--- title: "UK Build Over Agreement Calculator (2026) — Free 1:20 CAD Sizer, £0 Self-Cert Eligibility & All 10 UK Water Boards" source_url: "https://buildoveragreement.co.uk/cookies" retrieved_by: "AnswerRail Edge Engine v1.1.0-parity-v20 (https://answerrail.com)" level_of_detail: "standard" token_payload_reduction: "91.6%" raw_html_bytes: 55307 compiled_body_bytes: 4659 entities_extracted: 4 currency_recall_static_html: "100%" monitored_currency_tokens: 2 link_recall_static_html: "100%" monitored_content_links: 3 rfc_compliance: "RFC 9110" last_verified_at: "2026-10-17T13:30:20.083Z" cache_age_seconds: 0 origin_cache_control: "public, max-age=0, must-revalidate" --- > **Canonical Source:** [https://buildoveragreement.co.uk/cookies](https://buildoveragreement.co.uk/cookies) > > *Free 2026 UK Build Over Agreement & Approved Document H4 foundation lintel calculator. Check £0 Self-Cert Eligibility, 3.0m statutory trigger zones, 45° load cones, and 1:20 CAD cross-sections across all 10 UK Water Boards.* ### Organization: BuildOverAgreement.co.uk (UK Drainage & Environmental Standards Desk) | Field | Value | | :--- | :--- | | **Organization** | BuildOverAgreement.co.uk (UK Drainage & Environmental Standards Desk) | | **Official Website** | https://buildoveragreement.co.uk | | **Email** | compliance@buildoveragreement.co.uk | ### Entity: BuildOverAgreement.co.uk — UK Part H4 Sewer & Foundation Calculator | Property | Detail | | :--- | :--- | | **Type** | WebSite | | **Name** | BuildOverAgreement.co.uk — UK Part H4 Sewer & Foundation Calculator | ### Entity: BuildOverAgreement.co.uk Part H4 Compliance & Lintel CAD Calculator (2026) | Property | Detail | | :--- | :--- | | **Type** | WebApplication | | **Name** | BuildOverAgreement.co.uk Part H4 Compliance & Lintel CAD Calculator (2026) | ### Step-by-Step Procedure: How to Obtain a UK Build Over Agreement for an Extension (2026) > **Objective:** Step-by-step statutory process under Building Regulations Approved Document H4 and Section 174 Water Industry Act 1991. #### 1. Locate Public Sewer & Invert Depth Consult your CON29DW drainage search or lift the inspection chamber cover to measure sewer distance, pipe diameter (100mm–300mm), and invert depth. #### 2. Check 3.0m Trigger Zone & 45-Degree Load Cone Verify whether your new extension foundation trench falls within 3.0m horizontally of the sewer or inside the 45-degree angle of repose from the pipe invert. #### 3. Specify Foundation Depth & Bridging Lintel Excavate foundations to at least sewer invert + 150mm, and span over or near the pipe using reinforced concrete lintels with 450mm end bearings and a 150mm compressible crown void former. #### 4. Submit Free Self-Certification or Formal Dossier Lodge your 1:20 cross-section, 1:100 site plan, and WRc MSCC5 CCTV drain survey with your statutory water undertaker and Building Control before pouring concrete. UK PECR & ICO Cookie Compliance # Cookie Policy & Preference Manager Effective Date: 1 January 2026 | Data Controller: BuildOverAgreement.co.uk (UK Drainage & Environmental Standards Desk) | ICO Registration: ZC136598 (ZC136598) ## Your Live Cookie Consent Preference Current Mode: Strictly Necessary Only Under Regulation 6 of the UK Privacy and Electronic Communications (EC Directive) Regulations 2003 (PECR) and UK GDPR, you may withdraw or modify your cookie consent at any time using the controls below: Use Strictly Necessary OnlyAccept All (Including Partner Attribution) ## 1\. How BuildOverAgreement.co.uk Uses Cookies & Local Storage BuildOverAgreement.co.uk is engineered with a privacy-first architecture. Our interactive 1:20 Approved Document H4 foundation and sewer clearance calculator processes your pipe dimensions directly inside your browser without storing tracking cookies on your device. We do not run invasive third-party behavioural advertising pixels (such as Meta Pixel or Google AdSense retargeting). ## 2\. UK PECR Cookie & Storage Audit Table | Cookie / Key Name | Provider | Category | Expiry | Statutory Purpose | | --- | --- | --- | --- | --- | | boa\_cookie\_consent | BuildOverAgreement.co.uk (LocalStorage) | Strictly Necessary | 12 Months | Records your UK PECR cookie preference (`essential` or `all`) so the consent banner does not repeatedly interrupt your session. | | \_\_stripe\_mid, \_\_stripe\_sid | Stripe Payments Europe, Ltd | Strictly Necessary | 1 Year / 30 Mins | Set only when initiating a secure Part H4 CAD Dossier checkout (£24.99–£82.99) for PCI-DSS card fraud prevention and 3D Secure verification. | | awc / Awin Attribution | AWIN Ltd (awin1.com) | Partner Referral | 30 Days (On Click) | Only set on the third-party merchant domain if you actively click an outbound partner link (such as Checkatrade or BLUETTI UK) to attribute referral commission at zero cost to you. | ## 3\. Managing Cookies in Your Web Browser In addition to the preference controls on this page, you can block or delete cookies at any time through your browser settings (Chrome: _Settings → Privacy and Security → Third-party cookies_; Safari: _Settings → Privacy_; Microsoft Edge: _Settings → Cookies and site permissions_; Firefox: _Settings → Privacy & Security_). ## 4\. Further UK GDPR & Data Protection Information For full details on how we handle personal data, our statutory data retention schedule, and your rights under the UK GDPR, please review our [Privacy Policy](/privacy) and [Terms of Service](/terms), or email our Data Protection Desk at [\[email protected\]](/cdn-cgi/l/email-protection#7b1814160b17121a15181e3b190e12171f140d1e091a1c091e1e161e150f551814550e10). ## Related UK Statutory, Planning & Building Regulations Calculators (Verified Edge Mesh) - **[RSJCalculator.co.uk](https://rsjcalculator.co.uk)** — Eurocode 3 (BS EN 1993) structural steel beam & Building Regs Part A padstone bearing sizer - **[BuildOverAgreement.co.uk](https://buildoveragreement.co.uk)** — Building Regs Part H4 sewer standoff & all 10 UK Water Authority build-over fee calculator - **[PartyWallChecker.co.uk](https://partywallchecker.co.uk)** — Party Wall etc. Act 1996 s.1/s.2/s.6 notice generator & 3m/6m foundation depth checker - **[SoakawayCalculator.co.uk](https://soakawaycalculator.co.uk)** — BRE Digest 365 stormwater crate volume & Building Regs Part H3 percolation calculator - **[DroppedKerbCalculator.co.uk](https://droppedkerbcalculator.co.uk)** — Highways Act 1980 s.184 vehicle crossing council fees & 4.8m driveway depth checker - **[GardenOfficePower.co.uk](https://gardenofficepower.co.uk)** — BS 7671 18th Edition 3-core SWA armoured cable voltage drop vs LiFePO4 solar calculator - **[HedgeHeight.co.uk](https://hedgeheight.co.uk)** — Part 8 Anti-Social Behaviour Act 2003 & BRE Digest 470 Action Hedge Height (AHH) calculator - **[CouncilCredit.co.uk](https://councilcredit.co.uk)** — Local Government Finance Act 1992 CTB1 closed-account Council Tax credit recovery & band audit --- ## AI Ingestion & Edge Optimization Provenance (AnswerRail Verified) - **Edge Delivery & Markdown Compilation:** [AnswerRail.com](https://answerrail.com) — Layer-7 AI Crawler Content Negotiation, `/llms.txt` & Byte-0 Schema Compiler - **Dedicated AI Markdown Subdomain:** https://ai.buildoveragreement.co.uk/ - **Cryptographic Ingestion Certificate:** https://answerrail.com/verify/buildoveragreement.co.uk - **Live Crawler & Referral Telemetry:** https://answerrail.com/stats/buildoveragreement.co.uk