Brush Aging

Brush in a new hand packed fence is usually packed in two layers, one with its cut bushy end upward in the top of the fence and the other layer with its bushy end downward and standing on the base.  The stick 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.  The bushy tops and bottoms are then trimmed off.

In a machine packed panel, the tough stems and bushy ends are randomly arranged throughout the panel which is machine compressed and close stapled forming a far more durable panel.

Image:  Top 'layer' of brush has it's bushy end up - most common hand packing technique

Image:  Bottom 'layer' of brush has it's bushy end down.

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.


 Image:  Aging - a new hand packed brush fence

Image:  Aging - a hand packed fence at about 25 years

Image:  Aging - a hand packed fence around 40 years or more


Image:  Aging - a fence older than 50 years


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 and 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 necessary to restore machine packed panel fences, which do not sag due to the density of packing, proximity of wire staples and composition of the brush layup.  The panels are simply and cheaply replaced when they reach the end of their life or if they are damaged by various incidents such as vandalism, vehicle impact, storm damage etc.


Restoration of Sagged Hand-Packed Brush Fencing

Hand-packed brush fencing will require maintenance from time to time as with any other structure and eventual replacement This section looks at the common types of repair and restoration work required as a result of natural aging and deterioration of hand packed brush fences as well as that due to the premature sagging caused by poor brush hand packing and wiring practices.  

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 25 years. They are easily replaced.  Sagging does not occur with 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, but thin out as the fine material is lost.

Brush fences mostly have a life of between 25 and 40 years although fences as old as 80 years are known to exist.


Category  1.  'Lift' Work Required - where brushwork is in good condition and little or no repair brush needed

 'Lifting' Repair 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, but has settled.  The general rule of thumb is that if one can grip about 75mm to 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 fitted to obvious holes and thin spots to the top and bottom of the fence and over any exposed posts and brush is also fitted to repair post rolls and in the case of brush roll top fencing, to replace the roll-top.   In this type of work all wiring is straightened and all capping straightened and tek screwed down to the posts and post heights are shimmed if out of alignment.   Extra wire clips are fitted to the fence mid-wires at half spacings, to tighten the fence and minimise future sag.

It is important that any brush used for patching is light in colour 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 another 10 years or so ... 


Images:  Examples of fences that are still quite thick and able to be lifted' without requiring much new brush.

Images:  A 20 year old fence that may need a light facing of brush at the top if the old brush crumbles at all in the lifting process.


Image:  All the wire clips/staples are firstly removed in the top two or three fence running wires preparatory to lifting/separating the top layer of brush to recover the fence height.


Images:  This hand packed fence is relatively young and may not need to have additional brush fitted at all after 'lifting'.


Image:  This hand packed fence would only be about 12 years old and should not have sagged.  The brush is quite thick and in good condition and has either come off its base or was badly wired/pinned when installed.




Image:  This fence is about 20 years old and should lift OK without much brush needed.  However a garden bed/soil has been placed against the brushwork which could push it off the base and will rot the brush prematurely with moisture/time.

Image:  This brushwork is in marginal condition and will need lifting and a light facing of new brush.



Category  2.  'Facing' Work Required - where fence is in need of new brush through the top of fence.

Facing Repair 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 and the core between the two layers packed with offcuts of brush or panel strips to provide a seamless repair.  As with lift type work, lighter coloured brush should be used, to match the colour of the bleached brush in the fence for a good result.

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 (post tops and brush) 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 or affect the look with regard to adjoining gate heights.  The final appearance if trimmed, is a fence slightly lower in height and straight, tight and well maintained.

Where the bottom of a hand packed fence has deteriorated to a condition where it too needs to be faced with new brush, that is the time to remove all the brushwork to the tip and fit new machine compressed never-sag panels.   It is not viable to face the top and bottom of a fence with new brush - too labour intensive. 


Images:   Whilst still thick, the fences above and below have sagged / deteriorated about 250mm beneath the original height and will need new brush fitted to the top on both sides and to the central core to recover height, plus new roll top or capping.


Image:   Fencing that is too thin at the top to lift, requires significant quantities of new brush to be fitted to the top of the fence on both sides - called 'facing'.  The end result is a new looking fence for the top half.


Image:   As a common fence, privacy is generally important and so trimming post tops is unlikely to be an option with this fence.


Image:   This fence is very thin at the top and will need a full facing of brush on both sides to restore.

Image:   The post tops could be trimmed off and new roll top fitted to save cost, but fence is thin at top and should be faced with new brush.


Image:   If privacy is not an issue, the post tops could be trimmed off and new roll top fitted with a fence such as this.  Facing the other side with tennis court mesh in place would be difficult.


Image:   This fence is very thin in the top half and will need a full facing of brush on both sides to restore.




Image:   The top layer of brush appears to have been pulled out of the top of the fence in the image above exposing the stick ends of the bottom layer, but is still quite thick in the bottom half of the fence and will need new brush fitted both sides at the top to restore.


Image:   It can be seen from the exposed posts that this fence is very thin at the top and will need a full facing of brush on both sides of the fence.




Image:  Roll tops generally only last about 12 years before needing replacement.  In this case the fence it self has sagged about 150 to 200mm and will need facing with new brush both sides and the centre packed prior to a new roll top being fitted.

Image:   This 20 year old common front divider is thin in the top half and needs facing both sides.



Category 3.    New Brush Panels Required (or 'Rewire & Repack') - where the brushwork needs to be replaced but posts and base can be re-used

New Brush Panels Required (or "rewire and repack")After 30 to 40 years a hand packed brush fence reaches the end of its life and the brush reaches a condition that is not cost effective to repair.  In that situation all brush and wiring are removed to the tip and all new brushwork fitted.  The posts, concrete base and internal rails can often be re-used and sometimes the capping, although it is more usual to replace the capping with new capping or a brush roll top finish.  In most cases these days, it is preferable to fit machine compressed brush fencing panels to the old posts and base as this is a more cost effective and durable option than rewiring and hand packing.  Machine compressed brush fencing panels are a good choice because they do not sag or settle like the hand packed fences although they do thin out with age.

Images:  These hand packed fences have served their useful lives and are just too thin to repair cost effectively.  The posts and base are still sound and can be re-used with new machine compressed brush fencing panels fitted cost effectively.


Image:   With this corner fence, the left hand side can be repaired by lifting and patching, but the brushwork on the right hand side section has reached its use-by date will need to be replaced with new machine compressed panels.  The posts and base can be re-used, but the capping should be replaced.  Sometimes it is necessary to sleeve or replace old posts where non-galvanised material was used and they have corroded.


Image:  On this corner fence the posts and base can be re-used on the left hand side section and the brushwork replaced with new machine compressed panels.  The sagged section on the right hand side can be lifted to restore.

Image:  The post and base in this fence can be re-used and new machine compressed panels fitted, with either colorbond capping top finish or new brush roll top fitted.


Image:   In general with low hand packed brush fences it is not possible to lift the brush top layer due to the nature of the layup.  This fence could be faced with new brush to restore, but with fences up to 1060mm high, tall 2120mm high machine compressed panels can be cut into two sections to provide a cost effective replacement option.


Image:   The brushwork in this fence should be replaced with new machine compressed never-sag panels.  The posts and base are still in good condition and can be re-used.


Image:  The owners of this fence have removed creeper which has suckered to the brush and have destroyed the old brittle brushwork in the process.   This fence is over 20 years old and the best option would be to replace the brushwork with new machine compressed panels.  The posts and base are still fine and can be re-used.


Image:   The brushwork in this fence should be replaced with new machine compressed never-sag brushwood panels.  The posts and base are still in good condition and can be re-used.  The rails would be replaced.


Image:   The brushwork in this fence should be replaced with new machine compressed never-sag panels.  The posts and base are still in good condition and can be re-used.  Using 2120mm high panels split into two strips is a cost effective replacement option.

Image:   The brushwork in this fence should be replaced with new machine compressed never-sag panels.  The posts and base are still in good condition and can be re-used.


Image:   The brushwork in this fence should be replaced with new machine compressed never-sag panels.  The posts and base are still in good condition and can be reused.

Image:   The creeper and vegetation should be cleared back from this fence.  The brushwork has reached the end of its useful life and should be replaced with machine compressed never-sag panels.

Image:   The brushwork in this fence should be replaced.  The posts and base are still in good condition and can be re-used.

Category 4.  Complete New Fence & Base Required
Complete New Fence Required.    In the case of old timber posted, hand packed fences, it is usually most cost effective to completely remove the old fence and concrete base to the waste station and to replace with a new galvanised steel posted fence.  The timber posts invariably rot beneath ground level and are only held up/wedged by the concrete fence base above ground level.   Other situations where complete fence replacement may be necessary, include fences with damaged concrete bases due to tree root upheaval or bases overturned by backfill/soil removal/undercutting and where the steel posts have rusted out (eg where painted black tube posts have been used rather than galvanised material).

Images:   It is not worthwhile fitting new brush panels to old timber posted fences as the posts rot beneath ground level and need to be replaced.


Image:   This fence should be replaced with a new fence comprising galvanised steel posts, reinforced concrete base, machine compressed never-sag panels and either brush roll top or colorbond capping finish.

Image:  Hard to produce a silk purse from pigs ears .... needs a new fence.



Image:   The concrete base has not been reinforced and has moved with ground or tree root movement.  The small end section at least should be replaced with a new fence.



Causes of Sagging in Hand Packed Fences

'Sagging' in hand packed fences is inevitable due to the nature and layup of the traditional method and generally caused by either one of, or a combination of three different factors and compounded by loose or thin hand packing and poor wire staple (clip) tensions or wire staple spacings.  The causes are;    1) loss of top and bottom fine brush leaf material,   2) inter-layer settlement of the brush and  3) dislodgment of the brushwork off its base. 

Cause 1)  Top & Bottom Loss of Fine Brush Material   As the fine materials in the bushy ends of brush 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 overall height of the brushwork tends to shorten and as the brush is standing on the concrete base, the effect of both factors combines as a gap at the top of the fence from a few centimetres to about 20cm.  Where the wiring assumes a sagged line rather than straight, this is indicative of the cause - top and bottom deterioration of the brush.  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 and spacing of the wire staples in a hand packed fence, also have a bearing with regard to the time taken for a fence to 'sag' in the foregoing manner.  

Cause 2)    Fence inter layer settlement  in a hand thatched fence, is the relative movement of the top and bottom 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.  The mid-wire clips actually compress the top and bottom layers of brush together laterally, where they overlap in the fence, preventing the top layer from settling relative to the bottom brush layer (which is standing on the base).  This also can occur as a fence ages and the fence loses brush leaf mass and fence volume with consequent reduction in tension of the wire staples/clips allowing the brush in the top layer to settle relative to the bottom layer.

Cause 3)    Dislodgement of the fence off its base will have a similar, but more immediate sagging effect as the other two mechanisms.  The most common cause of fences coming off their bases is where there is soil buildup on one side.  Quite often a neighbour will create a garden bed or planter box next to a brush dividing fence or raise general ground levels next to the fence and use the fence as the rear soil retainer.  The weight of soil pushes the brush fence off its base and moisture in the soil rots the brush with time.  The fence suffers sagging at the top and deterioration of the bottom as a consequence.

Image:  Fences off their Bases ........cause immediate sagging at the top of the fence.


Image:  Most brush fences pushed off their bases have as a cause soil introduced on one side in planter beds of approx 300mm or so in depth.  In some cases up to a metre depth of fill is placed against a fence in a three sided planter box with the fence forming the fourth side - causing leaning of a brush fence and rotting and destruction of the brushwork.

Image:  Hand packed brush fences can also be knocked off their bases by car  eg in unit complexes where where car ports have a brush boundary fence in front of it.  


The reason hand packed fences sag when they are pushed off their bases?   .....  because with hand packed fencing the wires are generally tensioned off around every 5th post (4 panels) and the wiring is not attached to the intermediate posts at all.  The length and slack in wiring spanning 4 panels is insufficient to support the weight of brushwork in the event of dislodgement of the panel from the support base and when it is pushed off the edge the brushwork slides down the face of the concrete base causing the sag at the top .   Machine made panels do not suffer the same problem as they have integrity and stiffness in their own right with compressed brush and staples at 100mm spacing firmly holding all the brush together and when the panels are installed the wiring is tied off around the posts at each end of each panel making it more difficult to dislodge from the base under side impact or weight.

However, fences are not designed to be retaining walls and should not be used as such.


How Can Sagging of Hand Packed Fences Be Minimised?

Premature fence sagging can be caused by poor packing techniques, the type of brush used, wire staple spacings and tensions and other poor practices.   However, eventual sagging of a hand packed fences is almost certain and is inherent in the way they are put together and one that is not altogether avoidable even with the best of hand packing techniques.

As a natural and biodegradable material, deterioration of the brushwork with age and weather can never be cost effectively halted, but sagging can be prevented by use of machine compressed brush fencing panels instead of hand packing.

Note:  Brush roll top finishes only have a life of around 12 years before needing replacement on both hand packed and machine made panel fences.


1.    Fix Horizontal Wiring to Each Post

The effects of sagging in hand packed fences 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 laterally through the drilled post and attached to the running wiring on each side.  See history of brush fencing here HISTORY Unfortunately with current industry construction methods for hand packed fencing, wiring is now 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.

When wiring is located/fixed to each post, the wiring is then only able to sag between each pair of posts.  The wiring and each post therefore act to provide some support to the wiring and brushwork as it shrinks with age, whereas when the wiring is fixed to only the first and fifth post, the wires have sufficient length and scope to move downward with the brush allowing sagging at the top. 

Machine made panel wiring is fixed to a post at each end of each panel and sagging is not an issue in any case due to the layup, compression and close staple spacings of the machine made panels.


2.    Wire Clip Spacings

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.  In machine made panels, the wire pins are fixed at centres a maximum of 100mm apart and brush is laid up differently with woody stick and fine leaf material interwoven throughout the height of the panel under machine compression.


3.    Use of a Wide Base

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 hand packed brushwork to be dislodged, causing immediate sagging of the fence.


For information on damaged brush fences and fence alterations, see these pages.......









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