Foundations, Subfloors, and Screeds

Foundation Type Selection

  • Your foundation type should be chosen by this stage.
  • For a standard foundation, your engineer will specify the foundation system, including concrete and reinforcement details.
  • Specialized foundations, like piles or insulated foundations, will require contracting a specialist company whose engineer will provide the specifications.

Site Inspections and Reinforcement Ordering

  • Your engineer will visit the site to verify that work is progressing according to plan.
  • Building control inspection (NI) and certification from your certifier (which could be your engineer) are required at this stage.
  • Concrete is typically ordered from a truck. If access is difficult, you may need to hire a pump or an extension to reach the site.
  • Reinforcement, usually steel (known as rebar), can be sourced from a builder’s merchant.

Subfloor Installation and Plumbing Preparations

  • Once the foundation is laid, follow your engineer’s specifications for the subfloor.
  • Ground conditions may require additional reinforcement, such as bars or mesh.
  • Before pouring the concrete slab, the groundsman must install piping for kitchen and bathroom waste, extractor hob ventilation (if needed), and waste pipes for appliances like washing machines.
  • Confirm plumbing and electrical plans with the plumber and electrician.

Radon Sump and Service Installations

  • The groundworks contractor should install a radon sump if required, and an external air supply if you plan to use a stove or combustion appliance.
  • Check if an additional outlet is needed for the hob extractor, depending on your chosen model.
  • Services might be installed in the screed, but this depends on the depth; ensure all services are accounted for.
  • If pipes require cutting through the radon barrier, it will need to be resealed using proprietary clips, ‘top hats,’ and an approved adhesive system.

Drying Time for Wet Pours

  • Wet pours, whether for slab or screed, will need drying time depending on type and thickness.
  • Verify the drying duration in advance, and monitor moisture levels using a meter after pouring.
  • It is recommended to avoid painting or applying undercoats until both the floor and plaster are dry. This can take one day per mm of thickness with cross-ventilation but depends on specific conditions.

Tiling Preparation

  • Before tiling, the underfloor heating must be gradually heated to commission the screed.
  • Some additives can reduce drying times, but for tiling on anhydrite screeds, the surface must be primed with a calcium sulphate screed-compatible primer as per the tile adhesive manufacturer’s instructions.
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Information on building your own home is for general purposes only and may not be accurate or up-to-date. Always consult with licensed professionals before making any decisions. We are not responsible for any errors or outcomes based on this content.

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