British Standard

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Timber has many qualities that make it so appealing. Its aesthetically pleasing, diverse in its uses and offers a very affordable option as well as being a renewable resource when managed correctly. However it does have its limitations and the British Standard outlines these.

Defects affected by changing climatic conditions shall not be considered a valid reason for subsequent rejection after the initial inspection with 14 days of delivery either to the preservation treatment works or to the site.

So what does this mean?

During the year our weather can vary dramatically, warm summers lead to twisting, splitting and warping. Gates move out of plumb. These are all naturally occurring movements and cannot be prevented. Each piece of timber will react differently and move differently. Splits will open and close.

POST STANDARDS

All Knots & Knot Holes -Total K.A.R (Knot area ratio) not greater than half. (Within a parcel not less than 90% of the number of pieces shall have a K.A.R of 1/2 or less. A K.A.R not exceeding 3/5 shall be permitted in up to 10% of the number of pieces in the parcel.

Wane -Not more than 15mm on any corner. At least two adjacent corners shall be free of wane

Checks- The depth of each check shall not exceed one half of the thickness of the piece.

End Splits - Not longer than 150mm except that for feather edge boards and pales they shall not exceed 25mm

Pin Holes - Not more than 20 in any 0.3m length.

Straightness -Bow -Not more than 25mm within the length of the piece. Spring-Not more than 25mm within the length of the piece. Twist-Not more than 20mm within the length of the piece. Cup - Not more than one-twenty-fifth of the width of the piece.

Checks/ End Splits & Straightness are all effected by climatic conditions as detailed above. All these characteristics and movements etc are permitted within the limits detailed above for the fist 14 days after it has been cut (so this is before it has even been treated). After 14 days there are no limits to the movements or ‘defects’ detailed above.

Please note the 14 days is counted down from the moment the timber is cut not from its arrival in our yard or from the date it is purchased from us.

Main Rails/ Non Structural Components

All Knots & Knot Holes - Size of knot shall not exceed half the width of the face

Wane- Not more than 10mm on any corner. At least two adjacent corners shall be free of wane. Not more than 7mm in width of feather edge boards and capping.

Checks-The depth of each check shall not exceed one half of the thickness of the piece.

End Splits - Not longer than 150mm except that for feather edge boards and pales they shall not exceed 25mm

Pin Holes -Not more than 10 in any 0.6m length

Straightness -Bow -Not more than 25mm within the length of the piece. Spring-Not more than 25mm within the length of the piece. Twist-Not more than 20mm within the length of the piece. Cup - Not more than one-twenty-fifth of the width of the piece.

Please note the 14 days is counted down from the moment the timber is cut not from its arrival in our yard or from the date it is purchased from us.

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Timber shall be preserved in accordance with the requirements for fencing timber BS5589

So what does this mean?

All our timber is treated in accordance to the British Standard. You will find almost all our timber is treated to UC4. This is timber that is suitable for ground contact. It has a expected service life of up to 15 years. Timbers that have been cut, drilled & not resealed or those that are exposed to constant attack from moisture will have a considerably shorter life.

Some timbers are only treated to UC3 this means it is suitable for outdoor use but for above ground only. We clearly mark these items in our price list enabling you to make an informed decision about its use.

What can I do to help?

To prolong the life of the timber we recommend that all cuts are resealed with Osmose end seal or another good quality timber preserver, taking extra care to seal end grains. Take steps to maintain fences & outdoor structures every couple of years by using paints or stain that are suitable for this type of application. Take some time to clean decking each year and remove leaves and moss that sit on top during autumn and winter.

Flower beds and planters should be lined with a suitable membrane and you should use stone to aid drainage.

You could fit posts into bolt down feet or drive in anchors to allow you to change them when they have reached the end of their life.

Consider if softwood treated timber is right for the job and consider alternatives if needs be. Concrete, stone, and more modern plastics are readily available as well as engineered and more innovative materials. If you see some of the above as unacceptable timber may not be the material for you or this particular project.

You can try to prevent the fall out of knots in fence panels by using a suitable knot treatment. there are a few on the market that help to seal and stabilise knots. Ultimately knots are naturally occurring and cannot be prevent or excluded from our timber. Knots are more common in feather edge boards and timbers that are sawn from the edges of the logs. We do not see it as suitable reason to class a product as ‘faulty’ or ‘unfit for purpose’.

Movements in gates can be limited by placing Brenton bolts top and bottom and keeping the gate closed when not in use but especially with in the first month of being hung. Drop bolts should be used on field gates. Hinges of a suitable sizes should be used.

Appropriate fixings that are suitable and strong enough for the job in hand can also help but ultimately timber is a natural product and these are natural ‘side effects.’ We would not deem these natural processes as a reason for classing a product as ‘faulty’ or ‘unfit for purpose’.

Full copies of the British Standard can be obtained for a fee from BSI.org