Common Questions and Answers
Are Oz-Posts as strong as concrete?
Oz-Posts have been tested to high levels of horizontal forces and have been found more than suitable for the majority of fencing and sign projects. A fence or sign constructed as recommended using Oz-Posts will be equally as strong as traditional concrete installation. A post placed in a standard 6"- 8" post hole with one or two bags of concrete takes minimum of an hour to install. (not to mention a day to dry) This method is not any stronger than an Oz-Post installed by one person in four minutes.
Testing has proven that the weakest part of almost any fence installation is the wooden or metal post. This also holds true for an Oz-Post installation. Testing has shown that the post will break or bend before the Oz-Post fails when installed as recommended. Of course Oz-Posts and 6"- 8" post holes with concrete are not suitable for all fence designs or all signs but most standard fence designs and signs allowed by city councils can be installed with the Oz-Post system. If you have any questions on the suitability of the Oz-Post system for your next project feel free to call our customer service department for more information.
How high can I go?
The maximum recommended height for a wood fence is 8' with post spacing at 6'. For a chain link fence the maximum recommended height is 8' with post spacing at 8'. (Please confirm with your local authority as these height restrictions may vary depending upon your location). Additional information on fence sizing and post spacing is available on our web site www.oz-post.com.
What length should my posts be?
The Oz-Post anchor system will drive with the top near flush with grade. You will therefore need posts for 'above ground'. For a 5' high chain link fence, terminal posts (end posts, corner posts, and gate posts) would normally be left out of the ground 1" taller than the height of fence being installed, 5'-1". Chain link line posts, or intermediate posts, would normally be installed at 4'-9", 3" less than the height of fence being installed. The loop cap which fits on top of the chain link fence and toprail will account for the difference. You may wish to order posts a little longer than this and cut once set if you'd like to be more on the 'safe' side of things. We do offer chain link posts cut to the foot and fraction of an inch.
What size and type should I use?
The size and style of Oz-Post is determined by post materials that you intend to use. For some post sizes Oz-Post offers several different styles for various applications. A good rule of thumb is to use the longest Oz-Post that can be easily driven into the ground. The more firm and compacted the ground is the shorter the Oz-Post you will require. If you have a special application that you would like to use Oz-Posts for let us know we more than likely have a special model for your needs.
What happens if I hit Rock?
The Oz-Post becomes an extension of your jackhammer. As a result it will break through loose shale and some rock. Smaller boulders will be pushed aside as the Oz-Post penetrates the ground. You may need to straighten the assembly a few times as the Oz-Post hits and deflects small boulders. Large solid bedrock and boulders cannot be penetrated by Oz-Post, in these extreme cases you will have to move the hole, or try a shorter or tapered Oz-Post. Remember a bobcat or post-hole auger will not penetrate most of the softer rock or concrete that Oz-Post can easily handle. Both Oz-Post and traditional methods will not penetrate solid rock!
Can Oz-Posts be removed?
Yes, Oz-Posts can be extracted if they are placed in the wrong spot, the fence needs moving, or they are only temporary. In lightly compacted soil conditions you can remove Oz-Post by using a 6' long pry bar. Place the pry bar under the housing, and using a piece of wood or a concrete building block placed at approximately 10" from the Oz-Post you can lever the Oz-Post out of the ground. If this fails your Oz-Post distributor can sell or rent you an Oz-Puller to make this process much easier.
What if the ground becomes water-logged?
Ground soil will expand and contract depending upon the water saturation levels. This is a natural property of ground soil and cannot be avoided. Due to the large surface area of the Oz-Post fins there is a high level of adhesion of the soil onto the Oz-Post. This helps to give Oz-Post their lateral strength and support. Where the ground is very water logged you may notice some increased movement in your fence, as the ground dries this deflection in your fence will decrease back to usual levels. It should be noted that these effects and properties are also evident when constructing a fence using concrete.
How does wood shrinkage effect Oz-Post?
Shrinkage in wood is a natural property, as moisture is absorbed and evaporated from the timber. This is not a concern as the Oz-Post housing fully encapsulates the timber post and also allows for drainage. It is recommended that the hardware be tightened 2-6 months after installation to assure the tightest possible connection. The use of a small amount of polyurethane glue is a great option to allow for a strong connection without the need to retighten the screws. Please review installation instructions for the model that you are installing for all installation options.
Shrinkage is a far greater problem when considering posts that have been secured using concrete. As the timber shrinks (the concrete does not) a concrete container is created which inevitably will hold water, thus your timber post becomes submerged until the water drains, a great environment for fungal decay. This is one of the reasons why posts rot out before the fence pickets and rails. Oz-Posts protect the wood posts from premature rot because they drain well and separate the wood from the soil.
What about Frost?
Oz-Posts perform excellent in both warm and cold climates. Frost is a force that can easily ruin any kind of post installation that is not done correctly. In areas that experience below freezing conditions evidence of damage caused by frost is easy to spot and very common. The best and easiest solution for this problem is Oz-Post!
Posts that have been installed with post holes and concrete can be heaved out of the ground by the freezing and thawing of the surrounding soil. If the buried concrete has rough sides frost can grab the post and heave it out of alignment and eventually completely out of the ground if it is left unattended. To assure that the concrete has smooth sides it is recommended that paperboard sleeves like sono-tubes be inserted in the augured hole to produce smooth sides and help prevent movement from frost. The use of sono-tubes is highly recommended for frost prone areas. This adds additional cost to traditional installations that should be considered when comparing with the Oz-Post System. In addition to smooth sides it is recommended that the post hole have an enlarged bottom like an upside down mushroom. This technique reduces the likelihood of the post being heaved. This is very time consuming and costly as it increases concrete requirements and removal of excavated soil. WARNING: many fencing contractors and do-it-yourselfers do not install fence posts this way and that is why you can often see crooked fence posts and sign posts throughout your neighborhood.
On the contrary the long, wide and smooth fins of an Oz-Post give the frost nothing to grab onto to push it out of the ground. In addition, an Oz-Post has a generally pointed shape and does not produce a horizontal plain for the shifting/expanding soil to push out of the ground. You can also think of it another way; it is much easier to push a pointed object into the ground (like an Oz-Post) then it is a blunt object (a wooden post). With frost heaving the exact opposite principle occurs. When the sub-terrain moisture expands from below freezing conditions it can easily push the blunt end of a post and or concrete out of the ground but because an Oz-Post is pointed with no blunt surfaces frost can't push it out of the ground. Oz-Post installations are far less likely to be heaved by the frost compared to the blunt and rough artificial rock that is formed with concrete.
If for whatever reason a post installed with Oz-Posts is heaved out of alignment it can easily be driven back in the ground or removed and reinstalled in the correct location. The same operation with a concrete installation would prove to be very costly and time consuming.
In addition to Oz-Posts tremendous long term performance in frost prone areas they can be installed even if the ground is already frozen!
Can Oz-Posts be used on a Gate?
Yes, Oz-Posts can be used for all kinds of gates that would normally be installed with a 6"- 8" post hole and concrete. This includes pedestrian gates up to 5'. If you are installing a gate that requires more strength there are several options you can use to obtain the desired stability. The simplest and possibly most effective method is to double up the posts on the hinge side of the gate. Placing two posts 10" apart will more than double the strength of the gate. Another gate strengthening technique is to join the top of the gate posts together with a header. These techniques are also a standard practice for installing with concrete.
Of course if standard practice calls for a 12" or even 24" post hole with concrete then that post will have to be installed in that way. These are not common situations and in most cases will only be 1 or 2 posts on a job. In these situations the post strength is increased with the large surface area in contact with the surrounding soil (large diameter) and the increase in mass of the concrete. A 12" diameter hole will hold at least 8 bags of concrete which is 480 lbs. In addition a much larger and stronger post should be used to take advantage of the increased strength of the foundation. There is no use in digging bigger holes if you do not significantly increase post strength.
What is an Oz-Hammer?
Our exclusive Oz-Hammer is a high grade steel attachment that fits most common jackhammers. The Oz-Hammer transfers vibrating forces of the jackhammer to the Oz-Post. You may need to get a Hammer-Spacer to adapt the Oz-Hammer to the Oz-Post model that you are using. See our web site to determine which Oz-Posts require the Hammer-Spacer.
If you are planning to rent a jackhammer most rental centers have Bosch, Brute or Wacker 60# electric jackhammers that are perfect for any size job. There are also gas powered jackhammers (Wacker model BH-23 is one popular brand) that are great for remote locations where power cords or generators would have difficulty reaching. Air operated jackhammers will also work, but are not recommended because they are very heavy and much more difficult to handle.
There are many other jackhammer brands and most of them will do the job. To be sure, the main feature that the jackhammer will need is to have a 1 1/8" hex chisel holder with a retaining collar. Custom Oz-Hammers can be made for those who would like to use their existing equipment.
What is a Hammer-Spacer?
The Hammer-Spacer is an adapter for the Oz-Hammer. An appropriate Hammer-Spacer is REQUIRED for many Oz-Post models. Please refer to your spesfic model to confirm if a spacer is required. You cannot install Oz-Posts that require a Hammer-Spacer without one.
Other Applications for Oz-Posts??
If you are considering using Oz-Posts for applications other than those specified in our literature please consult our customer service department. If we do not have a standard unit that is suitable for your needs our custom engineering department may be able to design and manufacture an Oz-Post to suit your requirements.
How long will they last?
Oz-Posts are hot dipped galvanized and under normal conditions will outlast the expected service of the post that they support. Oz-Posts have a much thicker zinc coating than most common steel fence posts available on the market. Oz-Posts are also suitable for use with pressure treated lumber.
Has Oz-Post? been tested?
Yes, Oz-Posts have been wind load tested to 120mph on a 6' high wood privacy fence. The testing report is available in the download section of our web site.
Does Oz-Deck meet building codes?
You may be required to get a building permit in your area to build a fence. Building codes for fence construction generally relate to the height and style of fence that is allowed on your property. Most of these codes are intended to keep uniform standards throughout a community. Other concerns on fence construction are sight lines for drivers and also to prevent land owners from constructing a fence that would be considered an eye sore.
Some cities have specifications for post holes for fence construction but most cases they will accept other equivalent alternatives like Oz-Post. In terms of the "post hole" many cities require certain depths and widths for fence construction. In frost prone areas this is to assure that the post holes are past the frost line to prevent heaving and in high wind areas these regulations are to assure post stability. Because you are NOT digging a hole with Oz-Post many of these codes do not generally apply.
Most inspectors do not have any issues with the use of Oz-Posts because they are specifically designed, tested and engineered for fence construction. Oz-Post also assures proper installation because it is difficult to "cheat" with Oz-Posts. Many contractors and homeowners do not follow the building code and dig their holes to the proper depth and width. This is the reason that post hole inspections are required for some fence construction projects. This is uncommon and in most cases is limited to commercial/government projects. Post inspections are not required for Oz-Post because there is no post hole.
In some areas especially high wind areas your inspector may request to see the wind load testing that is available for download on our web site. In all situations you should follow your local building code requirements. If your city requires 4' spacing for fence posts or a maximum height of 6' you will have to follow those codes.
How do they work?
Oz-Deck utilizes the floating deck building technique. Floating deck construction is a similar concept as concrete patio or slab foundation on a house. Patios, slab foundations or drive ways do not have piers in the ground they rely on distributing the weight over a large area to prevent them from sinking in the ground. Oz-Deck uses the same principle of spreading the load for the deck over more square inches of earth compared to the alternative method of digging post holes and attaching a ledger to the house.
With post holes and ledger construction one side of the deck is attached to the house with a ledger board that is bolted to the home. This requires special attention to assure that the board is properly attached to the home securely. Most deck failures occur because of improper ledger attachment. Oz-Deck is different because there is no ledger board required. The deck simply sits tight to the side of the home but is not actually attached to the home. This is why it is called a "floating deck". With post holes there is a great deal of pressure exerted on the posts because there are less posts compared to Oz-Deck. This is why it is very important that the piers be installed properly and why many cities require inspections of deck piers.
You can understand the concept of a floating deck vs. a pier and ledger deck by thinking about the old trick of a circus performer lying on a bed of nails. If there are hundreds of nails in the board the weight of the performer is distributed over many points of contact and there is no pain or injury. This is similar to a floating deck. Alternatively if the same performer lay on a board with just a few nails he would become seriously injured. This is similar to a post hole and ledger construction.
With Oz-Deck the construction of your deck is much faster and easier. Simply locate the deck plates where your posts are required and drive the Oz-Post through them.
How does Oz-Deck work on unleveled ground?
Oz-Decks are ideal for all types of terrain including areas that are unleveled. There are very few backyards that are level most having a slope away from the home to promote drainage. Traditional deck construction techniques are used with Oz-Deck which makes it very easy to adjust for varying grade changes. This technique is posts that support beams, joists sit on the beams and the deck boards are fastened to the joists.
After driving the Oz-Posts in the ground string lines are strung across all of the Oz-Decks at the desired height with a string level. This is an important step because this will make your deck posts all level. Simply measure from the string line to the base of the Oz-Post and cut a piece of 4x4 to the exact length. Repeat this for all posts. When this is complete your deck foundation is level with no digging, no concrete, and no mess. The posts are now ready for the beams to be installed. This process is very fast and does not require high skill levels. Please refer to the instruction manual for more information.
How high can I build my deck with Oz-Deck?
Oz-Decks can be used for decks that are up to 7' high. Cross braces are required for all decks that are 5' and higher. Cross braces are also recommended for decks that are built with post holes.
Does Oz-Deck meet building codes?
When used according to Oz-Decks recommendations, the Oz-Deck Foundation System conforms to all national and regional building codes when the deck is unattached from the house.
Even though a state may have one building code, the city/county may choose to impose greater regulations and restrictions. Confirm with your local building department before starting any construction.
When built according to Oz-Decks plan specifications, the Oz-Deck Foundation System meets structural requirements for deck construction. They are strong, durable, and safe. Oz-Deck is designed to meet a minimum load rating of 52 lbs. per square foot.
What is the difference between Oz-Deck and pre-cast concrete deck blocks or pier blocks?
The main difference between deck blocks/pier blocks and Oz-Deck is the construction technique for building the structure of the deck. Deck blocks do not use beams to support the joist structure therefore deck blocks are required under every joist on no greater than 5' spacing. For the average deck this requirement can add up to be twice as many deck blocks than Oz-Decks for the same size deck. Deck blocks are also heavy and difficult to move into location and must be located perfectly level and in line under every joist. This is a time consuming and tedious task. Getting the deck joist framing square is also challenging with this construction technique.
Because Oz-Deck uses traditional building techniques utilizing plans from deck magazines, books and web sites is easy to do. The only difference will be that with Oz-Deck there will be more beams.
One other advantage is that Oz-Deck offers lateral load strength and substantial vertical up load resistance. Because the wood support posts are attached securely to the Oz-Post there is no risk of the post becoming dislodged with the support. Oz-Posts also deliver substantial lateral load strength to keep long support posts stable. Deck piers offer no lateral load strength and no vertical load resistance because the support post or joist simply sits on the deck pier.
Is Oz-Deck available for post sizes other than 4x4?
No, Oz-Deck is only offered for posts that are 4x4's. The main reason for this is that there is no need to increase the post size because the added strength of a larger post and added cost is not necessary. Oz-Decks must be installed on 6' centers which do not produce a load that would require a larger post.
What beam and joist sizes should I use?
For the beams it is recommended to nail 2 2x6 boards together to make the beam and rest them on top of the post and attach with steel connectors. If the deck is going to be very low profile the beams can be mounted on the sides of the posts and attached with large bolts and/or brackets. For the joists 2x6 boards is all that is required. Spacing between the boards should follow building code and manufacturers guidelines (for composite decking). Generally 2x6 decking boards can be on 24" centers and 5/4 and composite decking should be on 16" centers.
Can I install a hot tub with Oz-Deck?
Yes, Oz-Decks can be used to support the load of a hot tub. In the area where the hot tub is going to be located it is required that the beam and post spacing be decreased to 3' centers from 6'. Also it is recommended to install extra Oz-Decks so that there is a minimum of 6 under most standard hot tubs. For larger tubs or other special projects call customer service.
How long do Oz-Decks take to install?
The actual installation of an Oz-Deck is about 2 min. but for project planning about an allocation of 10-15 min each post should be expected. So for a standard 12' x 12' deck that will require 9 Oz-Deck plates you should have all of the piers in place in about 2 hours. We have taken into account the time to run string lines and locate the post locations and cutting the posts to the proper height. It is assumed that this process is being done by two people. After the posts are in the rest of the project is very fast. Making the framing for the deck and squaring it up is easy and then all that is left is the deck boards. A basic 12' x 12' can easily be completed in one day by two people.
What does frost heaving and thawing mean?
Frost heave is caused by water that is trapped underground in layers of soil that have become frozen. When the water freezes it expands causing the surface to move vertically. This natural occurrence can cause the surface to move up in the winter and back to the original location in the spring when the frost thaws. Even if you live in a warmer climate like Texas, the principles are the same. The soil will expand and contract with temperature and moisture changes in the soil. This is less of a problem in these climates, but movement can occur.
How does frost heave affect conventional deck construction?
When footings are not buried below the frost line or without smooth edges, damage can occur. During cold seasons, ice lenses form, exerting pressure against the rough edges of the concrete post, forcing it upward. A pocket will form under the post where the soil is not affected by frost. Dirt particles and water will then accumulate into this pocket. During the spring thaw, it is likely that the post will not return to its original position (due to the accumulation of soil deposits). When repeated throughout the life of the deck, this process of lifting the post can cause significant damage to the structural integrity of the deck.
How is frost heave prevented?
The standard method is to anchor the post down by digging a large hole to or below the frost line. The shape of the hole should be like a bell. The hole must wider at the bottom than at the top. This is difficult to do but is typically required by building codes. If this is not done correctly, there will be heaving over time which could damage your structure. Building inspectors will often require "hole" inspections to make sure that it has been dug correctly significantly adding to the time necessary to build your deck.
How does frost heave affect the Oz-Deck Foundation System?
The Oz-Deck sits on top of the ground, moving up and down just as your driveway or sidewalk would. The deck structure is part of the anchoring system and is designed to accommodate the frost movement. Not fight against it.
When building next to a door, place the deck height a minimum of 1/2 inch below the door's threshold
Will my deck move sideways or pull from the house?
No. When frost heave occurs, the forces in the ground have nowhere to go except up. The deck may move slightly up and down, but not from side to side. In addition the anchor in the ground prevents any side to side movement. A deck built with Oz-Deck will not move away from the house
Should I put anything under the Oz-Deck piers?
It's not necessary to put anything under the Oz-Deck piers. They can sit directly on top of the soil or grass. The use of a jackhammer to install the Oz-Deck post is recommended because as the Oz-Post reaches the Oz-Deck plate it compacts the top soil and removes any air pockets in the soil providing a sturdy foundation. If you want to put something on the ground you can put fine gravel on the surface.
Will my deck sink?
Even on poor soil conditions, your deck will not sink. Oz-Deck foundation system is designed to distribute weight EVENLY across the ground. It is essential that you follow the recommended spacing of Oz-Deck piers.
A simple non-technical method to determine if your soil is suitable for Oz-Deck is the shoe print test. Under normal situations, if a person's shoe sinks into the ground more than 1/2 inch while they are walking, the soil may not be suitable for construction and corrections to site drainage and soil composition may need to be made.
My local building code and/or Inspector require footings. What do I do now?
Your local building code may assume that the deck you are building will be attached to your house. You will need to make it clear that you will be building a "floating deck? and that you will not be attaching the deck to the house. It is extremely unusual for a local building code to require footings for all types of deck construction. Typically footings are required if the deck is attached to a fixed object, similar to a house. A floating foundation is a different building method and clarification with the inspector should resolve any problems.
In some cases you will need to present a construction plan that you will be using. The inspector may also require additional technical information that is available in our download section.
Do I need to have my utilities marked?
Yes, the Oz-Post is driven into the ground 24"- 34" and therefore you must call for locations of all utilities. This service is free and can be accessed nationally by calling 811 or your local utility companies.
Can I use Oz-Deck for a gazebo or open roof structure?
No, open roof structures act like an umbrella can cause uplift in high wind. Oz-Posts do not offer adequate uplift resistance for roof structures. Open arbors and pergolas where wind can easily pass through can be built with Oz-Deck. Closed structures like a garden shed can be supported with Oz-Deck