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.