A. OUR VAST EXPERIENCE AND KNOW-HOW
BALI PREFAB WORLD (INTERNATIONAL) has developed a special system and technique to have our models safely built over water, either in lakes or coastal waters. Our senior in-house Civil/Hydraulic and Geotechnical engineer with 50 years of International experience under his belt, - in particular with over water building technique -, may help and advise you on the required piling type, piling depth and superstructure. In order to safely determine the pile capacities one need to take into account the pile's end bearing capacity + negative or positive friction along the pile shaft. This will define the safe pile driving depth. Waves have minor influence on piles, however, it needs to be investigated if wave run up caused by cyclones need a special superstructure. We will prepare a wave propagatiion calculation to assess this. Our company would be happy to prepare a quotation for the engineering works for your over water project, even when you will not order one of our units. Pile structures can be made from either concrete, steel or wood. the latter being the cheapest.
You may also request us to prepare a free of charge ballpark volume estimate for your over water project. To this end we need data such as the seabed subsoil configuration (sand, clay, coral, rock. or a combination thereof) and the water depth and the type of the house that will sit on the pile structure. We can only provide a general Bill of Quantities (volume estimate). Unfortunataly we are unable to make a cost estimate since we do not know the prices of materials (piles, concrete, etc) in your area. You need to inquire the prices by yourself based on our BOQ as to axquire a ballpark cost figure.
It is a prerequisite by most, - if not all -, building authorities that a professional engineer or company be engaged having sufficient experience with over water building in order to safely build the wooden prefab units on top of fhe piled superstructure. There seem to be companies in Indonesia who have posted pictures on their web sites showing over water build structures. These pictures only count for the wooden superstructures and NOT for the concrete and piled sub structrues. Third party engineering companies were involved for this part as to peprare the structural calculations. Based on A above our company is more than capable to design a fully integrated structure (the piling system, the concrete sub structure and the wooden prefab houses). As such you will keep both the design and the approval by the building authorities in one hand.
B. APPLIED TECHNIQUES
Properly employed timber marine piles are a long term, low cost, environmentally sustainable solution. They do not corrode and proper treatment protects them from environmental degrade mechanisms such as marine borers and rot. They do not require expensive cathodic protection systems or expensive coating systems to provide them with adequate service life, but they will benefit from wrap or a PVC tube encasement between the mud line and the high tide mark. If this is done the piles will outlast their counterparts with low initial cost, very low ongoing maintenance costs and wil last for > 50 years.
Piles below the mud line will not decay or be attacked by marine borers. Above the mud line and below the high tide mark (splash zone) they are susceptible to various levels of marine borer attack. This is generally classified in various standards as high hazard in salt water (coastal and some salt water rivers). In these waters we recommend a treat with a special wrap. Such treatment protects the timber from all kind or marine borers such as the most dangerous shipworm (Toredo, Bankia), the less dangerous gribble, piddocks, pill-bucks, and more.
In the event that you will not order an over water unit from us but only need the design for the over water substructure + piles, let us know via our contact form. Our senior civil/hydraulic engineer would be happy to help and advise. Click <here> for his credentials.