Timber and steel horizontal Slat fences, The Modern front fence

The current growing trend in modern house design in Australia is very square and rigid buildings and angles and therefore modern fences are being built to match.
Traditionally a premium front fence would be a picket fence with some kind of feature such as a wave or step feature. In recent years however horizontal slat fences have increased in popularity compared to the traditional picket fence.
Horizontal slat fences (also called post and rail fences or privacy screens by some) come in a variety of materials including treated pine, (which is usually dressed treated pine, primed and ready to paint) premium hardwoods such as iron bark, merbau etc, or steel/aluminium.
Each type of material has its advantages and disadvantages when utilized for horizontal slat fence construction.
Dressed treated pine is strong and durable but should be painted when complete as the slats come pre primed (undercoated) ready to be painted and looks unfinished if left unpainted. Painting the timber will help seal the timber and prevent warping thereby increasing the life of the timber. Painting the fence however, can be costly and tedious.
The hardwood timber used for horizontal slat fencing is generally the same timber used for most timber decking however the timber is cut differently so that both sides are smooth where as with decking the underside is cut with grooves. Being the same material as decking means when hardwood is used for slats fences, it has the same maintenance requirements that decking has. The timber needs to be oiled or stained regularly otherwise it will dry out and turn brittle.
Another trait of hardwood is that after a couple of weeks in the sun, the next rain or hose down with will result in the hardwood leaching tannin. This is a reddish brown natural substance that leaks from the timber almost like its bleeding and will stain concrete or tile surfaces underneath. Property owners should be careful about where they position a hardwood horizontal slat fence as this leaching will undoubtedly occur more than once and therefore may cause problems.
There is relatively recent product now in the market called mod wood or eco timber which is made from 100% recycled materials, mostly plastic from plastic bottles. This product looks similar to timber, especially hardwoods but has none of the maintenance requirements required of hardwood making it a very appealing material. The downside however is that it costs over double the price of the cheapest hardwoods and despite the effort to make it look like timber, it still looks and feels like plastic up close.
Aluminium slats are the premium horizontal slat material and come in most widths and spacing requested. The slats come powder coated (similar to painting) in any of the popular colorbond colours and therefore require no maintenance and looks great with most modern houses. The only downside of aluminium slats is the price as they are approx 3 times more expensive per square metre than other slat fences.

Treated pine posts vs hardwood posts, vs steel posts when building fences

Hardwood and treated pine are the two traditional types of timber posts used in fencing. Being a natural material, both types of wooden post will eventually rot and require replacing but the speed at which this disintegration occurs depends on many different factors. There is a growing trend in the use of steel posts for timber fencing in Sydney. Steel posts have much greater longevity and strength but a higher cost. The question I commonly get asked is does the increased cost of steel posts represent good value in the long run?
Treated pine is treated to withstand rot for longer and also protects against termite attack. In the past, fence posts were commonly put in the ground without concrete so it makes sense that these posts should last longer than hardwood posts. However, concrete is almost always used for fence posts today which means a hardwood post doesn’t come into contact with the wet soil. The speed of rot is dramatically reduced and if built correctly, hardwood posts can have a long life too.
For this reason, I believe that hardwood posts will outlast treated pine posts as long as dirt is not allowed to build up around the base of the concreted area. This doesn’t protect hardwood from termite infestation, so if there is a high risk of termite attack in your area then take the treated pine option as this will minimize this risk.
Steel posts are stronger than both hardwood and treated pine posts when heavy gauge (2.5mm thick) steel is used. They are galvanised against rust so they will outlast timber posts by quite a long time if built correctly and will not bow like timber may so the posts will remain straight. Although they are galvanised against rust, in salty areas near the coast the posts will rust eventually, and sometimes in less time than a timber post may rot.
We can also look at the longevity of a post on a time scale. Taking into consideration the Sydney climate, a well maintained treated pine post would roughly last 15-25 years, hardwood 20-30 years (if un-infested by termites), and steel posts 35-100 years depending on the thickness of the steel.
Although steel posts may last 100 years, the timber on the posts won’t and will require replacing eventually. The advantage of steel posts is that when this happens it’s simply a matter of removing the timber and replacing it with new timber. The advantages of this is you avoid the labour cost of digging holes, concreting posts in and dealing with boundary disputes the second time around!
So how much money does the additional cost of steel posts save you and over how long?
As a rough estimate a basic closed paling fence 30m long may cost you $2400 including the cost of demolition and removal of the old fence. Steel posts will increase the cost by $21 per post and since there are 10 posts the additional cost would be $315, bringing the total cost of a steel post fence to $2715. In 20 or so years when palings and rails need to be replaced, we can re-use the existing steel posts, and the cost of replacing the fence again would be approximately $1650. This is a saving of $750, when compared to re-purchasing an all timber fence at the cost of $2400. Multiply that saving by the 3 fences you share with your neighbours and you can see that over time you’d be getting great value from your choice of steel posts!

Timber fencing with steel posts

Traditional timber fencing is built using timber posts, however a growing trend in the Sydney market is the use of steel posts with timber fences.
The first steel post/ timber combinations used round posts which were more readily available. You may see older timber fences that still have round steel posts. Initially, they were made quite thick for fence building so you will find that most of the round posts are at least 2.5mm thick. Steel posts used in fence building today are generally 50x50mm square posts. Initially, square posts were manufactured with similar thickness to that of round posts.
A relatively new product on the market in Sydney is a 50×50 steel post which is 1.6mm thick and often referred to as light gauge posts. These posts are substantially cheaper than 2.5mm thick posts, which are often referred to as heavy gauge posts.
The cost of a light gauge steel post is approximately $16, whereas a heavy gauge steel post will set you back an average of $28. Over the length of a decent sized fence, the price difference can be quite significant. To complicate things further, the naming of these posts can be deceptive for customers purchasing a fence installation. Always check the thickness of the posts you have been quoted for before booking a job. This will ensure you receive the quality of posts you’re after.
People often ask me what the cost difference is between a standard treated pine post or a steel post. The cost is close to the same for light gauge steel posts and timber posts. Briefly, treated pine posts with rail holes morticed (cut out from post) costs approximately $16. An additional cost of steel posts is that the rails are often bracketed to the post using Z shaped brackets which cost approximately $3 each. This increases the cost of the steel post option by $9 per post when built using brackets. Please see my article “Treated pine posts vs hardwood posts vs steel posts for timber fencing” for more information for the steel versus timber post debate.
So which steel posts are right for you?
Light gauge steel posts are not as strong as Heavy gauge steel posts but it also depends on what you’re attaching to your posts. Fences come in many different styles and timbers and there are some where light gauge steel posts are sufficient to hold the weight of the fence, but also situations where light gauge isn’t enough. With no clear standards for fence post thickness versus the weight of fence; this is a bit of a grey area in fencing. No one likes grey areas so I offer you my opinion based on my experiences, my colleagues and various suppliers who’ve been in the industry for many years:
Treated pine is lighter than hardwood so light gauge steel can be used for treated pine fences up to 1.8m high for standard paling fences. I would not recommend light gauge steel posts for a lapped or lapped and capped treated pine fence. These fences hold one and a half times the weight of a standard paling fence and would not be well supported. In addition light gauge steel posts are not suitable for any hardwood fence jobs over 1.5m in height: the weight is too much for the frame to handle.
When fences are higher than standard and heavier due to materials used, the thickness of the steel or the size of the post should be increased also. The most common size post used in these circumstances is 65x65mm.

Timber fences vs colorbond fences in the Sydney market

Sydney is a very popular market for timber fences. But are they worth their price when compared to a colorbond fence?
A basic timber paling fence and a basic colorbond fence are usually very similar in price. Colorbond is usually slightly cheaper on level ground but slightly more expensive on sloped or uneven ground.
I am often asked by customers, “which one will last longest”?
In my opinion if properly maintained a colorbond fence will outlast a timber fence by 5-10 years. Colorbond fences are made from steel so the paint will fade and the steel eventually rust but not so quickly as treated pine or even hardwood posts will rot through enough to lose stability.
A modification growing in popularity to increase the life of the timber fence is to use Galvanised steel posts. Galvanised Steel posts may eventually rust but the steel is thicker than colorbond steel so the posts will outlast colorbond posts however the timber will still generally warp, fade and rot therefore still living less time than a colorbond fence however if the fence is maintained correctly when the timber has seen its last days you can simply cut the timber frame away and re-use the same steel posts for your next fence.
This will reduce the cost of your next fence substantially because most of the labour in fence building is the setting of the posts which won’t be necessary. The price of a standard 1.8m high paling fence is not increased using steel posts as light gauge steel posts can be utilised for the same cost as timber posts. If you wish to upgrade to a higher fence or lapped palings then this will increase the cost of the steel posts as heavier gauge steel will be required.
Although steel posts will increase the life of your timber fence, many people don’t like the look of steel posts and wish their entire fence to be made from timber therefore opting for timber posts.
Although colorbond is generally longer lasting than timber fences with timber posts, it has other disadvantages. The heat from our hot Australian sun is absorbed into the steel and radiates onto plants close to the fence which can be harmful to the plants depending on how well the plant handles increased temperature.
Also colorbond fencing is easily bent or dinged by kids, animals or vandals. For this reason I do not recommend a colorbond fence that backs onto a public area because vandals seem to love tagging them, (spraying them with spray paint) or kicking and denting them.
Although there are over 32 colours to choose from with your colorbond fencing, neighbors often do not agree and it can be costly to paint one side a different colour.
In summary both colorbond and timber fences have their advantages and disadvantages and your personal circumstances will depend which fence type would best suit your needs.