Board Backed Envelopes & Hard Back Envelopes

What Are Board Backed Envelopes?

Board backed envelopes are protective mailing envelopes designed to keep documents and other flat items from bending or creasing during postage.

They combine a strong cardboard or board backing with a paper front, creating a much more rigid envelope than an ordinary paper mailing envelope.

You may also see them described as hard backed envelopes, hard back envelopes, card backed envelopes or Do Not Bend envelopes.

They are widely used for posting documents, photographs, certificates, artwork and other items that need to remain flat during delivery.

What Are Board Backed Envelopes Used For?

Board backed envelopes are particularly useful for sending items that could easily be damaged by bending or folding.

Typical uses include:

• certificates and qualifications
• contracts and legal documents
• photographs
• artwork and prints
• reports and presentations
• brochures
• important business documents
• application forms
• educational materials
• photographs and collectables
• drawings and plans

The rigid board backing helps protect the contents as the envelope passes through postal and courier networks.

Board Backed Envelopes vs Ordinary Envelopes

An ordinary paper envelope provides very little protection against bending.

A board backed envelope adds a substantially stronger card backing, helping its contents remain flat.

For this reason they are particularly useful where the appearance or condition of a document matters.

An ordinary envelope may be suitable for general correspondence, while a board backed envelope is a better choice for certificates, photographs, presentations, contracts and artwork.

For items requiring even greater rigidity, some of our board backed envelopes are also available with additional cardboard stiffeners.

C4 / A4 Board Backed Envelopes

C4 board backed envelopes are one of our most popular sizes.

They are designed to accommodate standard A4 documents without folding, making them particularly useful for reports, certificates, contracts, artwork and business paperwork.

Our range includes:

• standard heavy-duty C4 board backed envelopes
• lightweight C4 envelopes
• Tariff Beater C4 envelopes
• C4 envelopes with additional stiffeners
• white C4 board backed envelopes
• white C4 window board backed envelopes

This allows you to choose between maximum protection, lower postal weight, presentation and additional rigidity depending on the application.

C5 / A5 Board Backed Envelopes

Our C5 board backed envelopes are suitable for A5 documents and many smaller printed items.

We stock both PiP and Plus formats.

The C5 PiP version has been designed around Royal Mail's Pricing in Proportion dimensions and can be particularly useful where keeping the finished mailing within an appropriate postal format is important.

Always check the completed envelope's dimensions, thickness and weight against Royal Mail's current requirements before posting.

C6 / A6 Board Backed Envelopes

For smaller documents, postcards, photographs, invitations and similar items, our C6 board backed envelopes provide rigid protection without the unnecessary size of a larger mailer.

Both classic and PiP versions are available, allowing customers to choose the most appropriate format for their contents and postal requirements.

C3 / A3 Board Backed Envelopes

Large C3 board backed envelopes allow A3 documents, artwork, drawings and other oversized flat items to be posted without folding.

Defenda stocks standard C3/A3 board backed envelopes as well as white and reinforced versions with additional stiffeners.

These are particularly useful for artwork, plans, presentations and documents where folding would damage or substantially reduce the presentation quality of the contents.

What Does “Please Do Not Bend” Mean?

Many board backed envelopes are printed with a “Please Do Not Bend” message.

The board backing provides the physical resistance to bending, while the printed message alerts postal and courier handlers that the contents should ideally remain flat.

For particularly valuable or delicate contents, we recommend choosing an envelope with sufficient board strength for the item rather than relying solely on the printed warning.

Board Backed Envelopes for Photographs and Artwork

Photographs, prints and artwork can easily become creased or damaged if sent in an ordinary paper envelope.

A board backed envelope provides additional rigidity while keeping the overall package relatively slim.

For photographs or artwork requiring greater protection, you can also use an appropriately sized cardboard envelope stiffener inside the envelope.

Defenda stocks both standard board backed envelopes and versions supplied with additional stiffeners for applications where greater resistance to bending is required.

Heavy Duty or Lightweight Board Backed Envelopes?

The best envelope depends on what you are sending.

Heavy Duty Board Backed Envelopes

Choose a heavier board where maximum rigidity and protection are the main priorities.

These are particularly suitable for important documents, certificates, photographs and artwork.

Lightweight Board Backed Envelopes

Lightweight versions can be useful where postal weight is particularly important.

Reducing the weight of the packaging itself may help keep the complete mailing within a lower postal weight band, depending on the contents.

Board Backed Envelopes with Stiffeners

For particularly vulnerable contents, an additional corrugated cardboard stiffener provides another layer of rigidity.

This can be especially useful for photographs, artwork, certificates and important presentation materials.

Board Backed Envelopes and Royal Mail Postal Sizes

Several of our board backed envelopes have been designed with common Royal Mail postal formats in mind.

For example, our C5 PiP board backed envelope is approximately 238mm x 163mm and is specifically designed around the Royal Mail Standard/Small Letter format.

Our standard C4/A4 board backed envelope measures approximately 324mm x 229mm and is intended for A4 documents.

However, postal charges depend on the finished package, not the empty envelope alone.

Always check the total dimensions, thickness and weight after inserting your contents against Royal Mail's current limits.

Brown, White and Window Board Backed Envelopes

Alongside traditional brown manilla envelopes, Defenda Packaging also stocks white board backed envelopes for applications where presentation is particularly important.

White C4 envelopes are suitable for A4 documents, while our white C4 window board backed envelopes allow the delivery address printed on the enclosed document to remain visible through the window.

White C3/A3 board backed envelopes are also available for larger documents and presentation materials.

What Size Board Backed Envelope Do I Need?

Choose an envelope slightly larger than the item you need to send.

As a general guide:

C6 / A6 – postcards, photographs and smaller documents

C5 / A5 – A5 documents and A4 sheets folded once

C4 / A4 – full-size A4 documents without folding

C3 / A3 – A3 documents, artwork and oversized paperwork

Defenda also stocks several specialist and oversized board backed envelopes for products that do not correspond neatly to standard paper sizes.

Buy Board Backed Envelopes from Defenda Packaging

Defenda Packaging supplies an extensive range of board backed and hard backed envelopes for businesses throughout the UK.

Our range includes brown and white envelopes, lightweight postal options, PiP sizes, window envelopes, reinforced envelopes with stiffeners and larger formats for A3 and oversized items.

Bulk quantities are available for businesses with regular mailing requirements, with competitive price breaks on larger orders.

Choose your required size and style above to view current prices, specifications and quantity options.