How to Protect Books, Records and Documents from Damp and Mould

Old books that smell musty, damp spines, wavy paper, discoloured records or brown spots are often not simply signs of “old books”; they are directly related to storage conditions. To keep books, records and documents free from damp and mould, humidity, temperature, light, dust and storage methods must all be managed together. Most importantly, keep documents in a dry, stable environment, away from walls or floors at risk of damp, and inspect them regularly. For materials requiring long-term storage, use suitable boxes or storage materials and consider a space with temperature and humidity control. For bookshelves at home or filing shelves in the office, check the wall corners behind them and the undersides of storage boxes after prolonged rain; these areas are easily overlooked when only the outside is inspected.

Why Are Books, Records and Documents Prone to Damp and Mould?

Paper and books absorb moisture from their surroundings. When humidity is high or fluctuates unpredictably, paper can become distorted and conditions can favour mould growth. Areas such as basements, attics or garages are often unsuitable for long-term book storage, because temperature and humidity are difficult to control there and the risk of water ingress is greater than in other areas of the home.

How Does High Humidity Affect Books and Paper?

Paper is an organic material that naturally absorbs moisture, so it responds noticeably to changes in its surroundings:

• Paper absorbs moisture and becomes soft or wavy
• The risk of mould growing on the surface increases
• A distinctive damp or musty smell may develop
• Book covers and spines can be affected
• Documents become less durable over time

A practical tip is to place a humidity meter near your books and records, rather than relying only on whether the room feels dry or cool when you enter. If readings remain high, paper starts to soften or a damp smell develops, check for water ingress and review storage conditions so you can address the problem early.

Why Are Books More Likely to Develop Mould During the Rainy Season?

The causes can be understood as a chain of effects: prolonged rain raises ambient humidity, paper absorbs moisture from the air, poor ventilation makes it harder for moisture to escape, and mould eventually finds favourable conditions to grow. Certain areas of the home or office need particular attention during the rainy season, including:

• Closed cabinets that are rarely opened
• Wall corners with little air circulation
• Storage rooms or rooms with poor ventilation
• Areas where books are packed too closely together
• Areas near windows
• Areas at risk of seepage or roof leaks

Signs That Books and Records Are Becoming Damp

Recognising the following signs early helps you act before documents suffer more serious damage:

• A damp or musty smell
• Soft or wavy pages
• Spots appearing on the paper surface
• Distorted book spines or covers
• White, green or black mould appearing
• Pages of records sticking tightly together

High Humidity or Fluctuating Humidity: Which Should You Worry About?

The humidity percentage is not the only concern; the stability of the storage environment is equally important. In everyday use, avoid repeatedly moving books and records between air-conditioned rooms and hot, humid areas. Monitoring conditions directly at the shelf or document cabinet helps reveal changes that the room’s overall temperature does not fully reflect.

7 Ways to Protect Books, Records and Documents from Damp and Mould

The most effective approach is to control the environment before relying on moisture-control products. Keep documents somewhere dry, clean and stable, prevent direct contact with floors or walls, limit strong light, use suitable packing materials for storage and inspect them regularly.

1. Control humidity in the storage area: use a dehumidifier when necessary, monitor conditions with a humidity meter, prevent prolonged high humidity and prioritise a stable environment over constant fluctuations. At home or in the office, check readings at consistent times and after prolonged rain to track changes. When using a dehumidifier, position and operate it according to the manufacturer’s instructions, check its tank or drain line, and reassess the condition of the paper. For special or highly valuable documents, consult their specific preservation requirements rather than applying one setting to every type of paper.
2. Do not place books and records directly on the floor: use shelving to raise documents above floor level, avoid areas at risk of flooding, and do not position them close to the floor where moisture may seep up from below.
3. Do not place them against damp walls or in areas prone to condensation: pay particular attention to exterior walls, corners, walls showing signs of water ingress and areas near windows, as these often have higher humidity than the rest of the room.
4. Do not pack books and records too tightly: leave suitable gaps between items to improve air circulation, make documents easier to retrieve, allow regular inspections and help detect early signs of mould.
5. Use suitable boxes, folders and storage materials: for important records or documents requiring long-term storage, use document folders and purpose-made storage boxes, and consider acid-free materials that meet long-term archival standards where appropriate. The Canadian Conservation Institute recommends suitable protective boxes or enclosures to help protect books and paper from water, unsuitable humidity and other physical damage during storage; acid-free materials are worth considering for documents intended for long-term retention.
6. Limit direct light: light is not the main cause of mould, but it can cause paper to fade, discolour or age more quickly over time. If a bookshelf is beside a window, use curtains to reduce direct sunlight and place important documents where they receive less light. Avoid leaving books or records on a desk next to a glass window for days at a time.
7. Inspect regularly: routinely check storage-area humidity, unusual smells, mould spots, paper condition, book spines, packaging or boxes, signs of insects and water ingress, so problems can be identified and addressed before they spread.

How to Pack and Store Books and Records for Long-Term Storage

For books and records stored for months or years, packaging is only one layer of protection; a stable storage environment remains more important. Do not use sealed plastic bags or containers to trap moisture inside an already humid space, as this can increase the risk of mould rather than protect documents. Before packing, check that both documents and containers are dry and clean. If books have just been transported through rain or records retrieved from a damp area, assess and address any dampness before sealing them for long-term storage.

Preparing Books and Records for Storage

Before putting documents away for a long period, complete the following preparations:

• Sort documents into categories
• Separate damp materials or those showing signs of mould from clean documents
• Remove surface dust
• Carefully inspect the condition of each item
• Arrange them in suitable groups
• Label and record the storage location of each group

How to Arrange Books to Reduce Damage

The way you arrange books on shelves also significantly affects their lifespan, so follow these principles:

• Do not squeeze books too tightly together
• Do not place heavy objects on top of books
• Place books on suitably constructed shelves that do not sag
• Use protective folders or boxes for loose papers when necessary

Should You Use Plastic Bags or Boxes to Keep Moisture Out?

Many people ask this when looking for ways to preserve documents at home. Plastic bags or boxes can protect documents from water in specific situations, such as transport through areas exposed to rain, but they are not a long-term humidity-control solution. If the air or materials inside are already humid and the container is completely sealed, the risk of mould can still increase over time because the moisture has no way to escape.

Should You Use Desiccant Bags?

Desiccant bags can provide additional support, but they cannot fully replace a dehumidifier or overall environmental control of the storage area. Replace or check them regularly because their moisture-absorption capacity decreases with use, and their effectiveness also depends on the size of the space and the quantity of documents being protected.

What Should You Do When Books or Records Become Damp or Mouldy?

If books or records have just become wet, act as soon as possible by drying them and controlling the surrounding temperature and humidity. If active mould is already present, prioritise safe handling, isolate affected materials and control the environment to limit the spread to other documents. For highly valuable documents or severe damage, consult a conservation service or specialist rather than attempting aggressive treatment at home.

What Should You Do When a Book Has Just Got Wet?

When you discover wet books or documents, follow this sequence: remove them from the moisture source, gently open or space them out where appropriate to allow airflow, dry them gradually, control relative humidity in the treatment area, and inspect thoroughly before returning them to storage. During treatment, avoid pressing wet pages together or forcing apart pages that are firmly stuck. If there are too many wet documents to dry promptly or the materials are important, contact a specialist early for suitable advice.

What Should You Do When Mould Has Appeared on Records?

Documents with visible mould require much more careful handling than documents that have only just become wet:

• Immediately isolate them from clean documents
• Avoid spreading mould to other areas
• Control temperature and humidity in the treatment area
• Assess the extent of damage before deciding on treatment
• Consult a specialist if the documents are important or valuable

When you see mould on books or records, do not shake, dust or brush them vigorously beside clean documents, as this can spread mould. Minimise unnecessary handling, separate affected materials from occupied areas and seek a treatment appropriate to their actual condition, especially if the mould has spread widely.

Should You Dry Books in the Sun?

Be very cautious with this approach. Sun-drying should not become the default response whenever books become damp, because direct sunlight can cause fading and long-term damage to the paper structure, potentially causing more harm than the original dampness.

When Should You Seek Professional Help?

In the following situations, consult a conservation specialist rather than attempting treatment at home:

• Valuable or rare books
• Important legal records
• Documents of historical value
• Mould that has spread over a large area
• Documents that have been submerged for a long time
• Documents that would be irreplaceable if damaged

Should You Rent Storage for Books and Records to Prevent Damp and Mould?

If you have large quantities of books, records or documents, need long-term storage, or cannot control humidity effectively at home or in the office, renting storage with stable environmental conditions may be a suitable option. When choosing a facility, prioritise temperature and humidity control, security, cleanliness, protection against water ingress and access to documents when needed, rather than comparing rental prices alone.

When Should You Consider Renting Storage?

The need to rent storage for books and records often arises in the following situations:

• The home or office lacks storage space
• Records must be retained for years under applicable requirements
• There is no separate storage room
• The home or workplace regularly experiences damp and mould during the rainy season
• Valuable books or documents need greater protection
• Office space needs to be freed up for other uses

What Should a Book and Records Storage Facility Provide?

A suitable book and records storage facility must meet several storage-rental criteria, not just offer an attractive price:

How Does Standard Storage Differ from Temperature- and Humidity-Controlled Storage?

It should not be assumed that temperature- and humidity-controlled storage is always better than standard storage in every situation, because suitability depends on the type of documents and their intended storage period. For paper documents stored long term, the most important factor is maintaining a stable environment suited to the materials, rather than simply whether air conditioning is present. A standard facility that is dry, well ventilated and subject to little temperature fluctuation may sometimes suit short-term document storage, while valuable materials or records retained for years generally need a more closely controlled environment.

Checklist Before Putting Records into Storage

Before sending records to a storage facility, check the following:

• Have the documents been sorted?
• Are any documents already damp or mouldy?
• Have the documents been packed correctly?
• Is there a detailed inventory?
• Has every box or container been coded?
• Can the facility control humidity?
• Does the facility have cameras and a warehouse security system?
• Does the facility have a fire prevention and protection system?
• Can you retrieve the documents when needed?

Indicative Prices for Moisture-Control Equipment and Document Storage

The cost of protecting books and records from damp and mould varies with the solution, from simple packing materials to renting environmentally controlled storage. The following are general indicative market price ranges at the time of writing:

These are general market estimates for reference, not official quotations from any particular provider. Actual storage rental prices vary by brand, material quality, area and rental terms. For large volumes of records or documents that must be retained for years under legal requirements, contact the storage provider directly to arrange an assessment and obtain an accurate quotation based on the quantity and type of documents.

Protecting books, records and documents from damp and mould does not depend on a single measure, but on a combination of environmental control, suitable packing and regular inspections. For small quantities of low-value documents, simple measures at home are often effective enough. However, for large volumes, valuable materials or records retained for years, investing in suitable archival materials or a space with stable environmental control can substantially reduce the risk of damage compared with relying solely on basic moisture-control methods.

Frequently Asked Questions About Preserving Books, Records and Documents