How to Build a Boathouse Floating Foundation

What You'll Need
Pontoon boat(s)
Marine grade plywood
Marine paint
Saw and painting tools
Aluminum beams or thick metal conduit
Welding torch and rods
Rivet gun and rivets

If you want to get away from it all, then few things are better than a boathouse. A boathouse will allow you to enjoy peace and scenery only the water can provide. Building a floating boathouse is not an impossible DIY project; however, it does take some planning and commitment. The most important part of your new boathouse will be the floating foundation. This simple how-to guide will walk you through the basics of creating a foundation for a boathouse.

Step 1 - Plan Your Home

Before you do anything, you should take the time to carefully consider how large you want your floating boathouse to be. This will determine the size and number of pontoon boats you will need to purchase for the base of the foundation. You should also do some research on design types so that you can make better decisions as to the type of pontoon boat(s) you will need to buy.

Step 2 - Buying a Pontoon Boat

When thinking about pontoon boats to buy, you will need to choose between new and used vessels. Also, you need to ask yourself if you want to purchase one large pontoon boat or a large Lash type pontoon or barge. While larger pontoons or barges will be easier to work with, smaller types will usually result in a lower cost of construction with your new floating boathouse. If buying new vessels, you should ask the manufacturer to leave out roofs, seating, upper rails, and other items you won't need. If you purchase used boats, you won't have this option, and finding matching pontoon boats may be difficult if you need more than one to form your foundation base.

Step 3 - Creating the Floating Base

If you will use several smaller pontoon boats to create your foundation, you will need to weld the boats together. It is best to use even numbers of boats for greater stability (i.e. 2,4,6 or 8 depending on size). However, you should not pierce the hulls of the boats when welding the them together. Instead, use metal rails or connectors to create weld points. Then you will need to weld in flooring support braces across the width of the hull and cover it with marine grade plywood to create the flooring. Create trap doors in the flooring in important areas where the motor or steering assemblies are located.

Step 4 - Considering Motors and Steering

If you want to be able to propel the boathouse, leave the motors and rudder assemblies in place at the rear of the boathouse foundation. On forward boats, you should remove these components. If you have two or more pontoon boats in the rear row, attach steering linkage assemblies to make steering easier.

Step 7 - Preparing to Frame

Once you have the marine plywood installed, you will be ready to frame your new boathouse. You should paint the surface of the flooring with marine paint and also use a paint protector (top and bottom). This will help avoid floor damage.