About 30 cm long. The cap is small and knob shaped, overlapping in an irregular pattern. Wide, shaped like a fan, and directly attached to the trunk of a tree, it has a shelf-like appearance and is sulfur-yellow to bright orange in colour and a suedelike texture. When it is old, the cap fades to tan or white. The shelves often grow in overlapping clumps, and each one may be anywhere from 5 to 60 cm (2 to 24 in) in diameter and 4 cm (1.4 in) thick. The fertile surface is sulfur-yellow with small pores or tubes and has a white spore print.
Laetiporus sulphureus is widely distributed across Europe and North America, although may be restricted to east of the Rockies.
The mushroom causes brown cubical rot on of the heartwood in the roots, base, and stem. At first, the wood is discolored yellowish to red. Later on, it becomes reddish-brown and brittle. At the last stage, the wood can be rubbed like powder between someone's fingers.