Self Build Guide

At a glance

Choosing a self-build route with HebHomes means you act as your own Main Contractor. It can be highly rewarding — and you could save 20–30% compared with a turnkey build (and up to 50% if you take on finishing tasks yourself) — but you’ll also take on responsibility for cashflow, safety (CDM), quality and compliance.

Before you commit

Find & assess land — condition offers on surveys (topo, ground investigation, percolation/drainage), servicing quotes and access feasibility.
Secure finance & cashflow — align stage releases to your programme (land → foundations → shell → completion).
Get approvals — planning → Building Control (E&W/Ireland) / Building Warrant (Scotland with SER). Appoint a Principal Designer (your architect/engineer) for CDM pre-construction.
Understand the build — readiness for kit erection, inspections, commissioning and sign-off.
Plan your finances: Carefully map out your spending and lender stage payments using our Estimate of Cost spreadsheets. Always keep a contingency of around 10–15%.
Understand your role: As a domestic client acting as Principal Contractor, you’ll be responsible for managing site safety, coordinating trades, arranging inspections and maintaining proper records.
Do the right work yourself: Focus on safe, simple finishing tasks. Leave structural, drainage, electrical, plumbing, heating, ventilation and compliance work to professionals.
Finance options: Use a stage-release self-build mortgage. Ecology Building Society can even support off-site kit payments before on-site valuations.

Reviewed by Alasdair Stephen, Managing Director, and Neil Stephen RIAS, Director.

Trade-by-Trade Quick Reference

Trade / taskDIY?Professional?Key guidance

Groundworks & Foundations

✗

✔

Engineer design & inspections; major risk if wrong.

Kit Erection (CPS/SIP)

✗

✔

HebHomes erects CPS; DIY not permitted (warranty).

Drainage & Sewerage

✗

✔

Design, install & testing to regs; photograph before backfill.

Roofing

Limited (simple metal)

✔ (slate/membranes)

Work-at-height rules; pro install recommended.

External Cladding

✔

—

Good DIY saving; follow details for weathering & fire-stops.

Windows & External Doors

✗

✔

Airtightness & warranty depend on pro fitting.

First Fix (Electrics, Plumbing, Heating, Ventilation)

✗

✔

Certification required (EIC, GasSafe, MCS).

Plasterboard

✔

—

Big DIY saving; use a lifter; follow acoustic guidance.

Taping & Filling / Plastering

Possible

✔ (for best finish)

Most self-builders hire pros to save time.

Second Fix Joinery

✔

—

Pre-hung doors/MDF skirts are DIY-friendly with care.

Kitchens & Bathrooms

✔ (carcasses)

✔ (connections)

DIY fit; pro for plumbing/electrical & waterproofing.

Floor Finishes

✔

—

Laminate, engineered timber, vinyl, carpet — good savings.

Tiling

✔ (small areas)

✔ (wet rooms/large format)

Keep tanking & complex layouts with pros.

Decoration

✔

—

High saving; prep determines quality.

External Works & Landscaping

✔

—

DIY most soft works; use pros for retaining walls/drainage.

Common Questions

What are my responsibilities if I’m the main contractor?

You plan the works, hire trades, coordinate safety and ensure compliance. Under CDM 2015 you (as domestic client) can let duties pass to a Principal Contractor — but if you are running the site, you effectively are the Principal Contractor and must:

Prepare a simple Construction Phase Plan (site rules, RAMS, welfare, emergency arrangements).
Appoint a competent Principal Designer (architect/engineer) for pre-construction H&S.
Check trade competence, insurances and method statements; hold inductions and keep an accident log.
Coordinate Building Control/Warrant inspections and collect all certificates (EIC, MCS, SER etc.).
Maintain a tidy, safe site and secure materials; manage deliveries and lifting.

How should I package trade work without a Contract Administrator?

Use simple trade packages with fixed-price quotes and milestone payments:

Issue drawings/specs and a short written scope; ask for a fixed price, programme, inclusions/exclusions and warranties.
Set payment triggers (e.g., “slab poured & signed off”, “roof complete & watertight”).
Agree a small retention (e.g., 3–5%) or a “snag holdback” until defects are resolved.
Keep a one-page Order/Agreement per trade with start/finish dates, insurance details and H&S responsibilities.
Track every commitment and payment in your Estimate of Cost spreadsheet.

How much can I actually save — realistically?

Typical self builds save 20–30% vs turnkey by removing main-contractor overhead/margin and DIY’ing some finishes. Savings closer to ~50% are possible if you take on significant finishing work and keep programme discipline. Use the Estimate of Cost spreadsheets to test best/worst cases before committing.

Which surveys should I complete before buying land?

Topographical survey; ground investigation (trial pits, bearing/strata, groundwater); percolation/drainage feasibility for off-mains; services quotes (water/power) and access/road feasibility. Avoid deep peat and long new tracks if possible. Ask a merchant/engineer to sanity-check costs before missives conclude.

How do self-build mortgages work without monthly valuations?

You’ll receive funds at key milestones (land, foundations, shell/watertight, completion). Some products are valuation-based; others (via brokers like BuildStore) can be cost-based to reduce risk. Ecology can support off-site kit manufacture before on-site valuation. Your job is to line up trade payment milestones to those releases and keep a 10–15% contingency.

Can I get a mortgage on a SIP or CPS HebHome?

Yes. SIP/CPS are mortgageable with an accepted 10-year structural warranty. HebHomes’ CPS is BOPAS-accredited, reassuring lenders about modern methods. Provide drawings/specification, programme, warranty confirmation and professional appointments in your application pack.

What must be ready before my HebHome kit is delivered?

Slab cured, level and checked to drawings; all penetrations in place and photographed.
3m+ access and turning; compacted hardstanding; safe telehandler routes and lay-down areas.
Temporary power/water and welfare; scaffold plan agreed where required.
Inspections scheduled (engineer/BC/Warrant). HebHomes erects CPS kits — DIY erection is not permitted.

How can I control build quality without a QS or Contract Administrator?

Use checklists for each stage; photograph key works (rebar, drains, penetrations); require installation to manufacturer’s guidance; keep all certificates; and schedule Building Control/Warrant inspections. If you want extra assurance, hire a clerk-of-works-style snag inspector for half-day visits at critical points.

What are my health-and-safety and insurance responsibilities?

CDM: create a short Construction Phase Plan, ensure welfare, inductions and RAMS, and keep an accident log. Appoint a Principal Designer (architect/engineer) for pre-construction H&S. Insurance: site insurance (works, public liability), trades’ liability, tool/theft cover; employers’ liability only if you employ labour directly.

Which parts of a HebHome can I complete myself?

Yes — cladding, decorating, some joinery, floor finishes and small-area tiling are common DIY savings. Keep waterproofing, wet-room tanking, large-format tiling and complex joinery with pros.

How should I plan heating, MVHR and solar PV?

Use MCS installers for ASHP/UFH/MVHR/PV; fix plant locations and penetrations on drawings; coordinate PV while scaffold is up; retain commissioning certificates for Building Control/Warrant and your lender. Check grants (e.g., BUS in E&W, Home Energy Scotland).

How should I organise utilities, waste and deliveries?

Book temporary electricity/water early; plan skips & recycling; schedule deliveries to avoid double-handling; protect the slab and keep clear access routes. A tidy site saves time and wins over inspectors.

What happens at completion — and VAT reclaim?

After testing/commissioning and final inspections, obtain the Completion Certificate (Scotland) or final sign-off (E&W/Ireland). Keep a 12-month snag log for defects. New builds may qualify for VAT relief/refund on eligible materials/services — keep all invoices and take early tax advice.

Do I need a Quantity Surveyor for a self-managed build?

Not usually on site for a self-build. If you want extra confidence, hire a QS for a one-off budget check pre-tender or to review big quotes. Day-to-day cost control is handled by you using the Estimate of Cost spreadsheets.

Further resources (UK)

Potton Self-Build Knowledge Hub — structured learning, live builds, online courses.
Homebuilding & Renovating — Self Build — deep guides, calculators, expert sessions and shows.
Build It — design tools, cost advice and Build It Live exhibitions.
Federation of Master Builders — step-by-step guide and vetted builders directory.

External sites are independent of HebHomes; verify details for your location and project.

Action Points

Download the Estimate of Cost spreadsheets — set baseline, stage cashflow, and contingency.
Speak to a specialist broker (BuildStore, Ecology, The Lending Channel) about stage-release options.
Plan your approvals — planning, Building Control/Warrant, surveys and engineering.
Read the Build Process — readiness for kit, inspections and handover.

Other guidance pages