Consists of a large concrete slab...
Raft foundations are often used if the conservatory is more than one storey to spread the load across a larger area – this is usually the whole area of the structure. They may be necessary if there are other structural loads close by in case the individual pads affect each other. They consist of a large concrete slab; this has to be large enough to spread across the whole area of the structure. The raft is sometimes made even less flexible by incorporating ribs or beams into the concrete slab.
Resists soil movement...
Raft foundations usually work well in areas where the soil is loose and soft and this means that it has a low load bearing capacity. Using the concrete slab means that the load of the building is spread over a greater area. When the soil is loose it often shifts or resettles; using foundation helps to considerably reduce settlements where the soil level becomes uneven. The concrete slab aids to resist these movements between the loading positions which makes the foundation safer.
Can break away from the existing property...
One of the problems is that they can break away from the existing property if there is insufficient care taken to make sure that the edge of the raft which is against the edge of the property doesn’t break away when the raft has settled. This is because the existing property and the new conservatory settle at different rates.
Raft foundation issues can be avoided providing the builder has taken the time to ensure that the weight of the conservatory has been calculated correctly and whether the ground is sufficiently packed to support the load.
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