply-only jobs come unstuck. The door is fine; the ironmongery it was hung on was chosen for a door half the weight.

It is also why a solid core door is worth having hung by somebody who hangs doors every week rather than occasionally.

How much can a door be trimmed to fit an old frame?

A hollow core door only takes a few millimetres off before you cut through the outer lipping and expose the honeycomb, which ruins the door.

Solid and semi-solid doors allow noticeably more adjustment, which matters a great deal in older Dublin housing stock where openings are rarely square.

If your frames are original and out of true, the core you choose is partly a fitting decision and not only a comfort one. That is the thing worth knowing before you order.

Which should you fit in a Dublin house?

Semi-solid on most rooms, solid on bedrooms and bathrooms, hollow on cupboards. That pattern suits the majority of houses we measure.

In a period house with uneven openings, lean further towards solid, because you will need the trimming tolerance whether you want it or not.

In a new build where every opening is square and standard, a lighter door is a defensible choice on the rooms that do not need privacy.

How we handle it

We measure every opening for height, width, thickness and square before anything is ordered, and the core is itemised on your quote so you can see it.

Doors are supplied and fitted by our own team, with the frame replaced where the existing one will not carry a new door properly. All our doors carry a 10 year warranty.

The full range and how fitting works is on our internal doors page.

Frequently asked questions

Are solid core doors worth the extra money?

On bedrooms and bathrooms, yes. The difference in how the door sounds and feels when it closes is the thing people notice every day.

Can you tell a solid core door by looking at it?

Not from the front. Lift it or knock it. A hollow core door is noticeably light and sounds hollow when tapped in the middle.

What is a semi-solid door?

A door with a denser fibreboard or chipboard core rather than a honeycomb one. It sits between the two on weight, noise and price.

Do you have to replace the frame as well?

Only where the existing frame is twisted or out of square. We check each opening at the free measure and the quote says which frames need replacing.