The World Federation One Stop Fiqh

Ruling 1070

If a person does not have anything on which it is permitted to perform sajdah, or if he does have something but cannot perform sajdah on it on account of severe heat or cold and suchlike, then performing sajdah on tar and asphalt takes precedence over performing sajdah on other things. However, if it is not possible to perform sajdah on them, one must perform sajdah on his clothes or any other thing on which performing sajdah is not permitted in normal circumstances However, the recommended precaution is that as long as it is possible for one to perform sajdah on his clothes, he should not perform sajdah on anything else.