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Hand-packed brush fencing will require maintenance from time to time as with any other structure. This chapter looks at the common types of work required as a result of natural aging and deterioration of a fence as well as that due to the premature sagging caused by poor brush packing and wiring practices. Images shown in the 'Categories' section above, give a quick reference to the four main types of work that are likely to be required for sagged fences, contingent upon the level of deterioration. Hand packed fences mostly have a life of between 25 and 40 years although fences as old as 80 years are known to exist.
Restoration of a hand-packed fence is usually prompted by the unsightly gaps ('sagging') which begins to appear between the steel capping and the top of the brushwork as the brush column shrinks and settles and is often undertaken in conjunction with replacement of brush roll tops and repairs to damaged sections.
Machine-packed panels do not sag, but tend to thin out with age. They are generally not repairable or restorable and have a life of over 20 years. They are easily replaced.
The following pictures give a quick reference to the four main types of work that are likely to be required for sagged hand packed fences, contingent upon the level of deterioration. Sagging does not occur to machine-packed panel fencing due to the proximity of wire staples and density of brushwork. ie they retain their shape and size for the life of the fence (up to 40 years), but thin out as the fine material is lost.
Category 1. 'Lift' Work Required |
Category 2. 'Facing' Work Required |
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| Category 3. 'Rewire & Repack' Required | Category 4. Complete New Fence Required |
The Four Main Levels of Fence Restoration Work |
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Category 1. Lift Work, can be undertaken in hand packed fences of up to about 20 years of age, where the brush has settled/sagged en-masse i.e. where the brush is still quite thick at the top and not too brittle. The general rule of thumb is that if one can grip about 100mm thickness of brush at the very top, then there is sufficient brush to effect this type of repair. To ensure a maximum life after restoration, the most effective method of repair is to remove all wire clips in the top two and sometimes three horizontal wires, and then to lift the brush top layer back up to its original height. A small quantity of brush is then required in obvious holes and thin spots to the top and bottom of the fence and over exposed internal posts, to post roll repair and in cases of brush roll top fencing, to replace the rolltop. In this type of work all wiring is straightened and all capping straightened and tek screwed down and post heights are shimmed if out of alignment. Extra wire clips are fitted throughout the fence at half spacings, to tension the fence and prevent future sag.
It is important that any brush used for patching is light in colour (eg Kangaroo Island brush) to match the bleached look of older brush. If dark brush is used, the end result can be patchy/poor.
The end result of this type of work, when done properly, is a neat, straight, tight fence of well maintained appearance that will last for many more years..
Category 2. Facing Work. Where there is insufficient brush in the top to lift the brush top layer, then facing with new brush along both sides of the top of the fence is required. This involves similar fence preparation as for lift work including straightening and fixing of capping and wiring, but new brush is fitted to both sides of the fence at the top. As with lift type work, lighter coloured brush should be used, to match the colour of the bleached brush in the fence.
The final appearance after 'facing' (when done properly), is a 'new-fence-look' to the top half of the fence and a well maintained appearance to the lower half.
In some cases the top of a fence may be trimmed off where height is not important and the amount required to be trimmed does not interfere with the fence framing/ internal rails. The final appearance if trimmed, is a fence slightly lower in height and straight, tight and well maintained.
Category 3. Rewire & Repack. Where the brush condition is such that it is not cost effective to repair, then all brush and wiring are removed to the tip and all new brush and wiring fitted. The posts, concrete base and internal rails are often re-used and sometimes the capping, although it is more usual to replace the capping with new material, or a brush roll top.
Category 4. Complete New Fence Required. Old timber posted hand packed fences were drilled to take the wiring and the concrete bases were poured between the posts. Consequently when the posts eventually rot beneath the ground it is not possible to replace the posts without replacing the wiring and where the brush condition is poor it is usually most cost effective to completely remove the old fence and base to the tip and to replace with a new galvanised steel posted fence. Other situations where complete fence relacement may be necessary include fences with damaged concrete bases due to tree root upheaval or bases overturned by backfill/soil removal/undercutting and where steel posts have corroded where painted black tube posts have been used rather than galvanised. Where brush condition is still good Adelaide Brush has developed techniques for the relocation of fence panels to a new frame and base.
'Sagging' is generally caused by either one of, or a combination of, three different factors and is compounded by loose or thin packing and poor wire clip tensions or spacings. The causes are; 1) loss of top and bottom fine brush material, 2) dislodgment of the brushwork (off its base), and 3) inter-layer settlement.
Cause 1) Top & Bottom Loss of Fine Brush Material As the fine materials in the bushy ends at the top and bottom of the fence deteriorate more quickly than the thick stalks in the middle of the fence, and drop out, the height of the brushwork tends to shorten and as the brush is standing on the base, the effect of both factors combines as a gap at the top of from a few centimetres to about 20cm. Where the wiring assumes a sagged line rather than straight, this is usually the cause. In initial packing of the fence, if an insufficient length of tops and bottoms are left protruding, prior to trimming, then sagging is likely to occur more quickly. The density and thickness of the fence also have a bearing with regard to the time taken for a fence to 'sag' in the foregoing manner.
Cause 2) Dislodgement of the fence off its base will have a similar but more immediate sagging effect as top and bottom deterioration.
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Dislodgement of Fences off their Base |
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Cause 3) Fence inter layer settlement in a hand thatched fence, is the relative movement of the two brush layers i.e. settlement of the brush top layer into the bottom layer. This can occur within a year or two of construction, if the density of packing is too low or if the wire clips through the fence (which connect the horizontal runs of wires on each side of the fence) are spaced too far apart or incorrectly tensioned. These clips actually compress the top and bottom layers of brush together laterally, where they overlap in the fence, and prevent the top layer from settling relative to the bottom layer (which is standing on the base).
Premature (hand packed) fence sagging is partly a result of current industry construction techniques, which have been driven over the past two decades by cost and competition to the lowest acceptable standard. It is also an inherent flaw in the way that hand packed fences are put together and one that is not altogether avoidable.
Deterioration of the brushwork can never be cost effectively prevented, but sagging can be minimised by the following means. The only way to prevent it entirely is to use machine packed modular panels instead of hand packing
The effects of sagging are minimised, where the horizontal wires are fixed to each post. With the old timber posted fences, posts were drilled to take the wiring and through the 1950's and 60's when steel posts began to replace timber, the wires were fixed to each post with a wire clip passing through the drilled post and attached to on each side. Unfortunately with current industry construction methods for hand packed fencing, wiring is only fixed to every fifth post (four panels), which means that little support is given to the brushwork by the wiring, and integrity of the brushwork (with respect to settlement) relies mainly on the tension and spacings of the wire pins/clips which pass through the fence and on the density of packing.
In fixing the wiring to each post, the wiring is only able to sag between each pair of posts. The wiring and each post therefore act to provide some support to the brushwork, whereas when fixed to the first and fifth post, the wiring has sufficient length and scope to move downward with the brush.
Machine made panels are fixed at each post or to a frame behind, depending on installation system.
In a hand packed fence, wire clips should be tightly fitted at no more than 350mm apart, to bind the brush top and bottom layers together and prevent slippage between the two layers and also to firmly secure the brushwork to the wiring. Machine made panel wire pins are fixed at centres a maximum of 100mm.
The base supporting the fence should be at least 150mm in width and be level across the line of the fence. If it is too narrow or sloping sideways, it is easy for the brushwork to be dislodged, causing immediate sagging.
Brush in a new hand packed fence is usually packed in two layers, one with its cut bushy end upward and the other with its cut bushy end standing on the base. The ends of the two layers cross/weave at mid-fence level although some packing techniques involve a mid layer standing on the ground in the core of the fence. In a machine packed panel the brush stalks and bushy ends are randomly arranged throughout the panel.
Most brush is packed 'green' within a few weeks of cutting. It initially undergoes a considerable loss of weight (as much as one third) and shrinkage as it dries out over a period of several months, and then over the course of its life in a fence (30 to 40 years) it suffers gradual loss of fine material and bark. A brush fence starts its life with green tops and dark grey stems. Within a few months the green ends and 'fluff' turn rusty brown and then the whole fence gradually bleaches to a light grey colour over a period of 10 years or so. Brush in a fence at the end of its life is comprised mainly of bleached sticks with very little fine material left at all.
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The level of restoration work required to a hand packed fence is dependent on the age of the fence and the degree to which it has weathered and deteriorated. Factors which can extend or reduce the life of a fence, include the density and type of initial packing, type of brush used (sappy or dry origins), wiring clip spacings and tension, aspect, shade and physical damage. Generally the side of the fence facing the afternoon sun will deteriorate more quickly than the opposite side and where garden sprays are directed permanently at one section or side that area will also deteriorate more quickly, both due to rot and water impact. The brush in the vicinity of internal steel posts also tends to deteriorate more quickly, both due to the thin covering and from the heated steel in summer.
It is not possible to restore machine packed panel fences, due to the density of packing and proximity of wire staples. The panels are simply and cheaply replaced however.
© Copyright 1999; Adelaide Brush, Fairview Park, South Australia 5126; Tel +61 8 82513309, Fax. +61 8 82893155, Mobile 0418 841 889.
Page Last Edited: 8th May 1999
