Knowledge base
Construction intelligence, plain English
Expert guides on project costs, planning, compliance, and property investment — written by the Dwellinger editorial team.
Property Development Profit Margins: What to Expect in 2026
UK property developers typically target 15–25% profit on GDV — but in practice margins are squeezed from every direction. This guide covers realistic return expectations, what eats into margins, and how to model a project correctly.
HMO Conversion Guide: Planning, Costs and Licensing in 2026
Converting a house into an HMO can significantly increase rental yield — but the planning, licensing, building regulations, and fire safety requirements are substantial. Here is what to expect in 2026.
What is a Principal Contractor and Why Do You Need One?
A Principal Contractor is the legally responsible party for managing health and safety during the construction phase of a project. If your build involves more than one contractor, you almost certainly need one — and you need to appoint them in writing.
House Refurbishment Costs UK 2026: Full Guide
A full house refurbishment in the UK costs £30,000–£150,000+ depending on size, scope and specification. This 2026 guide breaks down costs room by room, trade by trade, and explains what drives prices up or down.
Do I Need Planning Permission for a Rear Extension?
Most single-storey rear extensions in England can be built under Permitted Development — but only if they meet specific size, height, and material conditions. Here is the complete 2026 guide to what requires planning and what does not.
How to Find a Trusted Builder in London: 7 Steps
Finding a reliable builder in London is harder than it looks. There are over 90,000 construction businesses in the capital, and no central register that verifies who is actually trustworthy. Here are 7 steps that will cut the risk.
How to Use an Extension Cost Calculator (2026 Guide)
Online extension cost calculators give you a starting point — but they can be dangerously misleading if you treat the output as a quote. This guide explains what calculators get right, what they miss, and how to use one sensibly.
Loft Conversion Cost in London: 2026 Guide
A loft conversion in London costs £60,000–£130,000 depending on type and specification. This 2026 guide covers costs by conversion type, London borough premiums, what's included, and how to get accurate quotes.
House Extension Planning Permission UK: Complete 2026 Guide
Many house extensions in England do not need planning permission. But the rules are specific and the exceptions matter. Here's exactly when you do and don't need to apply.
How Much Does a Quantity Surveyor Cost in the UK? (2026 Guide)
Quantity surveyor fees in the UK range from 1% to 3% of project value, or £800–£6,000+ fixed fee for domestic projects. Here's what you get for your money and when a QS is worth it.
Average Cost to Build a House in the UK (2026 Guide)
Building a new home in the UK costs £1,750–£3,500/m² depending on spec, location and build method. A full 2026 cost breakdown with real figures by region, specification level, and project type.
Building Costs Per m² in London: 2026 Guide
London building costs range from £1,800 to £4,500+ per m² in 2026. This guide breaks down costs by project type — extensions, loft conversions, new builds, and refurbishments — with borough-level context.
Garage Conversion Cost UK: 2026 Price Guide
A garage conversion costs £7,500–£22,000 in the UK in 2026. This guide covers what affects price, planning permission rules, Building Regulations requirements, and how to verify your contractor.
Why Star Ratings Are Not Enough: Introducing Builder Score™
Star ratings can be bought, faked or manipulated. Builder Score™ is a 0–1000 trust rating calculated from verified compliance data — here is how it works and why it matters.
How to Choose a Building Contractor in the UK: 7 Things to Check
Choosing the right contractor is the most important decision in any building project. Here are 7 things to verify before you sign anything.
Loft Conversion Planning Permission: A UK Homeowner's Complete Guide
Most loft conversions do not need planning permission — but the rules depend on your property type, location and what changes you make to the roof.
CDM 2015 Regulations: What UK Homeowners Need to Know
The Construction (Design and Management) Regulations 2015 apply to most domestic building projects. Here is what homeowners need to know about their legal duties.
How Much Does a Rear Extension Cost in the UK? (2026 Guide)
UK rear extension costs range from £1,800–£3,500/m². This guide covers typical costs, what affects price, planning requirements and how to verify your contractor.
How much does a rear extension cost in the UK? (2025 guide)
A realistic breakdown of rear extension costs across London and the South East — including groundworks, structure, M&E, finishes, and professional fees.
Why star ratings aren't enough — the case for Builder Score™
Anyone can buy reviews on Checkatrade. Anyone can create a Companies House record. But neither tells you whether a contractor pays their subcontractors, holds valid insurance, or knows what a CDM Construction Phase Plan is.
Residual land value explained — and how to calculate it in 5 minutes
The single most important number in property investment is the maximum you should pay for a site. Here's how to calculate it — and why the build cost assumption is the number most developers get wrong.
CDM 2015 for homeowners — what you actually need to know
If your project involves more than one trade working at the same time, CDM 2015 applies. Most homeowners have never heard of it. Most contractors ignore it.
Meet the Dwell Agents — AI built for construction businesses
Four AI agents designed for the specific, unglamorous reality of running a construction business: responding to leads, generating scope of works, writing CDM documents, and coaching your commercial decision-making.
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