I am preparing to strengthen the floor joists in my basement. I am planning to add a room below these joists, and want to reduce the excessive bounce.
I noticed an article showing six tried and true methods for strengthening floor joists. http://www.taunton.com/finehomebuilding/PDF/Protected/021184090.pdf
As for my situation, the only viable solution offered in this article is the metal strapping method #6. However, I am not really sure if this would be as effective as my initial idea.
My idea was to place angle iron along the joists at the bottom to strengthen, reduce deflection, but reduce the amount of mass and interference insulation, wiring, etc.
I noticed that this method has been addressed in prior forums, and it sounds like it is a good option. Has anyone else used this option of angle iron, and if so, how did it work?
Are there any other suggestions?
Thanks!
Replies
Greetings seiverth,
This post, in response to your question, will bump the thread through the 'recent discussion' listing again which will increase it's viewing.
Perhaps it will catch someone's attention that can help you with advice.
Cheers
BTW, it was method #5 you were pointing out, using the Simpson strap.
I have a 4:12 roof over my garage, and I needed to add storage over my garage door. With that low of a pitch, every inch makes a dramatic difference in possible storage space.
The max height at the peak there is only about 4'. If I used conventional building materials, I would have ended up with something about 8" to 10" deep. Instead, I choose to strengthen 2x6 lumber with 1.5" angle steel epoxied to the underside. I routered the inset into the lumber so it sould sit within conventional metal hangers. I used 1" screws at a 45 degree angle to clamp the wood and steel together while the epoxy cured
Now, I was not actually concerned with bounce on this, as it is a storage space and not a dance floor. If I was I would have added blocking and put it on 16" OC.
If I were to alter this technique for an existing installation, I might suggest the following: Instead of angle steel, use a flat piece 3" wide. Pre-drilled holes down the center every 12" would keep the metal clamped to the wood while the epoxy bonded the steel and wood together. This method would make the floor joist into a half I beam. The strength of the steel is utilized entirely, and the epoxy transfers the loads continuosly instead of just at the fasteners.
Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Oh, good Lord, no. But I can give him two dollars and an assault rifle.
Have you ever held up a chunk of angle iron and sighted down it? It sags under it's own weight. Poor choice at best. "C" channel would be much better, but that's a lot of work for something that's so easy to do with wood.
Beer was created so carpenters wouldn't rule the world.
It does sag under its own weight, but that is not the axis of strength you are using. In this example, applying it to the bottom, you are actually stretching the steel, not flexing it.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Oh, good Lord, no. But I can give him two dollars and an assault rifle.
you are actually stretching the steel, not flexing it
In theory you are correct. The problem is connecting the steel well enough that it is actually in tension since even minor movements of the ends defeat the purpose and most installs that are through bolted have enough slop in the connections to be of little use. I've had this same discussion with an engineer who wasn't convinced until we installed the angle per his instructions and it did little to improve the situation.
Attaching with a structural adhesive in addition to through bolting sounds like a good solution, but few guys who use this actually clean the steel well enough to allow a good bond between the two.
In my mind the proper way to attach steel to the lower section of a joist is with sesimic connections made to bolt or nail onto wall studs, one on each end of the steel to pretension it, combined with through bolting and structural adhesive. That's a lot of work.
Even with a crap-load of wires and pipes, it's easy to cut, glue and install 1-1/8" ply, notched out for the penetrations and overlaped with a few layers to eliminate weak joints. Most times it's easy enough to pull out the crap temporarily and reinforce things correctly. One of the best is skinning the underside of the joists with ply, which doesn't involve anything other than getting things in the joist cavities squared away before covering them up.
We use a good bit of steel in our projects where we need the strength within tight spaces, but I have yet to see a floor joist that is easier to stiffen with steel rather than wood.
Steel will work, my argument is simply that wood is a more cost effective solution.
Good building
Beer was created so carpenters wouldn't rule the world.
I think that is a great idea - building a box. In a sense, the whole floor becomes a continuos series of interconnected I beams, or box beams, with very wide flanges. The only thing I would add is to use the longest sheets of sheathing you can get, or at least fit down the stairs! 10' OSB is cheaper than ply, and when placed dead center of the span would have maximum effect.
A second idea, combining mine with yours, is to use a 1x4 - glued and screwed to the bottom of each joist.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Oh, good Lord, no. But I can give him two dollars and an assault rifle.
I once had to build a 12' x 8' deck. The only constraint was to maximise the space under it and leave the long side open. I used clear DF 2x4's, full 12' span, 12" OC with blocking 4' OC, 2 layers of 3/8" CDX, seams staggered, glued and nailed on bottom, and a 3/8" CDX topped by 1/2" ACX glued and nailed on top.When I was done, I set a water glass in the middle and jumped my 200+# off a two foot step ladder next to the glass.It bounced about 1/4" high and didn't tip over.HO was immmmmpressed to the tune of a $200 bonus for moi.SamT
My fav. method is a simple bolted on strap.
Attached pix is of 5" wide strap to double (2X) the strength of a 6 by 14 garage door opening. Note the many bolts at the ENDs of the span.
View Image
Edited 8/12/2007 10:53 am ET by junkhound
Thank you to all who provided input. I think I am ruling out the steel option at this point. It is really cost prohibitive.
I have very little head room to work with, and will need to place ceiling tiles and brackets directly to the floor joists - so my only good solution would be to sister wood product to the sides in the space.
I am leaning towards ripping some #2BTR 2x8 in half and gluing and screwing. I suppose ply would work too, but feel that I would be better to have full length spans with no seams.
For a 14 foot span including plate and girder, I would think that using an extra 2x4 on each joist would be adequate. I will also look into LVL to do the same.
Any takers?
Edited 8/12/2007 3:49 pm ET by seiverth
2x4 will be laughable for the problem you have described. You still need to deal with a three foot offset of that load from above, which you still have not identified, yet you are coming up with this seat of the pants engineering scheme!That is a dis-service to your customers. They should have some assurance that you know what you are doing and it is obvious that you do not."Any takers?"
What is that supposed to mean? Why ask, since you are ignoring the advice given you and proceeding with less than anything anybody has already offered to suggest, even given the limited amt of information you could provide.
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still need to deal with a three foot offset of that load from above, which you still have not identified,
Did I miss something, or is this topic being discussed in a separate thread in addition to this one?
OK, I was mixing this thread with another similar one in my memory
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Will some get Piffin out of the sun..... he's delirious I tell ya. :)
Back to the subject at hand.
Rip yourself 2 pieces of 3/4" plywood and sandwich the joist with them centered on the joist. Glue and screw with Piffin screws. I guestimate, 2 screws vertical at 4" oc. Use a good structural glue.
The center point between your two supported ends would be you largest bending moment, thus your largest deflection point. If you are concerned about running the entire span, cut one 6' and 2 8' pieces of 3/4" plywood. Overlap the joint between the 6'/8' with the second 8' section, and glue and screw as above. When set, glue and screw to joist in above stated joist sandwich.
You can also try to pre-camber your fix by jacking up the center span 1/8" or so prior to attaching the plywood sisters and allowing the glue to set up, plus add additional 24 hours, before removing jack support.
Hope that helps
"If guns kill people, a spoon made Rosie O'Donnel fat!"
Hey Engineerguy,
Do you happen to be a structural guy? If so, I have a couple of questions for you!
Ought be structural screws, not sheet rock screws. They will break under much load
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Thanks to Engineerguy with the most recent advice. Engineerguy and some of the others who were so nice to help are the reason why this is such a great place to come for sharing information. That's what this is here for, right? I don't need to deal with some piffin jerk that has nothing else to contribute other than fly off the handle criticism.
Simple fact of the matter is, this is a tight spot and a short span. It shouldn't take much to beef up these joists. So, once again thanks to everyone that has made a positive contribution to this thread. They are the ones that helped me make my decision.
I'm piffin out a here.
Hold on there cowboy. Piffin made an honest mistake. There is another thread dealing with reinforcing joists that has a bearing wall 3-ft from the carrying beam.
Speaking from personal experience, he is not a jerk. This forum wouldn't let him post nearly 41,000 times if he was. For the problem you're describing, he might just be the best resource here.
Hope you find the advice you need - good luck with your project.
Oh OH!
"I don't need to deal with some piffin jerk"
Talk like that'll get you shunned around here. The man's a hero. They even named a screw after him!
Problem with some people is that they keep screwing up even when they have facts to keep them from doing so. Piffin made an aknowledgement of his error before your last post but you keep going down the wrong path. If you missed that how many other details on this thread did you miss?
sheesh!
Happy Monday
Piffin made an aknowledgement of his error before your last post but you keep going down the wrong path.
Piffin made an acknowledgement, but it was in reference to my post, not the OP's. Piffin's direct apology to the OP came after the OP's last post.
All of us "regulars" here know that Piffin is not a jerk -- but the OP has had only very limited exposure to Piffin and thus cannot know his character.
Let's cut seiverth some slack -- he had a natural and understandable reaction to Piffin's misplaced comments.
You guys are great. The more I read, the more fun I have! This site is unseen territory for me, so thanks for letting my comments slide.
Engineer guy must be psychic, because in the 8 posts you've made on BT, you've never said anything about the floor structure except that it's sagging and bouncy. Not much there to run any numbers on.But since he only garuntees that he'll refund your consulting fees, it won't cost himn anything if his advice is no good, will it?IIRC, EG has some rather controversial engineering ideas. Why don't you search and read his 59 posts, then compare them to some of Piffens' 40798 posts.SamT
"Engineer guy must be psychic, because in the 8 posts you've made on BT, you've never said anything about the floor structure except that it's sagging and bouncy. Not much there to run any numbers on."
I gave advise based on the situation as I understood it. And yes, I didn't have the complete facts such as decking material, joist oc, joist wood type, and loading. But we rarely get a complete picture when someone comes to BT to ask a questions.
I have done similar work in the past to stiffen floors. Does anyone have issue with this methodology?
"But since he only garuntees that he'll refund your consulting fees, it won't cost himn anything if his advice is no good, will it?"
Maybe I should have OPs from here on out contact their local engineers so they can give an opinion and charge each one of them. And of course I get a fee for telling them to consult their local PE.
"IIRC, EG has some rather controversial engineering ideas."
I calling you out on this one SamT. Which of my post are controversial other than in the Woodshed? I have over seen and done everything from unexploded ordnance removal, to airfield repair, to digital xray installation projects. I stick with what I know, and am damn good at what I do.
"Why don't you search and read his 59 posts, then compare them to some of Piffens' 40798 posts."
Hmmm. Since I joined last October, and only interact with the subjects that I have a good first hand knowledge of, why should number of post matter. Do you have a #### complex going on with number of postings or what that makes one an expert?
Regarding Piffin, I respect what he says, and for the most part he is on.... although he was off yesterday. I still blame the sun. :)
Now do a cranialectomy SamT.
"If guns kill people, a spoon made Rosie O'Donnel fat!"
Well, sounds like everyone has gotten fired up, including me. Piffen, I retract my statements directed at you, as I now realize the errs in my ways. My skin is pretty thick, so you didn't hurt this "cowboys" feelins.
Fact of the matter is, there are alot of different ways of doing things, hopefully they end up at the same goal.
Sorry I didn't give enough information for some of you.
1932 House, single story. Block foundation with reinforced walls in the inner with steel. Don't know the species of the joist, or what was common in the area at that time. Looks to be a pine species. The span is from outside wall to the center girder. Girder is made of sistered 2x8, resting on 16x16 block columns every 10 feet OC.
Span of joist in question is 2x8x14, end to end. Subfloor is 3/4 TG plank diagonally with 1/2" hardwood flooring at right angle to the joist. Stringing a line shows about 1/4" sag at the bottom/center of the joist. No cracks or any other signs of serious failure are noted. My goal is to straighten out that sag, and provide a sturdier floor.
The opposite side of this center girder has 2x8x10 foot joists end to end. This side, I would say is adequate and would not need any reinforcing. So there is a difference in only 4 Feet with exactly everything else being the same, less the sag and bounce.
Span of joist in question is 2x8x14,
Seiverth,
That's a pretty long span for 2x8s (I'm assuming they're at 16" centers, and not 12" oc, right?).
My own house (1911) had 2x8s over a 13-foot span and I ended up sistering on 2x10s. It made a huge difference and I'm very happy with the results. Of course, it was a lot of work, but it's going to be a significant amount of work no matter what course of action you choose. I wanted to err or the side of caution and make sure I wouldn't be unhappy with the results after I was done.
For reference, a 2x10 is 2.1x stiffer than a 2x8 in bending. The equation is such that resistance to bending is a cubic function of the joist depth (I=1/12 bh^3, where h is the joist depth), so you get a lot of bang for your buck by increasing the depth.
Yes, they are 16" OC. And this old house has definitely been alot of work. This is about the last thing that I could possibly fix/improve. So one way or the other, I need to get down there and start pulling wire out, suck it up and move forward. Just wish I would have reinforced earlier on before all of my wiring was run.
According to the AWC's span calculator, see below, 2x8 SPF floor joists have a maximum span of 12' at a deflection limit of L/360, normal floor stiffness.Even at a DL of L/240, real bouncy, the max span is only 13' 9". If yer bildin a trampoline, DL of L/180, you could span 15' 1".According to the Southern Pine Councils' tables, using structural select SPF 2x8s, 16 OC with the lightest loading, 30/10, the maximum span allowed is only 14'8". With a more reasonable loading, 40/20, and #1 grade, the limit is 13'1".It looks like you are pushing the limits of your floor system. IMHO, you should spring the $300 or so for a local engineers review of what you have and his reccommendations.AWC Span calc
http://www.awc.org/calculators/span/calc/timbercalcstyle.asp?species=Spruce-Pine-Fir+%28South%29&size=2x8&grade=Select+Structural&member=Floor+Joists&deflectionlimit=L%2F180&spacing=16&wet=No&incised=No&liveload=40&snowload=-1&deadload=10&submit=Calculate+Maximum+Horizontal+SpanSPC span tables
http://www.southernpine.com/spantables.shtmlSamT
It looks like I am at L/240 with actual span of 13'8". Not quite the trampoline, but enough for the dogs to rock the pictures on the table!
now that I am focused on the right problem...In general, a 2x8 @ 16"oc will span 12'.By adding 2x4 on the flat underside with PL Premium you can solve the problem by creating a sort of I-joist. This is the easiest and least expensive solution, and it has been engineered for me in a similar situation and it worked. additionally, if you have sagging, this method can be used in conjunction with jacks to take some of that problem away.If the height is too much of a concern, Engineer guy's suggestion will probably work if you use structural screws instead of piffin screws along with the PL premium adhesive, and if you stagger the joints on either side of the joist. This would be the more expensive solution.The angle iron seems to work for paul, but it is far from a good choice in most situations.BTW, Glad to have met you. Keep the saddle under ya, Cowboy
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By adding 2x4 on the flat underside with PL Premium you can solve the problem by creating a sort of I-joist. This is the easiest and least expensive solution, and it has been engineered for me in a similar situation...
What (besides the adhesive) did you use to secure the 2x4 plate to the bottom of the joist? I'm assuming nails.... what size and spacing?
shoot a 16d about every 16-20"
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I would spend the extra bucks for epoxy instead of PL. PL is great, but is elastic, it helps a lot but there are better glues for this application. The PL/Nail solution offered will definetly improve the situation, but by reducing the spacing and using a better adhesive for this application, you will get a better result.
Glulam beams are manufacturered with Resorcinol adhesives for many reasons, but you cannot develop the bond pressure required to get its strength in situ. I worked with a PHd researcher (World Renouned Wood Expert) and some of his first research tests for reinforcing glulam beams was with PL type products and what he found with actual lab tests was the gluelines would stretch under full loading when compared to a more rigid adhesives. This is a lot of work and I would go the extra distance and use a better adhesive. West Epoxies are stocked by lots of marine repair shops and is used heavily to repair decayed wood members (actually re-build/shape rotted sections back to new). Nail spacing is incredibly important and serves one primary function, that is to develop bond pressure so you get the full glue strength. After the glue is cured the nails serve little purpose. Don't get me wrong, they help, but the glue is far more efficient. To achieve the resistance required at this glueline with only nails requires an excessive number of nails. As far as the nail spacing is concerned, I would suggest closer than Piffin and use an air nailer. More along the lines of 4". Air nailing will result in a greater bond pressure than simply hand nailing.
One last point, do not use 2x2. Rip 2x4 or larger to get your stock, but I am sure you already know this. Better yet, contact a glulam manuf and ask to buy some 2x2 stock. Many of them machine stress rate, and can give the actual moisture content of the material.
Ciao
The long term concern with epoxy is brittle failure. Looking at stuff I did 30+ years ago with epoxy and with aliphatic resin, it's the aliphatic resin that held up better. There's also the urethane "gorilla" stuff, too.
-- J.S.
aliphatic resin.
Could you expound on this a tad? Thanks.
be
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Aliphatic resin is the good yellow woodworking glue.
-- J.S.
FineWoodworking did a review of different glues on the same joint... the polyurathane glues did surprisingly poor. The PVA glues did surprisingly well.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Oh, good Lord, no. But I can give him two dollars and an assault rifle.
a glue or adhesive should be chosen for the type of joint and the conditions for use. Taking one test and applying it to other applications is like buying a tractor tire for your CRX.So what kind of joint was that in FWW and how does it compare to sistering or building up floor joists?
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
It's in the latest, or maybe last month's issue. I was reading it in the bookstore.
BTW, how are you ever going to pull a plow across a muddy field without the proper tires on your CRX? Man, some people just have no sense at all. ;)Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Oh, good Lord, no. But I can give him two dollars and an assault rifle.
One thing I remember about the article is that they actually tested the break point of the same joint using different glues with the help of some special measuring equipment. They actually gave weight values that each held before they came apart.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Oh, good Lord, no. But I can give him two dollars and an assault rifle.
That is niceBut my question was what kind of a joint was it and how did it compare to the proposed glue joint here????if it was like most woodworking joints, it did not compare in any way
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Are you sure you are referring to the right PL product?
The PL 200 or 400 is definitely elastic and will slip.
But PL Premium is the polyurethene adhesive with no discernible shear movement. Unless he had early access, your PhD could not have been testing it back then as it was not on the market yet. it is a whole different animal from the old PL lineup
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Might be the case as it was ten+ years ago we were involved in designing the retrofits for school beams.
Interesting to know. Of late we are only working with Concrete and steel.
FWIW, I first used PL Premium on a job in 1991. It had just arrived to my Colorado lumberyard at the time, and I conducted tests to compare it to PL 400. The Premium won the tests, which were adhesion of wood to exterior brick.One point to consider is that the PL, while not a rated structural adhesive like resorcinol, will work fine for reducing the bounce due to transient live loads such as walking across the room. And it is easy to use. A fully noncreeping adhesive is only needed for prolonged loading, such as grand pianos, waterbeds, and dead loads like structure mass. For this, WEST epoxy is a very good field-applied choice. Epoxies do not require tons of clamping force to develop their bond strength the way resorcinol does.I personally do not know about the creep of PL Premium under load, but I suspect that it will creep some, since it is soft-bodied when cured. So it should fix the bounce issue, but not the sag issue.Bill
For me, it was just about ten years ago that I first used it, when it first showed up here.
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One point to consider is that the PL, while not a rated structural adhesive like resorcinol,
It's my understanding that PL is rated as a structural adhesive, as are the other polyurethane adhesives.
Beer was created so carpenters wouldn't rule the world.
I should perhaps have stated that PL is not rated as a "primary structural adhesive." It is rated to AFG-01 as a subfloor adhesive, as are various rubber mastics and polyurethanes. To be rated as a primary structural adhesive requires higher performance levels than most glues can attain.To achieve that rating, an adhesive must withstand continual loading of the glueline without any creep or failure over decades of service, must adhere the wood so well that the wood fails prior to the glueline, and must be completely waterproof.In certain applications, fire resistance also matters. For instance, WEST epoxy cannot meet the boiling immersion requirement of the US Navy, but resorcinol can. This may come into play during combat or boiler accidents, but WEST System epoxy is fine for boats that will not be subjected to enormous wet heat in service.Glue laminated structural beams absolutely will deform under load if the gluelines creep, plus creep can concentrate loading on one part of the assembly in a way that causes catastrophic failure (in some instances.) Fire resistance also matters in glulams. They need to behave like giant timbers, with integrity that degrades no faster than a solid sawn beam of the same size during a fire.Bill
PL is not rated as a "primary structural adhesive." It is rated to AFG-01 as a subfloor adhesive, as are various rubber mastics and polyurethanes. To be rated as a primary structural adhesive requires higher performance levels than most glues can attain.
Of course it meets the minimums of AFG-01, as does every low end subfloor adhesive. It passes that standard 3x over in sheer strenth, and that's not a typical joint, but one wood member has had a wet soak. That doesn't mean that's the maximum suitable useage for the product. Sheer strength in dry wood joints has been near twice that of the wet joint test.
Obviously PL premium has the bonding strength to do just about anything we can ask when sistering joists and whatnot, the main question has to do with long-term creep. It's still my understanding that the polyurethane glues and PL premium have long-term creep low enough to be used in the type of situations we're talking about here.
In many residential projects where we are reducing bounce rather than loading a wood member to near failure points, the stress levels for glued joint are well below, perhaps 10-20%, ultimate failure points. As you also probably know, the lower the stress on an adhesive joint, the less creep resistance an adhesive needs to function reliably for the life of the structure. In wooden aircraft frames I can buy the argument that poly adhesives aren't suitable, but we are talking about situations that are much less demanding.
I'm basing my assertion that polyurethane adhesives are suitable for the majority of residential structural applications on some field built structural project specs requiring polyurethane glues. Specs suplied and approved by a structural engineer.
As for the short term real life sheer of polyurethanes in framing materials the test specs from the manufacturer I've seen show close to 1000 lbs/sq inch before failure in an actual glued up wood joint. The stresses we put on glued up joints is a small fraction of that.
As for the Fine Woodworking tests, and I don't think FWW has really proven anything about the long-term strength of wood joints as used in residential construction by their tests. I have yet to separate a joint in pine or doug fir joined with PL Premium that doesn't rip the wood off one side or the other.
I'd respectfully submit this is another case where the boad reaching textbook answer and what turns out to be suitable in residential construction are two different animals.
Beer was created so carpenters wouldn't rule the world.
Don,We agree on all the salient points. PL Premium is great glue, and I use it a lot. I just didn't want some lurker here to get the idea that it can be substituted for resorcinol in a laminated structural member subject to glueline creep.As you and I have both said earlier in the thread, the requirements for bounce reduction are far less severe than are the requirements for sag reduction when bonding a bottom flange of wood/steel to a joist in the field.I also agree that the flat 2x4 PL'd and fastened to the joist bottom represents the best bang for the buck in the OP's situation, giving 6'-10" headroom with 1/2" drywall.Bill
I also agree that the flat 2x4 PL'd and fastened to the joist bottom represents the best bang for the buck in the OP's situation
Bill,
Would you concur with Piffin that a 16d nail at about 16" to 20" oc would be an adequate nailing schedule in conjunction with the PL?
Yes, I would agree. The great thing about the PL Premium is that it doesn't need pressure to develop a bond, just good contact.Bill
Thanks, Bill.
This has been a great thread.
yes indeed
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Wow! You guys are definitely down with your details. To be honest, I had no idea that there were folks on here with that much information to provide.
Prior to reading through these last threads, I had been looking for the PL adhesive, don't recall seeing the premium, just the 200 and 400. I ruled this out because of the elasticity.
I did at that time pick up a case of Liquid Nails Heavy Duty or Heavy Use (Don't have it in front of me at this point.) I didn't see anything that would note elasticity like the others. I have heard a lot of suggestions on epoxy's and poly's and all the way to good ol' wood glue. Gorilla glue always sounds good. Never heard of resorcinol. But no comment on Liquid Nails.
Liquid Nails Heavy Duty - - to be or not to be? Hoping that it is comparable to the PL Premium.
Edited 8/15/2007 7:39 pm ET by seiverth
LN isn't even close to what PL is....
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!Forget the primal scream, just ROAR!!!
I quit using it cause it was more of a panel and trim adhesive in my thinking
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I gave up on it because I felt it just didn't perform well...Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!Forget the primal scream, just ROAR!!!
Did end up finding the PL Premium this AM. Thanks for the prompt response!
I haven't used LN for twenty some years now, so I am not familiar with what they have.The PL Premium is a polyurethene glue with fillers to give it body and solids for heavy construction use. Gorilla glue is also a polyurethene glue sans fillers. both require moisture for curing so they are moderately tolerant of damp wood found in cnstruction.So if the LN Heavy is a poly glue, it may be acceptable if that is what is available in your location.
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Paul, the joints they tested are bridle joints where all the strength is in the shear provided by the glue. It was interesting that they tested joints that were tight and needed to be hammered together, a hand fit, and a loose joint that would allow a playing card to fit in the slop.
The main weakness of the test was absolutely no mention of long-term creep between the various adhesives used. Even in furniture, a strong joint today isn't the same as a strong joint 20 years from now.
Beer was created so carpenters wouldn't rule the world.
Related to our discussion is an aviation article that is very applicable to floor framing. In aviation they are piecing together I-joist and box beam type structures throughout the airframe. There's some good graphics and explainations here: http://www.auf.asn.au/scratchbuilder/beams.html
edit: The entire section on wood is worth reading for those who want to know more than the basics: http://www.auf.asn.au/scratchbuilder/contents.html
Beer was created so carpenters wouldn't rule the world.
Edited 8/15/2007 2:06 pm ET by IdahoDon
> I would spend the extra bucks for epoxy instead of PL.I used Elmer's yellow carpenters wood glue in this application. Plus a fair number of ringed nails.George Patterson
Brad,
Thanks very much for all the additional information.
I don't actually have a project like this looming at present, but I'm sure the opportunity will arise again someday. It's good to know some alternate solutions and keep them in my back pocket.
Several people have had this conversation with you before, and I seem to recall that you've been called out on your handle, ENGINEER guy, before.I don't recall that you ever said that you hold a license or degree in engineering.You wanna clear that up for me?Do you hold an engineering license or degree, and, what field is it in and where did you recieve it?Enquiring minds want to know.SamT
Several people have had this conversation with you before, and I seem to recall that you've been called out on your handle, ENGINEER guy, before.
Who? Topics? Thread? Post it or shut up.
I don't recall that you ever said that you hold a license or degree in engineering.
You aren't very good at reading now are you.
You wanna clear that up for me?
91852.32 90697.22 89896.28
Do you hold an engineering license or degree, and, what field is it in and where did you recieve it?
BSCE, 1989. Working on my Masters in Construction Management.
P.E. If you want me to post my license number, come see me and pay for me to use it. And yes, I do have a PITA 15-50% factor surcharge.
Enquiring minds want to know.
You are really clueless." If guns kill people, a spoon made Rosie O'Donnel fat!"
"You are really clueless."
OOOOH!
That's even worse than the Piffin incident. Review those books on your schooling. Sam wrote them.
"You are really clueless."And you give definitive engineering advice before you have any clues.Care to share your methods of calculating the improvement in stiffness of sistering 2x4s to the sides of floor joists of unknown size, of an unknown species spanning an unknown distance, with an unknown spacing and unknown loading?And I have never questioned your knowledge or ability, just your credentials. What I questioned in this thread was your giving definitive solutions to problems with unknmown parameters.SamT
The very first sentence from the OP in this thread, "I am preparing to strengthen the floor joists in my basement. I am planning to add a room below these joists, and want to reduce the excessive bounce. "
I answered with a method that I have used in the past to reduce the bounce in floors that was by the far the best for a previous client. Similar situation. And in that case I did do a field inspection, which really isn't an option here now is it.
Do we always get the details from people asking questions here on BT? NO.
Back to my question in 93333.31
"Several people have had this conversation with you before, and I seem to recall that you've been called out on your handle, ENGINEER guy, before."
Who? Topics? Thread? Post it or shut up.
We are here to share methods, tricks of the trade, and learn from each other as I have done. There are many methods that can achieve the end result. I just answered with a fix that that has worked for me in the past.
"If guns kill people, a spoon made Rosie O'Donnel fat!"
I can't but sit here and laugh. Theres definitely some testosterone floating on the keyboards. Egos are bound to get hurt here!
Thanks for all of your input. I guess that I was thinking a little too "light" with my reinforcing idea.
There seems to be some dispute about the validity of using plywood for this idea. While this may not be best for my situation, recall that it is mentioned as a method in the article that I hyperlinked in the initial post.
http://www.taunton.com/finehomebuilding/PDF/Protected/021184090.pdf
I agree. These people need to stop typing with their nuts.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Oh, good Lord, no. But I can give him two dollars and an assault rifle.
people need to stop typing with their nuts.What - you want we should type with our bolts instead?!
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
You need to hold the keyboard upside down to type with your bolt. I guess if you mounted it to the underside of your computer desk...
"Honey, what are you doing?"
"Oh, just answering a post Dear!"Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Oh, good Lord, no. But I can give him two dollars and an assault rifle.
"Theres definitely some testosterone floating on the keyboards"LOL, oner thi9ng you have to keep in m,ind is that FHB attracts some of the best of the best. It is inevitable that theere are some strong egos attached to top guns in every field of worthwhile endeavor. We are no different. Thanks for your great attitude and good humor! One of my life rules is that a man with no sense of humor is a man who cannot be trusted.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
> There seems to be some dispute about the validity of using plywood
> for this idea.Not from me. That worked very well for me in repairing some joists that the previous owner cut into. Engineering Guy has the right idea.George Patterson
Though many here think I should go with the I joist method and lose the space, I just can't do it. I will be lucky to get a 6'8" door in as it is. I actually need to use two methods for my purpose, both which have been suggested on this thread.
Sister, glue and nail with 2x8 in the areas that I can get full lengths in.
Tougher areas I will be using the plywood as required. To many pipes to work full lengths into.
I must have misunderstood. I thought we were talking about sistering the joists with plywood. That's what I did, and I used glue and nails to do it.George Patterson
"Do we always get the details from people asking questions here on BT? NO." No, we don't, but we generally refuse advice before finding out more of the particulars in the case. Personally, I think your suggestion can work, but it is one of the more expensive and difficult to implement and the wording was rather incomplete, specifically in that it is important to offset the but joints in the ply and piffin screws are only sheet rock screws which should never be used for any kind of structural work. Sam probably over did his criticism of your post, but not without reason. Maybe you two can make peace. No kissy kissy now...just a firm handshake
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
PITA 15-50% factor
*chuckle*
Beer was created so carpenters wouldn't rule the world.
I deserve that and I'm sorry. There was another thread with a guy who had a very similar problem and I confused the two.Now grow a skin
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Rip yourself 2 pieces of 3/4" plywood and sandwich the joist with them
Plywood??? You may just get the guy to rip himself something else? <G>
I thought your post with the plywood advice was meant to be satire, but the orig poster apparently took it as fact.
Edit: OH Yeah, I think it was Piffin once replied to a guy degrading my (or anyone's) DIY capabilities in that he tried to pick on the wrong DIY <g twice>
Edited 8/13/2007 2:11 pm ET by junkhound
Edited 8/13/2007 2:12 pm ET by junkhound
When I read that article I was surprised they did not mention gluing and nailing a 2x4 on flat to the bottom of the existing joists. Deflection such as you describe is caused by a lack of stiffness or mass. Adding depth to a section is far more efficient because the sectoinal stiffness increases at a much greater rate by adding material below than beside. Now don't use subfloor adhesive as it is too flexible and make darn sure you find some reasonably dry material otherwise shrinkage will ruin all your hardwork. We used an epoxy (West System) to reinforce gym beams in several schools.
my 2c
I cannot place anything under the joists due to low head room. I only have about 84" to begin with, so headroom is a premium. I was kind of thinking along these lines when I was thrashed by my idea of just using ripped 2x8 on the side of the joist. My thought was that if this 2x8 should be a 2x10, then how much extra sistering is just overkill? If a 2x8 is good over a 10 foot span, then I can't be far off with a 14 foot span. I am definitely not an engineer, nor did I stay at a Holiday Inn Express last night - - so let the onslaught begin with my comment of overkill.
If you note my post previous to this, I tried to clear up my situation a little better for all of you.
Myself, I would lose the 1.5" and go to the underside. Using steel to each joist and getting it right would be fun and expensive to save 1.25". I am renovating a floor with a similar problem and that is exactly what I will do. SamT mentions matching materials, and I agree that is very important. The deflection criteria mentioned does not give a great indicator of floor bounce because it is based solely upon strength. I doubt you are anywhere near full loads right now, yet you are experiencing bounce problems. Say your room is 500sq ft, the total self weight would be 5000lb and the live load would be 20,000lb. Do you think you are anywhere near this? Our Canadian Code has Vibration criteria requirements, and I am sure the UBC has the same.
good luck
"Myself, I would lose the 1.5" and go to the underside. "Me too
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
The strength you desire comes from depth, not width, so by adding a 2x4 half sister alongside, you will have marginal benefits. Doing the ply sister or a full 2x8 sister will take care of the problem.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
> If a 2x8 is good over a 10 foot span, then I can't be far off with a 14 foot span.
Well, actually, no. Span related stuff generally varies with the square, so a 14 foot span is nearly twice as bad as 10 ft. 10 x 10 = 100, 14 x 14 = 196.
-- J.S.
Edited 8/13/2007 6:27 pm ET by JohnSprungX
Very good point. I didn't think I was far off either - - until getting advice here.
Any chance you could work some magic with the basement floorplan? Maybe a 2' closet or some built-ins so you can get that span down to 12' or less. Hopefully, you'd be able to do flush headers above some openings. Just a thought.
My outer walls are reinforced with steel, which amounts to around 5" in from that side once my wall goes up. The other side with the girder actually does have a closet to hide the large columns, which would give me just under another foot. I was planning to use steel studs, but your idea is a good thought.
I'm half way home to pulling my insulation and wires, so I will just press forward with doing it the sure way - - and not losing any head room - 2x8 sisters.