How to select quality lumber for use in construction
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How to select quality lumber for use in construction

Varieties of lumber

The lumber widely available on the market, they can be purchased at almost any store building materials. However, to assess the quality of the products is not always an easy task, especially ordinary consumers.

Cut wood          The types of boards

In turn, the quality of the lumber depends on the strength and durability of the future design. Therefore, it is important to notice and to cull low-quality material.

The lumber needs to sgotovitsya of coniferous pine, spruce, fir, larch and cedar.

Cut lumber is lumber having a rectangular cross-section with a possible tolerance of wane (wane - a defect in sawing hardwood, lingering on the edge of the Board, for example, the bark of a tree), if it does not exceed the specified standards of significance.

Also there is a group of timber edging, which edging can be neoprene or cutting part. Often gets cut lumber with a poorly cutting edges, this suggests that the company is preparing to cut lumber trying to get extra profit by saving hardwood, trying from raw material cut into more products.

You need to understand that this timber has very good performance and should be used as expendable material for construction of the facility. For internal and external trimming, the lumber needs to look perfect.

The classification of lumber

Types of lumber - KALK.PRO

The main types of timber:

1. Logs (logs) - logs, logs.

2. The carriage - beam, traveled once on the sawmill and have two sides of the plane. "Incidental" order of the carriages is:

  • Croaker
  • timber Board

3. Cut the material (when all four sides propylene). Is obtained by cutting the mast. Divided into:

  • timber
  • edged Board
  • small bar

4. Planed mouldings. Can be dry and natural humidity. It relates to:

  • floor boards,
  • sheathing Board (lining and lining),
  • fold,
  • small molded products (plinth, casing, bead, etc.).

5. Glued products. These include glued laminated timber, etc.

The timbers are very expensive woodworking product, as the yield is only 65% and rest 35% waste in the form of slabs (14%), sawdust (12%), scraps, trifles (9%).

The quality of the material

The speed of sawing lumber and hardware settings depends on the range of lot sizes of lumber, as in thickness and in length. The variation in size affects the complexity of fitting the boards to each other, resulting in gaps and inconsistencies in length.

There are the standards characterizing the quality of the lumber, its dimension. This includes Standards, e.g., GOST 8486-86, GOST 10950-78, and a great many others.

The grade of the lumber determines the number of knots per unit length and their number. When choosing the material for the bearing structures, for example, inter-floor beams grade lumber is a more important indicator than its appearance.

The quality of wood and processing boards and the bars are divided into five grades (select 1, 2, 3, 5) and parallel bars - four varieties (1, 2, 3, 4-d) and must meet certain requirements.

The lumber selected, 1, 2, 3rd grades are made dry (with a moisture content of 22%) and crude antiseptic. In the period from 1 may to 1 October, the production of the raw antiseptirovannye and raw lumber allowed with the agreement of the consumer (customer). Moisture content of timber the 4th grade is not standardized.

Aboutzenka quality lumber, except the deck, shall be made on the face or edge, the worst for this Board, and beams and bars of square section - at the worst side.

The roughness parameter of the surface of the lumber should not exceed 1250 µm for selective 1,2, and 3rd grades, and 4th grades - 1600 µm.

Wood defects in timber

Norms of limits of defects

Wood defects
GOST 2140-81
norms of limits of defects in sawn timber for sorts
selected 1st 2nd 3rd 4th
   
1. Bitches

1.1. Fused healthy, and in uneven bars and partially accrete and not accrete healthy:
Permitted size in fractions of the width of the part and quantity on any one meter section of length on each side, not more than:
Size Number,
PCs
Size Number,
PCs
Size Number,
PCs
Size Number,
PCs
Size Number,
PCs
plashchevye and leg
edge: at sawn timber up to a thickness of 40 mm
thickness of 40 mm or more
1/5
1/3


1/4, but
no more
15 mm
2
1


2
1/4
1/2


1/3
3
2


2
1/3
2/3


1/2
4
2


3
1/2
In the entire edge

The same
4
2


3
Allowed
Allowed

Allowed
Note. In the bars the number of knots is not standardized.
1.2. Partially fused Permitted in the total number intergrown sound knots the size in fractions of the width of the part and quantity on any one meter section of length on each side, not more than:
Size Number,
PCs
Size Number,
PCs
Size Number,
PCs
Size Number,
PCs
Size Number,
PCs
plashchevye and leg
edge: at sawn timber up to a thickness of 40 mm
thickness of 40 mm or more
1/8
1/4


10 mm
2
1


1
1/5
1/3


1/4
2
1


1
1/4
1/2


1/3
3
2


2
1/3
In the entire edge

2/3
3
2


2
1/2
In the entire edge

The same
4
2


3
1.3. Decayed, rotten and tobacco Not allowed Permitted in the total number of partially accrete and not accrete healthy knots of the same size and no more than half their number

Wood surrounding tobacco knots, should not have signs of rot.
  In sawn timber for bearing structures, the sum of sizes of all knots, placed on a plot length of 200 mm, shall not exceed the limit size of permissible knots.

Notes:

1. Bitches are smaller than half the maximum are not taken into account.

2. In lumber with thickness of 40 mm or more (excluding selected varieties), allowed the medulla and stitched knots the size in the minor axis up to 6 mm and a depth of up to 3 mm without restriction of the size of the major axis.

3. Stepson is allowed according to the norms dropped out knots. In otonom grade is not allowed.

4. The size of the bitch is determined by the distance between the tangents to the contour of a knot, held parallel to the longitudinal axis of the lumber. For the size of the oblong and sewn together at bitch PlasTech lumber and on all sides of beams and bars take half the distance between the tangent drawn parallel to the longitudinal axis of the lumber:

5. In sawn timber with length more than 3 m is allowed one bitch of a size prescribed in the norms of adjacent lower grade.

6. On a plot of lumber with a length equal to its width, the largest sum of the sizes of knots, lying on a straight line crossing knots in any direction, shall not exceed the limit size of permissible knots.

Continued

Wood defects
GOST 2140-81
Norms of limits of defects in sawn timber for sorts
selected 1st 2nd 3rd 4th
   
2. Cracked

2.1. Plashchevye and edge banding, including facing the end
Allowed length in fractions of the length of lumber of not more than Allowed
while maintaining
the integrity of lumber
Shallow Shallow and deep
1/6

1/10
1/4

1/6
1/3
Deep
1/2
2.2. Plashchevye through, including coming to the end Allowed length, mm, not more: Allowed total length in fractions of the length of lumber:
100 150 200
2.3. Mechanical (excluding shrinkage cracks) Not allowed Permitted at one end of length in fractions of the width of the lumber, not more than: Permitted while maintaining the integrity of lumber
1/4 1/3

1/2

 

Note. The allowable size of cracks are established for sawn timber with moisture content not more than 22%, with more humidity, the dimensions of the cracks are reduced by half.

Continued

Wood defects
GOST 2140-81
Norms of limits of defects in sawn timber for sorts
selected 1st 2nd 3rd 4th
   
3. Defects of a structure of wood
3.1. The inclination of fibres

Allowed
no more than 5 %

Allowed
3.2. KREN Not allowed Allowed
not more than 20%
square plasti
material
Allowed
3.3. Pockets Allowed
unilateral
on any
one meter
length segment
in the amount of
1 PC.
length
more than 50 mm
Allowed on any
one meter of the plot
the length of the lumber in pieces,
no more
Allowed
2 4
3.4. The core and the double core Not allowed Allowed
without otlupnye
and radial
cracks
only
lumber
40 mm thick
and more
Allowed
3.5. Sprout Not allowed Allowed unilateral width in fractions of the corresponding sides of the timber, not more than: Allowed
1/10 1/5 1/4
length in fractions of the length of lumber:
1/30 1/10 1/10
3.6. Cancer Not allowed Allowed for fractional lengths of lumber to Allowed
1/5
but not more than 1 m
1/3

 

Continued

Wood defects
GOST 2140-81
Norms of limits of defects in sawn timber for sorts
selected 1st 2nd 3rd 4th
   
4. Fungal destruction

4.1. Mushroom sound spots (strips)


Not allowed


Allowed total area in % area timber:


Allowed
10 20
4.2. Zabolonnye mushroom colourings and mold Not allowed Permitted surface in the form of spots and stripes. Deep allowed total area in % area timber: Allowed
10 20 50
4.3. Rot Not allowed Not allowed Allowed
only colored
screen jadrovaja decay
in patches
and bands shared
area of not more than 10%
square lumber
5. Biological damage

5.1. The wormhole


Allowed shallow on obzolnoj parts lumber


Allowed on any odnometrovom the whole plot of the length of the lumber in pieces not more than:
2 3 6

 

Continued

Wood defects
GOST 2140-81
Norms of limits of defects in sawn timber for sorts
selected 1st 2nd 3rd 4th
   
6. Foreign inclusions, mechanical damages and defects of processing

6.1. Foreign bodies (wire, nails, metal fragments, etc.)


Not allowed
6.2. Wane (square-edged sawn timber) Sharp is not allowed Allowed
blunt and sharp
provided that
plasti propylene
not less than
1/2 width
and edge not less
than 3/4 length
lumber
Stupid is allowed on PlasTech and edges in the size in fractions of the width of the respective sides of the lumber with no limit on length, no more:
1/6 1/6 1/6 1/3
Allowed on certain sections of the edges in the size in fractions of the width of the edge:
1/3 1/3 1/3 2/3
and a length in fractions of the length of lumber:
1/6 1/6 1/6 1/4

Notes:

1. The bark on alsalah export of timber is not allowed

2. Unsurfaced lumber, appropriate for all indicators with the requirements of a certain sort, but with wane in excess of the established norm for this class are allowed to transfer untrimmed, preserving the grade.

Continued

Wood defects
GOST 2140-81
Norms of limits of defects in sawn timber for sorts
selected 1st 2nd 3rd 4th
   
6.3. Bevel cutting The lumber one end (in the export timber both ends) should be cutting perpendicular to the longitudinal axis of the lumber. The deviation from perpendicularity of end to face and edge is allowed up to 5% of the width and thickness of the lumber, respectively.
6.4. Risks, waviness, digging May be in the range of deviations from the nominal size specified in GOST 24454-80 Allowed depth of less than 3 mm Allowed
7. Pokoroblennost

7.1. Pokoroblennost, longitudinal on plasti, and edge krylovatost
Allowed deflection in fractions of the length of the lumber,%, not more: Allowed
0,2 0,2 0,2 0,4
Note. Uncut lumber in the longitudinal pokoroblennost on the edge not specified
7.3. Pokoroblennost cross Allowed deflection in fractions of the width of the lumber,%, not more: Allowed
1 1 1 2

Notes:

1. Rules of pokoroblennost set for lumber with a moisture content of 22%. At higher humidity these standards is halved.

2. Faults not mentioned in this standard, are allowed.

The defects

 

Pay attention to the quality of lumber

Purchased lumberthat you are going to work should be not only durable and "healthy" - odnorodnymi in color, without any traces of destruction of wood pests. Don't need to use a hardwood for the work affected by the fungus. It is easy to determine to change the color of hardwood and splitting of fibers in the damaged area. The color of the affected timber may vary from cream and brown to bluish and greenish.

Mold affects wood only outside, so the wood can still be saved if promptly clean it from the mold plane and dry well. Rot, especially sound striking a hardwood from the inside, destroying it structure and makes it unusable.

Buying sawn timber of natural humidity, be prepared for the upcoming difficulties: after installing the material will dry out, change shape (warp), decrease treskaetsya.

If you want to avoid the above problems, it is necessary to choose one of the following decisions: to buy already dried according to GOST special equipment lumber or dry already bought. It is possible to dry lumber in natural conditions. This lumber is laid open from the sides of a canopy in the draft, in a shaded place. Each layer of lumber stacked to dry naturally, laid transverse narrow bars.

In the process of natural drying is necessary to ensure that the timber is not rotten under padded bars. In this form, it needs to dry approximately 20-30 days

In order to choose the right suppliers trimming of lumber carefully review existing standards and choose the most suitable class, both in quality and price. In some cases, it may be advantageous to switch to a different wood species, instead of looking for a specific breed with a higher quality class.

Try to estimate how much it will cost you problems with the quality edged lumber. Call up different suppliers. Sometimes it is beneficial to purchase various design elements from different suppliers. If you specify the parameters you need of saw-timber, then you will be able to find a product of excellent quality, and at the most competitive prices!

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