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Door Cores

The Heart of Performance Doors

We all know that having a strong and stable core helps to keep us strong and allows us to perform at our best. We’re told having a weak core can lead to less endurance, fatigue and injuries. The exact same can be said about doors. And whilst not everyone here at Principal Doorsets may have an enviable six pack, we know what it takes to make a quality doorset, and that starts with the core.

With more than 400 years combined experience of doorset manufacturing, here at our site in North Devon, we are experts in producing quality doorsets, fit for the purpose in which they are needed. We know that every part of the door matters from the core of the door to the fixtures and fittings.

We work with clients across industries including education, healthcare, leisure, hospitality and high end residential and we know that no two projects are the same. That is why we offer our clients a range of doorsets with different performance needs, frames, finishes, fixtures and of course cores.

We are here to service your needs and with our enviable reputation for collaborative working and innovative solutions, we will work with you to understand your individual project and will help ensure you are getting the best quality doorset, for your budget.

Our range of door cores include:

Principal Core

This timber lamel core is bonded together and faced with a flat boarding (MDF, Chipboard or Ply). This gives a good fire performance (up to 90 minutes), exceptional duty ratings and is often used in more demanding surroundings such as mental health hospitals, custodial settings and in cross corridor doorsets, in hospital “streets”.

Acoustic core

This is a hybrid core with cork inserts in the centre of the core, covered in lamel sheets then faced with chipboard for accommodation of additional faces. These cores are high end acoustic and offer a working performance of 42dB.


These cores are the thickest we provide. The high-performance insulation comes from a mix of softwood lamels, hardwood stiles and rails, sandwiching super insulation, with board faces in ply, chipboard or MDF. These cores deliver an exceptional performance in thermal efficiency of 0.54 W/m2K, fire performance up to 60 minutes, interior and exterior. This can be enhanced security rated and the core carries a steel strip offering superior stability and is certified component from the Passive House Institute in Darmstadt, Germany.

Softwood core

This has lightweight solid laminated timber cores. Ideal for front entrance doors in residential settings. The performance of these cores is fire resistant up to 60 minutes and has a range of faces to suit requirements (ply or, MDF). As with the Passivhaus cores, this is configurable to enhanced security standards.

HSS (Homogeneous Solid Sheet)

These cores consist of solid tri layered particle board in a range that is up to 90 minutes fire resistance.  This is the standard bearer core for commercial, interior residential settings. It’s a highly configurable core where the centre of the core has long grain fines with the outer layers being much smaller fines, offering a smoother surface ideal for faces like veneers, high pressure laminates, PVC, and prime papers.

We are proud that all our cores are FSC certified products.

To find out more about how we can help you with your next project and help improve your core strength, please visit www.principal or call us on 01237 439 152.