250x50 Merbau Step Tread 1.2m

Merbau stair treads, especially 1200mm long, are very strong due to Merbau's inherent hardwood density (F27 rated), natural rot/insect resistance, and high durability (Class 1), making them ideal for heavy use indoors or outdoors, but proper installation with strong fixings (like cup-head bolts) and sealing from all sides is crucial for longevity and to prevent cracking.
 
Key Strength Factors
Hardwood Density: Merbau is a dense, hard timber, often graded F27, indicating excellent structural strength for bearing weight.

Durability: It has a Class 1 durability rating (above ground), meaning it resists decay and pests, ensuring a long lifespan for stairs.

Versatility: Strong enough for demanding applications like external stairs, decks, and even bushfire-prone areas (BAL29 rated). 
Installation Considerations

Secure Fixings: Use cup-head bolts with nuts for primary fixing, not just coach screws from underneath, to avoid cracking the wood.

Support: For longer spans like 1200mm, ensure adequate support from stringers and consider potential flexing, especially with steel stringers.

Sealing: Seal all sides of the timber before installation to protect it from moisture, which prevents movement and stress. 

In summary, 1200mm Merbau treads are robust and suitable for most stair applications, but their performance relies heavily on correct, secure installation to handle foot traffic and environmental stresses.