I have these really great wide burl boards (22 inches wide 10 feet long) that I intend to put down as a finished floor.. What I was wondering is if I could glue them together and then screw the whole assembly to the subflooring from below. I was thinking of using bisquits to join the boards together so that with woodglue on each boards edge the whole assembly would “float” held to the subflooring only by the screws..
Yes the whole assembly would shrink and swell with changes in moisture so Of course I’d leave plenty of expansion room. everything would be long grain to long grain..
Replies
If you are screwing it to the subfloor from below it won't be floating and I think you would have trouble with splits as the boards dried out and contracted. Do you know anything about the dimensional stability of this lumber?
If you really want it to float I wouldn't attach to the subfloor at all. Just do it like you would do a laminate floor, edgegluing the boards and leaving enough room at walls edge on the cross grain side for seasonal expansion and contraction.
It sounds like it would make a really cool floor but I don't know about the movement characteristics of the wild grain that is burl.
ripmeister,
the boards are all at least five years old and have dried down to a moisture content (depending on when I measure them) of 7% or less. To prevent splits I would use wood screws that were significantly smaller in diameter than the hole they are in. thus allowing a great deal of movement without any tendancy to bind and cause splitting..
That sounds like a good idea, kind of like the screw in an elongated hole in a table with a breadboard end. I do think the concerns about the stability of this burl have merit though. Perhaps if you are not in a great hurry to get this down you could take a sample board and measure its dimensions over time with different atmospheric conditions to gauge its movement properties.
I will say that the burls took longer than any wood ever has to dry to stability, three years afterwards Theywere still wanting to curl and flex and bend. It's only been in the last couple of years that they flattened out enough for me to start to feel comfortable with them..
Frenchy,
Have you considered ripping them to a more stable width and installing them as pattern matched sets?
With a really thin blade the patterns will match quite well giving the appearance of 22" wide boards.
The only other thing I can think of is to cut slots in the back sides and saturate them with glycol as a stabilizer, though this would tend to soften the wood some, which is not a good thing for wood floors if you expect severe wear.
Thinking outside the box, this sketch.
View Image
After snugging down the fender washer to the previously laid piece, drive the second piece tight to the first.
SamT
SamT
I'm sorry, but are you out of your mind? Ripping them to a more stable width? like what? 2 1/2 inches? Rant over.. Again I apologize...
God gave me these wonderful pieces of wood and I figured that's his challenge to me to use them as he made them.. The method you showed would only work for the edges leaving the middle floating and as the wood shrinks during the heating season exposing your fastening method..
Wood swells and shrinks and it's foolish to believe we don't need to accomidate for that swelling/shrinking. with typical flooring there is usually enough space between each board and each board swells so little because of it's narrow width there is usually enough space to accomidate that little relative movement..
Luckily the subflooring is also made of wood and the only real accomidation needed is the differance in shrinking and swelling between the wood types.. In my case the subflooring is 2 inch thick tamerarck which isn't that differant than white oak in it's rate of expansion. Plywood or OSB would have differant rates of expansion because the fibers are not oriented in the same direction..
I'm going to exagerate for clarity. Imagine I drill a 1/2 hole every 6 inches in the sub flooring.. Into that I place a 1/8th inch screw that is 2 1/2 inches long from the basement up. (2 inch {actual} subflooring and 1 inch {actual} finished floor . To prevent the screw head from being sucked thru the 1/2 hole I use a large washer and as the wood moves the head of the screws pivots on the washer and not only can the screw move back and forth the extra 1/4 inch but the threads of the screw can also cut into wood fibers and move even a bit more! Since the threads would be cutting into Tamarack which is softer than Oak I think that is a safe bit of additional insurance..
There is nothing about wide boards themselves that cause splitting. Properly dried as these have been the only thing that will make them split now is if I fasten them down in a fashion which won't accomidate their movement.. I've been in homes where very wide boards like these are used and they can be well over a hundred years old..
I would "work", BUT.
First you going to go crazy(ier) trying to get it glued up and clamp it properly and keep it flat and at the same time not gluing it to the joist at the same time.
The second thing is that you will have so much movement at the outside edges that you will need a trolly system to carry the screws to hold it down, but still allow movement.
I see a lot of checking in that future.
everything would be long grain to long grain. With burl? What long grain?
One method that I've often used is to slice relatively thin veneers, no more than 1/4", finished, and use the burl as a thick veneer over whatever substrate. Movement's not an issue and there's enough wood to finish well.
Don't forget to post pix of the product.
PAHS Designer/Builder- Bury it!
This spells trouble. To truly make it float, biscuits are okay but it can't be screwed from underneath unless you make a slotted hole to allow for movement. And fastening from underneath is a tricky proposition at best because it can be difficult to know when the screw is sunk tight v. pushing up the flooring.
If the house humidity is stable via cold/hot air, standard t and g flooring installation will work, but at 22" wide, some buckling might occur.
Frenchy, I don't think that's such a hot idea. If you are sure the wide boards won't cup badly, then run them thru the table saw, scoring the bottom like regular strip flooring. Use subfloor adhesive and face nail with a 15 ga nailer, 2 1/2" nails.
If face nailing does not appeal to you, then rip the boards narrower, toe nail .
mike
I agree with all that was said above. Don't do it. BUT, if if ya HAD TO, ya might be better off with a mastic rather than screws. It will allow some stretch, and is far easier than the screws.
I don't see any way that a glue/mastic that would work. movement across boards that wide would be rather dramatic and any glue strong enough to hold it down would also tend to split the wood as it shrinks and swells..
I've walked on too many floors where the mastic has given up and you hear the cracking sound as boards flex back and forth... Not a big fan of mastic for anything except subflooring.
I have this big old rolltop desk that is made up of glued up boards and in the 30+ years I've owned it the boards haven't split I see tables that are 50 inches wide made up of glued up borads and they don't split
Products made for floors are made to be different than others. They have quite a bit of elasticity to them(think gummy rubber cement) which allows them to move with a floor WITHOUT tearing it apart. For example Bruce flooring (a division of Armstrong) says that 3/8 floors up to 3" may be stapled or glued, but anything wider MUST be glued. I recently did some 8" material as a glue down. I've never done anything wider, which brings me back to my first point; I wouldn't do it.
Try contacting Bruce or Bostick as they both make good adhesives. Good Luck!
Wango1,
The guys who do really wide boards for a living all face nail and never glue them in place.
True. I just figured with the burl, you wouldn't want to do that. Again, I would NOT do it, but if were dead set to do it, these are the things I'd do.
So you've got burl planks, but what species? The type of wood and it's individual characteristics are so varied, that to discuss this without that info is pointless. Some wood species, regardless of its installed MC is going to move with only the slightest changes in relative humidity.
And 22" wide planks are really pushing the envelope no matter the species.
As you probably know, burl wood, fiddle back, tiger....any of those grain variations are the result of abnormal growing conditions for the tree and to try to anticipate the behavior of such "reaction" wood is often just guesswork, or the result of long experience.
If you haven't already, I'd throw this question to those characters over a Knots.
Edited 7/11/2005 9:16 pm ET by Notchman
Notchman,
It's white oak and the burl is very pronounced. It looks like the dashboard of a Rolls Royce. The reason for a glue up is concern that shrinkage during the winter heating season would be enough so that the tongue would drop completely out of the grooves and cause the wood to buckle up.