Introduction (thinking to build affordable floating houses in Indonesia using SIP)

Hi, my name is Samuel Hadinata, was born in Indonesia, with 21 left to study in Germany, since 1983 live in California. Indonesia has 240 million, is the fourth largest population in the world with territory of roughly as large as United States, with 17,000 islands. With my friends, we recently formed a group of International expatriate professionals with intention to help the country. I myself is an Architect thinking to build affordable floating houses in Indonesia using SIP (Structural Insulated Panel) made out of (ideally Bio) Polyurethane foam core. We start approaching one of the governor and instead they asking us to build boats for the poor fishers. None of us have knowledge about building boats. Therefore, I am asking my new friends in this forum a helping hand.
I did a study, I thought I am going to use male female molds, spray both surfaces with Polyurea as skin and fill the gap with Polyurethane foam. SPI shows a video about boat coated with Polyurea, the entire boat become very durable. But today, Rest-O-Leum told me that the Sun’s Ultra Violet will destroy Polyurea within a year. This shocks me since I’ve been thinking that Polyurea was designed to be used for open surfaces. Could somebody explain it to me? Your advise is highly appreciated.

 

Polyurea is an interior coating. Also, it is not structural. If you want advice, get one of the designs from the FAO and build it. They are perfect for the use you are describing and the plans and construction details are free. Re-inventing the wheel will not help anyone. You need a low-tech, well behaved boat.

 

Thanks, Gonzo.

 

Polyurea can be used outside, but as a coating, not a load bearing skin and it will chalk up in time from UV exposure, but if the formulation is correct, it'll hold as well as most of these thick, "rubberized" coatings do.

Designing SIP's isn't as easy as you might think and clearly you haven't put the engineering into this design, unless the goal is a decorative panel that isn't self supporting or load bearing, in which case, it's not a SIP, but a simple foam cored panel.

 

almost all plastics, including epoxy, break down in sun light. There are a few specifically formulated for sun exposure (like the stuff the dashboard on most cars are made from), but none of these are good structural elements.

The cheapest and best way to go is find out what suitable materials are available where you want to build it. Typically local wood, but reinforced concrete has also been used. Plywood is the best if made with waterproof glue, but often hard to get in remote locations. Welded steel can be low cost as well.

good luck.

 

A good example of properly formulated plastics (in this case PVC) is plastic electrical conduit. It's formulation permits it to last decades in direct sunlight. Yes, it chalks up and loses some color, but does hold up well. Polyurea can be painted, which will protect it from UV, but it's still not a structural material, just a coating.