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wide plank floor over concrete.

Started by losttheplot, April 19, 2013, 01:18:40 PM

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losttheplot

I am involved in a renovation of an old building.

The flooring is 10-12" wide by 2" thick Douglas-fir.

The remodel is likely to involve in-floor heating.
This would be a couple of inches of light weight "concrete" over 2x10 floor joists with pex pipe.
This part would be done by a contractor.

The boards are decades old and have straight sides, no tongue and groove or ship lap etc..
They have a lot of damage from powder post beetles or similar and the edges of many are soft and crumbly.
I do not think it would be possible to mill any kind of profile on the edges (t n g  or a spline etc..)


The home owner has insisted on using these boards against our recommendations.


Our job would be to lay the boards over the concrete sub floor.

I would normally recommend a floating floor.
The only other option I can think of is to glue sleepers to the concrete and face screw the boards to the sleepers.

Does anyone have any other options ?

Thanks in advance.
LTP.

DON'T BELIEVE EVERYTHING YOU THINK !

beenthere

QuoteThe flooring is 10-12" wide by 2" thick Douglas-fir

I take this to mean that this flooring is already down in the old building. What is the plan for taking it up and laying it down again?

You suggest you can't tongue and groove the flooring because of imperfect edges. Seems you could still do it and either make sound edges or just not have good tongues/grooves where the imperfections are at, but still have the benefit where the edges are sound.

Not much one can do if the owner insists on poor installation. Just have it in writing that repair costs are not on you, nor warranted in such a way that you have to fix what goes wrong. IMO

Didn't notice the double other post.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Jay C. White Cloud

Hey LTP,

I liked everything you thought of doing, excellent.  Most folks don't realise that finish floors can be floated. One of the leading authorities on this system is Radiantec here in Vermont, the founder, held several patents on this system and kinda brought it all to fruition as we know it today.  I am in the middle of engineering a radiant floor as I write this, and have had to consult on several jobs with your current challenge. 

First thing that comes to mind, is make sure you protect yourself from, "other folk's concept which could be bad practice." 

Next is Why embed the tubing in anything like concrete, I would ask them that.  If they ever have to service it they have to do a lot of tearing up of material.  A sand bed would do just as good for adding additional thermal mass if that was there goal.  Radiant  tubing functions better with a radiant reflective barrier and no encapsulation at all. Present it, (in writing) and if they chose otherwise you have a record of your recommendations.

Second that is a soft wood floor (~1.3 to 1.6 R per inch) and it's thick?  That is going to require an in floor thermostat sensor array, do to the "dampening effect" of the thick wood floor.  It's going to slow the entire system down, contributing to much slower response times.

Now for the floor.  You can still float it, there are several options.  One is you glue it to sleepers (which float) with a structural adhesive, then use a wood solidifier on the "soft spots."  You can also take nylon webbing/strapping and create floor sections that are strapped together from underneath then laid as a unit. (my least favorite, but it has some merit in certain applications)  The next system is my preferred, often in combination with splining, however you will either have to do a lot of joinery or invest in a toggling mortiser which is a wonderful tool to have in your kit.  Festool makes two sizes, a large and a small, you will need the larger of the two.  These toggles (they call them dominos) are placed every 300 mm to 600 mm (~12" to 24") apart depending on the soft edge.  The go in 75 mm (~3") from the sides, each toggle being 150 mm (~6") long.  This negates the need for T&G or splining, and gets your joinery into good wood while fulfilling the client wishes not to re-edge the boards, thereby loosing width, but you still get a solid jointing and can float the floor.

Well that's it in a "nut shell."  Hope it helps.

Regards,

jay
"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

beenthere

JC
Good ideas, but about the sand in lieu of concrete, OP says .....
QuoteThis would be a couple of inches of light weight "concrete" over 2x10 floor joists with pex pipe.

As a side note, my folks bought a home in '57 that had radiant heat in the poured concrete floors. Quite an elaborate system to monitor changes in outside temps and adjusting circulation of hot water in advance if dropping, or cutting back if outside temps rising.
Very comfortable home.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Jay C. White Cloud

Yes Sir, you are correct, and that is still an encapsulation method, and the least desirable for serviceability reasons.

Alternatives that have been successfully used, even on raised floors are as follows,

No embedment at all, just a radiant barrier and sleepers.

The above plus either sand, pea gravel, cobb, or plaster, to name the more common thermal mass enhancements.

Regards,

P.S. your parents system is probably some of the first and may even be done with copper pipe.  Some of the older systems have held up really well, glad to hear about one that old still working!! That's great.

jay

"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

losttheplot

Thanks for the comments so far.

Just to try and clarify.

The floor was previously face screwed to the floor joist. There have been a few issues with the previous work done to the building.
The floor boards are currently stacked under a tarp, on the deck outside.
( I have asked questions on moisture content on the drying/processing forum)

The entire floor system has been removed and we are currently underpinning the existing perimeter footing and trying to solve some drainage issues.
When it is finished it will be over an insulated/conditioned crawl space.

The heating is being done by a consultant and the contractors he recommends.
We have no say on the heating system.

We are working for hourly rate, the homeowner is paying for the materials.
aside from blatant stupidity on our part, this releases us from any liability.

The issue for us is to provide the homeowner with the best floor we can given circumstances.

I am thinking of gluing all the boards together with white glue, like a huge cabinet door glue up, and letting it float. 
DON'T BELIEVE EVERYTHING YOU THINK !

Jay C. White Cloud

QuoteI am thinking of gluing all the boards together with white glue, like a huge cabinet door glue up, and letting it float.

Hey LTP,

I have seen this done before, but only a few times did it behave nicely, (worked with white pine under 200 mm (~8") ) though you could give it a shot and see what happens.  I would still recommend the jointing and floating method. 

Good Luck,

jay
"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

Holmes

  just a note on radiant installation.  I am not a fan of putting sand in for a thermal mass.  It generally ends up being a home for critters if any moisture gets into the sand.
Think like a farmer.

muskoka guy

You could put down your sleepers as you stated, and glue and screw the boards to the sleepers. Drill holes first, then plug them. We install lots of hemlock plank floors. We glue them down to the subfloor. We drill the screw holes with a forsner bit, screw them to the floor,  then glue plugs of the same material in the screw holes. Sand the plugs down, then finish the floor as normal. I find the look of the plugs appealling.  Dont know how the space between the concrete and flooring will do for the floor heat. Sometimes if you let customers talk you into doing things that you believe are not the best practice, it will come back to haunt you. When it screws up, they may not make you pay, but when someone asks about it, they seldom will take the blame themselves and you end up looking bad. I have long since learned that if I dont like they way they want it done, and we cant come to a compromise, they can get someone else to screw it up for them. Good luck on your project.

Jay C. White Cloud

Hello Holmes,

I guess that decisions has already been made for LTP, but to your point about sand.  Of the ones I listed, it is my least favorite also, I would rather use pea gravel.  As for the sand harboring critters, it doesn't at all, and this point I have seen a few floors done this way just because that's what they had.  It drys out very quick if you spill something because of the heat in the tubes.  The few times I have seen either sand or pea gravel, they both are dusted with borate which also inhibits mold or critters. Cobb is my favorite, (then plaster) of the thermal mass enhancers, and it does a great job of it.

Muskoka Guy,

If I don't float a floor with joinery, I do it the way you described, or variations there of.  It works really well other than some gaping on occasions but that is to be expected with wide plank floors.  The only way around that is by the joint method, as you can re-tighten the space between the boards as the dry, and/or acclimatise to there location.  With the correct tools, it is also the easiest.
"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

Satamax

If it can help, i've seen some UK guy lay a floating layer of plywood, 22MM thick (nearly an inch) criss cross screwing the edges, sinking the heads, and then gluing an oak flooring on top of that, perpendicular of the long lenghs of plywood.
French CD4 sawmill. Latil TL 73. Self moving hydraulic crane. Iveco daily 4x4 lwb dead as of 06/2020. Replaced by a Brimont TL80 CSA.

losttheplot

Thanks for all the ideas and suggestions.

I have just found out that the concrete sub floor will have composite nailing strips imbedded into it.

The big Festool domino machine is around $1500 in Canada. Plus  $2 each for a couple of hundred domino's.
Some of the boards are 20ft long, getting all the mortises lined up might be tricky.
The mortises would also have to be referenced from the bottom, the boards are not all exactly the same thickness.

We still have a ways to go until the floor boards are ready to go down, so plenty of time to mull it over.

Cheers.
LTP

DON'T BELIEVE EVERYTHING YOU THINK !

Jay C. White Cloud

Hey LTP,

Ya, that "puppy," is one expensive tool, but it's one of those tools that you just can't believe till you use it.  Then once you have, you can't believe how much time it saves, or how you lived without it.  I have the small one, and have to borrow the large one for certain jobs, like yours.  Now I need it so often, I'm just biting the bullet and buying it.  The small one is great for many jobs, but the big one is a must have for larger projects, like timber framing and wide plank floors.  I have considered selling the small one, to off set cost, but I can see it being needed on some jobs for one thing and the large one for another at the same time.

You have it peg, (no pun intended) you would reference off the bottom of the board.  Don't worry about the holes lining up, you won't have any problem at all with that.  There are different settings for the hole sizes to choose from, so it can be an exact fit for one edge, then just a larger setting for the receiving edge; though I have done it with exact hole on a few jobs and had no problem lining things up, not that it is necessary for this application.  You can even make your own toggles (dominos) instead of buying them.

The stability it adds to the floor is unmatched.  You don't have to attache it to anything except the next plank.  You end up with on giant slab that is traditionally jointed and stable because of all the joints, it can move with the seasons, and be taken apart if something needs to be serviced.  The last board to go on may be a bit tricky, but there are a number of edging methods and treatments.  These are often referred to as "Key Boards," and are normally of quarter saw stock.  For this floor, and the condition you described the edges to be in, I would go the full 75 mm (~3") depth into each edge.  With that, you will have a supper stable floor and a 3" wide "key board."

Regards,

jay
"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

Fallguy

Just suggestion the pro's can shoot holes into, but what about using a biscuit jointer? I would us the largest size biscuits every couple feet.

Jay C. White Cloud

Hello Fallguy,

Not a bad suggestion at all, just not big or strong enough for this kind of job.  "Biscuit" joints rely on edge glue a great deal and aligning the joint for good assembly.  The "toggle mortiser" is a more structural form of the "biscuit" jointer.  "Biscuits" at best can only take a few hundred pounds of pressure in shear or tension without failure, unless they are a specialty type made of plastic composite or metal, and even those aren't as strong as the toggles which have a shear strength over 1000 pounds.  I'm still waiting to see complete load specs. on them, but can tell you from "real world" testing they are "bomb proof," and even have application in Large furniture, wide plank floor, boat building, and even some full scale timber frame joints.

Regards,

jay
"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

Fallguy

Jay I Googled the Festool Domino machine. I have not that unit before. That sure beats a biscuit jointer I see why you recommend that for a floor application.

losttheplot

The homeowner would like to use the building, we are working on, for a couple of months this summer.

we are hoping to have the sub floor down by the beginning July, then return to the project around September.

This should give the floor boards plenty of time to dry out.

I was wondering if it would be possible to glue the toggles into the boards ?
Would this make the boards act as a monolithic slab and move any shrinking/ expansion to the edges ?

It seems like it would work, in my mind anyway.
DON'T BELIEVE EVERYTHING YOU THINK !

beenthere

Wood has a lot of strength in compression so when it expands, it will push the floor out easily.

However, very little strength in tension perpendicular to the grain, so when the wood in the floor shrinks, likely it will split at its weakest point, and not pull the rest of the floor with it.

Make sense?
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Jay C. White Cloud

Even'n Losttheplot,

You could, but with the bigger machine, (which is what I use for flooring, particularly large planks,) they go in 75 mm (3") so you really don't need to go through the process of gluing anything.  Some the German tech. folk at "Tooltechnica" (the owner of Festool) explained the use in flooring with this metaphor:

  When you are done with an installation you have basically made a giant wood carpet.  The other nice aspect of this more traditional application is you can easily service the floor and anything under it.

Once everything is jointed and put together it is really easy to take it apart, should you have to for some reason, anytime in the future.  Finishing the edges can be a little challenge, not that its hard, just different and you have many ways of doing it.

Regards,

jay
"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

classicadirondack

All in all, I like inches instead of metric.

Jay C. White Cloud

QuoteAll in all, I like inches instead of metric.
::) ???
"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

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