– Parasteatoda tepidariorum – A.K.A. American House Spider – is found worldwide and is the most commonly seen type in homes. They are no threat to humans and will normally let your hand approach them. They can be found weaving spider webs under window sills and in wall corners. Common House Spiders are a dull brown in color and the average body size is 6 mm long and can measure longer than an inch with leg span.