Structural engineers and Building Control

Building Control often needs structural calculations when work affects the structure of a property.
 

The structural engineer does not usually “approve” the work. They design and calculate the structural elements. Building Control then checks the submitted information and may raise comments or ask for clarification.
 

The usual process may involve:
 

1. homeowner or designer identifies structural work;

2. structural engineer reviews drawings or site information;

3. engineer designs beams, foundations or structural elements;

4. engineer prepares calculations and structural details;

5. calculations are submitted to Building Control;

6. Building Control reviews the information;

7. builder installs the work on site;

8. Building Control inspects key stages;

9. final certification is issued when the project is completed satisfactorily.
   
    

Why Building Control asks for calculations

Building Control needs evidence that the structural work has been designed properly.
 

For example, if a wall is removed, Building Control may need to know that the beam is strong enough, the bearings are adequate and the loads are safely transferred down to the foundations.
 

If a loft is converted, Building Control may need to know that the new floor, beams and roof alterations are structurally adequate.
 

If an extension is built, Building Control may need foundation details, steel calculations and roof structure information.

 

Structural calculations are not the same as a builder’s quote

A builder’s quote tells the homeowner how much the work may cost.
 

Structural calculations tell the builder and Building Control how the structure should be supported.
 

The two should work together, but they are not the same thing.
 

A builder may be experienced, but they should not be expected to guess beam sizes, padstone requirements or foundation design for structural work without engineering input.

 

Structural engineer, architect, designer and builder

Different professionals have different roles.
 

An architectural designer may design the layout, planning drawings and Building Regulations package.
 

A structural engineer designs the structural elements.
 

A builder carries out the construction work.
 

Building Control checks compliance with the Building Regulations.
 

On a good project, these roles work together. The design should be practical, the structural solution should fit the design, the builder should price from clear information and Building Control should receive the necessary details.

 

What information does a structural engineer need?

A structural engineer needs enough information to understand the existing building and the proposed work.
 

The information required depends on the project, but may include:
 

• property address;

• photos of the existing area;

• existing floor plans;

• proposed floor plans;

• sections;

• elevations;

• measurements;

• wall thicknesses;

• ceiling heights;

• roof structure information;

• floor joist direction;

• proposed opening sizes;

• chimney details;

• foundation information;

• drainage information;

• soil or ground condition information;

• previous structural calculations;

• Building Control comments;

• planning drawings;

• builder questions;

• site photos or videos.
   

For some projects, a site visit may be needed. For other small projects, the engineer may be able to work from drawings, photos and measurements, provided the information is reliable.

 

Site investigations

Sometimes the engineer cannot answer the question from drawings alone.
 

They may need parts of the building opened up to check:
 

• whether a wall is load-bearing;

• joist directions;

• beam positions;

• wall construction;

• padstone locations;

• foundation depth;

• roof structure;

• chimney support;

• hidden steelwork;

• previous alterations.
   

This is common in older houses where previous changes may not be documented.

 

Why accurate dimensions matter

Structural design depends on accurate information.
 

A beam span, wall thickness, opening width or joist direction can change the design.
 

If the measurements are wrong, the structural calculation may not match the real building.
 

This is why drawings, surveys and site checks matter.

 

Structural engineer reports, calculations and inspections

Homeowners often use different phrases when looking for structural help.
 

The most common are structural calculations, structural engineer report, beam calculations, RSJ calculations, structural survey and structural inspection.
 

These do not all mean the same thing.

 

Structural calculations

Structural calculations are usually needed for design work.
 

They are used where a structural element is being designed or altered.
 

Examples include:
 

• beam calculations;

• steel beam design;

• lintel design;

• padstone calculations;

• joist calculations;

• foundation design;

• retaining wall calculations;

• roof structure calculations;

• loft conversion structural design.
   

These are often submitted to Building Control.

 

Structural engineer report

A structural engineer report may be needed where the homeowner wants advice or an assessment rather than a design.
 

This may include:
 

• cracks in walls;

• movement;

• subsidence concerns;

• leaning walls;

• sagging roofs;

• uneven floors;

• previous alterations;

• suspected structural defects;

• property purchase concerns;

• insurance issues.
   

A report may include observations, likely causes, recommendations and whether further investigation is needed.

 

Structural inspection

A structural inspection is usually a visit to inspect a particular issue.
 

This may be needed before a report or before calculations can be prepared.
 

For example, if a homeowner wants to remove a wall but does not know whether it is load-bearing, an inspection may be needed to check the structure.

 

Structural survey

The phrase structural survey is often used by homeowners, but it can mean different things.
 

In property buying, people may refer to a structural survey when they mean a detailed building survey by a surveyor. For engineering issues, a structural engineer may provide a structural inspection or structural report.
 

The important thing is to explain what you need:
 

• Are you buying a house and worried about defects?

• Are you removing a wall?

• Are you forming a new opening?

• Are you converting a loft?

• Are you dealing with cracks?

• Are you trying to satisfy Building Control?

• Are you responding to a mortgage or survey issue?
   

The right service depends on the question.

 

What should be included in structural calculations?

Structural calculations should provide enough information for the design to be checked and built.
 

Depending on the project, they may include:
 

• project address;

• engineer details;

• design standards used;

• assumptions;

• loading information;

• beam design;

• column design;

• padstone design;

• bearing details;

• connection details;

• foundation details;

• timber design;

• steel design;

• masonry checks;

• deflection checks;

• stability considerations;

• notes for the builder;

• drawings or sketches;

• limitations;

• references to site information.
   

For a simple wall removal, the calculation package may be relatively short. For a loft conversion, extension or basement, the package may be more detailed.

 

Steel beams and RSJs

Homeowners often search for RSJ calculations.
 

RSJ is a common phrase for steel beams, although modern steel sections may be described using different technical names.
 

A structural engineer may specify:
 

• beam type;

• beam size;

• steel grade;

• length;

• bearing length;

• padstones;

• connection plates;

• bolts;

• fire protection;

• installation notes;

• temporary propping requirements.
   

The builder should install what has been designed, not simply choose something that “looks strong enough”.

 

Padstones

Padstones are structural blocks used to spread the load from a beam into the supporting wall.
 

They are often needed where steel beams bear onto masonry walls.
 

A beam calculation may specify:
 

• padstone size;

• material;

• position;

• bearing length;

• load transfer requirements.
   

Ignoring padstones can lead to concentrated loads and cracking.

 

Deflection

A beam may be strong enough not to fail, but still bend too much.
 

This bending is called deflection.
 

Excessive deflection can cause:
 

• cracked plaster;

• sticking doors;

• uneven floors;

• damage to finishes;

• movement in glazing;

• problems with large openings.
   

Structural engineers consider both strength and deflection.

 

Temporary support

Structural design is not just about the final beam.
 

The building may need temporary support while the work is carried out.
 

For example, if a load-bearing wall is removed, the builder may need props and needles before the new beam is installed.
 

Temporary support should be considered carefully, especially in older houses or where multiple walls are being altered.

 

Structural engineers and project cost

A structural engineer can feel like an extra cost, but structural design is usually a small part of the overall project compared with the risk of getting the structure wrong.
 

Costs vary depending on:
 

• project type;

• complexity;

• number of beams;

• whether a site visit is needed;

• whether drawings are available;

• whether calculations are for Building Control;

• whether site inspections are required;

• whether revisions are needed;

• whether the work is urgent;

• whether the property is unusual or older;

• whether there are cracks, movement or defects.
   

Small domestic calculations may often be quoted as a fixed fee. Larger projects such as loft conversions, extensions, basements and complex refurbishments may need a more detailed fee.
 

Homeowners should not judge structural engineering by price alone. A cheaper engineer may be fine for a simple calculation, but for complex projects, experience, responsiveness, insurance, clarity and Building Control acceptance are important.

 

Choosing a structural engineer

A homeowner should choose a structural engineer who is suitable for the type of project.
 

For domestic home improvement projects, it is useful to ask:
 

• Do they regularly work on houses?

• Do they deal with extensions and loft conversions?

• Do they provide calculations for Building Control?

• Do they carry professional indemnity insurance?

• Are they qualified and experienced?

• Are they a chartered structural engineer or working under suitable professional supervision?

• Do they understand local housing types?

• Can they explain the design clearly?

• Will they answer Building Control queries?

• Will they provide drawings or sketches where needed?

• Is a site visit included?

• What information do they need from you?

• What is included in the fee?

• What is excluded from the fee?

• How are revisions charged?

• What is the expected turnaround time?
   

For more complex projects, homeowners may prefer a chartered structural engineer or a structural engineering practice with clear professional credentials.

 

Structural engineer and insurance

Professional indemnity insurance is important.
 

It helps protect both the engineer and the client if there is a professional design issue.
 

Homeowners should not be embarrassed to ask whether the engineer has suitable insurance for the type of work being carried out.

 

Cheap structural calculations

Very cheap structural calculations can be tempting, but homeowners should be careful.
 

The key questions are:
 

• Are they based on accurate information?

• Is the engineer insured?

• Will Building Control accept them?

• Do they include drawings or only calculations?

• Will the engineer answer Building Control comments?

• Are revisions included?

• Are site checks included?

• Are assumptions clearly stated?

• Has the engineer understood the existing building?
   

A cheap calculation that causes delays, is rejected by Building Control or does not match the real site can become expensive later.

 

Common mistakes homeowners make

Structural mistakes can be serious and costly.
 

Common homeowner mistakes include:
 

• assuming an internal wall is non-load-bearing;

• asking a builder to remove a wall without calculations;

• installing a beam before Building Control has reviewed the design;

• using planning drawings instead of Building Regulations drawings;

• forgetting padstones;

• not checking what the beam bears onto;

• ignoring foundations below the supports;

• forming large openings without considering deflection;

• cutting roof timbers without engineering advice;

• converting a loft without checking floor strength;

• removing chimney breasts without checking support above;

• starting work before party wall matters are considered;

• not keeping structural calculations for future sale;

• assuming Building Control will design the solution;

• changing the design on site without telling the engineer.
   

Most problems can be avoided by involving the right advice early enough.

 

Structural engineers and older houses

Older houses can be more complicated than they first appear.
 

Victorian, Edwardian, 1930s and post-war homes may have been altered several times. Walls may have been removed, chimney breasts taken out, beams installed, openings changed and roofs repaired.
 

Sometimes previous work has been done without proper records.
 

A structural engineer may need to be cautious because the original structure may not be obvious.
 

Older houses may involve:
 

• solid walls;

• shallow foundations;

• old chimney structures;

• timber floors;

• non-standard roof framing;

• movement cracks;

• previous alterations;

• mixed materials;

• hidden beams;

• poor historic workmanship;

• party walls;

• shared structures.
   

This does not mean the project cannot be done. It means the structure should be properly checked.

 

Structural engineers and party walls

Structural work and party wall matters often overlap.
 

A structural engineer may design the beam or foundation, while a party wall surveyor deals with the legal process under the Party Wall etc. Act 1996.
 

Party wall matters may be relevant where:
 

• steel beams are inserted into a party wall;

• a loft conversion affects a shared wall;

• chimney breasts are removed from a party wall;

• excavations are close to neighbouring foundations;

• a new wall is built on or near a boundary;

• underpinning is proposed;

• structural work affects adjoining property.
   

Homeowners should not confuse the two roles.
 

The structural engineer designs the structure.
 

The party wall surveyor deals with notices, adjoining owners, awards and protection under the Act.

 

Structural engineers and contractor quotations

Structural engineering information can help contractors price more accurately.
 

A builder asked to quote without structural details may have to guess.
 

This can lead to:
 

• provisional sums;

• exclusions;

• later extras;

• unclear pricing;

• risk allowances;

• delays;

• disputes.
   

For projects involving structural work, it is often better to obtain structural calculations before asking contractors for final prices.
 

This is especially true for:
 

• wall removals;

• large openings;

• extensions;

• loft conversions;

• garage conversions;

• basements;

• roof alterations;

• chimney removals.
   

A builder can then price the actual steel size, padstones, temporary works, installation method and making good.

 

Structural Engineering Checklist for Homeowners

Before starting structural work, check:
 

• whether the work affects a load-bearing wall;

• whether the roof, floor or wall structure is being altered;

• whether a structural engineer is needed;

• whether Building Control approval is required;

• whether planning permission is also required;

• whether party wall notices may be needed;

• whether drawings are accurate;

• whether a site visit is needed;

• whether joist direction has been checked;

• whether wall thickness has been confirmed;

• whether beam spans are accurate;

• whether padstones are required;

• whether foundations below the supports are adequate;

• whether fire protection is required;

• whether temporary support is needed;

• whether structural calculations have been submitted to Building Control;

• whether the builder is pricing from the structural information;

• whether Building Control inspections are booked;

• whether final certification will be obtained;

• whether structural calculations are kept safely for future sale.
  
   

Frequently Asked Questions About Structural Engineers
 

What is a structural engineer?

A structural engineer is a professional who designs and checks the strength and stability of buildings and structures. For homeowners, they often deal with beams, load-bearing walls, foundations, loft conversions, extensions, roof alterations and structural calculations.
 

When do I need a structural engineer?

You may need a structural engineer if you are removing a wall, creating a large opening, building an extension, converting a loft, converting a garage, removing a chimney breast, altering a roof, building a basement, forming a retaining wall or carrying out work that affects the structure of your home.
 

Do I need a structural engineer to remove a wall?

If the wall is load-bearing, yes. A structural engineer may need to design a beam or other support and provide calculations for Building Control.
 

How do I know if a wall is load-bearing?

It is not always possible to tell by looking. A structural engineer, surveyor or experienced professional may need to inspect the property, check joist directions, roof loads, walls above and other structural clues.
 

Do I need Building Control to remove a load-bearing wall?

Yes, removing or altering a load-bearing wall normally requires Building Regulations approval because it affects the structure of the property.
 

What are structural calculations?

Structural calculations are technical calculations prepared by a structural engineer to show that beams, foundations, joists, walls or other structural elements are strong enough and suitable for the proposed work.
 

Are structural calculations the same as Building Regulations drawings?

No. Structural calculations deal with the structure. Building Regulations drawings deal with the wider construction requirements, such as fire safety, insulation, drainage, ventilation and other Building Regulations matters.
 

Do I need a structural engineer for an extension?

Most extensions need some structural engineering, especially where the rear wall is opened up, steel beams are needed, new foundations are formed or large roof or glazing openings are proposed.
 

Do I need a structural engineer for a loft conversion?

Yes, loft conversions normally need structural engineering because the existing roof and ceiling structure usually need to be altered or strengthened to create habitable space.
 

Do I need a structural engineer for a garage conversion?

You may need a structural engineer if the garage conversion involves structural changes, new openings, infilling the garage door, roof alterations or checking whether the existing structure is suitable for habitable use.
 

Do I need a structural engineer for bifold doors or sliding doors?

If a new large opening is being formed, a structural engineer will usually be needed to design the beam or lintel above the opening.
 

Do I need a structural engineer for chimney breast removal?

Often, yes. Chimney breast removal can affect the remaining chimney structure and may also involve party wall matters if the chimney is on a shared wall.
 

Can a builder calculate a steel beam?

A builder may have practical experience, but structural beam design should be carried out by a suitably qualified and insured structural engineer, especially where Building Control approval is needed.
 

Will Building Control accept my builder’s beam size?

Building Control normally needs structural calculations or suitable evidence for structural work. A builder’s opinion may not be enough.
 

Does a structural engineer visit the property?

Sometimes. A site visit may be needed where the existing structure must be checked, measurements are uncertain, defects are present or the project is complex. For some simple projects, drawings and photos may be enough.
 

What information should I send to a structural engineer?

Useful information includes drawings, photos, dimensions, wall thicknesses, opening sizes, joist directions, roof information, proposed layout, Building Control comments and details of the work you want to carry out.
 

How long do structural calculations take?

Timescales vary depending on the complexity of the project and the engineer’s workload. Simple calculations may be quicker than full structural packages for loft conversions, extensions or basements.
 

How much does a structural engineer cost?

Cost depends on the project, complexity, site visit requirements, number of beams, calculations, drawings, inspections and whether revisions are needed. Homeowners should ask what is included and whether Building Control queries are covered.
 

Is a chartered structural engineer better?

For more complex projects, many homeowners prefer a chartered structural engineer or an engineering practice with suitable professional credentials and insurance. For simpler domestic work, the key is competence, experience and insurance.
 

Do structural engineers deal with cracks?

Yes, structural engineers can inspect cracks, movement, sagging roofs, uneven floors and other structural concerns. They may provide a report and recommend further investigation or repair.
 

Do I need a structural engineer before getting builder quotes?

For structural projects, it is often sensible to get engineering information first. This helps builders price the same scope and reduces the risk of later extras.
 

Can APN Home help me find a structural engineer?

APN Home can help homeowners understand whether a structural engineer may be needed and, where appropriate, may be able to introduce homeowners to suitable structural engineering support for their project.
 

Need Structural Engineering Support?

APN Home helps homeowners understand the type of professional support they may need for extensions, loft conversions, garage conversions, structural wall removals, chimney breast removals, large openings, roof alterations and wider refurbishments.
 

If your project affects the structure of your home, it is worth checking whether structural calculations, Building Control approval or professional structural advice are needed before work starts.
 

Tell us about your project and APN Home can help you understand the next sensible step.