54 sandbags proved less effective than building duct tape: scientists tested door flood protection

British scientists tested an unusual way to protect a front door from floodwater. On one side: 54 sandbags and plastic sheeting, on the other: wide building duct tape. The result surprised researchers: correctly applied tape reduced leaks by 97–98%, while sandbags performed significantly worse.

The results of the experiment were published on 15 October by the University of Hull in Great Britain. Scientists tested six types of doors at water depths of up to 60 centimetres and discovered another unexpected detail: protection effectiveness even depended on which way the door opens.

54 sandbags vs one roll of tape

The tests were conducted in a special laboratory where flooding of residential buildings can be simulated and the amount of water penetrating inside can be accurately measured.

The researchers used wooden, plastic, and composite doors. The water level was gradually raised in five-centimetre increments, with leaks observed under different protection methods.

For one of the tests they prepared 54 sandbags and plastic sheeting. In other cases, the doorways were sealed with various types of adhesive tape.

The comparison results were unexpected:

• Wide reinforced building tape reduced water penetration through the door by 97–98%.
• Special rubber sealing tape provided up to 99% leak reduction.
• The least effective tape tested reduced leaks by about 80%.
• Sandbags under the best test conditions cut water penetration by about 70%.

Note that the percentages show the reduction in water volume seeping through a particular door compared to no protection at all. They do not mean that tape can protect an entire house from flooding by 99%.

Why ordinary building duct tape performed better

The main weakness of sandbags is the gaps through which water continues to seep even when tightly stacked.

Adhesive tape works differently: it seals gaps directly around the door perimeter, reducing the possibility of water seepage.

However, there is an important nuance. The experiment did not use thin transparent office tape, but strong reinforced building tape like duct tape, designed for repair and installation work.

Separately, experts tested specialist sealing materials, including rubber tapes.

According to University of Hull Professor Stuart McLelland, the results show that relatively inexpensive and accessible materials can be useful in preparing properties for minor flooding.

Even which way the door opens matters

During the tests scientists discovered another detail: outward-opening doors allowed about 74% less water through than inward-opening doors under comparable conditions, even without additional protection.

Furthermore, applying tape from the outside proved more effective than sealing from the inside.

This explains why the outcome depends not only on the material, but also on the door design, condition of the door frame, and how the protection is applied.

In the laboratory it took approximately 10–20 minutes to prepare one door. The work was carried out in advance, before water was introduced.

When building duct tape will not help

Despite the impressive results, scientists do not claim that adhesive tape can stop any flood.

The experiment was conducted under controlled conditions at water depths of no more than 60 centimetres. In a real flood, water can enter not only through doors but also through walls, floors, ventilation openings, and drains.

In addition, strong currents, prolonged flooding, and water pressure on structures create additional risks that laboratory comparisons cannot fully assess.

Therefore, tape should only be considered as a possible additional temporary protection measure against shallow flooding, not as a replacement for professional flood barriers.

It is especially important not to try sealing doors when water is already rising rapidly. Such actions can be dangerous, and a blocked exit may hinder evacuation.

Main conclusion of the study

The University of Hull experiment showed that heavy bulky materials are not always needed to reduce leaks through a front door. Under certain conditions, correctly applied building tape can provide more effective protection than sandbags.

However, the depth of flooding, door design, and timely preparation are crucial. If there is a threat of dangerous flooding, people's safety and following the instructions of rescue services remain the priority.

Sources: University of Hull — test results, 15 October 2026, Flood Re — research on flood protection for homes, Phys.org — explanation of experiment results