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.
The building now supported excavations can begin and the structural work can be performed. Depending on your scope once again you and your builder will determine who you need and when. Subcontractors are often preferred by a particular building company over others and sometimes you the owner may have preferences as to who you prefer to use. Its not usually to much of an issue most contractors and subcontractors are willing to get along to get on with the job so there is freedom to move there. The builder will make their recommendations however you will have more than the fair say here. Whereas the subcontractors has obligations you may over the builder have more responsibility in ensuring they provide to satisfaction what their engaged to do.
Building and Restumping Subcontractors
More commonly stumping subcontractors are contracted for this work. In some cases such as blocking in a brickie or chippie may provide this work in the case of structural build ins over infill wall sections between stumps.
Restumping has several serious tasks at hand. These tasks and in no particular order consist of. The fabrication of the stumps constructed to the engineers specifications and requirements. The removal of the old stumps or supporting structure. Excavation for the new supports or stumps. Installation of the new stumps in readiness. And pouring of the concrete around the stumps at their footing. High set houses can have very deep footings, concrete can be built up around them and where land is not stable old techniques of stabilisation walls were used this needs to be removed. On a low set house there is very little room to move and although the old footings stumps etc are not such a big deal the restrictions in height make it an equally difficult task.
Price Guide – $18 000 – $30 000A very accessible low set house with less than 20 stumps would be on the low end with the high end representing a very large low or high set home, or smaller bearers on smaller homes with over 35 stumps.
Hot dipped galvanised steel in our opinion is without any doubt the best stump that has been produced since concrete stumps were formed. Concrete has stood the test of time still present under some older homes. They look good however are heavy and replacement costs are high. Timber needs constant maintenance and a 20-30 year replacement strategy. Steel prior to hot dipping would also have the same replacement needs however through alloying steel in the galvanising process that produces a product comparable in longevity to concrete.
Steel stumps need not be offensive and there are certain advantages to finishing off with timber or panelling. Although quite often left as they were installed with budgets making the decisions. They serve their functional purpose however appearance of your home is diminished. Appearance is certainly not everything in fact to some it’s of little importance. However it’s not only appearances that are gained by finishings. The timber or panelling have the added advantage of sealing up your home helping to keep vermin and other unwanted animals from access. And also helping to keep the weather out.
With some home styling the long lasting and rigid security of the steel stumps can be combined with timber finishing to provide the look right for your home. Vertical and horizontal slatting will help protect the underside, footings and foundations. Keeping it clean pest free and drywhile providing a great look for your home.
This can be taken a step further and the harwood timbers slating and or panelling can be selected and constructed to give you extra lateral structural support. Treated hardwood framing between the stumps on a low set house go along way to minimising the damaging movement in your home.
Bracing the stumps onto each other providing a finished timber infills to your home is inexpensive and will help to make your home safer and provide a great look.