Materials for wood flooring
In residential buildings, wooden floors are most often laid out of coniferous floor sawn timber, from floor boards, made of floor slabs and floor slats (staves).
Floor lumber is made of coniferous species of wood, mainly pine trees, spruce and fir. Planks in five thickness classes can be rough (unthinkable) and planed.
For floors in residential buildings, it is best to purchase three-sided or four-sided planed boards with lengths corresponding to the dimensions of the rooms to be lined..
The boards are made of different lengths, basically from 3,0 m up, co 10 cm. The width of planed floor lumber ranges from 95 mm do 195 mm with gradation every 10 mm.
Planed boards have three types of profiles (drawing).
Drawing. Profiles of four-sided planed softwood floor sawn timber: a) tongue and groove joint, b) connected to the notch, c) butt joint
The choice of the profile depends mainly on the method of fixing the boards to the ground. Planks with tongue and groove should have the width of the groove (d.) greater than the thickness (b) tongues by 0.5-1.0 mm and the depth of the groove (e) more by 1,0 mm from the height of the blade (c). In addition, each board should have an undercut on the bottom surface on the groove side (f) amounting 1,0 mm. The tongue and groove boards are suitable for any type of fixing to the ground. Shapped boards shall have a top flange (b) wider by 1,0 mm from the bottom rebate (c). They are only suitable for fastening with naked nails or screws.
Nominal dimensions of floor sawn timber relate to wood with moisture 15%. When purchasing wood and using it for flooring in rooms with central heating, one should take into account the loss of 7-8% moisture content of the lumber at the end of the heating season. It means shrinkage of the board in the radial or tangential direction by 4-8%, and in absolute numbers by 4— 8 mm at 100 mm of the width of the board (!)
When buying planed floor sawn timber, pay attention to the following defects in wood and processing:
- the face of the boards should not contain rotten and broken knots, signs of rot, sinizny, graying, insect galleries and bullet damage,
- the face surface should be free of wane, burrs, fluffiness and roughness,
- compliance with nominal dimensions, mainly joints and widths of boards along the entire length, and maintaining the perpendicularity of the face plane to the side planes. If the deviation of the board width from the nominal size exceeds +0,5 mm means it, that has a humidity over 15% and absolutely requires drying.
Glued floor boards are the second flooring material.
The floor board consists of three layers (drawing).
Drawing. Cross-section of a glued floor board: a) the middle layer of softwood slats, b) the top layer (facing) made of hardwood slats, c) bottom layer (counter-face) made of softwood slats.
Top layer (facing) It is made of hardwood planks, stacked in two, or three lanes. Bottom layer (counter-face), in contact with the ground, is composed of boards made of coniferous wood. Middle layer (inside) it is composed of softwood slats. All elements of the floor board are glued together with a thermosetting glue. They have humidity 8% and are suitable for direct laying on a dry concrete substrate. Thick floor boards are produced in Poland 15 mm (the thickness of the top layer boards is 4,0 mm), width 137 mm and length 3,0 m, with further gradation in length every 0,25 m. They are (top layer) sanded and covered with varnish. They are connected with a tongue and groove.
When buying glued floor boards, you should mainly pay attention to the quality of the wood and the finishing treatment of the facing layer, and the quality of gluing the boards. They should not show signs of delamination on the foreheads and sides, and significant streaks, stains and blisters after varnishing. The latter in the 1st quality class should not exceed 5% total plane area.