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House extension materials, stage by stage
Planning an extension? This is the order materials usually go in, so you can see what’s coming and get it priced in one go. Your builder and architect will set the exact specification.
Groundworks and foundations
- Concrete or ready-mix
- Ballast, sharp sand and cement
- Type 1 sub-base
- Damp-proof membrane and damp-proof course
- Below-ground drainage pipe and fittings
Walls
- Facing bricks to match the house
- Concrete blocks for the inner leaf
- Cavity wall insulation
- Wall ties and wall starter kits
- Lintels and cavity trays
- Building sand and cement
Roof
- Roof timbers or trusses
- Joist hangers and restraint straps
- Breathable membrane and battens
- Flat roof deck and covering, if it’s a flat roof
- Fascia, soffit and guttering
- Roof insulation
Windows and doors
- External doors or bi-folds
- Window boards and reveals
- Door linings and frames for any new internal openings
First fix
- CLS studwork for internal walls
- Floor insulation and floor deck
- Ceiling and wall insulation
- Fixings, screws and adhesives
Plastering and second fix
- Plasterboard and beads
- Multi-finish plaster
- Skirting and architrave
- Internal doors and ironmongery
- Flooring and underlay
This is a general guide, not a specification. Your builder, architect, building control or the manufacturer will confirm exactly what your project needs.
Get it priced
Send Allan your extension materials list, or your builder’s, and get one delivered price.
Common questions
When should I order extension materials?
Stage by stage is usual, so materials aren’t sitting on site for weeks. Agree a schedule with your builder and get the whole list priced up front, so you know the total.
Can I buy the materials myself instead of my builder?
Yes, some homeowners do. Agree it with your builder first, so the right materials arrive at the right time and it’s clear who is responsible for what.