Why Does Water Spray Into Your Home Through Air-Conditioner Openings and Window Frames During a Typhoon? Emergency Tips to Stop Backflow

Why Do Windows Leak Only During a Typhoon and Turn into "Fountains"?

Ordinary rainfall falls vertically and naturally drains away through the drainage holes on the outside of the window frame. During a Category 10 or stronger typhoon, however, strong winds create wind pressure (positive pressure) of up to several hundred pascals on the windward side of a building:

• Backflow through drainage holes (the water seal is broken): When the small drainage holes outside the tracks of sliding or casement windows are directly exposed to strong winds, the rain cannot drain away. Instead, it is blown back through the drainage holes and into the interior track channels. Once the water level rises above the inner water barrier, it overflows into the room like a fountain.
• Failure of worn seals and gaskets: The sealing brushes between a sliding window sash and its frame can be penetrated by strong wind pressure, allowing wind-driven rain to spray directly into the room through the gaps.

Why Does an Indoor Air-Conditioner Unit Hum and Even Leak Water Into the Room?

• Backflow through the condensate drainpipe: If the drain hose connecting an air conditioner to the outdoors is left exposed to the wind, strong typhoon winds can blow air and rainwater back through the pipe and into the room. This can produce alarming "gurgling or howling" noises and blow water from the drip pan onto the wall.
• Failed sealing around the wall penetration: If the expanding foam or waterproof sealant around the outdoor side of the hole through which the copper pipe passes has deteriorated and cracked, rainwater can flow straight into the room along the pipe.
• Recommended response: At the height of a typhoon, stop using split-system air conditioners on the windward side and unplug them. Regularly inspect the sealant around wall penetrations, and, if necessary, install a wind- and insect-resistant check valve at the end of the outdoor drainpipe.

A 3-Minute Emergency Water-Stopping Method for a Leaking Window

• Using a water bottle or plastic bag to cover the drainage hole: If you discover that water is being blown back through the drainage holes in a window track, place a wet towel or a plastic bag filled with water over the track channel to reduce the splashing.
• Using diapers or sanitary pads as an absorbent dam (a brilliant trick): Ordinary towels become saturated and stop working within minutes, while baby diapers and overnight sanitary pads contain superabsorbent polymer (SAP). Laid along gaps in the windowsill, they can absorb seepage weighing many times their own weight, swelling to block the gaps!