Groundworks & Foundations: Ground Floors

ABOVE: Insulation - It is now a requirement of Building Regulations that ground floors are insulated. The standard method is to lay sheets of polystyrene or similar above the ground floor and then lay a screed or a timber floor over. However, a number of systems are now available which incorporate insulation within the ground floor itself. The best known are Tarmac’s Heatsave Plus (ABOVE, tarmac.co.uk) and Hanson’s JetFloor (hanson.co.uk), which works with beam and block floors. Another system, Eco Slab, is designed to work as a layer of insulation under a solid floor.

There are two distinct methods of constructing ground floors. One is to lay the floor directly onto the ground (known as solid floors); the other is to lay beams across between the walls (known as suspended floors). Solid slabs have been seen as traditional, but there has been a marked trend towards suspended floors over the past few years, driven in part by perceived problems with solid floors. Suspended floors also have the advantage of being a largely dry construction system — i.e. it doesn’t involve the use of ready-mixed concrete. Inter mediate floors are usually built from timber, but timber is now rarely used at ground floor level (though it was commonly used in the Victorian home). These days, the preferred material is precast concrete beams: the spaces between the beams are filled with concrete blocks, hence they are known as beam and block floors. They are now widely available across the country, having once been more or less confined to the clay lands of southern England.

Which Floor?

In general, there’s little to choose in cost between solid and suspended, but suspended is sometimes preferable on difficult or sloping sites. Ensure that you get adequate insulation installed in the floor, and watch out for other requirements which can affect some sites, such as radon or gas protection.

Beam and Block Floor Structures

1. Beams lifted into place 2. Suspended floor takes shape 3. beams are laid, ready for blocks 4. Blocks are inserted between beams 5. Nearly completed brick and block floor.

Floor Types

1. Suspended Timber; 2. Solid Concrete Oversite; 3. Suspended Beam and Block.

These are the three main floor types available for new homes. Suspended beam and block is the most common, timber far less so, although ecofriendly homebuilders may prefer one. If the ground level is flat, solid concrete is the cheapest option.

Further reading:

• Groundworks & Foundations: Excavations
• Groundworks & Foundations: Foundations
• Groundworks & Foundations: Drainage
• Groundworks & Foundations: Rainwater Management

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