The options for preparing the base to DPC are:
- Ground bearing floor
- Suspended floor
The construction types in these pages are suitable for
a number of finished floor surfaces, the most usual being carpets, laminate, solid timber
flooring,
engineered wood flooring (here a real wood top layer is laminated onto
a plywood
under layer), ceramic/stone tiled floors, vinyl tiles.
Ground bearing floor
This consists of solid fill to support a concrete slab. If there is sufficient depth then ask your architect if a large gauge sub-base could be used. This is the cheapest backfill but is very difficult to handle, get level and compact so, if you do use it, you will need to finish off with smaller gauge sub-base such as scalpings. Even if the delivery lorry can unload into the build you will need a digger, telescopic handler or JCB type machine to get the sub-base into place.If the depth of infill will exceed 600mm then the concrete slab must be re-inforced (or a suspended floor used). This is usually done by getting a re-inforced concrete mix from the readymix company - where fibres are added to the mix (rather than re-inforcing the concrete the hard way, with steel mesh).
The SAP requirement for insulation will most probably require insulation at the slab level. This insulation can be put all under the slab or, as we prefer, split equally above and below the slab. Which of these options used will affect the SAP calculation – putting some above the slab increases the insulation effectiveness and may reduce the total amount of slab insulation required – this may, for example, replace a cavity type insulation with expanded polystyrene – a cheaper type of insulation.
The slab is usually poured concrete to a depth of 100mm, and 150mm for garage floors.
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