Hampstead Renovations

Introduction to Structural Calculations

Structural calculations are mathematical analyses that prove your building alterations are safe and comply with Building Regulations. Whether you're removing a load-bearing wall, adding an extension, or converting a loft, structural calculations from a qualified engineer ensure the structural integrity of your property and provide the documentation required for Building Control approval.

At Hampstead Renovations , we work with certified structural engineers across London to provide comprehensive structural design services. From initial feasibility assessments to detailed calculations and on-site inspections, we ensure your project is structurally sound and fully compliant.

What Are Structural Calculations?

Definition and Purpose

Structural calculations are detailed engineering analyses that:

• Calculate loads and stresses on building elements
• Specify appropriate materials and sizes for structural members
• Demonstrate compliance with Building Regulations (Part A - Structure)
• Provide evidence of safety for Building Control approval
• Guide builders on correct installation methods

What They Include

• Load calculations: Dead loads (permanent weight), live loads (occupants, furniture), wind loads, snow loads
• Structural analysis: How loads transfer through building structure
• Member design: Sizing of beams, columns, foundations, etc.
• Connection details: How structural elements join together
• Technical drawings: Plans, sections, and details showing structural elements
• Specifications: Materials, grades, installation requirements

When Do You Need Structural Calculations?

Removing or Altering Load-Bearing Walls

• Opening up ground floor (kitchen-dining-living spaces)
• Creating open-plan layouts
• Removing chimney breasts (if load-bearing)
• Inserting steel or concrete beams to carry loads
• Engineer specifies: Beam size, type, bearing lengths, temporary support requirements

Extensions

• Single or multi-storey extensions
• Foundation design for new structures
• Connection to existing building
• Roof structure calculations
• Engineer provides: Foundation depths/widths, wall thicknesses, beam specifications

Loft Conversions

• Strengthening existing floor joists or installing new floor structure
• Ridge beams and roof alterations
• Dormer structures
• Staircase openings
• Engineer calculates: Whether existing joists sufficient or need strengthening, steel beam sizes for ridge/hips

Basement Conversions

• Underpinning existing foundations
• Temporary support during excavation
• New basement floor and walls
• Retaining wall design
• Engineer designs: Underpinning sequence, temporary works, waterproofing integration with structure

Other Situations

• Installing mezzanine floors
• Adding balconies or terraces
• Roof alterations (hip to gable, raising roof height)
• Structural repairs (crack stitching, wall ties, etc.)
• Change of use increasing loads (e.g., residential to commercial)
• Installing heavy items (hot tubs, large aquariums)

The Structural Engineering Process

Step 1: Initial Consultation

• Discuss your project requirements
• Review architectural plans (if available)
• Site visit to assess existing structure
• Feasibility assessment
• Fee quotation

Step 2: Site Survey

• Visual inspection: Assessing building age, construction type, existing conditions
• Measurements: Dimensions of existing structural elements
• Material identification: Brick, stone, timber species, concrete grade
• Defect identification: Cracks, movement, dampness affecting structure
• Photography: Documenting existing conditions

Step 3: Design and Calculations

• Analysing loads and load paths
• Designing structural solutions
• Performing calculations to relevant standards (Eurocodes, British Standards)
• Selecting appropriate materials and sections
• Preparing technical drawings
• Typical turnaround: 1-3 weeks (depending on complexity)

Step 4: Documentation Delivery

Engineer provides complete package including:

• Structural calculations (signed and stamped)
• Structural drawings (plans, sections, details)
• Specifications for materials and construction
• Engineer's certificate of design compliance
• Ready for submission to Building Control

Step 5: Building Control Submission

• Calculations submitted as part of Building Regulations application
• Building Control reviews and approves (or requests amendments)
• Approval typically within 2-4 weeks

Step 6: Construction Phase

• Engineer available for queries during construction
• Site inspections at key stages (optional but recommended):
  • Foundation inspection before concrete pour
  • Steel beam installation check
  • Critical connection verification
• Building Control also inspects at required stages

Step 7: Completion

• Final inspection confirming works match calculations
• Completion certificate from Building Control
• Documentation for property records

Types of Structural Solutions

Steel Beams (RSJ - Rolled Steel Joist)

Most common solution for load-bearing wall removal:

• Universal Beams (UB): Standard I-shaped steel sections
  • Sizes: 127x76mm to 914x419mm (depth x width)
  • Typical domestic: 178mm to 305mm depth
  • Strong in bending, relatively lightweight
• Advantages:
  • High strength-to-weight ratio
  • Predictable performance
  • Available in standard sizes
  • Can span long distances (up to 8m+ for domestic)
• Installation:
  • Requires temporary support of loads above
  • Adequate bearing required each end (150-200mm typical)
  • May need padstones to distribute loads
  • Fire protection required in some cases (boarding/intumescent paint)
• Cost: £800-£3,000+ (depending on size, supply and installation)

Timber Beams

• Engineered timber: Glulam (glue-laminated timber), LVL (laminated veneer lumber)
  • Stronger than conventional timber
  • Available in large sizes
  • Good for exposed beams (attractive finish)
• Solid timber: Oak, Douglas fir for smaller spans
  • Traditional appearance
  • Limited span capability vs. steel
• Applications: Loft conversions, roof structures, exposed ceiling beams
• Cost: £500-£2,500 (engineered timber beams)

Concrete

• Reinforced concrete lintels: Pre-cast or in-situ
  • Good for matching existing (older properties)
  • Fire resistant
  • Heavy (crane may be needed)
• Applications: Foundations, ground floor slabs, lintels, retaining walls

Padstones

• Concrete blocks that distribute beam loads to walls
• Prevent crushing of bricks beneath beam bearings
• Typical size: 440x215x140mm or larger
• Essential where beam bears on masonry walls

Building Regulations Compliance

Part A: Structure

The primary regulation for structural work:

• Requirement: Buildings must be constructed safely and remain stable
• Compliance: Demonstrated through structural calculations
• Standards: Design to Eurocodes (EC0-EC9) or British Standards

Approved Document A

Provides guidance on meeting Part A requirements:

• Loading assumptions
• Material properties
• Deemed-to-satisfy solutions for simple works
• When calculations are required

Structural Engineer Qualifications

Building Control requires calculations from qualified professionals:

• Chartered Structural Engineer: IStructE member (MIStructE or FIStructE)
• Chartered Civil Engineer: ICE member with structural competency
• Professional indemnity insurance: Minimum £1-2 million coverage
• Unqualified persons' calculations will be rejected

Costs of Structural Engineering Services

Typical Fee Structure

Structural engineer fees vary by project complexity:

• Simple single beam calculation: £300-£600
  • Removing one load-bearing wall
  • Straightforward loading conditions
• Loft conversion: £600-£1,500
  • Floor structure strengthening
  • Ridge beam calculations
  • Dormer structure (if applicable)
• Small extension: £800-£2,000
  • Foundation design
  • Wall and roof structure
  • Connection to existing building
• Large extension: £1,500-£4,000
  • two-storey or complex extensions
  • Multiple structural elements
• Basement conversion: £2,000-£6,000+
  • Underpinning design
  • Temporary works design
  • Retaining walls
  • Complex loading scenarios
• Full house renovation: £3,000-£10,000+
  • Multiple structural interventions
  • Comprehensive structural assessment

Additional Services

• Site inspections during construction: £150-£400 per visit
• Structural survey (pre-purchase or damage assessment): £400-£1,200
• Temporary works design: £500-£2,000
• Expert witness services: £150-£300 per hour

What Affects Fees?

• Project complexity and size
• Number of structural elements to design
• Unusual loading conditions
• Difficult site access
• Age and condition of existing structure
• Urgency (expedited service costs more)
• London location (inner London typically higher fees)

Common Structural Issues in London Properties

Victorian/Edwardian Houses

• Solid walls: No cavity, often 9-inch (230mm) brick thickness
• Suspended timber floors: May need strengthening for modern loads
• Shallow foundations: May require underpinning for extensions
• Lime mortar: Different properties than modern cement mortar
• Chimney breasts: Often load-bearing, removal requires careful design

Post-War Properties

• Cavity walls: Easier to work with than solid walls
• Concrete ground floors: Good base for extensions
• Non-traditional construction: Some properties have unusual systems requiring specialist knowledge

Modern Properties

• Engineered floor joists: Cannot be easily modified without calculations
• Trussed roofs: Individual members cannot be cut without structural assessment
• Cavity wall ties: May need replacing in properties 25+ years old

Flats and Conversions

• Shared structures: Alterations may affect neighbours
• Lease restrictions: May limit structural works
• Freeholder approval: Often required in addition to Building Regulations

Working with Structural Engineers

What to Provide

Help your engineer by supplying:

• Architectural plans showing proposed works
• Existing floor plans (measured or from original drawings)
• Photos of existing structure
• Details of building age and construction type
• Any previous structural reports or calculations
• Access for site visit
• Clear brief of what you want to achieve

Questions to Ask

• Are you a chartered engineer (IStructE or ICE)?
• Do you have professional indemnity insurance?
• What is your experience with similar projects in London?
• What is your fee and what does it include?
• What is the turnaround time for calculations?
• Do you provide site inspections during construction?
• Will you liaise with Building Control if queries arise?

Red Flags

• Unqualified "engineers" (no professional membership)
• Suspiciously low fees (may indicate lack of proper analysis)
• Reluctance to visit site
• Unable to provide professional indemnity insurance details
• Poor communication or unavailability

Why Choose Hampstead Renovations?

Our structural engineering coordination includes:

• Trusted partners: Network of qualified chartered structural engineers
• Seamless coordination: We liaise between you, engineers, and Building Control
• Experience: Understanding of what engineers need and how calculations inform construction
• Accurate installation: Following structural specifications precisely
• Problem-solving: Addressing unforeseen issues during construction with engineer input
• Documentation: Maintaining records for Building Control inspections
• Quality assurance: Ensuring structural works meet engineer's design intent
• Single point of contact: Manageing all aspects of your project including structural elements

Get Professional Structural Engineering

Planning structural alterations to your property? Hampstead Renovations can connect you with qualified engineers and manage your project from design to completion.