Building Knowledge,
Practical Advice
Expert articles on extensions, conversions, planning permission, and property maintenance — written by TCM's team with 15+ years on London sites.
7 Costly House Extension Mistakes London Homeowners Make (And How to Avoid Them)
Most house extension projects that go over budget or over time share the same root causes. After 15 years building extensions across London and Hertfordshire, we have seen the same errors repeat themselves. Here is what to watch for before you break ground.
How Long Does a Loft Conversion Take? A Week-by-Week Timeline
A dormer loft conversion typically takes 8–12 weeks from start to finish. But that figure hides a lot of variation. The type of conversion, the structural condition of your roof, and whether you need planning permission all affect the programme significantly.
The London Landlord's Maintenance Guide: What You Must Fix and When
Landlords in London face a specific set of legal obligations around property maintenance. The Homes (Fitness for Human Habitation) Act 2018 and the Landlord and Tenant Act 1985 set out clear duties. Failing to meet them exposes you to rent repayment orders, fines, and civil claims.
Loft Conversion vs House Extension: Which Adds More Value in 2025?
Two of the most popular ways to add space and value to a home — but they suit very different properties, budgets, and goals. This guide compares both options across cost, disruption, planning, and return on investment so you can make the right call for your specific situation.
Types of Loft Conversion Compared: Dormer, Hip-to-Gable, Mansard & Velux
Not all loft conversions are the same. The type that works best for your home depends on your roof structure, the space you need, your budget, and whether you need planning permission. This guide breaks down all four main types with costs, planning rules, and which properties suit each.
Should I Extend or Move? A Practical Guide for Hertfordshire Homeowners
Stamp duty, agent fees, and removal costs can add £30,000–£40,000 to the cost of moving. Before you put your house on the market, find out whether extending is the more financially sound option — and what your property can actually accommodate.
How to Choose a Builder in Hertfordshire: What to Check Before You Sign
The building industry is largely unregulated. Anyone can call themselves a builder. This guide covers the specific checks — insurance certificates, company registration, payment schedules, and contract terms — that will filter out unsuitable contractors before you commit.
How Much Does a House Extension Cost in Hertfordshire?
Accurate 2025 cost figures for every extension type — single-storey, double-storey, side return, wrap-around, and loft conversions — based on real TCM projects. Includes what drives costs up, what to include in your budget, and how to get a fixed-price quote.
Do I Need Planning Permission for a Loft Conversion?
A clear guide to permitted development rights for loft conversions in Hertfordshire and North London. Covers Velux, dormer, hip-to-gable, and mansard conversions, conservation areas, Article 4 directions, and listed buildings.
What Is a Structural Engineer and When Do I Need One?
A practical guide to the structural engineer's role in residential building projects — what they do, when their involvement is mandatory, what they produce, and what it costs in Hertfordshire and North London.
Kitchen Extension Cost Guide 2026 — Hertfordshire & North London
Accurate 2026 kitchen extension costs for Hertfordshire and North London. Single-storey, wrap-around, and open-plan kitchen-diner prices, planning rules, and what drives costs up or down.
Single vs Double-Storey Extension: Which Is Right for Your Home?
A direct comparison of single and double-storey extensions — covering costs, planning requirements, build time, disruption, and the value each type adds to a Hertfordshire property.
Which Home Improvements Add the Most Value in Hertfordshire?
Data-driven guide to the home improvements that add the most value in Hertfordshire. Loft conversions, extensions, kitchens, bathrooms — ranked by ROI with 2026 figures from TCM Building.
Signs Your House Needs Structural Repairs
Cracks in walls, sloping floors, sticking doors — TCM Building explains which signs indicate serious structural problems in Hertfordshire homes and when to call a structural engineer.
Is My House Suitable for a Loft Conversion?
Head height, roof type, pitch, party walls, and staircase access — TCM Building's complete guide to assessing whether your Hertfordshire property can support a loft conversion.
Common Roof Problems and When to Call a Roofer
Missing tiles, failed flashing, flat roof leaks, ridge failures, and moss damage — TCM Building's guide to the most common roof problems in Hertfordshire with 2026 repair costs.
Building Regulations vs Planning Permission: What's the Difference?
Two separate approval systems, two different purposes. TCM Building explains when you need planning permission, when you need building regulations approval, and what happens if you skip either.
How Long Does a House Extension Take? A Complete Timeline Guide
Week-by-week timeline for house extensions in Hertfordshire. Single-storey, double-storey, and wrap-around extensions — how long each phase takes, what causes delays, and how to plan around them.
Living in Your Home During Building Work: What to Expect
Honest guide to staying in your home during a house extension or loft conversion. What phases are most disruptive, how TCM manages the impact, and how to prepare your household.
How to Maintain Your Loft Conversion: A Complete Guide
Practical maintenance guide for loft conversion owners. Covers roof lights, insulation checks, structural monitoring, ventilation, and when to call a professional.
Commercial Building Maintenance Checklist 2026
Comprehensive commercial building maintenance checklist for property managers. Monthly, quarterly, and annual tasks covering roof, M&E, fire safety, and statutory compliance.
Energy-Efficient Extensions and Loft Conversions in Hertfordshire 2026
How to build an energy-efficient house extension or loft conversion. U-values, insulation specifications, MVHR, solar PV, and Part L compliance explained for Hertfordshire homeowners.
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