It can, depending on the type of siding and the install method. Some siding systems, such as vinyl and metal, can let rain in on trim pieces and on the vertical seams where the planks or panels connect. Wooden siding can also let in rain along unsealed vertical and horizontal seams. Fiber cement siding is less likely to let in rain, provided that the system is properly caulked and flashed to protect the seams from intrusion. But no matter the type of siding, all systems should have a protective moisture barrier installed behind the siding itself. This barrier can provide an extra layer of protection from rain and water intrusion. Proper installation by an expert will also ensure your warranty is effective and valid. Improperly installed siding does not typically qualify for warranty replacements, this would include if any rain did happen to come through the siding.