A cover keeps the sun off the boat and adds a permanent load the floats have to carry at 650 feet, not only on a pretty Saturday in July. Ameren’s lake-fluctuation note asks owners to design for a drawdown to 650 feet under normal conditions and 645 feet in an emergency. A heavy roof on light foam shows up when the water leaves.
What “covered” is allowed to mean
Appendix B is specific about what a dock is not. It is not a house. Permits are not issued for habitable structures. Temporary or permanent enclosures for living, entertainment, or gathering are not acceptable. Toilets, showers, kitchen appliances, water heaters, and most sinks are prohibited. A sink used only for cleaning fish is the exception Ameren names. Walled, roofed storage cannot exceed 80 square feet on the whole dock. Fabric pulled down to make a room counts as an enclosure even if you can roll it up.
A roof over a slip is a different thing from a room. It is still a modification if you are adding it to an existing dock, and it still has to be permitted before it is built. The permit guide covers the fee and the drawings. The prohibited-items guide is the list to hand to anyone drawing a “dockominium.”
A walkable sundeck is more dead load than an open roof. Describe it that way on the form. Do not assume a sundeck is approved because a neighbor has something that looks like one. Older docks are not a code book.
The load the floats must carry
For covered docks, Appendix B sets the roof live load at a minimum of 11.5 psf, unreduced. Flotation has to carry the full dead load of the dock and the roof plus that live load. Uncovered deck live load is 20 psf, and the deck also has to handle a 400-pound concentrated load on any one square foot. Those two deck loads do not have to happen at the same time. Under dead load, there must be at least 7 inches between the water and the bottom of the frame.
If the existing foam is original, cracked, or already low, a new roof without a refoam is a short-lived project. Say “roof and flotation” in the notes if both are true.
What to send
Choose roof, cover, or sundeck. Include well count, dock age, and whether a lift hangs under the roof. A lift plus a roof is a lot of weight in one well. Photos of the existing cover, the posts, and the freeboard at the outer corner tell the builder whether this is a panel replacement or a structure and flotation project.
Electrical lighting on a cover falls under the same fire-district rules as any other dock power. See electrical inspections.