Sourcing sustainably produced timber and manufactured timber building products requires checking the following -
- Was the timber sustainably grown?
- How far has it travelled?
- Does it contain chemicals such as adhesives or timber treatment?
The FSCForest Stewardship Council (who accredit timber) Woodmark or the PEFCProgramme for the Endorsement of Forest Certification. See their web site stamp are the most reliable means to know that the timber was sustainably grown. This is a ‘chain of custody’ method whereby woodlands are certified as being sustainable by a certifying body and then each piece of timber is marked, from the point a tree is chopped down right through to the delivery of sawn timber or a timber product, so that no matter how much batches of timber get mixed up during distribution, you can be sure it was grown sustainably.
Try when possible to source timber grown in the UK. It is extremely difficult to know where timber has actually come from as it tends to come off ships from all over the world and then get resorted and mixed in with other timber by the timber merchants at the ports of entry. A lot of information can be gleamed from the stamps on the timber and from the information on the plastic covers it is wrapped in. For instance ‘hem-fir’ indicates it is from North America, (hemlock and mixed fir species). Often the wrapping will have Finnish or Swedish company names on. However there is an increasing amount of construction timber being produced in the UK (e.g. you now quite often see James Jones timber which is mainly from Scotland) There are also a number of estates marketing their own timber
A somewhat different approach is to source your timber through local sawmills. This way you could check out whether it was grown in the UK but you might not get a woodmark on it (though it would probably be sustainably grown due to UK woodland policy). Sawmills often have access to stress grading for structural timber. This method leads to other possibilities. Very often UK sawmills handle locally grown hardwoods as well. If you need hardwood for other jobs in the building then this is probably a cheaper way of purchasing them than through a timber merchant, especially if you are flexible about the species you want.
This section tends to apply to the more ‘hands-on’ type of self builder or to someone with contacts in the joinery trade. If you happen to be in touch with a local landowner who is felling timber (or have some timber yourself) it may be worth contacting someone with a mobile sawmill who will convert the timber to boards and planks in the wood where it is felled. It is then stacked and covered to allow it to dry. This is probably one of the most ecologically sound ways of sourcing timber, it can save a lot of money but needs considerable long term planning. more+/-»
It is a pity that there are not more web sites like Woodlots , aimed at putting small scale suppliers in touch with potential customers. One possible drawback is that stress grading may be a problem. (Stress graders can be hired by the hour and if the requirement is to SC3 they will probably be able to go through a pile of timber in a few hours and visually certify it. Some links to mobile saw millers – here +/-»
There are several ways to obtain reuseable timber -
- from demolition you are doing on your own property
- directly from a demolition site
- from building material recycling merchants
- from private adverts
The problem comes that finding reuseable timber of the right size and quality just when you need it is quite difficult. Probably a good place to start is the Salvo vebsite
Timber is often available from demolition sites and it may be best to approach the site manager directly so that you can find out exactly what is coming out when. You need to be pretty quick on your feet because demolition companies are not going to wait around for you. There are a few things to look out for when buying from a demolition site -
- Remember to avoid timber which is infected with woodworm or dry rot.
- Timber whith a larger cross section than you need will probably require cutting down and this is a very difficult business because of damaging saw blades. Every nail has to be removed and you will need a metal detector to find them.
- Occasionally you may find parquet flooring which has been set in asphalt. This is extremely difficult to remove from the blocks.
There are a few merchants who specialise in supplying high quality resawn reclaimed timber for special purposes. An example is W. Machell & Sons Ltd of Guiseley.
Fixed furniture tends to suffer from the vagaries of fashion and at its worst is constantly being replaced for something more up to date. See Alterations and fashion. This is especially true for kitchen units and fitted wardrobes. This can represent quite a considerable amount of embodied energythe total amount of energy it takes to make a material (or a building). See more on embodied energy and also pollution in terms of the materials such as glass, formica and particle boards etc. It also creates a considerable amount of land fill. The question is ‘How likely is the furniture to last well into the future?’ There are three aspects to this.
- Will the furniture function well over time? For instance with kitchen furniture, will it be likely to be ripped out to make way for some different sized appliance? See Flexible design
- Is it repairable if it should get damaged? For instance a solid timber worktop can probably have a burn mark sanded out whereas a laminate one is extremely difficult to repair.
- Is the design of sufficient quality that it will still be looked on as beautiful with the passing of time?
Less fitted furniture? Whereas fitted kitched furniture was almost ‘de rigeur’ until recently, Ikea seems to have almost single handedly challenged that concept with the various units in their free-standing range. These can make a lot of sense ecologically because they can be moved to fit changing needs or sold on if no longer required.
In contrast, fitted kitchens are difficult to modify, especially if the carcass needs changing. The materials used in furniture should be considered for how sound they are ecologically and what effect they may have on indoor air quality. Particle boards such as chipboard can emit formaldehyde (which can be carcinogenic) for many years after manufacture and some European countries have introduced strict controls on emissions or outright bans on chipboard.
There is a general misconception about timber treatment. i.e. that almost all timber is better if treated (meaning treated against woodworm, dry rot and wet fungal decay). This is a blanket approach which does not properly address the needs of the building industry. Instead it tends to promote the widespread use of toxic chemicals when they are not needed.
If you are talking about telegraph poles, marine timber structures or agricultural fencing then there may be an argument for using timber which is heavily chemically treated (and there may not). For house building there is a much simpler approach. In fact timber which has been treated with creosote or CCA is now considered to be a toxic waste if you take it to your local reclamation centre where it has to be dealt with separately. There is a huge critique as to whether most timber treatments actually work for very long in the Green Building Handbook page 160. To quote:
Timber which is kept at a moisture content of below an average value of about 18% (equating to an indoors rlative humidity of about 60%) is extremely unlikely to attract infestations of woodworm or dry rot. If timber is protected from rain and also from internal leaks such as leaking gutters or leaking pipes then timber will last indefinitely; probably many hundred years.
There is ample evidence for this. Some of the oldest buildings in Europe are of timber and they have not been automatically treated with the sort of chemicals which are now commonly used on timber. Timber in an inhabited modern house normally has a moisture content of 12%-15% which is well below what will support dry rot or woodworm.
However there can be problems with House Longhorn Beetle which has special provisions in the Building RegulationsThese are the legal regulations which govern how a house is constructed. (not to be confused with Planning Permission which is about whether you are allowed to build the house at all or what it might look like) see Building Regulations) covering a few counties mainly South West of London. The third possible source of problematic damp is rising damp but this is covered by the Building Regulations part CC – Site preparation and resistance to contaminants and moisture. see more on part C which insist on a damp proof course (DPCDamp Proof Course - a strip of (usually) plastic built into walls to prevent damp rising or penetrating. see more) between damp ground and the main habitable area of a house.
Having said all this there may be an argument for treating the main timbers in a timber frame house such as a post and beamSubstantial, usually horizontal structural member. structure. The reasoning goes that maybe there might be a long standing unnoticed leak (roof, plumbing or bridging to damp ground) somewhere which could set up conditions which could cause dry rot. This sort of leak might happen if the dwelling was unoccupied for a long period or a small but persistent leak occurred. Then at least the main structure would be protected even if a limited area got affected. This would be similar to the risk with most masonry construction.
Alternative types of treatment
Probably the best way of guaranteeing this level of protection is by using a boron based timber preservative (often called Borax for short). ‘Borax’ is a very benign but effective method of treating timber because it has a general toxicity which is on a level with common salt but protects timber particularly well. The only thing to notice is that because it is water borne it must not leach out from the timber. This is prevented by protecting the timber from water penetration in some way. The suppliers of various borax based products have information on this.
Another possibility is to use acetylated timber. Acetylated timber is softwood timber that has been treated to make it as durable and resistant to rot as some of the best hardwood species such as teak. The treatment is based on a form of acetic acid which is simply a concentrated form of vinegar It is marketed as Accoya by Titan Wood Ltd. This is a relatively recent development in timber technology and has strong green credentials. The main drawback, as with much of the timber trade is the long distances travelled by the timber. Titan’s timber sources are global and the only treatment plant so far is in the Netherlands.
Another process for treating timber to improve its dimensional stability and durability is the Plato treatment which uses no chemicals, simply a cycle of heating moistening and drying
Timber mouldings are used for two reasons
- to cover gaps
- caused by ugly joints between differing materials such as timber and plaster.
- caused by shrinkage or seasonal movement. They form a kind of sliding joint.
- to add decoration
The mouldings come in a variety of designs but several of the better known ones are shown below. Most timber yards will stock the common ones in various widths. Many timber merchants will run up custom designs at extra cost; useful if you are trying to match up to existing work. Small joiners shops will do the same providing they have a spindle moulder. Some of the very high skirtings you find in Victorian and Edwardian houses are too wide to get out of a single board and come in two matching parts.
Joints between walls and woodwork – skirting boards and architraves
Architraves are the decorative strips of wood which cover the joint between the door frame and the wall plaster or other finish Traditionally the architrave mouldings match the skirtings but are smaller in scale; there’s no law about this.
Joints between panels and frames on doors
With traditional wooden panel doors there can be a considerable amount of movement between the panels in the door and the frame of the door. This is because timber expands when the air is more humid and it expands much more in its width than in its length. So in the image below the two top and bottom panels will expand and contract in width much more than the top and bottom rails will vary in length.
Mouldings are used round the frame mainly as decoration but also partly to take the eye away from possible visual irregularities due to expansion and contraction. These are still there because the moulding moves with the frame but they are less obvious.
There are two types of mouldings used in various sizes and profiles; bed mouldings
which are fixed thus-
and bolection mouldings which are a bit grander (some would say more bulbous). They totally cover the joint between frame and panel and they protrude from the surface of the frame.
and are fixed like this
Other mouldings commonly used are dado rails, picture rails and covings at ceilings.
Ceiling[for the purposes of part B of the Approved Documents] - A part of a building which encloses and is exposed overhead in a room, protected shaft or circulation space. (The soffit of a rooflight is included as part of the surface of the ceiling, but not the frame. An upstand below a rooflight would be considered as a wall.) covings, picture rails and dados
Generally the junction between walls and ceilings is not a problem because they are both of the same material (some form of plaster). However if they differ, say plaster and timber boarding, then this is where a timber coving moulding might be employed. However the use of a shadow line may well look a lot better Picture rails go in and out of fashion (along with high level shelves for Toby jugs and general nick-nacks) Dado rails were originally applied as protection for the wall from damage by chairs etc. They are now mainly decorative but may also still give some some protection.
Door panels are sometimes plain but usually they have a moulding round the edge, either ‘fielded’ (on the left) or ‘raised and fielded’ (on the right).
There are several factors which determine whether it is worthwhile milling your own timber
- firstly, obviously, whether you have access to a good supply of logs of the type of timber you will require and are they of a sufficiently high standard?
- is there space to stack and saw the logs
- is there space and time to air dry (and possibly kiln dry) the sawn timber. Air drying over summer will take at least a few months depending on thickness and kiln drying can take a few weeks
- can you get the timber machined for its final purpose?
In the order of easy to difficult, there are a number of possibilities
boards for external cladding and rain screensthis is a (usually thin) outer cladding on a wall which prevents rain, snow, etc getting at the structure of the wall behind. see more on rain screens. Usually in Douglas fir, larch, western red cedar, sweet chestnut or oak, this is relatively simple and may not require further machining unless you want to plane them. These boards will usually be in the range of 150 – 200mm wide and 18 – 25mm thick (possibly in two widths if you are doing board on batten – and this will produce less waste in cutting as thinner sections can be utilised).
Some air drying will be useful but not essential if the boards are use straight away as they will dry in situ. The first cuts can also be used for cladding garden sheds etc. providing the bark is stripped off. This is probably the most financially rewarding aspect of getting your own timber sawn
scantlings, temporary works, fencing etc. Most building work utilises a considerable amount of low quality timber and this can be derived from the left-overs of sawing for cladding and structural timber.
wood strip floors. Short and narrow strips of timber, usually in the range of 5 – 10mm thick can be glued directly onto OSBOriented Strand Board sheets on floors. This makes excellent and attractive flooring and utilises timber extremely well, especially hardwoods. It involves kilning the wood and machining it but this is not difficult. Because the volumes are relatively small the kilning can be carried out with an electric heater (or better still a solar kiln). The machining is easy using a circular saw bench and planer/thicknesser. The narrower the strips the less of a problem there is due to movement during kilning but the more work in machining and laying.
timber for furniture. It can be a relatively simple matter of sawing timber for built in joinery, kitchen cabinets etc, largely because the timber sections are seldom thick and usually not very long. This means that drying and kilning don’t take so long (and this material is not needed till towards the end of the building work) and logs do not need to be of the uniform high quality required for structural work. So for instance if you can get your hands on some local hardwood such as cherry, ash, sycamore, birch etc. you can make unique furniture from locally grown timber.
structural timber. The sawing of structural timber is relatively easy given decent log sizes but it will need grading by a licenced stress grader to meet Building Regulation standards. They can do on-site visual grading but obviously you will need a fair amount of timber to make a visit worthwhile. To get in touch with a local stress grader, ask around timber merchants and timber yards in the area as they tend to use them occasionally. Structural timber will need air drying at least, possibly kilning down to around 12%.
Timber can bend and twist quite a lot on drying and this is especially true of larch so it is best to overestimate the amount needed and then any bent stuff can be sawn down and used as scantlings etc. where the bend will not show up.Powered by Hackadelic Sliding Notes 1.6.5
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