The internal strips are generally made of light weight vertical grain spruce.
Blockboard is used to make doors, tables, shelves, paneling and partition walls. It is normally used for interior usages, due to the type of glues used. To achieve maximum strength, it is important to ensure that the core runs lengthways. Blockboard (also called lumber core) has very good screw holding and can be considered as solid wood; it has a good resistance to warping.
Blockboard panels are produced in 3-5 layers, with one veneer sheet (or thin MDF or particlebaord) covering each side, or 5-layers with two veneer sheets per side for better stability.