Can a Structural Engineer Work From Architectural Drawings?

What Additional Information Might the Structural Engineer Ask For?

Even with good drawings, you may be asked for:

photographs;

opening dimensions;

wall thickness;

joist direction;

floor construction;

roof construction;

foundation information;

ground information;

previous calculations.

This is normal.

Why Do They Need Photographs If They Already Have Drawings?

Because drawings explain:

geometry.

Photographs help explain:

existing construction.

For example, a photograph may reveal:

chimney breast;

previous opening;

existing steel;

wall thickness;

unusual ceiling arrangement.

Why Is Joist Direction Important?

Suppose a wall runs through the middle of a house.

If floor joists run:

perpendicular to the wall

they may bear onto it.

If they run:

parallel to the wall

the loading may be very different.

The floor plan alone may not always show this.

What If I Don't Know the Joist Direction?

Do not guess.

Send the drawings and photographs.

The designer can identify whether additional information is required.

Why Does the Engineer Need the Floor Above?

Because a beam on the ground floor may support structure from:

above.

For example:

Roof

↓

First-Floor Wall

↓

Ground-Floor Wall

↓

Foundation

If the ground-floor wall is removed, the replacement structure may need to support more than the first-floor joists.

Should I Send All Drawing Sheets?

Usually:

yes.

Do not send only the proposed ground-floor plan if you already have:

existing plans;

proposed plans;

elevations;

sections.

The wider set helps the structural designer understand the building.

What If the Drawing Set Has 20 Pages?

Upload the complete relevant set.

The designer can identify which sheets matter.

Removing sheets because you think they are irrelevant can accidentally remove useful structural information.

What If I Only Have the Planning Decision Drawings?

Send them.

They may provide enough information to start the review.

If more is needed, you can be told exactly what is missing.

I Have Planning Permission. What Happens Next?

This is a very common point in a residential project.

You may now need to move from:

planning design

to:

technical design.

That can involve:

Building Regulation drawings;

structural calculations;

Building Control application;

construction information.

Planning Permission Does Not Approve the Structure

Planning and Building Regulations are separate systems.

Planning approval does not mean:

the steel has been designed;

foundations have been checked;

Building Regulations have been satisfied.

The next stage may therefore require structural and technical design.

Can I Send My Approved Planning Drawings Directly to BuildRegs?

Yes.

This is one of the most efficient routes into the BuildRegs service.

If you already have:

approved plans;

existing/proposed drawings;

sections;

elevations;

upload them.

The technical scope can then be reviewed.

Do I Need to Go Back to My Original Architect?

Not necessarily.

You are not automatically required to use the same architectural practice for every later stage of the project.

Another suitably competent designer can potentially undertake:

Building Regulation drawings;

structural calculations;

subject to:

having suitable information;

the agreed appointment;

intellectual-property/licensing considerations.

Important: Check Your Rights to Use the Drawings

Architectural drawings can be protected by copyright.

Paying for drawings does not necessarily mean copyright ownership has transferred to you.

Your appointment or licence may define how the drawings can be used.

If another consultant needs to:

reproduce;

adapt;

modify;

third-party drawings, check that you have the necessary permission.

Does That Mean I Can't Send My Plans to a Structural Engineer?

Not necessarily.

Drawings are routinely shared between project consultants where necessary for the project.

The important issue is whether their use is consistent with the relevant:

appointment;

licence;

copyright rights.

If unsure, check your agreement with the original designer.

Can a Structural Engineer Work From an Architect's DWG?

Yes, where the file is suitable and you have the appropriate right to provide it.

This can be particularly efficient.

The structural designer may be able to:

use the existing geometry;

coordinate beam positions;

add structural references;

develop technical information.

Does the Architect Need to Send the DWG Directly?

Not necessarily.

If you already possess the file and are entitled to use it, you can provide it.

Alternatively, you can ask the original designer to send:

DWG;

PDF;

relevant technical information

to the structural designer.

What If My Architect Won't Release the DWG?

A DWG is helpful but:

it is not always essential.

A suitable PDF can often still be used.

Do not assume the entire structural process must stop because you only have PDFs.

Can Structural Calculations Be Prepared Before Building Regulation Drawings?

Yes.

Depending on the project.

For example, for a straightforward wall removal, the beam can potentially be designed from:

architectural plan;

dimensions;

photographs.

For a larger extension, it can be better to coordinate:

Building Regulation drawings

and:

structural calculations

together.

Which Should Come First — Drawings or Calculations?

There is no single sequence for every project.

The best approach is often:

Architectural Geometry

↓

Technical Design Begins

↙︎ ↘︎

Building Regulation Drawings Structural Calculations

↘︎ ↙︎

Coordination

↓

Building Control Package

The drawings and calculations can therefore develop together.

Why Coordination Matters

Imagine the architectural drawing assumes:

completely flush ceiling.

The structural calculation determines that the proposed solution requires:

downstand steel beam.

That affects the architecture.

Or the structural design requires:

C1 column

where the proposed kitchen drawing shows:

full-height fridge.

The documents need coordination.

Structural Design Should Not Happen in Isolation

Good technical design is iterative.

The structural designer may identify something that affects:

ceiling;

walls;

foundations;

roof;

doors;

kitchen;

stair.

That information should feed back into the drawings.

Can BuildRegs Coordinate the Drawings and Structural Calculations?

For suitable projects:

yes.

This is one of the advantages of commissioning the technical Building Regulation package and structural calculations together.

The structural information can be coordinated with the technical drawings rather than added as an afterthought.

What If Another Architect Prepared the Planning Drawings?

That is not necessarily a problem.

BuildRegs can review the existing information and determine what additional technical work is required.

This can avoid duplicating work that has already been done.

Example — Single-Storey Extension

You already have planning permission.

Your architectural set includes:

existing ground-floor plan;

proposed ground-floor plan;

elevations;

section.

Proposed design includes:

4m rear extension;

large opening through rear wall;

rooflight.

Possible next-stage structural scope:

B1

rear-wall beam.

R1 / R2

support reactions.

Roof Structure

where engineering input is required.

Foundations

where specific structural design is required.

The existing planning drawings provide the project geometry.

Example — Loft Conversion

Your planning drawings show:

proposed rear dormer;

loft plan;

stair;

section;

roof alterations.

The structural designer may then design:

J1

new floor joists.

B1 / B2

floor beams.

T1

stair trimmer.

D1

dormer structure.

R1

roof alterations.

Again:

the architecture provides the geometry.

the structural calculations provide the engineering.

Example — Load-Bearing Wall Removal

You already have a measured floor plan from your architect.

It shows:

3.6m proposed opening.

You also provide:

first-floor plan;

photographs.

The structural designer can potentially calculate:

B1

replacement beam.

PS1 / PS2

support arrangement where required.

No second full measured survey may be necessary.

Example — Garage Conversion

Architectural drawings show:

existing garage;

proposed habitable room;

garage-door infill;

new window.

The structural review may establish that:

no major bespoke calculations are needed;

or:

lintel;

foundation;

opening support

requires design.

The architectural plans help identify the actual scope.

What Does the Structural Engineer Calculate From the Drawings?

The architectural drawings can establish:

geometry.

The structural designer then establishes:

loads.

For example:

permanent loads;

imposed loads;

walls;

roof loads;

other relevant actions.

Then:

analysis.

For example:

bending;

shear;

axial force;

reactions.

Then:

structural design.

For example:

beam size;

joist size;

column size;

foundation size.

Drawings In — Engineering Out

A simplified workflow is:

Architectural Drawings

↓

Structural Interpretation

↓

Loads

↓

Analysis

↓

Member Design

↓

Reactions

↓

Supports

↓

Structural Calculations

This is why good drawings can make structural design much more efficient.

Do Architectural Drawings Tell the Engineer the Loads?

Not necessarily.

They help the designer identify what the structure supports.

The actual structural loading is then determined using appropriate design standards and engineering principles.

Do Architectural Drawings Tell the Engineer What Beam to Use?

They may show a proposed:

beam location.

But the structural designer determines the appropriate:

beam design.

A drawing saying:

“RSJ over”

is not the structural calculation.

What If the Architect Has Already Specified a Beam Size?

The structural designer should still establish whether that section has been properly designed for the project.

Do not assume that a beam written on an architectural plan has been structurally verified unless the structural design supporting it is available.

Can an Architect Design the Structure?

Potentially, where the individual is competent for that structural design, appropriately appointed and operating within their professional scope.

The title alone does not determine competence for a particular engineering task.

For more complex structural work, specialist structural-design input may be appropriate.

Do I Legally Need Someone With the Title “Structural Engineer”?

Building Regulations do not simply state that every domestic structural element must be calculated by somebody using that exact professional title.

The important requirements include:

compliant design;

appropriate competence.

In practice, bespoke structural work such as:

steel beams;

frames;

complex roof alterations;

unusual foundations

is commonly undertaken by structural engineering specialists.

Building Regulations Designer Duties

People carrying out design work under the Building Regulations have duties relating to their design.

Designers should have appropriate:

skills;

knowledge;

experience;

behaviours

for the work they undertake.

They should not undertake design work beyond their competence.

Does the Structural Engineer Become the Principal Designer?

Not automatically.

Preparing structural calculations means undertaking design work within that structural scope.

The Building Regulations:

Principal Designer

role is a separate dutyholder function involving coordination of the design work.

A structural designer is not automatically appointed Principal Designer simply because they provide calculations.

Can the Original Architect Remain Principal Designer?

Potentially, depending on:

project;

appointment;

competence;

contractual arrangements.

The dutyholder roles should be clearly established rather than assumed.

What Does Building Control Need?

For structural work, Building Control may need technical information sufficient to assess compliance.

This can include:

architectural / Building Regulation drawings;

structural calculations;

structural details;

specifications.

The exact requirements depend on the project.

Will Building Control Accept Calculations Based on Architectural Drawings?

Building Control assesses the structural design information submitted.

The important question is not:

“Did the engineer redraw the architectural plans?”

It is:

Does the submitted technical information adequately demonstrate the proposed structural design?

Does Building Control Require a New Measured Survey?

There is no general rule requiring a completely new measured survey every time a structural designer is appointed.

What matters is whether the project information used for the design is sufficiently reliable.

Can Building Control Ask for More Information?

Yes.

They may request:

calculations;

details;

clarification;

support information;

foundation information.

That can happen even where good architectural drawings already exist.

Does Full Plans Require Drawings and Calculations?

Where structural calculations are necessary to demonstrate compliance, they can form part of the technical information supporting a Full Plans application.

The drawings and calculations serve different but complementary functions.

What If I'm Using Building Notice?

The structural-design requirement does not disappear.

If a beam needs proper structural design, using a Building Notice does not turn it into an uncalculated beam.

Building Control can still request structural information.

Do I Need Building Regulation Drawings If I Already Have Structural Calculations?

Potentially.

A calculation may demonstrate:

B1 beam.

But it does not necessarily address:

insulation;

ventilation;

drainage;

fire safety;

wall construction;

roof construction;

other Building Regulations requirements.

For extensions and loft conversions, Building Regulation drawings are commonly needed alongside structural calculations.

What If I Only Need One Beam?

Then a complete Building Regulation drawing package may not always be necessary solely for the structural calculation itself.

For a suitable straightforward opening, BuildRegs can review:

existing drawings;

plans;

photographs;

dimensions

and determine the structural calculation scope.

Structural Opening Calculations

For suitable straightforward projects:

RSJ / Structural Opening Calculations — From £249

You can upload your existing architectural drawings directly.