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Tender Drawings for Accurate Builder Pricing
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Tender Drawings
Tender Drawings for Accurate Builder Pricing
Tender drawings help builders understand exactly what they are being asked to price.
The clearer the information, the easier it is to obtain quotations that are complete, comparable and based on the same scope of work.
Tholos prepares tender drawings for residential projects including extensions, loft conversions and renovations, helping turn approved designs into a package that builders can price with fewer assumptions.
Tender Drawings
What Are Tender Drawings?
Tender drawings are architectural drawings prepared to support the builder quotation process.
They sit between the earlier design and approval stages and the final construction stage.
Their purpose is to give contractors enough information to understand:
- what is being built
- what is being removed
- what is being altered
- dimensions and layouts
- relevant construction details
- materials
- interfaces between old and new work
- structural requirements
- the overall scope of the project
The more clearly these elements are defined, the less room there is for different builders to make different assumptions.
Why Tender Drawings Matter
A builder can only price the information they are given.
If the drawings are vague, incomplete or prepared only for planning, every contractor may interpret the project differently.
One builder may include something another excludes.
Another may make a generous allowance for an item while someone else assumes a cheaper specification.
This can produce quotations that look very different even when the builders are pricing the same project.
Tender drawings help reduce this uncertainty.
Tender Drawings
Are Planning Drawings Enough for Tendering?
Usually not.
Planning drawings are primarily produced to explain a proposal to the local planning authority.
They may show the size, layout and external appearance of the project clearly, but they often do not contain enough technical information for reliable builder pricing.
Important information may still be missing, such as:
- construction build-ups
- structural information
- insulation
- detailed dimensions
- materials
- junction details
- drainage
- specifications
- extent of demolition
- technical notes
Using planning drawings alone can therefore result in builders filling in the gaps themselves.
Tender Drawings
What Should Be Included in a Tender Drawing Package?
The exact package depends on the project, but tender drawings may include:
- existing floor plans
- proposed floor plans
- elevations
- sections
- roof plans
- demolition information
- detailed dimensions
- construction build-ups
- wall and roof details
- structural coordination
- door and window information
- drainage information
- relevant material information
- technical notes
These may be supported by specifications, structural calculations and schedules where required.
Existing and Proposed Drawings for Tendering
Builders need to understand not only what the finished design will look like, but also what is changing.
Existing and proposed drawings make that comparison clear.
They help show:
- walls being removed
- new walls
- altered openings
- extensions
- new stairs
- roof changes
- changes to windows and doors
- new room layouts
This is particularly important for renovation and extension projects where much of the work involves altering the existing building.
Tender Drawings for Extensions
Extension projects can contain many elements that need to be priced together.
Tender drawings may need to show:
- foundations
- external walls
- roof construction
- openings
- glazing
- connections to the existing building
- structural alterations
- floor construction
- insulation
- drainage
- internal changes
Without sufficient detail, builders may make different assumptions about how the extension is intended to be built.
Tender Drawings for Loft Conversions
Loft conversions also benefit from detailed tender information because they often involve structural and technical work that is not obvious from a simple floor plan.
A tender package may need to clarify:
- new floor construction
- steel beams
- stair openings
- dormer construction
- roof alterations
- insulation
- fire safety requirements
- windows and rooflights
- internal layouts
The clearer the scope, the easier it is for loft conversion contractors to price consistently.
Tender Drawings for Renovations
Renovations can be especially difficult to price accurately because the existing building introduces more uncertainty.
Tender drawings can help define:
- demolition
- retained elements
- altered walls
- new partitions
- structural openings
- new layouts
- floor and ceiling changes
- doors and windows
- kitchen and bathroom positions
- other relevant construction information
The drawings can then be supported by specifications to clarify the expected standard of work and materials.
Tender Drawings
Tender Drawings and Structural Design
Many projects include structural work.
This may involve:
- steel beams
- columns
- foundations
- roof alterations
- structural openings
- floor strengthening
- retaining elements
If builders are pricing structural work, the relevant engineering information should be coordinated with the architectural tender package wherever possible.
Otherwise, contractors may have to make allowances for structural elements that have not yet been properly defined.
Tender Drawings
Tender Drawings and Building Regulations
Building Regulations drawings often provide much of the technical information needed for tendering.
However, the two are not necessarily identical.
Building Regulations information is primarily prepared to demonstrate compliance with the relevant requirements.
Tender information focuses on clearly defining the scope builders are being asked to price.
Depending on the project, additional information may therefore be useful before the tender package is issued.
Tender Drawings vs Construction Drawings
Tender drawings and construction drawings can overlap considerably, but they serve slightly different purposes.
Tender drawings help contractors price the project.
Construction drawings provide the detailed information needed to build it.
For some smaller projects, the same detailed drawing package may serve both purposes.
For more complex projects, the construction information may continue to develop after the builder has been selected.
Tender Drawings
Why Comparable Quotes Matter
The cheapest quotation is not necessarily the cheapest project.
A low price can sometimes simply mean that more items have been excluded or left as allowances.
The real aim of tendering is to obtain quotations that can be compared fairly.
A strong tender package helps because each builder is pricing the same information.
That makes it easier to identify:
- genuine price differences
- exclusions
- provisional sums
- missing work
- unusual assumptions
- differences in programme
- areas requiring clarification
Tender Drawings
Reducing Provisional Sums and Allowances
A provisional sum is an allowance for work or materials that have not yet been fully defined.
Some allowances are unavoidable, particularly in existing buildings where hidden conditions cannot be confirmed before work starts.
However, too many provisional sums can make the final project cost difficult to predict.
More detailed tender information can reduce the number of decisions left unresolved at quotation stage.
Tender Drawings and Specifications
Drawings explain the project visually, but they may not define every material, product or standard of workmanship.
A specification can support the tender drawings by describing items such as:
- finishes
- fixtures
- products
- workmanship requirements
- insulation standards
- doors and windows
- sanitaryware
- flooring
- decoration
- other project-specific requirements
Using drawings and specifications together gives builders a clearer description of what they are pricing.
Tender Drawings
When Should Tender Drawings Be Prepared?
Tender information should normally be prepared once the design is sufficiently developed and the main technical decisions have been resolved.
Sending a project to builders too early can create uncertainty and produce unreliable prices.
Ideally, builders should understand the project well enough to provide a meaningful quotation without having to invent substantial parts of the specification themselves.
Tender Drawings Before Choosing a Builder
It can be tempting to approach builders as soon as planning permission is obtained.
However, obtaining quotations before the technical information is ready can create problems later.
A builder may provide an attractive initial figure based on limited drawings, only for the cost to increase once the missing details are developed.
Preparing the tender package first gives you a stronger basis for deciding who to appoint.
Tender Drawings
Issuing a Building Tender
Once the drawings and supporting information are ready, they can be issued to selected builders as part of a tender package.
Using the same information for each contractor helps keep the process fair and consistent.
Builders may then return:
- their price
- exclusions
- allowances
- proposed programme
- clarifications
- other relevant information
Those responses can then be reviewed before a contractor is selected.
Tender Drawings
What Happens After Tender?
Once quotations have been received, the next stage is not simply to choose the lowest figure.
The quotations should be reviewed carefully to understand what each builder has actually included.
After the preferred contractor is selected, the project may move into:
- quotation clarification
- contractor appointment
- building contract
- final construction information
- commencement on site
- construction administration
Tender Drawings
Already Have Quotes That Are Difficult to Compare?
If builders have already returned very different quotations, the problem may not necessarily be the builders.
It may be that they have priced different interpretations of the project.
Tholos can review the project information and quotations to help identify:
- missing information
- exclusions
- inconsistent allowances
- differences in scope
- areas that need clarification
Tender Drawings
Already Have Quotes That Are Difficult to Compare?
If builders have already returned very different quotations, the problem may not necessarily be the builders.
It may be that they have priced different interpretations of the project.
Tholos can review the project information and quotations to help identify:
- missing information
- exclusions
- inconsistent allowances
- differences in scope
- areas that need clarification
Those responses can then be reviewed before a contractor is selected.
Tender Drawings
Ready to Prepare Your Project for Tender?
If your design is approved and you are preparing to approach builders, we can help develop the information into a clearer tender package.
That gives contractors a stronger basis for pricing and gives you a better basis for comparing their quotations.
Client experience
"
Lorem ipsum dolor sit amet, consectetur adipiscing elit. We had a vision for our home but no idea how to realise it. Tholos Interiors took complete ownership of the project — every detail was considered, every decision explained. The result exceeded everything we had imagined.
– Lawrence Ipsum, Homeowner · London –
Frequently Asked Questions
Are tender drawings the same as construction drawings?
Not always. Tender drawings are primarily prepared for pricing, while construction drawings are prepared for building the project. The same detailed package may sometimes serve both purposes.
Do I need Building Regulations drawings before tendering?
For many projects it is beneficial to have the technical design developed before obtaining final quotations, because this reduces the number of assumptions builders need to make.
Do tender drawings include structural information?
Architectural tender drawings may coordinate with structural information, but structural calculations and details are normally prepared by a structural engineer.
Can Tholos review tender drawings prepared by another architect?
Yes. Existing project information can be reviewed to identify whether anything important is missing before it is issued to builders.
Disclaimer
This article is part of a series created by our dynamic marketing team for informational purposes only. While we strive to review all content thoroughly, occasional oversights may occur, even after publication. Therefore, we cannot accept liability for any interpretations or use of the information provided. For the most up-to-date information or to report any discrepancies, please contact us at hello@tholos-architects.com.
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