Timber basics article

On Fri, 20 Jun 2008 02:52:16 -0700 (PDT) wrote :

Nothing to do with law: having to label stuff in metric units is relatively recent (? last 10 years) whilst I am fairly certain that plasterboard and chipboard went to 2400mm from 8' around the time I started doing serious building projects 30 years ago, likewise the metric dimensioning of timber. Also note that a 2.4m length of timber is 2.4m, not an 8' (2438mm) with a metric label.
--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk


Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I think what was written has been misunderstood, I'll try to clarify it. Thanks
NT
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@care2.com wrote:

Still wants to be 4x2 to follow UK convention.
--
Cheers,

John.

/=================================================================\
  Click to see the full signature.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Jun 20, 10:52 am, snipped-for-privacy@care2.com wrote:
Good article but:

I would say:
When timber is sold as 'finished size' the stated size is what you get'
'Some large timber yards have a thicknesser for planing timber to a required size'
'With small mouldings and 'stripwood' the stated size is usually what you get.'
cheers, Pete.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Jun 20, 10:52 am, snipped-for-privacy@care2.com wrote:

I would just say:
'Where all timber needs to be absolutely straight, most reputable timber yards will allow you to hand pick wood for later delivery'
and follow with:

'Bent stock is rarely found at reputable timber yards, but can be more common at discount DIY retailers.'
BTW where do you buy your wood meow? ;)
cheers, Pete.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Jun 20, 10:52 am, snipped-for-privacy@care2.com wrote:
Couple more points:

Whitewood is usually spruce.
Whitewood is generally characterised by having a larger number of larger knots, and the end grain shows growth rings that are wider (Wider growth rings indicate a faster growing timber).

Redwood is usually pine.
Redwood is characterised by a smaller number of smaller knots, and the end grain shows growth rings that are narrower. (Narrower growth rings indicating a slow growing timber).
BTW some pictures in the DIY wiki may help illustrate different types of timber.
cheers, Pete.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

There are over 100 species of pine, most of them commercially available as timber.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Draft no 2 of the Timber Basics article... I've added more sections too. Lets see what you think.
==Timber Sizes== 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 ¼" 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.
===Length=== 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.
==Price== Most timber is sold by price per length, and some by price per cubic foot. Some example price lists: * http://www.woodyalan.co.uk/timberpriceseb.htm * http://www.fortimber.demon.co.uk/products.htm * http://www.adhectic.co.uk * http://www.wickes.co.uk/Shop/Timber/icat/timber * http://www.tottontimber.co.uk /
These are not company recommendations
==Terms== ;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.
==Qualities== ===Whitewood=== 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.
===Redwood=== 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.
===Joinery=== Joinery timber is clear, with a knot-free surface. Its used for [[Furniture Links|furniture]].
==Grading== 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.
==Species== 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.
==Buying Wood== 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.
==Problem Wood== Bent stock is a regular problem. ===Warp=== 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.
===Twist=== 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!
===Cupping=== 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.
===Stability=== 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.
===Uses for junk wood=== [[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.
==Water Content== 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.)
===Green & Seasoned=== 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.
==Durability== 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.
===Treatment=== 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.
==Board== 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.
==Pine== 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.
==Drilling holes== 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
===Pilot Holes=== 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.
===Countersink holes=== 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.
===Knots=== 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.
==Difficult screws== ===Going in=== 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.
===Coming out=== There are numerous ways to get stuck screws out. See [[Screws#Removing a Damaged Screw|Removing a Damaged Screw]]
==Used wood== 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.
==See Also== * [[Sheet Materials#Plywood|Plywood]] * [[:Category:Wood|All Wood category articles]] * [[http://216.239.59.104/search ? q=cache:IfN6hPrQTfUJ:oak.arch.utas.edu.au/glossary/glossary.pdf+timber +glossary&hl=en&ct=clnk&cd=1&client=opera Timber Glossary]] * [http://books.google.com/books ? id=mUGSaiTsBAIC&pg=PT145&lpg=PT145&dq=als+timber+OR +lumber&source=web&ots=yzFgcVS0MP&sig=neigDU6TFms5xcylsvqp9XUuBa8&hl=en&sa=X&oi=book_result&resnum=3&ct=result Timber abbreviations] * [[Special:Allpages|Wiki Contents]] * [[Special:Categories|Wiki Subject Categories]]
[[Category:Wood]]
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
As a scholarly epistle this fall far short: you make many generalisations that are not always the case.
e.g knotty timber is sometimes preferred in joinery for aesthetic reasons, to name but one.
However as a rough guide to someone who knows nowt about timber, its better than nothing by a fairly large amount.
Rather than go into horrendous detail I would say simply prefix the section with a warning that it IS 'generalised' and further information etc etc.. is available in more detail from specialised sites.
In particular issues to do with warping and wood movement ignore the fact that *all* wood moves under humidity changes, and its the actual structure of it and the way its cut that determines how it moves - warps, bows cups and so on.
And unless you use something like structural steel to constrain it its likeley to be stronger than anything you can throw at it when it wants to move.
i.e when using wood in a structure it WILL move. Forever. Unless you are not using it as the primary structure when it gets bolted or glued to something more massive. e.g veneering onto stable substrate.
The only way to get wood to adopt new shape permanentely is via steaming and/or ammonia treatment. Beyind noraml D--Y usage.
Ergo I would not tell people how to TRY and strighten wood. If it aint straight cut it into bits that are, or throw it away, or use it where it really doesn't matter.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

OK. I was thinking more about problem movement than all movement. I think that level of detail would be good for a timber article rather than timber basics. Maybe that'll come next.
NT
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@care2.com wrote:

Yep. I thnik that as a basic D-I-Y intro to lumber the article was pretty good, its the danger of stating as facts things which are more complicated than they appear and not in every instance true, that is the constant bugbear of anyone trying to distil a complex subject into a simple guide for the fairly ignorant.
Its a bit like "I before E, except after C" .. which has so maney execptions, but is still useful, so you add "as long as the word, sounds like the sea.."
Which is better, because rein, deity. reification and the like are now correctly identified...
But then you get 'ceiling' and 'seize'
So once again its in the ultimate analysis down to individal cases, and no general rule that is universally applicable.
The more I workd with wood in a structural context,the more I realise how much there is that I am either ignorant of, or not sure about.
Take the statement about heartwood being rot resistant, and the pith never. I can't say that has been my experience at all. Ive got firewood cut and left in the rain for years, and its rotten all the way through with very little discrimination between the parts. POSSIBLY the outer rings rot a bit faster than the inner.
Other useful things in understanding wood movement are that after first drying down to average internal humidities, you can get something like 1% variation along the grain, about 2% in the direction of the original radius of a trunk, and abuut 3% tangential or circumferentuially to the bole. THis allows you to dentify wood that wont cup (quarter sawn .Even close surface grain) from planks that will (flat sawn with wide wavy grain patterns). In addition wood that has grown laterally from a tree (check for rings closer underneath than above - and eccentricly placed heartwood, in effect) will always show differentlial mopvment between almost any tow parts. '
Going from green to dry is something like 4 times all of those..
Wood left on a building site - e.g. rafters stacked outside and put up and left for a period before being covered, even if dried OK in the first place, will still shrink by around 30% of green values once in place.
I know you will hate me for saying this, but by and large I eschew real wood for major structural work wherever possible, and use composites like PLY or MDF or chip or indeed steel, to make structural elements. Wood is lovely and decorative, but the art of getting a structure that allows movement is fairly rare in carpentry, though known to most of the better joiners and cabinet makers, and it takes time and money to produce and attractive wood structure than wont shift and move to the point of visible warping cracking or breaking of glue joints etc.
I thoroughly recommend Hoadley's 'Understanding Wood' as a book that perhaps you should read cover to cover, and then try and distil the main points down into a wiki. It's where mosts of the info quoted here comes from, and its also one of the best books I know on the properties of wood as an engineering material, and practical guides to using it in that context, as well as having some excellent tables. Sadly I gave my copy to one of the carpenters who built my house, as a Christmas present. I haven't replaced it yet, but I will.
For anyone going beyond just whacking up some rough sawn 2x4 for studwork, its a must.
His anecdote about rolling marbles on a kitchen worktop build with wet timber framing (accurately) after it had dried (no longer anything like level) is significant...

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The NP going on about spelling rules ?
Now I've seen everything ...
--
geoff

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
geoff wrote:

I thnik (stet) he knows how to spell - but not how to get his fingers to type what they should. Just like me - except I do try to go back over and correct what I notice.
--
Rod

Hypothyroidism is a seriously debilitating condition with an insidious
  Click to see the full signature.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Rod wrote:

I believe there's a new fangled invention called a spell checker
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 23 Jun 2008 08:03:18 +0100, stuart noble wrote:

Eye halve a spelling chequer It came with my pea sea It plainly marques four my revue Miss steaks eye kin knot sea
Eye strike a key and type a word And weight four it two say Weather eye am wrong oar write It shows me strait a weigh
As soon as a mist ache is maid It nose bee four two long And eye can put the error rite Its rare lea ever wrong
Eye have run this poem threw it am shore your pleased two no Its letter perfect awl the weigh My chequer tolled me sew.
--
Cheers
Dave.




Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Dave Liquorice wrote:

Best post of the day.
FWIW my spelling is around 99.8% good. My typing is around one missed key in six. Not helped byfag ash in the keyboards.
Sometimes I can't be bothered to correct it.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Jun 15, 9:12 pm, snipped-for-privacy@care2.com wrote:

Thanks to everyone for pitching in. Here it is http://www.wiki.diyfaq.org.uk/index.php?title=Timber_basics&rcid=9340
The points made that weren't included I hope to include at some poin in a more in depth article.
cheers, NT
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.