Recently, with the widespread application of synthetic underlays in construction, industry and other fields, how to determine

whether they need to be replaced has become a focus of attention for many users. Correctly judging the replacement time of

synthetic underlays is crucial for ensuring the normal operation and safety of facilities.

Visual Inspection is the First Step

When inspecting synthetic underlays, the first thing is to check whether there is any damage on the surface. Professionals

point out that when carefully examining the surface of the synthetic underlay, special attention should be paid to the

appearance of cracks, holes or tears. For example, for the synthetic underlay used on the roof, if the crack width exceeds

1 - 2 millimeters or the crack length is relatively long, more than 30 centimeters, it may affect its waterproof performance

and replacement may need to be considered. At the same time, the phenomenon of bulging cannot be ignored. Bulging

may be caused by water vapor accumulation under the underlay or incomplete air discharge during installation. If the area

of the bulge is large, accounting for more than 5% of the roof area, or the bulge is increasing continuously, it indicates that

the integrity of the underlay has been damaged, and its waterproof, heat - insulation and other functions may be greatly

reduced, so it should be replaced in a timely manner. In addition, the color change of the underlay is also an important

observation point. If there is fading, discoloration, especially uneven color change, or the underlay loses its original luster,

becomes dull and the material becomes brittle, this may be the result of material aging caused by long - term exposure to

sunlight and ultraviolet radiation, and replacement may also need to be considered.

Performance Testing is Key

In addition to visual inspection, performance testing is equally crucial. In terms of waterproof performance testing, a simple

water - pouring test can be carried out to observe whether water can penetrate under the underlay. If water can penetrate

easily, it indicates that the waterproof layer of the underlay has failed. At the same time, use professional humidity detection

instruments to check the humidity under the underlay and inside the roof structure. If the humidity is significantly higher than

the normal range, such as the relative humidity exceeding 70%, it may mean that the waterproof function of the underlay has

problems and replacement is needed. In terms of heat - insulation performance evaluation, the heat - insulation performance

of the underlay can be initially judged by comparing the indoor and outdoor temperatures. If the indoor temperature is

significantly higher than the same period in previous years during hot weather, and the factors such as air - conditioner failure

have been excluded, it may be that the heat - insulation function of the underlay has declined. In addition, professional thermal

imaging cameras can also be used to detect the temperature distribution of the roof surface and the indoor ceiling. If the

temperature difference is found to be small, it indicates that the heat - insulation effect of the underlay is not good and

replacement may be required.

Service Life Consideration is Necessary

The service life of synthetic underlays is also an important factor in judging whether replacement is needed. Different types of

synthetic underlays have different nominal service lives. The nominal service life of ordinary polyvinyl chloride (PVC) synthetic

underlays may be about 10 - 15 years, while that of high - quality ethylene - propylene - diene monomer (EPDM) synthetic

underlays can reach more than 20 years. Even if there are no obvious signs of damage to the underlay at present, if it has

approached or exceeded its nominal service life, its performance changes should be closely monitored, and preventive

replacement of the underlay can be considered to avoid potential problems. At the same time, if the underlay is exposed to

harsh environments for a long time, such as being eroded by salt spray near the sea, polluted by chemical substances in

industrial pollution areas, or in areas with high ultraviolet radiation, its actual service life may be shorter than the nominal life.

For example, for buildings near the sea, due to the corrosive effect of salt in the salt spray on the underlay material, the service

life of the underlay may be shortened by 30% - 50%. In such cases, it should be judged in advance whether replacement is

needed according to the actual situation.

Experts remind that the inspection and replacement of synthetic underlays should be carried out regularly, and it is best to be

operated by professionals to ensure the quality of inspection and replacement and to guarantee the safety and stable operation

of the facilities.