ferejoomla.blogg.se - Floating foundation for house explain

The edge of the raft must be carefully detailed for the damp course and membrane position, which may need a ‘step’ forming in the concrete at the raft edge.

‘Treading in’ the reinforcement during the concrete pour isn’t a suitable means of placing reinforcement - use the special ‘chairs’ or ‘soldiers’ to support the mesh.

You must ensure steel reinforcement is lapped at least 450mm (for both mesh and mild steel bars) and provided with 40mm concrete cover.

This stone should be mechanically compacted.

The raft design will normally need a hardcore sub-base to level the ground.

Very poor ground may mean you need a different solution such as piles.

A site investigation is usually needed for the engineer to understand what the ground is like.

These beams transfer the building loads through the rest of the slab and then evenly over the ground. Internal stiffening beams are sometimes needed too.

The raft design usually has an ‘edge beam’ formed by a cage of steel reinforcement, which will need carefully assembling on site.

Here are important considerations if you’re thinking about using a raft foundation: However it is important to note that raft foundations aren’t suitable in all cases and usually need designing by a structural engineer. This is an alternative if you can’t use a traditional strip or trench fill foundations. This type of foundation spreads the load of the building over a larger area than other foundations, lowering the pressure on the ground. A raft foundation is a reinforced concrete slab under the whole of a building or extension, 'floating' on the ground as a raft floats on water.