As a Washington State, Licensed Structural Pest Inspector, the inspection of House Boats for conditions conducive to wood destroying organisms almost seems like an oxymoron. And yet the few that I have inspected, or worked on, have had no more issues with wood destroying organisms than other Pacific NW homes.
It just isn’t logical that you could throw some logs in the water–chain them together–build a house on top–and not have any problems. Some of the Seattle House boats have logs that are 100 years old–and still floating. Many of the land-bound homes of Seattle, that are 100 years old, have foundations that are in worse condition. I suspect that the early houseboats did have problems–especially in the wood structures between the floating logs and the house floor structure. These structures most likely frequently needed to be replaced–until pressure-treated lumber came along.
Here is what the Washington State Law says about Conducive Conditions:
(2) Conducive conditions include, but are not limited to, the following:
(a) Earth in direct contact with wood or inadequate clearance between earth and any wood or material subject to damage from moisture. (Well I guess this doesn’t apply to houseboats–no dirt anywhere near it.)
(b) Vegetation, in direct contact with the exterior of a structure, which may contribute to moisture or damage by WDOs. (Not much in the way of vegetation around a houseboat either–gotta get out there and mow that water.)
(c) Restricted or nonfunctioning gutter systems. (You have to be kidding?)
(d) Conducive debris in substructures. (Does driftwood and flotsam and jetsam count?)
(e) Bare or unimproved ground in substructures. (Sounds like semantics to me–no ground anywhere near the substructures.)
(f) Standing water or evidence of seasonal standing water in a substructure. (Ruh Roh!)
(g) Failed or missing caulk or grout at water splash areas. (OK–safe bet)
(h) Moisture from plumbing leaks, lack of ventilation, or other sources that may contribute to damage by WDOs. (Well this covers a wide range of possibilities–but no different than any home.)
So why do these old log “foundations” do so well? To answer that question we have to go back to the basic survival requirements of most wood destroying organisms: Food (plenty of that), water (plenty of that–actually too much), adequate temperatures (ideal year-round), and oxygen/air (bingo–limited air in submerged logs).
There is one more thing that has to be factored into the equation–these old-growth cedar logs are naturally resistant to decay/rot and resistant to many of the Northwest’s finest wood destroying insects.
Usually Licensed Home Inspectors and Licensed Structural Pest Inspectors in the State of Washington are mostly interested in the control of moisture to reduce and eliminate the conditions suitable for Wood Destroying Organisms. Houseboats are a rare example where the elimination of oxygen helps do the trick.
For all the rest of the structure the usual rules and protocols apply.
By Charles Buell, Real Estate Inspections in Seattle
If you enjoyed this post, and would like to get notices of new posts to my blog, please subscribe via email in the little box to the right. I promise NO spamming of your email