Imported, treated, kiln dried timber is grown outside of the UK and is imported in. Imported Timber is usually identified by slower denser growth rings than the commercial softwoods grown within the UK
Treated timber is suitable to be used externally and is suitable for wet areas or areas where the timber will be coming into contact with the ground. Examples of treated timber uses are outdoor decking, shed bases, posts, sleepers along with joisting, stud walls and rafters / hip for roofing.
C16 or C24 Graded
C16 and C24 are strength grades; the higher the grade, the better the load bearing quality it has. C16 is normally the grade that is produced from faster grown UK timber. C24 is a premium product as the wood is slower grown and is also denser. Higher loads and longer spans can be achieved with the use of C24 grade timber often with a smaller cross section. The majority of grading is now performed by machines with x-ray scanning and imaging technology to ensure the timber is within grading guidelines.
Timber can also be graded visually by qualified visual timber graders who assess size, frequency and distribution, shakes, splits and slope of grain. This ensures only the pieces that meet standard limitations are accepted as a grade pass.
Carcassing is a generic trade term which refers to the use of a species of timber. Spruce/Pine and Fir are used to form floors, walls, ceilings and roofs of properties for example.