Patio Door Seal Leaking
If you cannot re create the leak problem inspect the interior of the door for stains or rust.
Patio door seal leaking. The gutters are clear and the patio is level. However in some instances the top corner of the door is the true culprit. Http youtu be hg2mfndacfw waterproofing how to weather seal door threshold water leak. Test the door for the location of the leak.
Moisture could be seeping into your home from the top. Spray the door and look for the leak location. If you have a water leak at your threshold you must watch this how. Aim a garden water hose with a sprayer set on mist or low at the outside of the sliding door.
Whether your door is sagging or bowed or just not making proper contact with the weatherstrip to seal out air and water the upper corners of your frame could be the problem. Step 2 fill a caulking gun with a watertight polyurethane or oil based sealant and hold it at an angle to insert the product directly into the gap. When a door leaks the most common suspect is the bottom corner of the unit. Leaks in wooden roofs are commonly caused by a gap between the panels which move during expansion and contraction.