I will be replacing the stringers under the floathouse I live on. I’m not sure which type of beam is the best choice. Ground contact-treated Hemlock is the most common. Pressure treated Doug. fir or pressure treated Glu-Lams are other options. I plan on using 6″ x 12″ x 33′ beams. Any advice or experience would be appreciated.
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Replies
what is a float house?
A floathouse is a house that floats. Mine is built on giant old growth logs crossed with stingers (beams) set at a 90 degree angle to the logs. The house is then built in conventional fashion on the stringers.
Got a picture? Where are you? I would imagine that moisture resistance would be a big factor.
All kinds of questions come to mind, like waste water connection, who owns the "earth" under the float house, do you pay rent to someone, is it considered personal property like a boat as opposed to a homestead ...
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
All the legalities, leases,permits, etc. are taken care of. I'm in Wash. state on the Columbia River. Have you worked with much ground contact type of treated wood? Although Doug. fir is better wood, I'm not sure if it absorbs enough treatment to make it a better choice in this application.
So your house floats on old logs? Don't they eventually become waterlogged? I thought most floating houses were built upon concrete barge hulls.I know we're not helping much with your question...we're just fascinated by the whole concept.
As long as the log has a certain amount above water it won't get waterlogged. Also, you add foam blocks as needed. Concrete over foam is another good way to go-it doesn't rot or absorb water.
I wasn't throwing out those questins for you to use as a checklist, I was curious how that stuff works. Do you pay rent to the state or feds? Who owns the Columbia? Do you have a long term lease?
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Sorry, I didn't mean to offend you. I guess I was just getting desperate for some answers. In answer to your questions: I own the uplands so I can then lease the bottomlands ( River bottom) from the DNR (Dept. of Natural Resources). I have a 30 gal. holding tank under my dock with a 1/2 h.p. motor that pumps all my waste water to a septic tank. These are all state regulations.
Reminds me of Sleepless in Seattle...
BTW - are solid 33' long PT beams actually available? I wouldn't think anyone except perhaps a very large company would have a tank that long.
Yes, they are available but it is a custom order........meaning "Expensive".
Ok, so you own the land up to the riverfront, so by definition you also own part of the river bottom? How far out into the river do tyou own? I though the river was a navigatible waterway and it it owned by the state or feds. Can you build a dock? Sorry for all the Q's but this is a totally foreign concept to me.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
I own the uplands-which is just the side of the dike on which the access road is located. I hold an Aquatic lease through the DNR (Dept. of Natural Resources) to enable me to drive piling and build docks and have my floathouse moored there. My lease extends 50 ft. out from the high water line.
So it is actually floating on water.I was thinking that it was "floating" on the earth. If I am not mistaken that is sometimes done in marsh and frozen areas.I am only familar with docks on lakes in the plain states. All of the places are now only allowing encapsulated foam.BTW, CCA is still aloud for industrial, agriculture, and in water use (maybe only salt water). But I don't know how available it is.
Yea, ecapsulated foam is the current requirement for foam, but they still allow logs in this area.
big... spec. PT for marine construction..... they treat it to a higher retention level than "ground contact"
same thing is true of any PT used for foundation work..
a good supplier won't have any problem getting it..
most of your PT6x12 is going to be for marine work anywayMike Smith Rhode Island : Design / Build / Repair / Restore
I've got a picture for you of part of a neighborhood of floating houses we have here in Winona, MNI posted about this just a couple of weeks ago:
81207.1Here is an interesting story about them:http://www.big-river.com/br.story.b.html
I'm south of you a couple hundred miles and have worked on a lot of docks and float houses on a local lake.
Those that are set on logs are really a PITA and require a lot of retro work when the flotation of the logs diminishes over time.
The most common solution is to use the styrofoam billets....they're typically about 9"X16"X109" and provide about 900 lbs flotation each. They're normally boxed into .40 PT frames that are open on the bottom with just a wood strap across the bottom to secure them.
I've built a number of these and also replaced the billets in existing ones....much easier to do than when we've had to replace a waterlogged timber or old log.
Knowing the flotation capability of the float structure is important since the loads under a floating structure are usually uneven and using the billets carefully enables the structure to remain evenly supported and relatively level without straining the framing structure under the floor.
The foam billets come in a variety of types from just plain white styrofoam which is inexpensive and will waterlog over time, to the better quality (and more expensive) orange or blue encapsulated billets which will maintain their flotation ability indefinitely.
Other options are to have pontoons designed and fabricated for your structure (expensive) or to purchase some used segmented barge floats (which might be available in Portland).
The float system is, for you, the foundation of your house and you don't want to be cutting corners. One good storm surge on the river and you can be in real trouble.
As far as the girders, or stringers, you don't mention your span, but I wouldn't hesitate to use the PT Doug fir in your application.
Are you in tidewater? If you are, your log floats and possibly your beams are vulnerable to being eaten up by toredos (ship worms). One of my cousins had a float house on the Columbia on the Oregon side for a number of years and the toredos were a real problem.
Edited 11/20/2006 1:38 am by Notchman
Hey thanks for the reply. You sound like you've built a dock or two in your day. I have had some encapsulated billets added. I have been thinking about buiding 4 large stainless tanks and plumbing them so I can add and take away air and water. If I put one under each corner of the house I can level the house at will. So, you think the Doug. fir will last as long as the treated Hemlock? I know its better wood, but I am interested in the longevity of each material. Thanks again.
You called that one right on. The old fir beams lasted about 20 years or so. Thanks for the info on the different treatments. This is my first time doing this ( and last, I hope) so its all kind of confusing. I know the fir is expensive right now, but I would be willing to go the extra expense if they last as long as the Hemlock. Thanks for the reply.
"fir is expensive right now...."
Actually, lumber prices, including Doug fir, are at their lowest in several years. Some of the lumber yard prices aren't reflecting the lower mill costs in their pricing, so you might want to shop around.
Another option is to find a sawyer with a portable mill locally to cut your beams and have them pressure treated in Portland. The Woodmizer dealership in WoodVillage in NE Portland can give you some referrals.
There is a treatment plant in Portland that will custom treat with a non-ACQ treatment that will work for you and it won't cost an arm and a leg. They're currently treating some log rail stock I'm replacing on a log home....I'll get the specifics and forward to you.
BTW, getting lam beams treated is also a good option.
Great info! Thanks. Do you think the Doug fir or Glue Lams would last as long as pressure treated Hemlock (Treated for ground contact)?
If the pt lams or sawn beams are not actually in ground contact, but are just the beams tying your float logs together, Doug fir should be fine.
I've used treated laminated beams here for dock supports and girders with no bad results.
You will want to treat any borings you do, or any sawcuts with an endcut treatment....the wolmanized brand is fine. And use galvanized or stainless hardware.
Another thing to consider is using Impel Rods in any notched areas.....They're little rods 1/2"X 4" that are formed of anti-fungal salts of some kind that when wet, slowly desolve into the wood preventing decay. Just bore a 1/2" hole in the site, tap the rods into place and seal them with a little tapered wood plug that comes with the rods.
I haven't bought any in awhile, but when I did, I got them in Portland. You'll find them in a Google search for Impel Rods and the home site will probably provide a local supplier.
Edited 11/22/2006 12:24 am by Notchman
I had no idea Winona had floating homes!Granted, these are slightly different than what you see in portland. In Winona, these are pretty much boathouses. In portland, they are truly floating houses. The exact same house you'd see in a McMansion farm in the 'burbs, except floating.
Hey, thanks again for the valuable info. My only concern is that the tops of the logs are damp most of the year. They do dry out in summer, but as we all know in the Pacific N.W. summer is fleeting, at best. Do you still thing the Doug fir would be better than the Hemlock? Sorry to sound like such a pest, but it is a big investment in time and money, and the sales people have some good opinions, but they are interested in their bottom line. Let me know what you think, and thanks again for your insights.
The Western Hemlock will definitely pull a deeper treatment than Doug Fir....it's just doesn't have quite as much structural strength, though it will be better than pine and probably on a par with PT Sitka Spruce (the second-growth stuff....with the big knots). All in all, most of the Hemlock PT I get is pretty decent lumber, but we have two local treatment plants down here and their quality is surprisingly good.
Lumberman's is one of the local yards here and they have a corporate contract with MacFarland Cascade who has some serious quality control problems and I (and most of my fellow contractors down here) refuse to buy their damned stuff.....I'm speaking mostly about MC's 2X dimenstional stuff....they might do better on post or beam stock.
Without knowing a little more detail about your structure, spans between your float logs, along with the size of the house, how much it might have to resist flex when a tug goes by, etc, I'm tending to recommend strength, but it's probably not even worth fussing about.
Your need for 33' stock surely doesn't have to be single pieces does it? Splicing two 20's or three 16's would likely suffice.
Can you post some photos of your crib?
Hey thanks for your thoughts. Yes, I would like a one piece beam. My house is small, only 25 x 40 with 8 and 10 ft. decks on two sides. With a one piece beam I think the strength factor might be greater.
bigfon,
the treated douglas fir that i meant to refer to is the ACZA (chemonite) treated product which is usually used for piling and beams exposed to saltwater and some fresh water applications. ACZA comes in different treatments depending on the service (saltwater submersion, saltspray, fresh submersion, etc.) . although i have not purchased any in the last 12 months, i've heard it has double or more in price.
here on the sound the only treated piling material that we are supposed to use is chemonite.
try http://www.chemonite.com/ it has a lot of information.
Thank you for taking the time to answer. I will definitely check out that web sight.
I wouldn't want to use glue-lams unless they're made with marine-grade glue.
People never lie so much as before an election, during a war, or after a hunt. --Otto von Bismarck
Glue Lams, at least the Doug fir ones out here, are glued up with resorcinal glues which meet marine specs.
since you have no restrictions placed on you by those having jurisdiction, check for savaged creosoted timbers. up in Puyallup, there is a place called Rhine Salvage. they are super strong (old growth fir) and cheap. but you definitely have to pick your own or else they'll give you some real crap.
i've heard chemonite (ACZA, the "ecofriendly" commerical quality treated fir) is really expensive these days. i used that stuff for my overwater beams and joists where exposed to fresh water exposure.
my thought is that since you are over fresh water, the current treated helmock should be fine. 33' is not going to happen though. the fir doesn't absorb the acq so it's not used. if you can get the cca, that'll work for sure.
if they are protected from frequent fresh water it shouldn't take much to protect them.
What was there and why did it fail? You should do the demowork to make sure that you don't repeat the things that failed first on the old stuff. things like fastner locations and methods are key.
i'll bet your old "stringers" were fir and they failed locally due to standing water/moisture problems.
bigfon
I think you need to step back a bit and consider everything.. for example how soon after they were installed did the originals rot? If it was longer than you can expect to remain there why worry? replace with whatever was original, in the end it will be the cheapest solution..
If you do want a decay resistant wood buy white oak (not red) it's among the most decay restant woods around and extremely cheap where it grows in abundance (most pallets are made from it for that reason).