classic teak boat decking for home interiors

Sorry if this deviates from the boating realm slightly but I have this project to install 2500 sq. ft. (275 sq. meters.) of 2” plank teak decking w/silicone expansion joints (boat deck) in a custom home here where I live and work in Thailand. I have done this work before but never in a home and never over concrete. I got to reject the gluing of teak directly to concrete for many reasons not least of all spring or the lack of (springiness) My idea is to slope the existing floor and anchor galvanized furring on built up (leveling) mortar beds 16” on center in the direction of my slope then sheeting all that in plastic as a moisture barrier. I would then lay a substrate of 5/8” to ¾” marine ply over that and drill many weep holes for drainage. Every part of that process would be coated with an appropriate sealer and the down slope end under the plywood will have probably 1” PVC pipe for drainage. I would then glue the deck over that. This will be installed in many different applications i.e. bathroom, bedrooms and exterior covered decks next to a Jacuzzi.
My questions are about products and any input on my procedure. SIKA is headquartered here locally but I don’t know much else product wise. What adhesive should I use (sika 298)? What about PU caulking vs. silicone? The designer calls for a teak oil finish but I’ve read about how this does not wear well and red wine stains etc. I know this is an unorthodox topic for this forum but I have searched the internet for links to people who have done this kind of work to no avail. My plan is to chronicle the execution of this project here (with the webmasters permission of course) and on an American woodworking trade site woodweb. I think anybody who has ever seen or walked on this surface before can testify to its beauty and luxury and in that most of us live in a conventional home it has cross purpose appeal. Maybe some people out of work in the boat business can make some money on the side. I am greatful for any input.

 

Look into using a subfloor system. Simply laying down 'sheets of plastic' is a great way to breed some nasty mold and other fun things that can lead to total destruction of a building.

It is too early in the morning for me to remember brand names, or if the products even have a generally accepted generic term. But basically the type of product I would suggest is a plastic or foam 'panel' that has a series of round 'pucks' or similar. This lifts the subfloor and provides an air gap and drainage for any moisture that does get under the floor. (Some are even designed for easily running in-floor heating loops, which can be a bonus if you want to use such a system.)

Just what are the rooms to be used for?

 

Thank you luckless for your reply. I should point out that every structure here in "Thailand" is made from concrete. Walls, floors, ceilings, everything.
the floor I'm talking about is 6" thick poured in a minimum of 2 pours. I believe the floor system your talking about might be a problem, things like that are very difficult source here (have to import by ship) No need for heating, rarely gets below 70 degrees. Good question about the rooms, the bulk of the space is great room and bed rooms so really the system I'm proposing is for exterior decks and the bathrooms. somebody already suggested going with a cement board instead of plywood which might remedy the possibility of rought but we have to test it to see if we get the spring out of it we want. I don't think that fungus is an issue either. I have not really ever seen it here in that kind of situation and the water (theoretically) should hit the plastic sheeting and roll down the slope and out the drainage line. right?

 

I've put down a lot of floors over the years, but I've never had the chance to work with teak. So really these are just random things to think about. Hopefully you can find someone who knows more about how teak can preform will come along.

One of the issues you need to deal with is insuring the gap is large enough to allow any water to flow, as well as allow water vapor to travel. Too small of a gap means the water just sticks to everything and sits there and that air can't allow moisture migration. And of course sitting water or dampness means a place for nasty little things to grow and breed. Plastic sandwiched between concrete and wood just traps water against both surfaces.

How do they normally handle wood to concrete connections there? Most common concretes allow moisture passage, and because of that here you are required to use a thin foam gasket material where wood touches concrete. Are any products like that easily obtainable there, or is it common practice to place wood directly against concrete?

I wonder if building your own subfloor panels could work. Basically rip up a bunch of mold/water resistant material into strips that are like 1/2"x6"x1/8 (maybe 1/4 high rather than an 1/8th), and fasten to the bottom of your subfloor with an inch or two spacings. It should hopefully add a slight give to the floors and make it more comfortable for walking. A little issue that too many people over look when they consider concrete based flooring, and don't notice unless they can spend a lot of time on one, and then spend a lot of time on a long span wood floor.

For exterior decks my first thought would be to try and go with more traditional decking methods. A thin deck board laid over thicker support members that are a held a few inches off the ground. A good air flow then helps the deck boards dry after heavy rains, and stay dry. After all, it just sucks to step out onto a deck and feel like the boards are just cold and damp.

I've never been a big fan of wood around bathrooms, and would usually push for tile or polished concrete, but maybe teak makes for a good exception.

 

Thanks again for your input. I'm still not sure if your getting the whole concept. Probobly my fault. My descripton is not clear enough. Let me try again. lets say the area that I'm working in is a square room with a concrete slab. I would lay mortar beds out like a drive-in movie theatre (16" on center) one end of the rows on what I want to be the high end and one end on the low. then I would screed off the tops to make them level and have a flat top on which to anchor my "galvinized furring" these (when anchored) will sit up off the mounds 3/4" high. In america they are used in many situations the one sitch that comes to mind is in a basement when you have block or poured slab walls you would ramset these to the walls and then screw drywall to them. can't come up with a good description of a cut-away view except to say it is an upside down "u" with feet and its toes are pointed out, the feet are where you anchor it to the wall and the bottom of the "u" is where your screw would go through to anchor the drywall giving that 3/4" clearance for your screw. So the plywood doesn't sit on the concrete it's 3/4of an inch off of it (big gap). Then with respect to the flat top mounds, on the high side it would be basicly flat all the way across and between the mounds splitting into a "V" between the mounds on the low side to create the slope which ends into a perferated 1" PVC pipe going across (and under) the ends of all the mounds on that low side Then I would cover all the mortar mounds, and anchored furring all the way down to that low side with a plastic vapor barrier. The perferated plywood would then be screwed to the furring createing the substrate for the Teak decking system to be glued to. hope anybody out there reading this got that. Like I said in my first post every part of that process would get a coat of (the appropriate) sealer. I think you asked how I would make the connection to the concrete that is usually done with a plactic anchor and galvanized screws. I like what you were saying about the water resistant material subfloor under the plywoood. this would be a treatment more for the bedrooms and great room I think. We had come up with a treatment where we use this galvanized c-channel that they use here for drop cielings, it is 1/4" thick 1 1/2" wide and comes in 4 meter (12') legnths. We were thinking of cutting it into 4" legnths and screwing it directly to the (c pointed toward the teak) back side of the teak at a 90 degree angle so you can anchor through the back side of the "c" to the floor and lay the next piece on top of it. You would then screw another piece to that plank (same size, c pointed away from the teak) right next to the first c-channel piece that would hook under the last piece. So one piece of this channel anchors it to the concrete and the other piece sticking out the other side hooks it under the previous piece running those on every plank every 16" inches or so. The c-channel has some give so it would compress enough so the screws would not hold it up off the floor or the teak up off the channel. The one concern is that in the procedure of running this we have difficulty maintaining our 1/8' tolerence between planks so alternatly we will do the above described treatment on plywood ripped into 6" strips like space sheathing and at a 45 degree angle to the finish decking which woud be glued in place of course.
finally about the exterior decks, they are concrete also and sloped to run off and out but it's hard to allow air flow in that sitch both visually (a big gap you can see from below and if your proposing a wood substrate it's a great place for the termites to fly in and have a field day. The termites are insane here! One of the reasons everything is made from concrete. You said you haven't worked with teak to much and I wonder if you undersatand the decking I'm talking about it's 2"x1/2" planks with an 1/8 gap between them that gets a silicone bead. It's a very long involved process of masking and drying times that eventually gets you this beautiful deck that expands and contracts and stays water tight. To my way of thinking I should be caulking this deck up to the walls and edges so tight that not a drop of water can ever get past it. All the things I'm talking about drainage wise under this deck are pure covering my butt contingincy measures in case there is a breach at some point. Am I thinking about this correctly? Still if anybody knows what should I finish this with? Varnish? Thanks again luckless hope you got all that.

 

It all sounds so complicated. Why not lay down a thin foam layer and make "boards" from 10" or so wide laminations of say, 1/2" teak epoxied to 3/4" plywood? They would appear as several narrow planks (which indeed they would be prior to gluing to the plywood). Exactly like the manufactured flooring you must be familiar with.
The flooring is layed in without fastening, just held down at the walls by a strip. The joints are sealed with black deck sealant and so are the "gaps" (really the top edge of each teak strip is rabbeted just like on boats).
cure and sand the excess off, oil or seal floor.

 

Alan, you would install a floating floor on exterior decks and in bathrooms and I have never heard of rabbiting teak decking wouldn't that defeat the purpose of the expansion joint. Does anybody know what is used for a finish over teak decking besides oil? you know inside the wheel house or where it's not so exposed to the elements. thanx

 

No, I wouldn't lay teak over concrete in a bathroom or outdoors on a deck in the first place.
Allowing the floor to expand and contract should make sense to you. However, the alternative is screwing directly into the concrete, hopefully into a bed of some very expensive polyurethane sealant. Each piece gets two screws, every 16" or so along the board.
Your idea is complicated and labor and material intensive. There should be no air space... no SPACE under the teak.
If you lay the teak (as I described, having the top half rabetted on one edge of each piece) and sealant is also filling the gap between each piece, the rabbetdue to its (say,1/8"-3/16" width) allows a smaller percentage expansion of the sealant in the rabbet than if the gap were narrower, which might pull too hard and release from one side.
They make, of course, screws that hold wood to concrete. I use them all the time. For your floor, expect to use dozens of drill bits, since each hole has to be drilled a ways into the concrete. Use dish soap to avoid bit breakage. Before pre-drilling through the teak in the shop, counterbore with a Forstner bit and match a couple thousand bungs to the counterbores. They will hide your screw heads.
The concrete should be sealed prior to all of this work, and use an epoxy to guarantee waterproofness.
For a durable finish, probably a two-part polyurethane is the best bet, and wax, wax, wax will add some more protection, something the owner can schedule if they want the floor to last a while before re-varnishing.

 

I recently stayed on the SS Rotterdam that has been restored at a cost of 250 mil Euros. The new, looked like teak decks, are laid on the original steel plate deck. Just a thought, termites would have a job getting through thin steel or alu plate with a steel frame containing a sealed floating floor!

 

We have a natural sense that concrete is a good environment for rot to take hold because we've always seen wood decay right up next to concrete, where further out the wood is sound.
Sealing concrete with epoxy, however, also seals its identity so that the wood isn't sure if the hard material it's screwed to is concrete or wood or plastic. That's how effective epoxy sealing can be.
Perhaps with teak we assume we're using a wood thaqt won't rot, and our main concern is preventing expansion and contraction issues.
Bedding the teak in a good waterproof sealant, and screwing it down, no air space can exist and therefore no moisture can enter the wood. Of course, moisture in the form of ambient humidity can very very slowly enter and exit the wood---- but so slowly that the wood simply eventually averages the ambient humidity with a very small swing in content because of lag time.
Anytime you lay teak over a sealed surface (usu. plywood or fiberglass in the case of a boat deck), it might as well be a concrete substrate if it's sealed well.
It's always a huge expense dealing with teak, an enormous investment. Doing it wrong can be catastrophically expensive.

 

For absolute safety, you could lay an underlayment grade of 1/4" plywood and adhesive that to the floor first. Underlayment grade ply has few voids and uses waterproof adhesive. It is a must to do when laying wood flooring in a basement.(slab)