Yes all engineered timber products should be acclimated to the average prevailing relative humidity of the locality An engineered door is made of several timber components. The core is normal a high density particle board, the veneer is normally real timber and the lipping's (edges of the doors) and inlays (normally routed decorative parts) are all solid timber The main reason for allowing a door to acclimatise is because of the solid timber lipping's and inlays.
Freshly cut timber (also known as green timber) is full of water. When a tree is first cut down the weight can be up to two and a half times the final dried weight, depending on the species and the part of the tree from which the timber comes.There are two types of water in the tree at this point. The first is free water and the second is bound water. Free water is very fast to remove but bound water is deep in the wood’s cells and has to be forced out. Once the process of removing the bound water commences the timber starts to move (contracting, cupping, bowing or twisting.) This is also true if the timber absorbs moisture after drying beyond the free water stage.Bound water is removed in most engineered products by means of a kiln.
Once the timber has undergone kiln drying it then has a moisture content of between 6% and 18%. It then heads to a factory to be made into an engineered door. When the timber arrives at the factory it will be allowed to acclimatise to the factory’s conditions for between 10 and 14 days. The conditions can vary from factory to factory. Some factories will be heated while others will simply be a covered location. The timber will generally absorb or expel moisture in the region of 15% to 18%. The solid timber is then used in production. Once the doors have completed production they will generally be packaged and shipped and stored in similar conditions to that of the factory.
When a door arrives at your property, what happens to the moisture content ? Well this is where acclimatisation is very important. In a continuously heated building timber will generally drop in moisture content from between 6% and 13%. But why does that matter? Timber moves in three ways: Longitudinal movement, tangential movement and radial movement (Fig 2). They all affect the timber in different ways but a simple calculation gives a rough guide to movement. For every 1% change in moisture, timber moves 0.25% to 0.38%. So although this is an approximate measurement, in the most extreme situation the solid timber in your door can be dropping from an 18% to 6% moisture content, resulting in an approximate movement of 3% to 4.56%.