Timber basics article

Hi

Bit of feedback would be good before this timber basics wiki article goes live, since it covers patches I dont know a lot about.... here goes:

=3D=3DSizes=3D=3D Most timber is sold in imperial sizes, with for example 2x4 meaning

2"x4". However this isn't the size of the wood as supplied, its the size its cut to before drying. The size when sold (after drying) is smaller.

'''Timber sizes''' for rough sawn wood: :Nominal Real :1x2 =BE x 1=BD :1x3 =BE x 2=BD :1x4 =BE x 3=BD :1x6 =BE x 5=BD :2x2 1=BD x 1=BD :2x3 1=BD x 2=BD :2x4 1=BD x 3=BD :2x6 1=BD x 5=BD :2x8 1=BD x 7=BC :2x10 1=BD x 9=BC :2x12 1=BD x 11=BC :4x4 3=BD x 3=BD

Planed wood is a little smaller, usually by around 5-7mm each way. 2x4 PSE is just 2x4 rough sawn that has been planed to make it smooth.

Some timber is sold in metric. With this the stated size is the size you get.

=3D=3DFinishes=3D=3D ;Rough sawn :Expect splinters aplenty.

;PAR :Planed All Round. There's no guarantee of accurate squareness with PAR, a lot of PAR is true, some not. PAR has mostly been supplanted by PSE today. Hand planing produces PAR.

;PSE :Planed Square Edge. This is planed all round with sides at 90 degrees.

;CLS :Canadian Lumber Standard. CLS is planed smooth, has rounded corners, and is free of large knots at the edge of the wood. These features reduce the spread of fire in [[Partition Wall|timber frame wall]] cavities.

=3D=3DQualities=3D=3D =3D=3D=3DWhitewood=3D=3D=3D Whitewood is a grade of wood intended for [[First fix & second fix| first fix]] use, ie domestic woodwork that will not be seen when the project is complete. It may have splits, stains, and some warp.

Whitewood is generally spruce pine. [[Special:Allpages|DIY]] sheds sell a lot of whitewood.

The quality of whitewood on sale has improved over the years, and a percentage is good enough for [[First fix & second fix|second fix]].

=3D=3D=3DRedwood=3D=3D=3D Redwood is a grade of wood intended for [[First fix & second fix| second fix]] use, ie domestic woodwork that will be seen when the project is complete. Its mostly free from splits & stains, and generally has much less warp than whitewood, though warp is still an issue.

Redwood is generally one of the many types of pine.

=3D=3D=3DJoinery=3D=3D=3D Joinery timber is clear, with a knot-free surface. Its used for [[Furniture Links|furniture]].

=3D=3DGrading=3D=3D Grading is a visual assessment of the structural strength of the timber. Key features assessed in grading are

  • Splits
  • Knots, especially large knots at the edge of the wood

Most timber bought for [[Special:Allpages|DIY]] use is ungraded. This means it has sizeable knots at the edges, which affect its strength. Graded wood is stamped with the grading details.

For new floor joists and roofing one should use graded timber. C16 is the most common grade, but C24 and some less common graded timber is also available. The higher spec grades may be used where dimensions need to be minimised.

=3D=3DSpecies=3D=3D Most wood used for [[Special:Allpages|DIY]] is pine of one variety or another, often spruce pine. Other species are also used, but command a higher price, limiting their use.

=3D=3DBuying Wood=3D=3D Ordering wood to be delivered means you don't pick the timber. This is ok for [[First fix & second fix|1st fix]], but with work where the wood needs to be straight it can be a problem, timber yards are known for sometimes using new customers to clear junk.

=3D=3DBent Wood=3D=3D Bent stock is ever a problem. =3D=3D=3DWarp=3D=3D=3D Selective cutting or 'docking' deals with a lot of warp. Wood often warps at points (knots) rather than all along, so cutting it at those points gives shorter pieces of straight wood.

In principle warp can also be stabilised by [[Adhesive|gluing]] and [[screws|screwing]] 2 pieces of warped timber back to back. Its not normally worth doing, but if you're stuck for one piece it may be quicker than going out.

Warped wood is good for [[Partition Wall|framing]], where considerable warping is tolerable. When the warp is too bad, the wood can be cut short and used for noggings.

=3D=3D=3DTwist=3D=3D=3D Twisted wood can sometimes be made good enough by cutting to short lengths, as the amount of twist on each piece is then much smaller. This often works for [[First fix & second fix|first fix]], but there's always more junk wood than uses for it.

Other ways to deal with twisted wood are:

  • Using it fixed firmly to something much stronger, thus forcing it to untwist
  • Use it for [[Partition Wall|framing]], which is somewhat tolerant of twist
  • Plane it to give smaller straight timber.
  • Don't buy it in the first place!

=3D=3DWater Content=3D=3D All timber contains some [[water]]. Where stabilty matters, which is most applications, timber should be either purchased with water content similar to final use, or else acclimatised before use. If ignored, warp and twist are more likely after fitting.

=3D=3D=3DGreen & Seasoned=3D=3D=3D Most wood for [[Special:Allpages|DIY]] work is seasoned. Green wood (meaning unseasoned rather than green in colour) has high [[water]] content, and is liable to move during drying, making it of limited use for [[Special:Allpages|DIY]]. The main exception is green oak used for oak frame.

=3D=3DDurability=3D=3D Most timber is not durable, meaning it soon rots if used outdoors without protection from water. The options for outdoor timber are:

  • durable timber
  • non-durable timber plus wood preservatives or paint

Well known durable species include

  • oak
  • red cedar

Note that the sapwood of all species is non-durable, its heartwood thats durable. The majority of timber is heartwood.

=3D=3DSee Also=3D=3D

  • [[Leylandii Wood]]
  • [[Holly]]
  • [[http://216.239.59.104/search?q=3Dcache:IfN6hPrQTfUJ:oak.arch.utas.edu.au/glossary/glossary.pdf+timber+glossary&hl=3Den&ct=3Dclnk&cd=3D1&client=3Dopera Timber Glossary]]
  • [[Special:Allpages|Wiki Contents]]
  • [[Special:Categories|Wiki Subject Categories]]

[[Category:Wood]]

Reply to
meow2222
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Sounds very good. Very little I'd change/add.

I might mention "regularised" as in "regularised & treated" which is becoming more common for structural work. Has all four edges radiused for easy handling and is "hit and miss" planed.

Also AIUI most structural timber is automatically stress graded by deflection testing, rather than visual grading.

And AFAIK all timber is sold in 300mm length multiples.

Reply to
dom

Although some (e.g. waney edge or rough sawn hardwoods) is priced by the cube (and some still mean cu. foot rather than cu metre).

Reply to
dom

I've never seen timber sold in imperial sizes. I know we all go to Wickes looking for a piece of 3 x 2 but its never marked, advertised or sold that way.

I buy a lot of 150 x 50 & 100 x 50 sawn treated timber that is pretty much smooth to the touch e.g. can be freely handled without gloves & no splinters. Depends where you buy it I guess.

Reply to
The Medway Handyman

The merchants I use regularly is entirely metric, but the other one in town still "talks" imperial.

Reply to
dom

What's "spruce pine" ?!

Redwood has more chance of being a pine than whitewood, but it's still a bit strong to call it "generally pine". Spruce or fir would be more likely.

Very little of what's sold in the UK as "pine" is actually related to pines.

Reply to
Andy Dingley

Check to see if it is marked CLS rather than just KD - the former is designed to be safer to handle.

Reply to
John Rumm

Minor point, but here in blighty we list the large dimension first. So that should be 4x2

These seem small for KD sawn. Perhaps right for CLS. IME 100x50 KD sawn is pretty close to those sizes.

I think most timber is sold in metric these days - even if we tend to order in imperial.

And make it safer to handle.

Quite often cheaper than KD as well. However you need to watch carefully if mixing types in one project to keep things lined up in spite of the subtle variations of size.

Much of the stuff you buy will be stress graded to C16.

In addition to C24 being graded stronger, there will be a statistically smaller distribution of strengths when looking at a number of pieces. Hence for calculation purposes, you can assume a higher average strength

- especially when a load is shared between several beams.

Might be worth a note saying not to confuse bent with "camber" - even straight enough stock may well have a slight camber (hence the tradition of sighting down each joist before laying, and cambering them all "up")

Much construction timber will have been Kiln Dried to a specific water content (and will be stamped KD). However that does not control how it is then stored by the timber merchant!

Reply to
John Rumm

Don't know the situation in the UK but over here some kind of wood is always smaller than the stated dimension. 5 mm thick plywood is more like 4.5 mm thick, for example.

Reply to
Andre Majorel

I seem to remember that, for practical purposes, ALS = CLS. (Maybe for all purposes, but I don't know.)

Reply to
Rod

Dear meow2

Laudible effort and will be useful. Thanks

Some points

1 White wood is (or should be) only Spruce eg Sitka (Picea sitchensis) or Norway (Picea abies) or the like and normally does not contain pine Redwood is normally (or should be) only Scots Pine (Pinus sylvestris) see '
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'2Decide where you mean spruce and where you mean pine and use one or the other 3 Moisture content Building regs require less than 18%w/w for structural timbers and if it feels heavy (say post treatment with Tanalith) don't buy it! It is always good to allow timber to equilibrate with the internal structure but most DIYs do not have the planning skills or SWIMBOs that allow timber to be bought 6 months in advance and put inside the house to equilibrate! Joinery timbers will shrink as they go from about 14 to 16% as sold down to 8 or 10% - its a fact of life unless you plan to avoid it. 4 Durability There are five grades of natural durability. All sapwood of all species is perishable. Only the heartwood can be graded for durability. There are five grades (BRE Digest 429) These are in order of durability Perishable (0 - 5 years in ground contact for a 2" x2" stake) Non-durable (5 - 10 years) Moderately Durable (10 - 15 years) Durable (15-25 years) and Very durable (25+). Examples are as follows: Perishable: Horse chestnut, birch, lime, poplar, willow, ramin, plane; Non-durable: Scots Pine, Beech, elm, fir (grand,noble sivler), hickory, maple, pine (American pitch, Canadian red, Corican, Jack, parana ponderosa, radiata), Spruce (Engleman European Eastern Canadian, Sitka American pitch pine Moderatetly durable: Central American cedar, Sweet Chestnut, Leyland Cyprus, kauri (NZ),Keuring, Larch (all types), Meranti, Pine (maritime), Oak (Turkey) Durable: Cedar (Western Red, yellow)Idigbo (getting popular these days) Meranti, American White oak, utile, yew Very durable: Oak (European), caphorwood, Ebony, Ekki, Lignum vitae, Teak, Greenheart

You have yet to mention treatment .... eg Tanalith Aqauvac and double vac Chris

Reply to
mail
4 Durability There are five grades of natural durability. All sapwood of all species is perishable. Only the heartwood can be graded for durability. There are five grades (BRE Digest 429) These are in order of durability Perishable (0 - 5 years in ground contact for a 2" x2" stake) Non-durable (5 - 10 years) Moderately Durable (10 - 15 years) Durable (15-25 years) and Very durable (25+). Examples are as follows: Perishable: Horse chestnut, birch, lime, poplar, willow, ramin, plane; Non-durable: Scots Pine, Beech, elm, fir (grand,noble sivler), hickory, maple, pine (American pitch, Canadian red, Corican, Jack, parana ponderosa, radiata), Spruce (Engleman European Eastern Canadian, Sitka American pitch pine Moderatetly durable: Central American cedar, Sweet Chestnut, Leyland Cyprus, kauri (NZ),Keuring, Larch (all types), Meranti, Pine (maritime), Oak (Turkey) Durable: Cedar (Western Red, yellow)Idigbo (getting popular these days) Meranti, American White oak, utile, yew Very durable: Oak (European), caphorwood, Ebony, Ekki, Lignum vitae, Teak, Greenheart

====

Chris,

Very useful list. Can you confirm that these grades are for non-treated timmber?

Thanks, Piers

Reply to
Piers Finlayson

Piers Yes This is NATURAL durability. The same digest deals with porosity - hence the propensity for proper treatment. For example, spruce is non porous and does not take pressure or other treatment well but Scots pine is permeable and does treat well.

Reply to
mail

Bit of feedback would be good before this timber basics wiki article goes live, since it covers patches I dont know a lot about.... here goes:

Any idea where the word timber came from, and there doesn;t seem to be a mention of using the word as a warning to "get out of the way" when cutting trees down ;-)

Reply to
whisky-dave

You shouldn't have asked that. :-)

timber

O.E. timber "building, structure," later "building material, trees suitable for building," and "wood in general," from P.Gmc. *temran (cf. O.Fris. timber "wood, building," O.H.G. zimbar "timber, wooden dwelling, room," O.N. timbr "timber," Ger. Zimmer "room"), from PIE *demrom-, from base *dem-/*dom- "build" (source of Gk. domos, L. domus; see domestic). The O.E. verb timbran, timbrian was the chief word for "to build" (cf. Du. timmeren, Ger. zimmern). As a call of warning when a cut tree is about to fall, it is attested from 1912 in Canadian Eng. Timbers in the nautical slang sense (see shiver (n.)) is from the specialized meaning "pieces of wood composing the frames of a ship's hull" (1748).

tim·ber (tim?b?r)

noun

a building building material wood suitable for building houses, ships, etc., whether cut or still in the form of trees a large, heavy, dressed piece of wood used in building; beam Brit. lumber () trees or forests collectively personal quality or character a man of his timber Shipbuilding a wooden rib

Etymology: ME < OE, akin to Ger zimmer, room (< OHG zimbar, wooden structure) < IE base *dem-, *dema-, to join together, build > L domus, house

Reply to
Rod

Ah. Someone else with a love of English!

Zooterkins!

Reply to
The Medway Handyman

Looks like it (zimbar/timber) could be an example of the High German consonant shift. (Thanks Wiki :-) )

Reply to
Rod

Thanks everyone for the feedback, lots of good stuff. When I get time I'll do more rewriting. For now a few comments & qs:

Dimensions - will rethink that bit.

Point taken, but I think thats outside of a basics article. This is more intended to be info for people not yet familiar with the basic terms and concepts, a place to begin. A 2nd article for that sort of info would be good, but I cant think of a good name for it

Going to keep that for a more in depth timber article, which would be a bit beyond me to write on my own, but I can make a start some time.

eg Tanalith Aqauvac and double vac

yes, but again for a deeper article I think. And I dont know much about it.

Timberboard: is the surface sanded or just planed? IME planing is unable to remove all surface imperfections since the angle of wood fibres is invariably wrong somewhere.

thanks, NT

Reply to
meow2222

Draft no 2 of the Timber Basics article... I've added more sections too. Lets see what you think.

=3D=3DTimber Sizes=3D=3D The timber industry has long operated in imperial sizes, and imperial terms are still in widespread use today. However legislation has outlawed the sale of goods in inches and feet, so timber is marked as the nearest metric size to the standard imperial sizes.

Most timber is bought in imperial sizes, with for example 2x4 meaning

2"x4", however sellers must describe it in metric and an increasing amount of timber is bought as metric sizes.

For rough sawn wood the nominal size is usually very close to the real size supplied. However this isn't so in all cases, especially when dealing with used wood. Its not unusual to find historic 2x4s that are nearer 1.5" x 3.5"

Planed wood is a little smaller than rough, usually by about =BC" or

5-7mm each way. 2x4 PSE is simply 2x4 rough sawn that has been planed to make it smooth.

When timber is sold in metric, the stated size is the size you get.

=3D=3D=3DLength=3D=3D=3D Timber is sold in various lengths that are multiples of 30cm (a foot). Most common are 6', 8' & 10'. Several longer sizes are also sold. Note however that the metric equivalent lengths are very slightly shorter than imperial, so if you need exactly 8', 2.4m is slightly short.

=3D=3DPrice=3D=3D Most timber is sold by price per length, and some by price per cubic foot. Some example price lists:

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    are not company recommendations

=3D=3DTerms=3D=3D ;Rough sawn :Usually a splintery finish, but smoother sawn surfaces are seen on some goods.

;PAR :Planed All Round. There's no guarantee of accurate squareness with PAR, a lot of PAR is true, some not. PAR has mostly been supplanted by PSE today. Hand planing produces PAR.

;PSE :Planed Square Edge. This is planed all round with sides accurately at

90 degrees.

;PFS :

;CLS :Canadian Lumber Standard. CLS is planed smooth, has rounded corners, and is free of large knots at the edge of the wood. These features reduce the spread of fire in [[Partition Wall|timber frame wall]] cavities and make it safer to handle.

;ALS : American Lumber Standard, very similar to CLS

;Regularised : Similar to CLS but the planed surface is not consistently smooth, it may be rough sawn in areas.

;Kiln dried, KD : timber dried to a specified moisture content. However poor storage by the merchant (after drying) may result in higher moisture content.

=3D=3DQualities=3D=3D =3D=3D=3DWhitewood=3D=3D=3D Whitewood is spruce timber intended for [[First fix & second fix|first fix]] use, ie domestic woodwork that will not be seen when the project is complete. It may have some splits & stains and some warp.

[[Special:Allpages|DIY]] sheds sell a lot of whitewood.

The quality of whitewood on sale has improved over the years, and a percentage is good enough for [[First fix & second fix|second fix]].

Spruce doesn't take dyes well, and preservatives have limited penetration.

=3D=3D=3DRedwood=3D=3D=3D Redwood is a grade of wood intended for [[First fix & second fix| second fix]] use, ie domestic woodwork that will be seen when the project is complete. Its mostly free from splits & stains, and generally has much less warp than whitewood, though warp is still an issue.

Redwood is generally spruce, fir or pine.

=3D=3D=3DJoinery=3D=3D=3D Joinery timber is clear, with a knot-free surface. Its used for [[Furniture Links|furniture]].

=3D=3DGrading=3D=3D Grading is an assessment of the structural strength of the timber. Key features assessed in grading are splits and knots, especially large knots at the edge of the wood.

Small timber bought for [[Special:Allpages|DIY]] use is mostly ungraded. Graded wood is stamped with the grading details.

For new floor joists and roofing one should use graded timber.

C16 is the most common grade, but C24 and some less common timber grades are also available. The higher spec grades may be used where dimensions need to be minimised.

=3D=3DSpecies=3D=3D Most wood used for [[Special:Allpages|DIY]] is spruce, fir or a pine. Other species are also used, but command a higher price, limiting their use.

=3D=3DBuying Wood=3D=3D Ordering wood to be delivered means you don't pick the timber. This is ok for [[First fix & second fix|1st fix]], but with work where the wood needs to be straight it can be a problem, timber yards are known for sometimes using new customers to clear junk.

=3D=3DProblem Wood=3D=3D Bent stock is a regular problem. =3D=3D=3DWarp=3D=3D=3D Selective cutting or 'docking' deals with a lot of warp. Wood often warps at points (knots) rather than all along, so cutting it at those points gives shorter pieces of straight wood.

In principle warp can also be straightened by [[Adhesive|gluing]] and [[screws|screwing]] 2 pieces of warped timber back to back. Its not normally worth doing, but if you're stuck for one piece it might be quicker than going out.

Warped wood is good for [[Partition Wall|framing]], where considerable warping is tolerable. When the warp is too bad, the wood can be cut short and used for noggings.

=3D=3D=3DTwist=3D=3D=3D Twisted wood can sometimes be made good enough by cutting to short lengths, as the amount of twist on each piece is then much smaller. This often works for [[First fix & second fix|first fix]], but there's always more junk wood than uses for it.

Other ways to deal with twisted wood are:

  • Using it fixed firmly to something much stronger, thus forcing it to untwist
  • Use it for [[Partition Wall|framing]], which is somewhat tolerant of twist
  • Plane it to give smaller straight timber.
  • Don't buy it in the first place!

=3D=3D=3DCupping=3D=3D=3D Planks are prone to cupping, whereby one side becomes convex and the other concave. If its desired to fix it, wetting the dished side will expand it a little, and it can then be dried while weighted flat. The thinner the plank, the more chance of success.

=3D=3D=3DStability=3D=3D=3D Timber defects can often be worked around, but warped or twisted timber has bent since cutting, and is thus unstable. Changes in moisture content are prone to producing movement again. This further restricts the uses for such wood.

=3D=3D=3DUses for junk wood=3D=3D=3D [[Partition Wall|Timber framing]] is the main use. All sorts of defects can be hidden behind [[Sheet Materials|plasterboard]] once finished.

  • Wood with [[paint]], [[nails]] or damage will all be hidden
  • Bent wood can be fitted bending sideways
  • Even wood bent both ways will only cause gentle undulation on the plasterboard if not too bad, and this usually isn't noticeable.
  • Split wood can be used too, adding a few [[screws]] to fix it together.
  • Almost anything can be used as noggings: undersize, odd shaped, badly bent, even [[Adhesive|glued]] offcuts.

Mildly bent wood can also be used in timber framed [[Sheds|shed construction]]. Its hidden by the cladding.

=3D=3DWater Content=3D=3D All timber contains some [[water]]. Where stabilty matters, which is most applications, timber should be either purchased with water content similar to final use, or else acclimatised before use. If ignored, warp and twist are more likely after fitting.

Timber used in new build for structural elements is required to have a maximum of 18% water content. (Many houses have been built with green timber.)

=3D=3D=3DGreen & Seasoned=3D=3D=3D Most wood for [[Special:Allpages|DIY work]] is seasoned. Green wood (meaning unseasoned rather than green in colour) has high [[water]] content, and is liable to move during drying, making it of limited use for [[Special:Allpages|DIY]]. The main exception is green oak used for oak frame. Timber frame [[sheds]] can also be built with green, as some movement on drying is usually acceptable.

=3D=3DDurability=3D=3D Most DIY timber is not durable, meaning it soon [[Wood Rot|rots]] if used outdoors without protection from [[water]]. The options for outdoor timber are:

  • durable timber
  • non-durable timber plus [[Wood Preservatives|wood preservative]] or [[paint]]

Well known durable species include

  • oak (very durable)
  • red cedar

Note that the sapwood of all species is non-durable, its heartwood that's durable. The majority of timber is heartwood, with only the outer layer of the tree (under the bark) being sapwood.

=3D=3D=3DTreatment=3D=3D=3D Timber is available ready treated against rot. Vacuum treated timber is most effectively preserved, as the [[Wood Preservatives|chemical]] soaks further into the wood. Cutting it exposes unpreserved ends, which should be [[Wood Preservatives|treated]] for best life expectancy.

When applying [[Wood Preservatives|preservative]], the cut ends need the most attention, as they soak up water like a sponge. Cut ends will usually sponge up several coats of preservative, which helps it last longer.

=3D=3DBoard=3D=3D Timber also comes in board form. The most common types are hardboard, chipboard, MDF, plywood and timberboard. These are all described in [[Sheet Materials]].

[[Sheet Materials#Hardboard|Hardboard]]: thin non-rigid brown board, typically 3mm thick. Most used as low cost drawer bottoms. [[Sheet Materials#Chipboard|Chipboard]]: wood chippings glued together, and sometimes coated with white melamine, brown imitation wood veneer etc. Most common furniture board in Britain. Usually fairly weak and vulnerable to water. [[Sheet Materials#MDF|MDF]]: a uniform brown material, can be machined and worked without grain being an issue. Vulnerable to water and not very strong. [[Sheet Materials#Plywood|Plywood]]: Available in many grades for different purposes. Dimensionally stable, strong in both directions, and one of the stronger wooden board types. Lower cost plywoods are vulnerable to water and delaminate fairly easily. [[Sheet Materials#Timberboard|Timberboard]]: Strips of wood glued side by side to create flat board. Gives a real wood finish. Strong along the grain, less so across. Cups badly if exposed to water on one side for a day, but normal cup spills don't do this.

=3D=3DPine=3D=3D Pine is a genus of conifers covering many different varieties of tree. Timber described as pine isn't necessarily a pine species at all, but it will have much the same appearance and properties, making the end result the same. Redwood has the highest odds of being real pine.

=3D=3DDrilling holes=3D=3D Most holes [[Drill Bits|drilled]] in wood are either pilot holes, clearance holes or countersink holes.

'''Clearance holes''' allow the [[screws|screw]] to slide through freely. An ideal size for this is the full width of the screw shank plus half a millimetre. Hole size isn't critical, but if too large the head may sink into the hole when tightened, enlarging the hole in the process.

'''Pilot holes''' are holes that enable [[screws|screws]] to be driven in without difficulty or risk of splitting the wood. A good size for pilot holes is half a milimetre slightly larger than the narrowest width seen on the screw spiral.

'''Countersink holes''' are very shallow tapering holes for the [[screws|screw head]] to sit in. These allow a counterunk head to sit flush with the surface. They are generally [[Drill Bits|drilled]] using a [[Drill Bits|countersink]], but can also be made with a large drill bit. In most cases the size and shape of the countersinking hole need not match the screw head well, as the head will distort the wood under it to some extent.

/| ____ /\/\/\/\/\/\/ | pilot hole ____ < | \/\/\/\/\/\/\ | \|

____ /| /\/\/\/\/\/\/ | clearance hole < | ____ \/\/\/\/\/\/\ | \|

____ /| /\/\/\/\/\/\/ | < | countersink \/\/\/\/\/\/\ | \| ____

Guide to Approximate Hole Sizes

=3D=3D=3DPilot Holes=3D=3D=3D Experience will soon tell you when to use a pilot hole and when not. Generally speaking, small screws in medium timber or bigger don't need pilot holes, but with medium to big screws or small timber the chances are a pilot hole would be wise. Lack of pilot hole can cause splitting in small wood, or jamming with medium to large screws.

=3D=3D=3DCountersink holes=3D=3D=3D Again sometimes they're needed, sometimes not. [[screws|Plasterboard screws]] have heads that penetrate less than traditional countersunk heads, and can usually be sunk fine without [[Drilling Techniques| drilling]] first.

=3D=3D=3DKnots=3D=3D=3D Knots are made of much tougher material than the surrounding wood. Screwing into knots with standard size pilot holes causes the wood to split. Its generally best to avoid knots when fixing, but sometimes a [[screws|screw]] is needed there. A simple solution is to use a slightly larger pilot hole, then they behave fine, good grip and no splits. Never try to screw a knot with no pilot hole.

[[Nails]] may be driven through knots if a pilot hole is [[Drill Bits| drilled]] first - though this is rarely necessary. Don't attempt to nail a knot without pre-drilling.

=3D=3DDifficult screws=3D=3D =3D=3D=3DGoing in=3D=3D=3D Awkward [[screws]] that are proving difficult to get in mean you need a pilot hole, or a bigger pilot hole. If the right [[Drill Bits|drill bit]] isn't to hand, dipping the screw in oil makes a difference and is often enough. Dipping a screw in oil before driving reduces friction, requiring less energy to get the job done. Various substitutes can be used, such as margerine, chocolate, etc.

Don't labour over a tough [[screw]], if it won't go in just take it out and fix the problem. If you keep at it you'll only end up with a well jammed screw that requires repeated curses to get out.

=3D=3D=3DComing out=3D=3D=3D There are numerous ways to get stuck screws out. See [[Screws#Removing a Damaged Screw|Removing a Damaged Screw]]

=3D=3DUsed wood=3D=3D There is a gotcha with used wood: most power [[saws]] and embedded [[nails]] really don't mix well. If you regularly use old timber, nail- safe circular saw blades are available. For occasional work one can use a hand saw or jigsaw. Nails can damage the blades on these, but not the operator.

Planes are also vulnerable, so used wood is generally better not planed.

=3D=3DSee Also=3D=3D

  • [[Sheet Materials#Plywood|Plywood]]
  • [[:Category:Wood|All Wood category articles]]
  • [[http://216.239.59.104/search?q=3Dcache:IfN6hPrQTfUJ:oak.arch.utas.edu.au/glossary/glossary.pdf+timber+glossary&hl=3Den&ct=3Dclnk&cd=3D1&client=3Dopera Timber Glossary]]
  • formatting link
    abbreviations]
  • [[Special:Allpages|Wiki Contents]]
  • [[Special:Categories|Wiki Subject Categories]]

[[Category:Wood]]

Reply to
meow2222

Draft no 2 of the Timber Basics article... I've added more sections too. Lets see what you think.

=3D=3DTimber Sizes=3D=3D The timber industry has long operated in imperial sizes, and imperial terms are still in widespread use today. However legislation has outlawed the sale of goods in inches and feet, so timber is marked as the nearest metric size to the standard imperial sizes.

Most timber is bought in imperial sizes, with for example 2x4 meaning

2"x4", however sellers must describe it in metric and an increasing amount of timber is bought as metric sizes.

For rough sawn wood the nominal size is usually very close to the real size supplied. However this isn't so in all cases, especially when dealing with used wood. Its not unusual to find historic 2x4s that are nearer 1.5" x 3.5"

Planed wood is a little smaller than rough, usually by about =BC" or

5-7mm each way. 2x4 PSE is simply 2x4 rough sawn that has been planed to make it smooth.

When timber is sold in metric, the stated size is the size you get.

=3D=3D=3DLength=3D=3D=3D Timber is sold in various lengths that are multiples of 30cm (a foot). Most common are 6', 8' & 10'. Several longer sizes are also sold. Note however that the metric equivalent lengths are very slightly shorter than imperial, so if you need exactly 8', 2.4m is slightly short.

=3D=3DPrice=3D=3D Most timber is sold by price per length, and some by price per cubic foot. Some example price lists:

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    are not company recommendations

=3D=3DTerms=3D=3D ;Rough sawn :Usually a splintery finish, but smoother sawn surfaces are seen on some goods.

;PAR :Planed All Round. There's no guarantee of accurate squareness with PAR, a lot of PAR is true, some not. PAR has mostly been supplanted by PSE today. Hand planing produces PAR.

;PSE :Planed Square Edge. This is planed all round with sides accurately at

90 degrees.

;PFS :

;CLS :Canadian Lumber Standard. CLS is planed smooth, has rounded corners, and is free of large knots at the edge of the wood. These features reduce the spread of fire in [[Partition Wall|timber frame wall]] cavities and make it safer to handle.

;ALS : American Lumber Standard, very similar to CLS

;Regularised : Similar to CLS but the planed surface is not consistently smooth, it may be rough sawn in areas.

;Kiln dried, KD : timber dried to a specified moisture content. However poor storage by the merchant (after drying) may result in higher moisture content.

=3D=3DQualities=3D=3D =3D=3D=3DWhitewood=3D=3D=3D Whitewood is spruce timber intended for [[First fix & second fix|first fix]] use, ie domestic woodwork that will not be seen when the project is complete. It may have some splits & stains and some warp.

[[Special:Allpages|DIY]] sheds sell a lot of whitewood.

The quality of whitewood on sale has improved over the years, and a percentage is good enough for [[First fix & second fix|second fix]].

Spruce doesn't take dyes well, and preservatives have limited penetration.

=3D=3D=3DRedwood=3D=3D=3D Redwood is a grade of wood intended for [[First fix & second fix| second fix]] use, ie domestic woodwork that will be seen when the project is complete. Its mostly free from splits & stains, and generally has much less warp than whitewood, though warp is still an issue.

Redwood is generally spruce, fir or pine.

=3D=3D=3DJoinery=3D=3D=3D Joinery timber is clear, with a knot-free surface. Its used for [[Furniture Links|furniture]].

=3D=3DGrading=3D=3D Grading is an assessment of the structural strength of the timber. Key features assessed in grading are splits and knots, especially large knots at the edge of the wood.

Small timber bought for [[Special:Allpages|DIY]] use is mostly ungraded. Graded wood is stamped with the grading details.

For new floor joists and roofing one should use graded timber.

C16 is the most common grade, but C24 and some less common timber grades are also available. The higher spec grades may be used where dimensions need to be minimised.

=3D=3DSpecies=3D=3D Most wood used for [[Special:Allpages|DIY]] is spruce, fir or a pine. Other species are also used, but command a higher price, limiting their use.

=3D=3DBuying Wood=3D=3D Ordering wood to be delivered means you don't pick the timber. This is ok for [[First fix & second fix|1st fix]], but with work where the wood needs to be straight it can be a problem, timber yards are known for sometimes using new customers to clear junk.

=3D=3DProblem Wood=3D=3D Bent stock is a regular problem. =3D=3D=3DWarp=3D=3D=3D Selective cutting or 'docking' deals with a lot of warp. Wood often warps at points (knots) rather than all along, so cutting it at those points gives shorter pieces of straight wood.

In principle warp can also be straightened by [[Adhesive|gluing]] and [[screws|screwing]] 2 pieces of warped timber back to back. Its not normally worth doing, but if you're stuck for one piece it might be quicker than going out.

Warped wood is good for [[Partition Wall|framing]], where considerable warping is tolerable. When the warp is too bad, the wood can be cut short and used for noggings.

=3D=3D=3DTwist=3D=3D=3D Twisted wood can sometimes be made good enough by cutting to short lengths, as the amount of twist on each piece is then much smaller. This often works for [[First fix & second fix|first fix]], but there's always more junk wood than uses for it.

Other ways to deal with twisted wood are:

  • Using it fixed firmly to something much stronger, thus forcing it to untwist
  • Use it for [[Partition Wall|framing]], which is somewhat tolerant of twist
  • Plane it to give smaller straight timber.
  • Don't buy it in the first place!

=3D=3D=3DCupping=3D=3D=3D Planks are prone to cupping, whereby one side becomes convex and the other concave. If its desired to fix it, wetting the dished side will expand it a little, and it can then be dried while weighted flat. The thinner the plank, the more chance of success.

=3D=3D=3DStability=3D=3D=3D Timber defects can often be worked around, but warped or twisted timber has bent since cutting, and is thus unstable. Changes in moisture content are prone to producing movement again. This further restricts the uses for such wood.

=3D=3D=3DUses for junk wood=3D=3D=3D [[Partition Wall|Timber framing]] is the main use. All sorts of defects can be hidden behind [[Sheet Materials|plasterboard]] once finished.

  • Wood with [[paint]], [[nails]] or damage will all be hidden
  • Bent wood can be fitted bending sideways
  • Even wood bent both ways will only cause gentle undulation on the plasterboard if not too bad, and this usually isn't noticeable.
  • Split wood can be used too, adding a few [[screws]] to fix it together.
  • Almost anything can be used as noggings: undersize, odd shaped, badly bent, even [[Adhesive|glued]] offcuts.

Mildly bent wood can also be used in timber framed [[Sheds|shed construction]]. Its hidden by the cladding.

=3D=3DWater Content=3D=3D All timber contains some [[water]]. Where stabilty matters, which is most applications, timber should be either purchased with water content similar to final use, or else acclimatised before use. If ignored, warp and twist are more likely after fitting.

Timber used in new build for structural elements is required to have a maximum of 18% water content. (Many houses have been built with green timber.)

=3D=3D=3DGreen & Seasoned=3D=3D=3D Most wood for [[Special:Allpages|DIY work]] is seasoned. Green wood (meaning unseasoned rather than green in colour) has high [[water]] content, and is liable to move during drying, making it of limited use for [[Special:Allpages|DIY]]. The main exception is green oak used for oak frame. Timber frame [[sheds]] can also be built with green, as some movement on drying is usually acceptable.

=3D=3DDurability=3D=3D Most DIY timber is not durable, meaning it soon [[Wood Rot|rots]] if used outdoors without protection from [[water]]. The options for outdoor timber are:

  • durable timber
  • non-durable timber plus [[Wood Preservatives|wood preservative]] or [[paint]]

Well known durable species include

  • oak (very durable)
  • red cedar

Note that the sapwood of all species is non-durable, its heartwood that's durable. The majority of timber is heartwood, with only the outer layer of the tree (under the bark) being sapwood.

=3D=3D=3DTreatment=3D=3D=3D Timber is available ready treated against rot. Vacuum treated timber is most effectively preserved, as the [[Wood Preservatives|chemical]] soaks further into the wood. Cutting it exposes unpreserved ends, which should be [[Wood Preservatives|treated]] for best life expectancy.

When applying [[Wood Preservatives|preservative]], the cut ends need the most attention, as they soak up water like a sponge. Cut ends will usually sponge up several coats of preservative, which helps it last longer.

=3D=3DBoard=3D=3D Timber also comes in board form. The most common types are hardboard, chipboard, MDF, plywood and timberboard. These are all described in [[Sheet Materials]].

[[Sheet Materials#Hardboard|Hardboard]]: thin non-rigid brown board, typically 3mm thick. Most used as low cost drawer bottoms. [[Sheet Materials#Chipboard|Chipboard]]: wood chippings glued together, and sometimes coated with white melamine, brown imitation wood veneer etc. Most common furniture board in Britain. Usually fairly weak and vulnerable to water. [[Sheet Materials#MDF|MDF]]: a uniform brown material, can be machined and worked without grain being an issue. Vulnerable to water and not very strong. [[Sheet Materials#Plywood|Plywood]]: Available in many grades for different purposes. Dimensionally stable, strong in both directions, and one of the stronger wooden board types. Lower cost plywoods are vulnerable to water and delaminate fairly easily. [[Sheet Materials#Timberboard|Timberboard]]: Strips of wood glued side by side to create flat board. Gives a real wood finish. Strong along the grain, less so across. Cups badly if exposed to water on one side for a day, but normal cup spills don't do this.

=3D=3DPine=3D=3D Pine is a genus of conifers covering many different varieties of tree. Timber described as pine isn't necessarily a pine species at all, but it will have much the same appearance and properties, making the end result the same. Redwood has the highest odds of being real pine.

=3D=3DDrilling holes=3D=3D Most holes [[Drill Bits|drilled]] in wood are either pilot holes, clearance holes or countersink holes.

'''Clearance holes''' allow the [[screws|screw]] to slide through freely. An ideal size for this is the full width of the screw shank plus half a millimetre. Hole size isn't critical, but if too large the head may sink into the hole when tightened, enlarging the hole in the process.

'''Pilot holes''' are holes that enable [[screws|screws]] to be driven in without difficulty or risk of splitting the wood. A good size for pilot holes is half a milimetre slightly larger than the narrowest width seen on the screw spiral.

'''Countersink holes''' are very shallow tapering holes for the [[screws|screw head]] to sit in. These allow a counterunk head to sit flush with the surface. They are generally [[Drill Bits|drilled]] using a [[Drill Bits|countersink]], but can also be made with a large drill bit. In most cases the size and shape of the countersinking hole need not match the screw head well, as the head will distort the wood under it to some extent.

/| ____ /\/\/\/\/\/\/ | pilot hole ____ < | \/\/\/\/\/\/\ | \|

____ /| /\/\/\/\/\/\/ | clearance hole < | ____ \/\/\/\/\/\/\ | \|

____ /| /\/\/\/\/\/\/ | < | countersink \/\/\/\/\/\/\ | \| ____

Guide to Approximate Hole Sizes

=3D=3D=3DPilot Holes=3D=3D=3D Experience will soon tell you when to use a pilot hole and when not. Generally speaking, small screws in medium timber or bigger don't need pilot holes, but with medium to big screws or small timber the chances are a pilot hole would be wise. Lack of pilot hole can cause splitting in small wood, or jamming with medium to large screws.

=3D=3D=3DCountersink holes=3D=3D=3D Again sometimes they're needed, sometimes not. [[screws|Plasterboard screws]] have heads that penetrate less than traditional countersunk heads, and can usually be sunk fine without [[Drilling Techniques| drilling]] first.

=3D=3D=3DKnots=3D=3D=3D Knots are made of much tougher material than the surrounding wood. Screwing into knots with standard size pilot holes causes the wood to split. Its generally best to avoid knots when fixing, but sometimes a [[screws|screw]] is needed there. A simple solution is to use a slightly larger pilot hole, then they behave fine, good grip and no splits. Never try to screw a knot with no pilot hole.

[[Nails]] may be driven through knots if a pilot hole is [[Drill Bits| drilled]] first - though this is rarely necessary. Don't attempt to nail a knot without pre-drilling.

=3D=3DDifficult screws=3D=3D =3D=3D=3DGoing in=3D=3D=3D Awkward [[screws]] that are proving difficult to get in mean you need a pilot hole, or a bigger pilot hole. If the right [[Drill Bits|drill bit]] isn't to hand, dipping the screw in oil makes a difference and is often enough. Dipping a screw in oil before driving reduces friction, requiring less energy to get the job done. Various substitutes can be used, such as margerine, chocolate, etc.

Don't labour over a tough [[screw]], if it won't go in just take it out and fix the problem. If you keep at it you'll only end up with a well jammed screw that requires repeated curses to get out.

=3D=3D=3DComing out=3D=3D=3D There are numerous ways to get stuck screws out. See [[Screws#Removing a Damaged Screw|Removing a Damaged Screw]]

=3D=3DUsed wood=3D=3D There is a gotcha with used wood: most power [[saws]] and embedded [[nails]] really don't mix well. If you regularly use old timber, nail- safe circular saw blades are available. For occasional work one can use a hand saw or jigsaw. Nails can damage the blades on these, but not the operator.

Planes are also vulnerable, so used wood is generally better not planed.

=3D=3DSee Also=3D=3D

  • [[Sheet Materials#Plywood|Plywood]]
  • [[:Category:Wood|All Wood category articles]]
  • [[http://216.239.59.104/search?q=3Dcache:IfN6hPrQTfUJ:oak.arch.utas.edu.au/glossary/glossary.pdf+timber+glossary&hl=3Den&ct=3Dclnk&cd=3D1&client=3Dopera Timber Glossary]]
  • formatting link
    abbreviations]
  • [[Special:Allpages|Wiki Contents]]
  • [[Special:Categories|Wiki Subject Categories]]

[[Category:Wood]]

Reply to
meow2222

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