Steel stumps are by far the most popular stump choice. They are favored by engineers and builders alike for a number of reasons. Easy to work, readily available, strong durable and provided they are treated properly steel stumps are long lasting. In many cases the stumps are later enclosed within walls, with the help of support beams to remove some of the internal posts the area under the house is built in. In this case the stumps themselves disappear from site completely being enclosed within wall framing.
Steel stumps can be engineered and fitted to your house in different ways. The two more common place methods in discussion here differ mainly in the way they brace the building. If you were to compare them to something else structural like a car for instance. You could say one method is similar to a chassis with a body mounted to it. The other more like the modern car is a framework braced onto itself. As with everything efficiency in construction, cost of material etc has made way for new and better ways to support your building.
Stumping with bracing
The first method and more commonly used today for many reasons is a steel stump footed by a dense concrete footing. For a high set building the building is fitted with significant wind bracing between the stumps. This holds the understorey of the building from movement by bracing the posts onto each other in critical locations. This bracing is usually replaced when the building is built in. The walls are built and provide the necessary bracing in different ways.
Stumping with less bracing
The second method of choice is a deep reinforced footing or pier with the stump bolted between it and the building. This method uses significant materials as there is little or no bracing used. The piers or deep footing are generally 2- 3 times deeper and the stumps up to double in size. In both cases there is approx double the materials used. This method draws it strength from the deep piers and stump engineering to take the sideways force thus reducing the building overall bracing requirements.
Timber stumps are not as popular as they have been in past times but they are making a come back in many ways. Transitioning from logging hardwoods to make the stumps to using farmed timber their popularity has decreased. Prone to rot and having a limited life timber has become more expensive. Whereas once a budget choice their quality’s shine in other areas. Timber stumps are now more expensive for the material purchase but easier and therefore less expensive to install. More so their value is in the ease to do them one or more at a time. The quality of the timber and its preservation are becoming a lot better. Whereas they can have a limited life they can be replaced singularly or one by one, without excessive expense. The combination of usability, the timber quality and treatments has revived its place.
Timber stump’s can be used anywhere however are well suited to particular application. This could be a feature row of stumps. Where the rest or the internal stumps are concrete or steel and a feature row on the outside of the house are used to match fencing or other aesthetic’s. Timber provides a nice rounded finish when the stumps are left exposed to view in particular where there are other timber finishes.
Timber also provides a very good way forward for ongoing maintenance on your building. Whereas steel or concrete stumps are usually done in large sections if not the whole house due to heavy expensive deliveries of materials concrete in particular. Timber stumps can be replaced piecemeal. Although it is slightly more expensive to do one or two at a time the building is constantly maintained at an affordable and manageable level. It can be quite a shock when the stump replacement costs bear to reality and therefore for ongoing maintenance they can be a great choice. And a clear choice for low to mid set buildings with lower ongoing maintenance budgets.
Concrete stumps are a great choice for a house. There are certain considerations that need to be met in the areas of central QLD and North. High wind and high water tables are probably among the more important. Concrete stumps in today’s day are made from very strong steel reinforced concrete. It hasn’t always been that way. Most of the early concrete stumps were made from local materials. The builder would more often than not build his own. Some form boxes, local sand and rock out of the creek, scrap steel for reinforcement and dry cement powder and water. Manufacturing the stumps locally and in many cases on site made them an easily achievable long lasting option for stumps.
Either way they have stood the test of time. Although their weight makes them an expensive choice, as with timber the can be used were a certain look or style is sought.
Concrete stumps can have a very long life provided some considerations are met. The stumps are very strong and robust however excessive force is exerted on them if they are not installed properly or later works is done.
Concreting around concrete stumps
Concrete stumps like timber are direct in the ground with another bell of concrete at the bottom. The bell at the bottom is usually around double the diameter of the stump. It serves as a base that stops the stump from sinking or lifting. This allow’s for some minute sideways movement of the building without excessive force being absorbed by the stump.
A common mistake made when concreting under a high set house with concrete stumps is to concrete the floor right up to the stump. This restricts the sideways movement of the stump. Strong gale force winds battering at the side of the house put pressure on the stump at the point where it is fixed by the concrete slab. This is easily overcome by expansion material in a control joint. Flexible products installed between the slab and the stump to allow for this movement. This expansion material, foam jointing and flexible polyurethane products within the control joint act as a shock absorber for your stumps.
Bracing is a critical component in this type of construction to limit and reduce the buildings lateral movement and the associated issues discussed.
As with all foundations the stumps need to be kept clean and dry. The entire underside of your building should be as dry as possible and kept well drain. Concrete stumps will benefit from regular maintenance and a coat of paint or sealer at times.
Steel Beams for upgrading bearers and eliminating stumps
There are a several very good reasons we incorporate steel beams intorestumping and other footing upgrade or renovation projects. Steel beams are available in different styles or types and sized to suite various different applications.
Some low set buildings may incorporate steel beams into the restumping project to eliminate stumps in more difficult to reach places. If a building is to close to the ground for safe working or perhaps even to work at all then another solution must be found. In some cases it may be easier to lift the building up to a safer and more manageable height. In other cases if the outside can be reached to install stumps then a beam can be installed to make the centre posts redundant. There is still some work that needs to be done under for instance the beam needs to be fixed or bolted to the bearer. However it saves an enormous amount of work excavating new holes for the stumps fixing the new stumps and a whole lot of concrete. This can also be the case for a high set house where there are a large number of centre posts it may be more cost effective to go this way.
Many older homes weren’t built to today’s standard and whereas they have passed the test of time weathering the severe North Queensland storms when it comes time to renovating or restoring they will need to meet the current standards. This isn’t usually to much of an issue and something you would probably want in any case for peace of mind. One of the problems that can present itself is bearers can be either inadequate or they may be of a smaller size requiring a large number of stumps to be installed or present. Reinforcing the bearer with steel minimises the need for stumps increasing the span between them and makes the floor more solid.
Floor space is another reason steel beam are used. As we previously mentioned installing beams increases the span between stumps and therefore in a high set scenario the underside of the house can be virtually stump free in the centre of the building. In this case some stumps are still used in the centre of the building however the design is such that they are built into internal walls.