A couple of years ago I built a 32 x 64 detached garage. I had a local lumber yard/truss manufacturer build all of the Gambrel trusses. I told the designer that I wanted to use the second floor a living area. I wanted to be able to do anything in it you would do in a normal home. They designed the truss system using all 2 x 8. Typical (meaning what I have seen on line from other manufacturers) gambrel design with a 16′ x 64′ “attic” on the second floor. Trusses are free span the entire 32′, no support beams. 24″ on center. Designed for 40# live load. Put in all bracing as per their plans. Used simpson metal cross bracing between trusses. Finished with 3/4 tongue and groove ply. Glued and screwed. Topped with 3/4 tongue in groove hardwood nailed perpindicular to the trusses, nailed into the trusses where possible.
Fast forward 18 months later. I have finally gotten around to finishing the space. Insulated, drywalled, interior partitions with kitchen, full bath, just like an apartment. We had always intended to use this as a game room/sleep over room for the kids.
About a month ago I had a couple of friends of mine over one a general contractor the other is an architect who works exclusively for a custom home builder. Tell them about my plan to put a pool table up there. Both say the same thing, no way. You will have to put a beam under that area, they have never seen truss span with this type of set up with out a beam.
Go back to the truss manufacturer. Guy I talked to is no longer there. Talk to new designer and he say he will pull the file and look into it. Calls me back a few days later and says how much does the pool table weigh. I tell him about 800#. He says he will talk to the engineer. Calls me back a couple of days later and says, trusses will hold no problem, but to keep the floor from bouncing and messing up your shots you should sister (2) 2 x 8 x 8 to the sides of the trusses centered in the middle over top of the connector plate. He says to glue and nail with 4 nails every 6 inches. Says one would probably be enough but says to put on two just in case I knock the metal connector loose in the middle when nailing, it will hold it on the other side.
Now for the questions.
This is going to cost a couple of bucks and quite a bit of time so before I proceed
1) Do you think maybe they mis designed the truss and they are trying to cover their a** by having me do this.
2) Do I really need to use 2 ea 2 x 8. If they are saying I am trying to stiffen the floor, one 2 x 8 should be enough. If I am using 3′ nails knocking off the plate shouldn’t be a problem.
3) I should just do what they say. You do not have enough information to properly answer the question.
4) I should probe for more information from the truss plant and you will give me some quality questions to ask them.
Thanks,
Chuck
Replies
I wanted to be able to do anything in it you would do in a normal home.
Chuck, I wouldn't put a pool table on any framed floor in any home and expect it to stay level. All floors bounce and have some degree of sagging.
blue
I guess I do understand that to a point. I guess I am more concerned about the whole thing collapsing. Even without the pool table their is some bouncing when the kids are up there dancing and so forth. Would a custom home have 32' spans for a second floor with no mid span supports. Even if they did you build it that way and not expect a call back from your customer about sagging or bouncy floors?
The question is, if you were building a home and you saw 32' mid span support second floor would you go back to the arch/eng and say won't build it that way customer won't be happy.
chuck
An 800# load isn't that much - like maybe 4 people's worth...
>> Designed for 40# live load. << Is that for the roof deck or the attic floor?
>> Calls me back a couple of days later and says, trusses will hold no problem, but to keep the floor from bouncing and messing up your shots you should sister (2) 2 x 8 x 8 to the sides of the trusses centered in the middle over top of the connector plate. << I don't understand. Are the 2x8s to be sistered to the bottom chord or what? If so, is the connector plate centered on the bottom chord or what? How does the floor feel now?
As far as trying to cut back on their recomendations, not sure that makes sense, since I'm guessing that the main hassle is going to be to remove and replace either all the floor covering or the ceiling below.
Really though, I think the only one here that would be qualified to answer your questions is Boss Hog. Even then, he would need the engineering sheets that came with the truss package.
40# is for the attic floor
Yes, sistered to the bottom chord. The connector plate is exactly in the middle of the 32' span.
If the kids are dancing and doing ddr a little movement, not like a trampoline though.
Below is a garage and work shop. Not finished ceiling below.
I am trying to dig out the engineering sheets. I guess I could ask the truss plant for another copy.
cd
I have a couple of questions.
First - Are you SURE the bottom chord is 2X8?
Are you sure the room width is 16'?
Do you have any pics of the trusses that you could post?
Do you have a copy of the original design drawing for the truss? (Or would you be willing to ask the manufacturer for one)
Is there a grade stamp on the bottom chors of the trusses that's visible? If so, can you post a pic of it or tell me what it says?
Give me a bit more info and I'll follow up from there...
Well as sure as my memory. But no I don't have the plans in front of me or have measured them recently. Talked to the truss plant a couple of days ago and that is what we discussed. So I would say 99% sure.
Yes I am positive the room is 16'. Exactly centered between the exterior walls. Total building width is 32' 64' long. Truss spacing 24" on center.
I don't have any pics. If I knew how to attach a drawing I could post one from another web site. When I was doing some investigating it seemed like all the ones I saw on line were the same as what I have. Except that I never saw any with a connetor plate in the center. All of the attic gambrels I saw were solid lumber to the point of the second floor side wall connection to the bottom cord/web connection.
The are in the same building as me I am sure I could walk over and get a copy of the plans. I am not sure if I could post or not.
I will try to remember to get a look at the grade stamp tonight and let you know what it says.
Thanks
chuck
Does your attic truss look more or less like the attached pic?And is the bottom chord splice right in the center of the truss/room?
Friends are those rare people who ask how we are and then wait to hear the answer [Ed Cunningham]
Give me a minute. I am going to run upstairs and get a copy from the truss plant. I will look at the picture and let you know. I could fax you a copy if you would like. If you don't want to post your fax number you can e-mail it to me at [email protected]
I just faxed you the plans. Maybe you can post the pics so everyone can follow along.
chuck
Just got the fax and your followup email. Unfortunately, I have no way of scanning them and posting them right now. First - Did Mitek O.K. the way you did your stairs? Cutting out one truss for stairs is not a good thing, unless they approved the way you did it. But that's a bit off topic. Your original question was: Did they do the design correctly? My answer is yes - Technically. But I also think they used really bad judgement. I don't know how long you've hung around, so you may not know that I'm very conservative when it comes to floor design. I prefer to keep the length/depth ratio of a floor system to around 18/1. (ie: One foot of depth for every 18' of span) That doesn't reflect any code or engineering requirement - Just personal experience and prefereence. Your attic truss floor has 2X8s spanning 16'. That makes the ratio 26.5/1. The engineering company our truss plant uses recommends we stick to around 20/1, and will not seal designs that are over 24/1. (We use Alpine, vs, Mitek that your truss company uses)Honestly, I'm surprised that the floor isn't a miserable trampoline. I would have expected it to be much worse. I suspect that when they checked the design after you called about the pool table, the connector place in the center of the room was borderline or undersized. That's why they suggested adding lumber to reinforce the joint. But putting the joint in the center of the room again reflects bad judgement, IMO. That the point where the bending moment is highest. I simply don't do that.So what do you do now? I doubt you have any recourse against the truss manufacturer, since it appears that what they did is "legal". My suggestion would be to reinforce the whole floor of the truss with some 18' 2X12s spanning from one side of the room to the other. That would take care of the plate reinforcement that they wanted. And it should make the whole floor stiffer. You might be able to get the truss company to supply the lumber if you pressed the issue. Tell 'em you aren't happy with the floor and that you think the lumber size they choose for the bottom chord was grossly undersized. But I doubt they will.It would be a long shot, but you could ask the manufacturer for sealed drawings of the trusses. It's possible that Mitek won't seal trusses with a B.C. length/depth ratio like that. The company may have done the design in house and not had them reviewed by Mitek engineers. If they refuse to provide sealed drawings, then I would be a bit suspicious. But again, it's a long shot. Even if they refuse to give you sealed drawings that may not give you any legal recourse. Sorry I don't have better news for ya...
I am strongly in favor of common sense, common honesty, and common decency. This makes me forever ineligible for any public office. [H. L. Mencken]
Thanks for the follow up. I had a feeling this is what I was going to hear. First the stairs. No, what they wanted me to do was put the t2 trusses on either side of the stairs and then stick fram in between them, hanging beams from the bottom chords of t2. I was trying to avoid having to match the profile of their truss by hand so I ordered another truss and then did what I said. The designer at the truss plant said that would be ok since it wasn't really any different than stick framing that center section and then hanging the stair well from the two t2 trusses.
Now on to your suggestion. If I sister 2 x 12 x 18's to the bottom chord, should I put it on both sides or on one only What would the nailing pattern be. Glue and nail or nail only. The other problem is that I already put in all of the cross bracing and if I use 18's I will have to remove all of the bracing to put them in.Or is there another way to do it. Also are you saying that I should do that parallel to each truss or ?. What if I ran a beam under the center or the truss perpendicular to the trusses? Would that serve the same purpose. The garage is divided in half with the stairs and walls under the two trusses next to the stairs. I couuld maybe put a beam pocket there and run some beams the remaining about 28' both directions. I would be hurting some on head room but less expensive and quicker?
What I really hate is that I questioned the original designer about all of this two years ago when I first got the plans. He said no problem he does it all of the time. I thought it was strange that the connector would be in the center and not at the wall connections. Now it going to cost me as much to fix it as I was going to spend on the table.
I want to make it so it will last. Don't want to be doing any repair work down the road.
Again I can't thank you enough for your well informed opinion and look forward to have BT members help me resolve this situation.
chuck
Putting a beam under the center of the room would certainly resolve the situation easily and would be much better overall. I didn't suggest that, as I assumed it wasn't an option over a garage. Of course - You really need a pad poured inder your posts that support the beam. That would be a pain too. No easy solution.What he told you about the stair framing really isn't true - It's not the same as stick framing it. But it may be O.K. too.
You no more win a war than you can win an earthquake. [Jeannette Rankin]
The problem with the beam is that one end would terminate at the garage door header. So I would have to use the door header to support one end. What is your opinion on that. What would be an approx guess on beam size? I don't have my book handy but it seems like it would be a guess anyway. With the truss no way to know what the actual load on the beam would be, or could it be calculated from the truss plan. I could go back to the engineer and ask them to figure that instead.
Give me more on the stair. Again I did build walls directly under the two trusses that are supporting both sides of the stairs. That is why I wasn't too worried about it after I put them up. Is your concern on the "header?" that I used to span between the two trusses to carry the stair load or the one truss that I cut and is also hanging from that stair header.
On your suggstion for the 2 x 12 are we still talking about 2 per truss one on each side or would that be one only for each truss.
I did go back to the truss plant and asked them for sealed plans before gussets and after. They said they would talk to the engineer and get back with me. The problem with the whole situation is that the original designer is no longer there and they don't know where he went. When I brought up my conversation with him regarding living space and pool table. They said we have no way of verifying that you ever had that conversation and these trusses were designed for storage not living and pool table. They said they are only giving me suggestions on how to modify them now because I want to use it for living space and pool table. And to make it worse the owner of the company is my land lord for my business. Don't want to piss him off and end up with double rent next time around.
How is this type of thing normally handled. If you are doing something for a homeowner do you require everything in writing so that it can be documented at at later date? I guess I should have been more diligent in my questioning in the first place.
chuck
"I would have to use the door header to support one end. What is your opinion on that. "
Depends on where you put your posts, what the door header is now, etc.
"With the truss no way to know what the actual load on the beam would be, or could it be calculated from the truss plan."
I did a rough design here, and came up with about 550 PLF. But the truss manufacturer should be the one to give you the exact number. They can run it with a center bearing and give you a revised drawing.
"On your suggstion for the 2 x 12 are we still talking about 2 per truss one on each side or would that be one only for each truss."
Either way would help. You could always try one side, then add the other one if you needed to. Or jus go back to what they suggested in the first place.
"The problem with the whole situation is that the original designer is no longer there..."
That doesn't relieve them of design responsibility. Stay on their case, especially about the sealed drawings.
"...these trusses were designed for storage not living and pool table."
A 40 PSF live load is normal for living areas. I would venture to say that the vast majority of residential floors are designed for that.
If you talked to the guy about a pool table, he should have checked that out ahead of time. But like you said - You can't prove you DID say it. Still, it might give you some leverage towards getting them to help out with any repairs/modifications.
To eat is human, To digest divine. [Mark Twain]
<<"On your suggstion for the 2 x 12 are we still talking about 2 per truss one on each side or would that be one only for each truss."Either way would help. You could always try one side, then add the other one if you needed to. Or jus go back to what they suggested in the first place. >>A question for you, Boss -- maybe it will help this guy out. I had some electricians destroy the bottom chord of a few attic trusses on a 32'-2" span a few years ago. I faxed a drawing of the damage to the P.E. who designed the trusses (he is excellent at what he does) and he had me rip some 1-3/4" LVL to 1/4" less deep than the bottom chord and install them on either side of the bottom chord with CA and bolts.The attic is now being used as a living room and the floor is good. I'm supposing some of that performance came from the stiffness of the LVL.Would this be a good approach in this case?A king can stand people fighting but he can't last long if people start
thinking. -Will Rogers, humorist (1879-1935)
Where do the stairs originate? Inside the garage? Nothing to do with the trusses, but per code there is fire separation required between garage and living space, and a sleeping room may not open directly into a garage. Just food for thought.
The stairs are in the garage. There is a exterior type double french door (steel) at the bottom of the stairs. First floor wall is traditional framing with drywall. Stairs lead into living area of second floor. Sleeping room in the area is really a storage room. It is framed seperate and has its own door. Building inspector was out the other day and asked if the room was a bedroom. I told him no was a storage room. I do realize that if this was an apartment and I was going to rent it out I would not do it. The idea was that the kids could have sleepovers up there etc. And if any of my 6 children ever come back after they move out, I told them you can come home you just can't come into the house.
The garage is not used for car storage anyway. I don't know how it worked out but I move from a 1300 sq ft home with a 1/2 car garage, into a 2700 sq ft home with a 1800 sq ft garage and 300 sq ft of storage and I still can't get my vehicles in the garage. I have to build a 6k sq ft barn so I could have somewhere to park my truck.
Chuck,
Do they manufacture the trusses where your office is? If they do, keep an eye out for an attic truss with the same room size that you have. It doesn't have to be a gambrel, it could be a common; but the room size has to be the same. If it has a 2x10 bottom chord, you have a leg to stand on.
I'm also going to point out that this is a pizz poor design -- the attic you are describing.
The level of the designer is very visible here. My guess is you got the "new guy" and nobody was watching him.
On the other hand, it could very well be how they build them. It's possible it meets the requirements (40 psf) and code. If that's the case, then what your experiencing is a quality issue, not a code issue and that needed to be addressed before construction.
Thus, checking to see what the bottom chord is on the attics they're spitting out now should tell you if it was the designer or company policy.
If they are 2x8's its probably company policy; if they're 2x10's there's a good chance it was the designer.
If it was the designer, you're not out of the woods yet. It just gives you a leg to stand on. You then will have to use guilt to get what you want:)
P.S. Forget about the seals idea. That would be an empty threat (it's not even a threat) and would just get the wrong people agitated.
Forget about the seals idea. That would be an empty threat (it's not "even a threat) and would just get the wrong people agitated."
I don't agree. If they won't provide seals, that would make me suspect that the engineers wouldn't back the design. And it would give him more leverage against the manufacturer.
I don't know who you consider the "wrong people". But I personally wouldn't care if anyone from the manufacturer got agitated.
If a woman has to choose between catching a fly ball and saving an infant's life, she will choose to save the infant's life without even considering if there are men on base. [Dave Barry]
At the time, the guy who designed the truss was the head guy. Yes they do build them here and I have a good relationship with the manager in the plant. I fix lunches and buy pizza for his guys every couple of months. He is working with me between the new designer and the engineers. He suggested that we ask the engineer for seals on the drawings as well. Both before and after the change they are suggesting.
What burns by a** is that everyone on BT is always saying get an engineer, call in an expert, here I did it and this is how it ends up. Being my own GC and really building the entire project my self, at the time I was questioning the designer and the plans because they just didn't look right. At the time he assured me that the engineer had rechecked them and they were good to go. I have a feeling he did not share the pool table information.
Yes, one of the few projects I have done on my property where I played by the rules and even got permits.
This is why I get so p***** off sometimes. You just never know who to trust anymore. I think this is why people are so easily swayed in the building industry to accept sub standard work because they rely on the word of someone who calls themselves an expert. How is the lay person to know that they are really getting the expert GC and Arch. that they are being portrayed as.
Even here, you read so many posts and everyone (most) sounds like an expert but who really knows. It takes an expert to distinguish who the expert really is. May some of the BT members need to get out of the GC business and go into business as advocates for the homeowners.
chuck
Chuckd, your advocate has arrived! Let me take my bow!
TA DAAAAAAAAAA!
I've got the solution and it won't take more that about $20. And it will work!
You've already mentioned that a beam is a possibility because it would land exactly in the center of the garage. The stanchions (poles) won't prevent your cars from parking because they'll land between them.
The reality is that you don't really have to put a beam under the entire floor. Sooooooo....all you really need is a bearing partition about 8' long because thats how long your pool table is.
Soooo, buy a chunk of treated 2x6 or two by 4 for the bottom plate. Get another (white wood will do) for the top plate. Purchase four stout studs (4x4's would be better) and cut them tight to fit. Center the wall under the trusses that you want stiffened and you'll effectively be creating a much stiffer floor.
If you put some sheating on each side of the partition, you'll have somthing to hang your girlie poster on.
Send my check to your favorite charity.
You don't need an engineer.
blue
Thank you for your suggestion. One caveat to this problem is that it is in the center of the garage but, two garage doors. One 16' door and one 8' door. The wall would be about two feet into the edge of the 16' door. If I do a beam the only way to handle it would be to hang one end from the garage door header.
Maybe a little early for the TA DAAAAAAAAAA but give me something else.
I have a 32 x32 shop in the back, plenty of room for girlie posters. Unfortunately I have 6 children, 5 girls 1 boy. The girlie posters don't go over to well with the majority.
chuck
> The wall would be about two feet into the edge of the 16' door. If I do a beam the only way to handle it would be to hang one end from the garage door header.
Being near one end of the header is a good thing. Beefing it up for a point load there could be a very reasonable way to go. Can you put a column directly under the other end of the new beam?
One thing I'd advise against is only beefing up the place where the table goes. Do that, and Murphy will send your wife up there to say "Let's move the pool table over here." ;-)
-- J.S.
Yes, there is an interior wall there, stairs and bathroom. It would be easy to put a column in here somewhere. Or cut into the wall and put in a beam pocket with a stud pack
chuck
Chuck,
Slide the beam over a couple feet until it is off of the garage header.
The splice in the middle of the room still would need to be addressed, but that should be an easier problem to fix than dealing with that header.
The reason why I said to forget about the seals is this:
In my neck of the woods, you don't need seals for residential, only commercial.
Depending on who your plate supplier is and the deal you worked out, you get x amount of seals /yr or buy them per seal.
I made the assumption that since you don't have sealed drawings, your area probably doesn't require them either for residential.
When seals are required, that is usaully factored into the price of the truss.
If no seals are required, it's not sop to "send" for a seal, therefore it is not factored into the price.
If you got a price without seals and later returned and asked for seals, you're going to get alot of resistance if they're buying per seal. This could give them a negative impression of you and that's not the picture you want to paint. If they get x amount per year, they're a little more willing to pass them out.
This is the "agitate the wrong people" part and the "wrong people" are the ones who are in a position to help.
Therefore, refusing to give out seals doesn't necessarily mean they don't stand behind their product.
After reading your post above, I see this isn't the case at all.
It is typical to send for a seal on an unorthadoxed design whether it needs one or not, but a gambrel attic doesn't fall into this category.
Do you know if they ever sent for a seal or if they just talked about doing it?
Also, an 800 lb pool table would easily equate into 40 psf. If you think about it, it probably isn't that much more weight than 3 people sitting on a couch.
You know, MiCrazy had a good thought - The beam/wall wouldn't have to be dead center under the attic room. Since you appear to have a good relationship with the truss company, I'm sure they'd be willing to analyze the truss with an off-center bearing. That way you could move the beam away from the 16' garage door opening, but still add some support.Sometimes more heads are better in solving a problem. It's a great suggestion, and I sure didn't think about it.
I live in a crummy apartment.
Once, opportunity knocked and a wall collapsed.
I talked to my contact on Thursday and he said he was going to ask. I wasn't in on Friday but will talk to the new designer on Monday about an off set beam.. I am sure they would give me a seal on a new drawing, I doubt if they would give me a seal on the old drawing but I don't really care about that now. I just want to make sure we aren't plaing pool on a floor of jello.
chuck
Chuck, the interior bearing wall would be strongest if centered under the table, but it would also significantly reduce vibrations if it was offset 4 feet too.
TAAAADAAAAAA.
blue
Alright I'll give you an assist on the TAAAADAAAAAA.
chuck
"I've got the solution and it won't take more that about $20. And it will work!"i thought you were going to tell him to forget about pool and get a dart board . . . . . . .
I hate to be too hard on you, but - You acted as your own GC rather than pay someone else to take the lead. In doing so, you take on some risk. An experienced GC may have knows there could be problems with the trusses and may have refused to accept them. Even if he hadn't, you would have been looking to him and/or his insurance company to take care of this.Problems are one of the risks of being your own GC. You took the risk, now you have problems.
Never go to a doctor whose office plants have died. [Erma Bombeck]
A minor point. If you're talking about liability insurance, you would not be looking at his insurance company to take care of this, since it's not a warranty.
It could be considered a construction defect, although that migth be pushing it a bit. And he could always sue the GC (If there was one) The insurance company would likely pony up some money to make the problem go away.
The best way to make your dreams come true is to wake up.
They would probably decline to defend the claim since defective construction is not covered, at least by my policy. Property damage and bodily injury... that's the realm of liability insurance. If the owner is concerned about quality issues they can require a performance bond.
I understand that completely. I have done many GC jobs for myself and understand that I have no one to blame but my self.
I am just lamenting that when relying on experts, who is policing the experts. You said if I had gotten a GC then this would be there problem. But there in is the problem. If I had gotten a GC I would expect that there would not be any problems. But we all know that is not the case. They are as likely to have not caught this error as I, and then I would of been out another 20+% on top of what I already spent.
If you had a GC, and your plans had called for a specific loading on the attic floor above the garage, then s/he would likely have read the engineering that came with the trusses and made sure that it was as planned. Whether or not the average GC would recognize visually that the trusses were inadequate, even if the engineering was in order... that's another question. I coulda got my foot stuck in that one. Lots of mistakes happen in construction. Sometimes you have to reinforce some trusses. Sometimes you have to replace the newly poured foundation for the Sydney Opera House. Get thru it and keep moving.
I can't get your garage out of my head. Maybe after I post this I'll be able to get some sleep.
This is the route I would look into.
If he adds interior load bearing walls or columns/beam the slab floor should really be thickened at these places, particurally if columns are installed which would create a load point on the slab where each column is. Not to do so might be OK, but on the other hand, it might crack the slab. Personally, I wouldn't want to mess with a perfectly good slab.
I did put a full block foundation around the perimeter of the building. Block was four deep on a poured concrete footer. What if the Beam hung from the SIP that sits over that perimeter foundation?
chuck
Yes, placing point loads over the foundation is what needs to be done. I don't know much about SIP construction but I'd bet that some framing members (post(s)) would need to be added to transfer the load rather than relying on the sip to do it. Are there any grade beams under the slab?
To tell you the truth though, I don't understand why you don't just do what the truss company specified, unless maybe you just, flat out, don't trust them. If there are no finishes to remove from the ceiling below the attic room, which I think you said was the case, you could have been done by now.
There is not a finished ceiling , but lots of wiring, plumbing, hvac. There is an apartment upstairs and all of that would have to be move etc. Also, the expense of 64 2x8's. But yes, wanted to get some second opinions and see if there may be a consensus on what the truss company is telling me. No, I could not have been done by now. It will take me a couple of weeks just to remove/move the mechanicals that are in the way. Not withstanding moving everything around that is already stored in both the garage and my workshop.
chuck
Did ya ever think this thread might get over 50 posts?Ya never know when a thread will take on a life of it's won.....(-:
If you want to sacrifice the admiration of many men for the criticism of one, go ahead, get married. [Katharine Hepburn]
It is really a testament to the knowledge and concern of the BT members. I do appreciate everyone taking time out of there schedules to share the experience and knowledge that they have. Thank you.
chuck
OK - I gotcha now. Does sound like a royal PITA
I can't open those attachments. Adobe says they're corrupt and can't be repaired. BTW - Great suggestion on moving the beam/wall off center.
I am very detail-oreinted.
What version of Adobe are you using? V7 opened those drawings on my comp.
Hope this helps, Jim
That looks like a good idea. If I do that, maybe I could then reinforce the connectors only under the pool table. Just using one 2x8x8 on each truss instead of two.
chuck
Right now, I wouldn't plan on getting away with less than a 12' 2x8.
This has to be done to each truss in which the new bearing condition is created, not just where the pool table goes.
I don't know what grade or species your bottom chord is or the plate sizes, but I created an example to give you an idea of what might happen.
The red hatching represents the 2x8. In this example, my bottom chord is SYP 2400 2.0E. If yours is less than this, it might take longer 2x8
Ignore the overhang detail, that's just how we make them.
Thanks, I'll bring this up when I talk to the truss company today.
chuck
If the new beam were under the splices, would it save you having to scab all the bottom chords and mess with the mechanicals in there? If so, beefing up the garage door header for the new point load might work out to be the easier way to go. It's probably worth running the numbers for both options.
-- J.S.
John,
We don't really know that he'll have to scab on to the bottom. It's like Boss said, it may be ok without. The ones who really know for sure is the truss company who made them. I just want to make sure we get all the questions asked.
As for the beam in the center, a 28' clearspan is going to be a large beam. There's really not a place to stick a post to cut down on that span, in order to reduce its size. He had mentioned about losing headroom (if I remember right) so if he has 8' walls and 7' garage door, a beam could get in the way of the garage door opening. Whatever the height is from the top of the garage door in the open postion, to the bottom of truss limits what the depth of the beam can be. Then there's an issue of what do you attach to?
So in going that route, the first question is -- Is there enough room for a beam?
Edited 1/23/2006 6:54 pm ET by MiCrazy
The general rule is to never cut trusses, but, if the beam option is used, what would the consequences be if a section of the bottom chord was cut out at the splice and a beam was raised into the space, rather than just propping up from under. A deeper beam could be used that would have 8" less impact on headroom. A large, long strap over the top of the beam, such as the Simpson HSA, tying the cut bottom chords together should be enough to replace the tension factor lost with the cutting.
We commonly attach a smaller LVL perpendicular to a main carrying LVL when we open up a room. There should be plenty of room next to the garage door headers to mount a really massive LVL across the span and not use the door headers to support the free end of the beam carrying the second floor.
Good thought if I didn't have two garage doors. One 16' and one 8'. There is no place to put a beam perpendicular to the other. It would be in the way of the garage doors when open.
I think we have already determined that the trusses are adequate based on load and "design" calculations. What we are trying to do is a a safety net, kind of a belts and suspenders approach. The engineers have agreed to give me a sealed drawing, but not with the pool table? Don't really understand that because 40# is 40#. So the beam would not really be carrying the full load of the upstairs, only partial. The truss designeer is doing those calculations now and is supposed to get back to me. I feel pretty good that the whole thing is going to fall in but am more concerned about long term sagging and just the trampoline effect when we have a full room of partiers.
Thank you for your input I will let you know as I get more information.
chuck
What you propose wouldn't work, for a couple of reasons. There's no way you could get a simple strap to hold the amount of tension that's in the bottom chord. And since the attic truss is an indeterminate structure (ie: not triangulated) you need the whole bottom chord to resist the bending moments for unbalanced loads. Interesting idea, though.
My advice to you is to get married. If you find a good wife, you'll be happy; if not, you'll become a philosopher. [Socrates]
I had a similar situation where the owner wanted a staircase built in his garage to access his 'attic' room above (attic trusses were used). I asked him to get an engineered detail for cutting one bottom chord, and he called a little while later saying it appeared too complicated and he decided not to do it. My assumption was that a flush beam could be used, along with some sort of tension ties, but apparently it was more complicated than that. I assume most people access their 'attic' via some method other than a stair that comes up thru the trusses.
The ideal situation for attic trusses is that the stairway is planned out ahead of time. Typically it involves a double truss around an opening, with stick framing inbetween. It isn't terribly difficult (I've done it myself) but some framers holler about it. If you simply cut one attic BC out and header it off, you've significantly increased the load on the adjacent trusses. Sometimes they can be repaired to handle the added load, and sometimes they can't. Depends on the situation.Like most things, attics and staris are much easier if planned ahead of time.
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> no way you could get a simple strap to hold the amount of tension that's in the bottom chord.
You'd have to design something better than that simple strap, but the real trick is that all that tension in all those bottom chords has to be held at all times during the cutting and installation of the beam. So, now we have either a lot of temporary rigging, or we have to design some very special highly engineered upside-down "U" shaped things that can be installed one at a time, with the beam then lifted up into the recess. The other option, with the off-center beam, is looking better now.
-- J.S.
On the cut-bottom-chord-install-stairway job I looked at, I was thinking of temporary 2x laid along the top of the chord, with large 3/4" plywood 'plates' at each end scabbed across the temporary and the chord. It should be fairly simple to find out the amount of tension on the chord and the resulting number of screws or spikes needed.
Of course, you'd find out if you were right as the sawzall approached the end of the first cut thru the chord.
One more thing, the 2x8 has to be the same species and grade as the bottom chord.
>> One more thing, the 2x8 has to be the same species and grade as the bottom chord. << Why is that? Not questioning the accuracy of your reply, just trying to learn something here...
I don't 100% believe that repair pieces absolutely HAVE to be the same species and grade that the bottom chord is. But - That's the way it's typically done. Every truss repair I've ever seen called for a scab member to be the same size, species, and grade as the repaired member.There's only one halfway rational explanation I've ever heard for not mixng species. Let's say you have a SYP truss and put a SPF scab on it. The 2 different types of lumber might react to changes in moisture content differently. So if one expanded and contracted more than the other, it would tend to bow the truss, and/or put more stress on the fasteners.The only reason I know of for not mixing grades is just because "We've always done it that way"..In this particular case, I'm thinking that if he puts another bearing under the truss, he may not need any scabs at all. But that's up to the truss company's engineer to decide for sure.
Compromise makes a good umbrella, but a poor roof [James Russell Lowell]