Three weeks ago we sat down with the project team for a chemical distribution center outside Kuching. The client had already approved the general layout, but the roof structure was still open for discussion. This post covers the decisions that came out of that session, and why some of them changed the way we approach the next phase.

The main question was simple: how do we span the 42-meter clear width of the main storage hall without adding interior columns that would interfere with forklift traffic? We compared two truss configurations, a Warren truss with verticals and a modified Pratt profile. Both fit the load requirements on paper, but the Warren variant used roughly 8 percent less steel for the same deflection limit. That difference matters when you are ordering several hundred tons of sections.

Corrosion resistance was the second topic. The site sits close enough to the coast that salt-laden air is a real concern, and the client stores bagged chemicals that release fine dust. We settled on a hot-dip galvanized finish for all primary members, with a two-coat polyurethane topcoat on the bottom chord and the first two meters of every column. The extra coating adds cost, but it protects the areas that are hardest to reach during maintenance.

We also reviewed the crane plan. The hall is long enough that a single mobile crane position would require very long rigging and slow lifts. Instead, we split the roof into four erection bays and planned the crane to move twice during the assembly. Each bay uses a temporary support tower at the far end, which keeps the truss stable until the permanent bracing is bolted in. The sequence adds a day of setup but reduces the risk of a truss twisting during the lift.

One detail that came up late in the session was the drainage layout. The roof has a 1.5 percent slope, which is fine for rainwater, but the chemical dust changes the equation. We added wider gutters and specified a steeper downpipe angle so that residue does not settle and trap moisture against the steel. It is a small change on paper, but it extends the life of the gutter system noticeably.

The next step is a full shop drawing review with the fabricator. We expect a few adjustments once the actual section sizes are confirmed against the supplier's rolling schedule. The planning session gave us a clear direction, and the remaining work is mostly about locking down dimensions and bolt schedules.