correct glue for homemade trus joists.
Does anyone have any good suggestions on an appropriate glue type for making a structural bond in lumber. I want to make the 2×6 ceiling joists in my 1927 bungalow into I-joists to support a second floor by laminating 2×6 and 2×4 lumber to the top and bottom surfaces.
Replies
Prepare for multiple posts telling you to get an engineer.
I was hoping for an answer from a knowledgeable source. I'm aware that the titebond adhesives are not suitible due to their tendancy to creep over time. I would use a resorcinol type of glue but have been unable to find a local supplier.
Engineer is your friend!
Again, I am hoping for a reply from a knowledgeable source. I can do my own load, shear, moment and fiber-bending calculations. But, I am not as informed as to the strengths and weaknesses of various glue formulations and their availability.
I would use resorcinol if I had to do that. Don't know why you can't find it to buy. Try looking for online sources with google.Buy a lot of clamps while you are at it, you will need them to take advantage of the glue in this fashion in place.I would think you are better off with an easier solution - sister 2x8 or 2x10 alongside what you now have. check that engineering for comparison while you are running numbers.What is the span and layout?
if you don't mind.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Welcome to BT, even though a bunch of folks tried to haze you.
Since " I can do my own load, shear, moment and fiber-bending calculations", simply use one of the common yellow wood glues like Elmers, do your shear calculations and whang in a bunch of 16d with the nail gun, dont need many at the center, lots at the ends where the lateral shear is, # of nails per your calcs,
That is all it takes.
or a bolt or two.I'd do it if it was my house.
Will almost 30 years as a PE satisfy your need for knowledge? If so, get yourself a structural engineer who actually knows how to design a truss. Homemade truss??!! Folks like you are dangerous. - lol
Edited 10/9/2009 7:37 pm by Dave45
Why not 'sister' 2 x 8s? Don't want to lose ceiling height? Or is is through-floor wiring/piping etc.?
You need an engineer!!! (as Blue said)
You need glue suited to the job and stresses of the application, but there is a sort of peck order to the operation.
Professional help needed to determine the loads and stresses which will be encountered in your particular situation.
That being said, the best glue for laminating 2x4 / 2x6 to the top / bottom of your existing 2x6 ceiling joists is
the one your structural engineer who stamps your plans recommends.
Keep in mind, he may also suggest alternatives that you like even better!
Sorry, I know you are probably hoping not to hire a qaulified engineer, but the possible alternative is having your new second floor sag, or worst case collapse.
Isn't a few hundred $ worth it in the long run? How much will you have invested in the new 2nd floor when it is all done?
I hire them all the time - one in particular, who has a reputation for being "fussy" and "overly cautious". I've never been disappointed, neither have my customers.
Jim
I am assuming if he wants to make his own I-joists, he sure doesn't want to pay an engineer for some advice.Although, he might be very surprised on how inexpensive that could be.
<!----><!----><!---->
I refuse to accept that there are limitations to what we can accomplish. Pete Draganic
You can lead a moderator to a computer, but you can't make him think. cussin2
Resorcinol is not a home handyman adhesive. It requires 100psi to develop a proper bond. You might be able to find a pic of a glulam glueup from a supplier, but trust me, it takes a lot.
PL Premium is rated as a structural adhesive, but I never have found any allowable bond stress values.
I think you might want to consider something like West Proset Epoxy (http://www.prosetepoxy.com/adhesives.html). The advantage of this type of glue is that it does not require a great clamp pressure to achieve its rated capacity. It is a rigid adhesive and will work for a structural application. It is most commonly used by boat builders/owers to re-build decayed parts, so that is usually a good place to start. The mixing gun and nozzle are very handy.
I am somewhat confused why you want to do this? The adhesive is one item, but the chord grade is also important. Personally, I dont think you will save much in the way of $$, but you sure could cause some problems if you have to deal with a BI or a future insp should you sell the home. Just read some of Frenchy's discussions about the permit process for his epic project. It took 6years of his fighting and all he was trying to do is use a ton of non-graded timbers.
Good luck
2x6 ceiling joists in a 1927 house, over 80 years old? Have you checked these for a crown, pointing down? If you attach something to these already sagging( maybe there're not) ceiling members, you are going to have the new floor as straight or crooked as the ceiling joists are now, unless you already have a scheme to take the curse out of these joists. Keep in mind you are tearing out all of your existing ceiling finish and lowering it 1 1/2" then putting on a new cieling. Saving the ceiling might be another reason to sister something. Maybe it's already tore out?
Another vote for resorcinol. Expensive, and a bit hard to work with, but the best glue I've ever found for PERMANENTLY bonding two pieces of wood together.
Our local HW store carried it last I looked (maybe a year ago), but it was a large fistful of $$ for a small amount. Probably best to look online for a good deal (though a little goes a long way).
I'm guessing I'd go over the mating surfaces with a belt sander (to remove the mill glaze), apply the glue, then fasten with lots of 2.5" deck screws -- one every 8-12 inches. It will be a little tricky mixing it and applying it all within the allowed "open" time. (Work on a cool day to extend the "open" time, but the stuff has to be above about 45-50F to set properly.)
I had an couple old cans of resorcinol glue that someone gave me with some paint and other stuff when they were moving. I looked inside the can of powder and put the lid back on. The can exploded when I pushed down on the top. Blew the lid to the top of the garage and all the powder burned up. Bizarre.
Interesting -- never heard of that problem. I don't recall any warning on the cans, and I can't find anything on the web suggesting this problem.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
I haven't seen anything either. It was old and the can had rust, maybe it mutated and went unstable.
Maybe your friend was a retired terrorist.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
He retired from Wright Pat AFB. I did some reading and it appears that the powder can explode, but not under normal conditions. All I remember is that it was a hot day, maybe it was out in the sun a while.Or maybe he stored gunpowder in the can.
Remember the guy's name, just out of curiosity? I worked there briefly in a former life.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
Bobby (Robert) Sands, from Georgia.
Doesn't ring a bell.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
It's a big place over there. I think he was a buyer in procurement.
Yeah, it was a longshot. But if he was in procurement we probably took his name in vain once or twice.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
In reply to all your stated and unstated questions. Yes, it's more trouble than it's worth but my wife selected the place. And yes, I shall deal with the crown as necessary. The two greatest spans are 15' 6", and 12' 6" and the current ceiling height is eightt foot three, so if I drop it 3 1/4" by adding two inches of wood and one and a quarter of drywall it won't matter that much. I've not crunched all the numbers yet, but I think that if I create the equivalent of six by tens on sixteen inch centers, I'll have sufficient load bearing capacity to give a sufficiently low deflection over those spans. All the lumber is material I've salvaged from other contractors that don't abhor waste as much as myself, so it has cost me nothing more than the time I spent recovering it from various job sites, thus reducing the amount of material buried in landfills. I believe I'll manage to achieve whatever pressure is appropriate to achieve a proper bond. And in any case the results shall be verified by determining the actual deflection under an imposed load at mid-point of the greatest span of the first 'trus joist', as well as a representative sampling of the others. It's currently a small brick bungalow with nominal eight inch brick bearing walls on somewhat cracked concrete footings and foundation. All of the ceilings and walls(sand based plaster over plaster-board) have cracked extensively. I had made a fairly substantial effort to repair them all when we wed 14 yrs. ago and they've re-cracked and peeled since. I've done new construction and rehab since leaving architecture as a field of study in '74. And if I have to correct a mistake, I'd rather it be my own, instead of someone elses. So, as St. Louis is an earthquake zone I'm having the structural engineer design new footings, parallel to the existing ones, that will resist the supposed load imposed by said theoretical occurance. My thoughts at this time are to use prefab foundation slabs anchored to these footings, but if the engineer decides that won't do, we'll find a suitable alternative, insulated concrete forms? The place is virtually un-insulated and I'm tired of wasting energy. Basically I'm a tree hugging eco-freak, and I'm going to try to re-build the place as a Leeds Platinum re-hab. I shall try to use most of the existing wood trim and structure over. But, I intend to replace the brick bearing walls with SIPs fabricated of three plys of 3/4" OSB that sandwich 9" of isocyanoacrylate insulation, I can get the OSB in eight by twenty-four foot sheets, and can use the crane that places the foundation slabs to position the sips. I think that may serve to shelter us a bit more than the plaster and brick. And the old brick will go back as a thoroughly anchored veneer wall supported by the new foundation. Basically, I think that every eighty years or so, a house ought to be brought up to speed, so while I'm at it I may as well be a little excessive. I intend to install sprinklers throughout, use mold resistant drywall, acheive a one hour fire rating, update the wiring to exceed all applicable codes. Do radiant hydronic floor heat, hopefully based on a solar hot water system. And install an energy efficient air handler/AC/energy recovery ventilator,all necessary in the miserably humid summers here. Add rain water storage for lawn irrigation, and possibly drinking water, a grey-water system with low use fixtures, and appliances. And since I do a lot of the cooking, re-do the kitchen with the resources I'd like to have. Add a second floor for more living space, much needed, as I thick we may persuade a neighbor that is now 87 to move in with us in another three or four years, as she starts to become a little more infirm. She could use our current first floor bedroom, so I shall plan to facilitate accessablity while I'm at itl. Just now she's doing fairly well, still does volunteer teaching of immigrant and special needs children with the St. Louis Public Schools, and beats most comers at tennis on the weekends. And if I can, I'd like to add enough photovoltaic capacity to offset our draw on the grid, we've had quite a few severe storms over the past three-four years and running a generator for a week, or more is a waste and a bother. And if nothing else, it shall be a great fight with the municipalitys' building commissioner, as I personally believe he's stuck somewhere in the midst of the last century, and needs to be shaken out of either his rut, or his position. And yes, I've always had difficulty being concise, and to the point. Thanks for the opinions, suggestions, and generally helpful input.
CLupis,That paragraph was interesting, but give our eyes a break!
As In, add some line spacing in that monster paragraph.
It makes it more pleasant to read.Your project is quite a challenge. Keep us updated...........Iron Helix
I've got a spare RETURN key.Wanna buy it?AitchKay
And if I can, I'd like to add enough photovoltaic capacity to offset our draw on the grid
1. PV does not work when it is raining <G>, so you still need your standby genset.
2. A friend who just built a new house outside Carson City, NV (He moved from El Segundo, CA and commumtes, just to escape CA taxes) spent $45,000 on solar cells and built his own electronics and arrays.
Even with the $45k outlay for just the cells/panels and DIY effort (approx 9 kW PEAK power), he still takes net power from the grid, esp if he does any welding<G> .
The $45K is probably cheap to an "eco-freak" when you consider how good it will make you feel <G>
Have you met Frenchy yet?
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
Have you met Frenchy yet?
it will be an interesting relationship"Put your creed in your deed." Emerson
"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
Sure, I'll take that return key. The real problem is that I've not learned where to employ it properly. It's always seemed that all things are interdependent. So when ought one be isolated from another?
As regards employing a structural engineer. I thought that was evident from my foundation musings. But, it was a long paragraph, and no one catches everything that's written. And although I will acknowledge that I'm stubborn enough to go ahead and make a mistake, in order to learn from it occasionally, I can't afford that big a mistake. So the engineer has great influence in my decisions. As does your feedback.
And, I don't expect to generate all my power all the time. Especially not in Missouri. Not on my budget, MO has no real support for alternative energy, and all I can count on is the federal tax credit to reduce the burden of acting on my beliefs. I'm a firm believer in community, and some of the costs and benefits that go with it. So, I will be on the grid, and even if I manage my power usage effectively I'll need to draw far more than I can generate for short intervals. I just want to, eventually, balance my demand with my generational capacity.
Whereabouts in Misery are ya?
SamTCOMO./
Webster Groves, a small semi-independent municipality in the hodgepodge of communities that border St.louis.
Check yer Email.SamTA Pragmatic Classical Liberal, aka Libertarian.
I'm always right! Except when I'm not.
There's a "green" construction adhesive that's used ( I think it's low voc?) for these LEED projects. Probably help score a point or two. I don't know how strong it is but if you use the glue and pepper these joists with all the nails,screws, and bolts that everyone is talking about, it outa work.
I'm planning a LEED house for myself, I know it will cost more, but I'm doing it just to do it. I've got 5 acres of pines I can use for it somehow.
Good luck with your project.
Heres what your version might look like with a few paragraph breaks (ramdomly inserted LOL)In reply to all your stated and unstated questions. Yes, it's more trouble than it's worth but my wife selected the place. And yes, I shall deal with the crown as necessary. The two greatest spans are 15' 6", and 12' 6" and the current ceiling height is eightt foot three, so if I drop it 3 1/4" by adding two inches of wood and one and a quarter of drywall it won't matter that much. I've not crunched all the numbers yet, but I think that if I create the equivalent of six by tens on sixteen inch centers, I'll have sufficient load bearing capacity to give a sufficiently low deflection over those spans. All the lumber is material I've salvaged from other contractors that don't abhor waste as much as myself, so it has cost me nothing more than the time I spent recovering it from various job sites, thus reducing the amount of material buried in landfills. I believe I'll manage to achieve whatever pressure is appropriate to achieve a proper bond. And in any case the results shall be verified by determining the actual deflection under an imposed load at mid-point of the greatest span of the first 'trus joist', as well as a representative sampling of the others. It's currently a small brick bungalow with nominal eight inch brick bearing walls on somewhat cracked concrete footings and foundation. All of the ceilings and walls(sand based plaster over plaster-board) have cracked extensively. I had made a fairly substantial effort to repair them all when we wed 14 yrs. ago and they've re-cracked and peeled since. I've done new construction and rehab since leaving architecture as a field of study in '74. And if I have to correct a mistake, I'd rather it be my own, instead of someone elses. So, as St. Louis is an earthquake zone I'm having the structural engineer design new footings, parallel to the existing ones, that will resist the supposed load imposed by said theoretical occurance. My thoughts at this time are to use prefab foundation slabs anchored to these footings, but if the engineer decides that won't do, we'll find a suitable alternative, insulated concrete forms? The place is virtually un-insulated and I'm tired of wasting energy. Basically I'm a tree hugging eco-freak, and I'm going to try to re-build the place as a Leeds Platinum re-hab. I shall try to use most of the existing wood trim and structure over. But, I intend to replace the brick bearing walls with SIPs fabricated of three plys of 3/4" OSB that sandwich 9" of isocyanoacrylate insulation, I can get the OSB in eight by twenty-four foot sheets, and can use the crane that places the foundation slabs to position the sips. I think that may serve to shelter us a bit more than the plaster and brick. And the old brick will go back as a thoroughly anchored veneer wall supported by the new foundation. Basically, I think that every eighty years or so, a house ought to be brought up to speed, so while I'm at it I may as well be a little excessive. I intend to install sprinklers throughout, use mold resistant drywall, acheive a one hour fire rating, update the wiring to exceed all applicable codes. Do radiant hydronic floor heat, hopefully based on a solar hot water system. And install an energy efficient air handler/AC/energy recovery ventilator,all necessary in the miserably humid summers here. Add rain water storage for lawn irrigation, and possibly drinking water, a grey-water system with low use fixtures, and appliances. And since I do a lot of the cooking, re-do the kitchen with the resources I'd like to have. Add a second floor for more living space, much needed, as I thick we may persuade a neighbor that is now 87 to move in with us in another three or four years, as she starts to become a little more infirm. She could use our current first floor bedroom, so I shall plan to facilitate accessablity while I'm at itl. Just now she's doing fairly well, still does volunteer teaching of immigrant and special needs children with the St. Louis Public Schools, and beats most comers at tennis on the weekends. And if I can, I'd like to add enough photovoltaic capacity to offset our draw on the grid, we've had quite a few severe storms over the past three-four years and running a generator for a week, or more is a waste and a bother. And if nothing else, it shall be a great fight with the municipalitys' building commissioner, as I personally believe he's stuck somewhere in the midst of the last century, and needs to be shaken out of either his rut, or his position. And yes, I've always had difficulty being concise, and to the point. Thanks for the opinions, suggestions, and generally helpful input.
Edited 10/8/2009 12:31 pm ET by jimAKAblue
that helps.
View Image
Edited 10/8/2009 12:34 pm ET by john7g
I didn't even read his post....do you think I should go back and toss in some of those curvy things?
curvy sometimes helps. :)
were we s'posed to read it?
"the current ceiling height is eightt foot three, so if I drop it 3 1/4" by adding two inches of wood and one and a quarter of drywall it won't matter that much."Help me understand this math.
Your bottom chord would be 1-1/2", not 2", and the drywall is 1/2" or 5/8" rather than 1-1/4", unless you plan strapping to level it out too.So your ceiling drops about 2" to maybe 3" with shims.You will probably want to be more accurate with your emngineering figures that this elevation sketch
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
it is starting to sound like the only thing you are keeping is the existing ceiling joists as you bring this up to speed. I think I'll read along for the entertainment
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Hard to say without seeing it, but I would laminate 3/4" name-brand exposure 1 OSB (I-Level Edge Gold or Huber Advantech - NOT Home Depot's Generic OSB) to the sides of the 2x6s. OSB is 4 times stiffer than plywood, and stiffer than lumber. Use plenty of PL polyurethane construction adhesive and drywall screws every 6 inches top and bottom as clamps. Polyurethane will remain a bit flexible, and not crack off under heavy load. The gluing surface area is huge as well. You said you know how to do the calculations, so you should be able to figure out how much OSB you need. Stagger the overlaps 1/2 panel left and right for runs longer than 8 feet. Jack up each floor joist level before gluing so you take up any sag.
Another alternative is to buy some I-joists and install them.
Paul Formisano, P.E.
Engineering and quality control aside, when I was in the prefab business many years ago before the age of metal plates, we used casein glue. It is still available from a company named National Casein I believe. You might check with the American Plywood Association. They have plans and specs for this type construction or at least they used too. Hope this helps.
Thanks! Reading it with your input almost makes it cogent! Well, almost. And I really appreciate the curvy things.
Now, about that math. There were a few things about my OCB I failed to mention. As maybe only 25-30% of the wood I salvaged is really Nice, I kind of thought I'd cut out the knots in the not so pretty pieces. Saw it into 3/8" strips, plane those to make them smooth, and then laminate them to make a nominal 3x6 with a 1 1/2x1/2" groove on one side to give me a little better grip on the 2x6 joists that I'm saving. I mean, while I'm glueing things up I might as well enjoy myself.
And I'm keeping the existing oak flooring, and quite a bit of the layout. Although I am going to extend one end of the house about three feet, to give a little more elbow room in the kitchen and dining areas. That way the layout for the stairway to the second floor can fit over the existing stairway from the basement to the first floor. So, that should about cover it. Though I'm certain there is some salient point I didn't address, if I go back to check, I'll loose what I've written. So, I'll leave it as is. And thanks again.
Oh yeah. Home Depot hasn't started to stock OSB in 8x24' sheets, so I have to make a special order through the regional sales office for the material, and take most of a full truck load. So maybe I'll have a little left over, and since I'm getting a full tractor trailer load of the isocyanoacrylate foam, I've a friend, or two, that could stand to have an energy efficient room addition. That about covers it.
I posted this earlier but for some reason it didn't take. So here it is again. I haven't read all of the post so this may have already been mentioned.
Short of proper engineering and quality control, when I was in the prefab business and before metal plates, I built plywood gusset trusses using casein glue. It comes as a powder and is simply mixed with water. We used 1&1/2 staples approx. 3' O.C. to fasten the gussets until the glue dried. It is simple and forgiving.
This glue is still available. I think the company was called "National Casein Co." or something close. The glue joint was stronger than the wood. My guess is that it is far cheaper than any of the high tech stuff made today.
For engineered plans and specs for these types of trusses, you might contact the "American Plywood Association". I still have detailed plans and specs for many spans and types of trusses that I got from them. They show the size thickness the plywood gussets and the nailing pattern etc. Hope this helps you. Casein glue is what they specified.
Here is another glue possibility.
It lists truss plates, structural joints as at least 2 of the uses.
http://www.dap.com/product_details.aspx?product_id=42
Readily available at L.Y. or big boxes.
Really really appreciate the leads on the different products. Might take a while to figure my cost benefit ratio, but the casein glue is, if I remember correctly, derived from cows hooves, or something like that. So it ought to be green enough for the LEED program. Thanks again to all of you.
Dunno -- remember all the CO2 they fart.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
View Image
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
You're close. It is made from milk by products. You have heard the terms, curds and whey? It's made from the whey IIRC.
If you need / want green, I don't think Resorcinol is going to make the cut.
Based on smell.....
Based on can:
>>Contains Paraformaldehyde, Formaldehyde, soft wood flour and hardwood flour.<<
>>VOC (during application /curing): 171g/L. Vapor pressure @20*C.; <40 mmHg.<<
Surprisingly enough there is no "California Proposition XX" warning --- probably just outright banned there......
JimNever underestimate the value of a sharp pencil or good light.
Casein Adhesives were used by Glulam manuf years ago, but most of them stopped since it is not rated for exterior applications. So long as you do not have any odd moisture conditions that may be an option, but I doubt it has great gapping ability.
Pay close attention to the comment from the fellow that mentioned glue gapping. To develop a proper bond you will need a reasonably smooth surface and the easiest clamping will be lag screws or nails unless you intend to attach some boards to both sides so you can use clamps. We retofitted long span beams in about about 20 schools years ago and the practical considerations were more important than some of the technical aspects.
Pay close attention to the moisture content of the existing timbers compared to new. If you simply buy No1/2 construction lumber and its moisture content is more than say 8% greater, any glue bond will fail.
I am not disputing the recent repair method suggested, but keep in mind that most manuf rated bond capacities require insane amounts of pressure to ensure a very thin glue line and yes, they actually do perform tests to justify these numbers. In residential applications such as yours it is not as critical since you can simply add some more wood to reduce the longitudinal shear stresses, but for a true structural design it is very important. Attached below is a tech sheet for a resorcinol that actually comments about how to use it to achieve the bond stresses. They acutally claim around 250psi is required.
http://www.cpadhesives.com/media/Cp0900TdSheet.pdf
After learning more about the problem I think your engineer should design this retrofit with nails only. Add some PL Premium or whatever glue that meets your LEED req'ts to make you happy, and move on with life.
Brad
Followed you link to CP Adhesives --- you are correct their material is not very user friendly!
However, I also get the impression that their product is geared strictly to production line usage - mechanical mixers, massive pressures, curing ovens, etc. I also never saw a package size listed, but suspect it is sold by the 55 gallon drum.....or perhaps by the railroad tank car......
For a much more user-friendly product, readily available in smaller packages try this product which I posted earlier:
Weldwood Marine Resorcinol Glue by Dap
http://www.dap.com/docs/tech/00030205.pdf
From above document:
>>Mate surfaces uniformly and squarely with a minimum sliding and repositioning. Glue line thickness should be about 0.005 inches. Pressures of 25 to 75 psi should be sufficient.<<
I did not think I was that lucky to have avoided any failures over the years if I really needed 252.50 psi clamping pressure.
Jim
Never underestimate the value of a sharp pencil or good light.
I must apologize, I didnt notice the DAP tech had that spec. I am not a big fan of the "should be" note or some of the other general terminology, but I agree that this could be a fine product for a residential application if it were not for his LEED req't. I doubt the longitundinal shear is more than 50 - 75psi at the interface between the new and existing, so achieving the rated capacity (>1000psi) is not extremely important. Avoiding long term creep is.
Your comment about the glue gapping is very important. From his descriptions of the structure I bet the existing joists are far from perfect, and power planing to mate the surfaces uniformly and squarely could be a challenge for the OP.
In reality, I think the OP will have difficulty developing 20psi of clamping pressure in situ. If his 2"x6" are 12' long that works out to a force of 4320lbs of clamping pressure and he does not have access to the top of the joists unless he rips out the subfloor. Sure he could screw on a number of lumber segments to install clamps to both sides or maybe install enough screws, but I get the impression this project is largely about the "GREEN" concept coupled with saving $$.
Brad
I suspect that a few screws would very easily achieve the required clamping pressure.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
I think it is probably a moot point as soon as he rolled out the "green" requirement.
I just knew I had used the DAP product which I posted many times over the years with a failure rate of zero......and I was positive that I had not been developing anywhere close to 200+ psi clamping pressure.
I first encountered Resorcinol in a wooden boat building shop in Christie, MD.
I watched the builder lay up strip planks of 1" x 1" mahogany to the white oak ribs of a hull he was building ~40 feet. The planks would be coated on the bottom surface with Resorcinol, top of plank already in place was also coated, new planks were bent to the ribs with clamps, nailed with monel nails to the plank below and then to each rib.
The hulls looked horrible in the rough with red / purple glue drips everywhere. Once the hull was finished, he attacked with a 7" disc sander - he was an artist with that thing. Once fully sanded and painted the hulls looked like fiberglass out of a mold - fair with no seams visible anywhere except at the keel....
There were several of his previously built work boats in the shop yard awaiting repairs of some sort --- the hulls showed the abuse and wear of a working boat -- but the seams were still invisible except where the hull had been gouged enough to expose the wood -- then you could see the color of the glue line.
JimNever underestimate the value of a sharp pencil or good light.
It is interesting to hear the boat application. I never understood resorcinol to be a very good gapping glue.
The glue line pressure is a bit of a unique problem. I agree with you and other posters that suggest a few screws will work in practical terms, but if he winds up with a picky engineer it could become more complicated. A screw will develop a great pressure initially, but shortly after it is installed the wood starts to relax around the screw. These type of repairs are not very common, so not too many of the glue manuf research this problem. Add to this the number of variables (wood density, wood species, moisture content, glue line thickness....) and it can be a bit of a #### shoot as to how much pressure actually develops at the glue line. I would probably aim for an adhesive that requires as little pressure as I could find.
The more I have thought about the problem I think I would use PL Premium. Its cheap, handy as can be, rated as a structural adhesive, short cure time, and would be easy for him to install. Any of the structural adhesives will be a nightmare if you get it on you or if too much squeezes out.
Brad
The main concern here is creep. The strength of the bond is secondary, as the force on the joint will never approach the yield strength of most adhesives, even if applied in less than ideal circumstances.Does anyone know the creep characteristics of PL Premium?
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
I cant seem to find the tech specs for this product, but I do have them somewhere. It is rated as a structural adhesive, but I suppose since it is still a polyurethane it could have some minor elastic properties. I know any of the globs that fell on the ground when I was gluing down retaining wall capstones sure became rigid once they cured. Not very technical, but a good sign anyway :)
Brad
Lots of materials that seem rigid will flow under constant stress. Has a lot to do with the types of chemical bonds that are formed as the adhesive sets.I'm not saying PL ***will*** creep, but it would be good to know before using it for creating any sort of laminated wood structural product.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
The answer to the problem of the upper cord is that at this time there is not a floor there. The 2x6s that I proposed to modify to a truss joist configuration are currently ceiling joists in a one-story home that I propose to change to a two-story.
As regards the issue of creep in the polyureathane, I think I will just call the manufacturer for that answer. But, the info on casien glue is very attractive. It's reasonably priced, easy to work with, does not need to be water-proof as I'm prefabbing everthing so it will be closed in within two days, at the most. One if I''m as organized as I intend to be. And the crane operator is competent.
"he does not have access to the top of the joists unless he rips out the subfloor."I might have misunderstood, but I thought he described adding an upper chord also which would require opening the floor above, thus my early comment on buying a lot of clamps.
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I havent been following his explanations that closely, so if he is adding a top chord it will be easy. I assumed that wouldnt be an option due to the number of problems it would create to lift his floor above 1.5" or more.
Brad
Seemingly the OP is sold on Resorcinol as a glue, but can't seem to find it locally.
Disclaimer: The following is not an engineering solution to the structural problem presented, but merely an informational post which contains published statements from the product manufacturer, and personal experiences with the product......
that should cover it......
It has been said that this product is not user friendly and requires 100 psi clamping force to form a proper bond..... Maybe so and I have just been lucky.
From the currently produced can:
"Weldwood Marine Resorcinol Glue" manufactured by DAP, Inc., Baltimore, MD.
>> Recommended for exterior and interior structural applications.<<
>> Excellent for lumber arches, sills, beams, trusses and all woodwork.<<
>>...Bond pieces together and apply adequate pressure or clamp while glue is wet. Apply pressure after mating surfaces.....<< No mention of a psi requirement, I used the criteria that if I had a normal amount of squeeze out, I had enough pressure.
DAP Helpline @ 888-DAP-TIPS or http://www.dap.com
Personal experience with this product:
Fairly user friendly, however, proper mixing is critical to obtain a reliable pot life and curing times. Mixing the two parts by the "weight method" rather than the "volume method" is the superior system (you will understand the difference once you read the can). I may be biased in what is "user friendly" due to extensive work with polyester resins and fiberglass in boat building.
Observe the required open times - don't rush it, this time is needed for it to properly penetrate the surface of the wood.
16 oz can (2 cans actually, 1 liquid resin, 1 dry powder catalyst) covers 20 - 23 square feet of joint area.
16 oz can retails locally (DE) for ~$25.
Application with a small paint roller (2" wide) seems to work best / easiest.
Smelly, adequate ventilation required.
Pot life of 45 minutes to 3 hours depending upon ambient temperature. Exposure to UV light seems to shorten pot life (although this may be just caused by solar warming of the dark glue). Not an issue for indoor use.
Pressure period (clamp time) ranges from 2.5 to 10 hours depending upon ambient temperature and wood density.
I use it infrequently in straight clamping pressure situations, most recently for laminating two 1-1/2" x 8" x 60" slabs of eastern white oak for a historic restoration exterior threshold. Lots of clamps due to size. Clamped 24 hrs @ 70 - 75.
Most common application for me is a few clamps for a few minutes while screws are run in then clamps removed, if needed, squeeze out removed with damp rag.
Not a good gap filling glue.
Very easy clean up with water, tools, hands, etc. -- unless it has hardened -- then "mechanical" removal is necessary.
That's about all I know about that......
Jim
Great stuff all of you are giving me!
How are you planning on assembling your sip panels. Do you have access to some sort of press? 8x24 is a monster panel, especially to diy the fabrication.
Yeah, first you have to find a 24-foot-long space that's FLAT.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
and the ability to handle 4'x 24' ft. (was that the right dims?). Maybe they'll just slide them off the truck.
8'x24'I know you can get sip's that size but I can't imagine how you diy it properly.
I wanna see the handling equipment.
In response to "why not just sister 2x8s?" I may have not given all my options fair consideration I've a prejudice against building to Code. specifically the minimum legaly accepted standard. I like building things that are well thought out, won't rot because the flashing wasn't right, and might as well be torn down when the mortgage is paid off, if not before. I like the idea that while my practices are not practical for 75% of the american public, I bet that if more people could participate in building, and designing their own home they would. Especially if they knew that what they were doing was likely to last for perhaps as long as some of the homes I've been lucky enough to have visited in europe. I want the floor to be flat in another 100 yrs. And there is my OCB to consider too!
As for moving things around. I'm intending to do my own excavation. I figured I could rig a sling that a backhoe/loader could use to move the stuff, but with the economy the way it is I could probably hire a bunch of teens for reasonably priced labor (extra eyes, hands, and hopefully heads,) and they might benefit from learning, I hope, some inovative building techniques.
I missed a chance at getting a good used four wheel drive backhoe/loader for $6500, but didn't jump on it fast enough. Now I may just lease one for the slow season, or maybe longer given the downturn in construction. Or maybe buy a used fork lift for a while.
And it shouldn't be that hard to create a platform that's flat, just set a bunch of posts, mark them all using a laser level, or auto/level and cut them accurately. I can use one OSB sheet temporarily as a work surface. It's not like I haven't hoarded enough lumber to build a 8x24 deck.
Now there's this walnut tree, that blew down last year, in a local park. And the supervisor will let me salvage it. So, do I post my question about curing lumber for the cabinets I'd like to build, here or on the Fine woodworking site?
>So, do I post my question about curing lumber for the cabinets I'd like to build, here or on the Fine woodworking site? Either one or both. You'll probably run into more wood hoarders over at Knots, but there's at least a few sawmill operators here & a lot of people that have cut & dried lumber.
And certainly a lot of people with cut & dried opinions.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
Hey!
You talkin bout me?
LOLSamTA Pragmatic Classical Liberal, aka Libertarian.
I'm always right! Except when I'm not.
I remember working at Kewalo basin in Honolulu doing haul outs for a while and back in the 70's the Japanese carpenters there all used resorcinol. The fellow I went over there with to do the haulout, (from Maui), brought along some West System epoxy. Almost over night, after observing us, the carpenters there switched from resorcinol.
The West System stuff is great and very easy to use, (no measuring issues, selection of working times, etc.). I use it almost exclusively for laminating up structural items. You can get it at a marine store although maybe online would be cheaper.
More , and more input. Options galore! Thanks, again. Each voice gives me a little more to think about. More ways to approach the problems. Each one of you help me a little bit to reach a conclusion.
I like west, but would be leery of using it overhead.
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What's worse to get in your hair, PL Premium Polyurethane adhesive, or West System epoxy?
depends on whether you know it's there or not.But the PL will not drip and run, the West will, so it is more likely.Funny thing, I alsways put on the nitrile gloves when working with West, but I just let them get black when using PL.
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Epoxy can be an irritant to skin. Black hands are an irritant to the psyche.
Good point. Adding the microballoons would be wise when working overhead. That makes for a pretty stiff mix, heh, heh.