Hot, humid, salty: specifying temporary housing for the Caribbean coast

Temporary housing on a tropical coast rarely fails because of the earthquake. It fails because of corrosion. Salt-laden air and permanent humidity attack the fasteners first, then the cut edges of the sheet, then the corner block. By the time it is visible, the unit is already compromised. The fix is in the purchase specification, not in later maintenance.

Three things to raise before discussing price

• Zinc grammage. Our standard is 60 g both faces, upgradable to 300 g. For a saline environment the recommendation is to go up, not to stay at the minimum.
• Fasteners. Dacromet carriage bolts, galvanised hex bolts and stainless self-tapping screws. Common screws rust and shear, and the joint opens with them.
• Powder coating. Virgin powder above 80 miu with a warranty over five years. Recycled powder in low-cost units carries no warranty on term or thickness.

The floor is the quiet weak point

In high humidity, grade B floor board develops salt efflorescence: a white crust appears, the board swells and the structure starts working badly. We use only grade A magnesium and sanded cement board, asbestos-free. It is a difference invisible in the quotation and obvious at eighteen months.

Installation in line on point supports: no slab, no excavation, no curing.

Ventilation and internal temperature

A closed module in the tropics becomes an oven unless ventilation is designed in. The combination that works: windows with insect screens on opposite facades for cross ventilation, an eave or shade over the facade with the highest solar exposure, and sandwich panel roof insulation rather than single sheet.

Our standard roof is 0.35 mm pre-painted steel sheet, 50 mm insulation and a 200-type ceiling. The roof is where comfort is won or lost in a hot climate.

What to write into the datasheet

Finished unit before shipment. Zinc and fastener specification belongs in the contract, not the catalogue.

Design support

The types most requested for this climate are a six-metre family bedroom, a sanitary module and a management module. We adapt layout, opening positions and electrical layout on the same frame, so the logistics package does not change between types and the loading ratio holds.

If your organisation is defining the specification for a temporary housing purchase, we can issue drawings and bill of materials within days.