Summer Buyer Posted August 25, 2007 Report Share Posted August 25, 2007 So I'm trying to decide if my deck is stressed correctly to hold the weight of a spa (in the 100-150 psf range) I just don't know which dimensions and supports equals an overall stressing of that psf. My deck was built be a professional company, so I have all of the official documents quoting the measurements that I can quote below: All joists, beams, headders, and ledger will be of 2" x 10" pressure treated lumber All deck footers will be 16" x 16" x 24" minimum with a minimum of 10" of concrete There are four 6" x 6" support posts underneath the spot in which the tub will be put, they are spaced 5' from eachother in one direction and 7' in the other From this information, can someone tell me what load my deck is stressed for? Thanks! Quote Link to comment Share on other sites More sharing options...
egbert Posted August 25, 2007 Report Share Posted August 25, 2007 What is the spacing on the joist? What sort of lumber is on the deck surface? Quote Link to comment Share on other sites More sharing options...
Summer Buyer Posted August 25, 2007 Author Report Share Posted August 25, 2007 What is the spacing on the joist? What sort of lumber is on the deck surface? the spacing on the joist in 12" on center and the lumber on the deck surface is deck cedar I think (but I know its not pressure treated) Thanks! Quote Link to comment Share on other sites More sharing options...
Brulan1 Posted August 27, 2007 Report Share Posted August 27, 2007 What is the spacing on the joist? What sort of lumber is on the deck surface? the spacing on the joist in 12" on center and the lumber on the deck surface is deck cedar I think (but I know its not pressure treated) Thanks! Your Deck is rated for over 2 1/2 tons on that particular area Quote Link to comment Share on other sites More sharing options...
Summer Buyer Posted August 27, 2007 Author Report Share Posted August 27, 2007 What is the spacing on the joist? What sort of lumber is on the deck surface? the spacing on the joist in 12" on center and the lumber on the deck surface is deck cedar I think (but I know its not pressure treated) Thanks! Your Deck is rated for over 2 1/2 tons on that particular area Wait so 2.5 tons is like 5000 lbs right? So does that mean the entire tub filled weight has to be 5000 lbs or less, or what would the lb per square footage be? Because the Pelican Bay for instance is 5100 lbs filled weight, so adding people would be over that, can my deck not hold that? Quote Link to comment Share on other sites More sharing options...
Brulan1 Posted August 27, 2007 Report Share Posted August 27, 2007 What is the spacing on the joist? What sort of lumber is on the deck surface? the spacing on the joist in 12" on center and the lumber on the deck surface is deck cedar I think (but I know its not pressure treated) Thanks! Your Deck is rated for over 2 1/2 tons on that particular area Wait so 2.5 tons is like 5000 lbs right? So does that mean the entire tub filled weight has to be 5000 lbs or less, or what would the lb per square footage be? Because the Pelican Bay for instance is 5100 lbs filled weight, so adding people would be over that, can my deck not hold that? It will support it but there may be settlement in that particular area of the deck in the later years. I wouldn't worry about it as it will definately support your unit filled with people in it. Quote Link to comment Share on other sites More sharing options...
cplarsen Posted August 27, 2007 Report Share Posted August 27, 2007 You say you have four "6 x 6" posts in a 5' x 7' configuration. I assume they are supporting "2 x 10" beams with the joists going across the beams? If so, you can easily shore up the joists for sag (which is all you really need to do with what you have) by attaching doubled "2 x 10" beams to the existing beams with hangers. You may need to do it in a "H" configuration, if you follow, to get a beam right down the centerline of the hot tub and under the joists. Should set you back all of $50 - $60. Quote Link to comment Share on other sites More sharing options...
Brulan1 Posted August 27, 2007 Report Share Posted August 27, 2007 You say you have four "6 x 6" posts in a 5' x 7' configuration. I assume they are supporting "2 x 10" beams with the joists going across the beams? If so, you can easily shore up the joists for sag (which is all you really need to do with what you have) by attaching doubled "2 x 10" beams to the existing beams with hangers. You may need to do it in a "H" configuration, if you follow, to get a beam right down the centerline of the hot tub and under the joists. Should set you back all of $50 - $60. Great Idea! Should the new beams be placed towards the floor or more towards the top? Quote Link to comment Share on other sites More sharing options...
cplarsen Posted August 27, 2007 Report Share Posted August 27, 2007 Er, lets see if I can illustrate. I have sorta the same situation on an existing deck and I ran it by the city inspector just to be sure on the calculations. Then I changed my mind and am now doing something else... But anyway, here we go. I'm leaving out the joists, as they just ride on top of everything else. And yes, the joists have to be sitting on the beams, or the beams don't do much good. P = Post B = Beam b = new Beam Existing, P...........P B...........B B...........B B...........B B...........B B...........B B...........B P...........P You want to end up like this, P............P BbbbbbbB B.....b.....B B.....b.....B B.....b.....B B.....b.....B BbbbbbbB P............P Hope that's somewhat clear. Double hanger brackets are down at Home Depot for about $1.80 each. "2 x 10"'s will run a bit more. Quote Link to comment Share on other sites More sharing options...
queenwench Posted August 27, 2007 Report Share Posted August 27, 2007 As you have mentioned, in your original post, you have original plans from the original insatllation of your deck. This was a professional installation. At the bottom of the plans you will find the names of the builders, possibly the designer, and the seal for approval from the city/village/county regarding your deck. This has been filed with you city/village/county. I strongly suggest you call these people, to ask them for the proper load requirements etc. regarding your situation. They can work with you and give you EXACT requirements. Once they have done that, in future, as long as you have followerd their recomendations and requirements, if anything goes wrong, they are liable for situations that may arise in the future. Better safe than sorry. Quote Link to comment Share on other sites More sharing options...
ronc Posted September 2, 2007 Report Share Posted September 2, 2007 Ditto on that last reply. I am a general contractor and the comment about your deck being designed to hold 5 tons is bad information. First of all the engineering is designed to give you a psf rating (pounds per square foot). If you deck is 5x7 and could hold 5000 lbs that would be 142 lbs/sf. That is really high and I doubd it is accurate. In addition - decks have a live load, a dead load and a combined load (of the two). Your tub can not exceed your live load as calcualted by the structural engineer that designed it. Also remember that the live load of your tub must include the people in it. Most tubs weigh in about 80 lbs/ sf with water (remember that is an average number). What you need to do is contact a structural engineer and have him do some quick calulations to see what you deck is rated for then find out what your tub will weigh (with people). No offense but the guy telling you about your 2x10 beams - does not know what he is talking about - first of all 2x10's are never considered "beams" just joists. Good luck Quote Link to comment Share on other sites More sharing options...
Summer Buyer Posted September 3, 2007 Author Report Share Posted September 3, 2007 wait my deck isn't 5' by 7', the area where I'm putting the tub is a smaller portion of my deck that's self supported, its shaped like a hexagon cut out of a 10' x 10' area Quote Link to comment Share on other sites More sharing options...
cplarsen Posted September 4, 2007 Report Share Posted September 4, 2007 No offense but the guy telling you about your 2x10 beams - does not know what he is talking about - first of all 2x10's are never considered "beams" just joists. Good luck Er, a beam can be whatever you want it to be. It's just a term for a load carrying member. "A structural member, usually horizontal and narrow in proportion to its depth, which supports superimposed loads primarily by its internal resistance to bending. The bending effect at any point in a beam is found by calculating the bending moment. The principal structural materials for beams are: steel, light alloy, timber, reinforced concrete, prestressed concrete or composite materials. " And doubled "2 x 10"s can make a fine beam, depending on application, of course. btw, a joist is also a beam... Quote Link to comment Share on other sites More sharing options...
ronc Posted September 5, 2007 Report Share Posted September 5, 2007 No offense but the guy telling you about your 2x10 beams - does not know what he is talking about - first of all 2x10's are never considered "beams" just joists. Good luck Er, a beam can be whatever you want it to be. It's just a term for a load carrying member. "A structural member, usually horizontal and narrow in proportion to its depth, which supports superimposed loads primarily by its internal resistance to bending. The bending effect at any point in a beam is found by calculating the bending moment. The principal structural materials for beams are: steel, light alloy, timber, reinforced concrete, prestressed concrete or composite materials. " And doubled "2 x 10"s can make a fine beam, depending on application, of course. btw, a joist is also a beam... Talk to any carpenter in the field and look up at 2x10's hanging off of a 4x12 and ask him to point at the beam and the joists and then get back to me. Quote Link to comment Share on other sites More sharing options...
ronc Posted September 5, 2007 Report Share Posted September 5, 2007 No offense but the guy telling you about your 2x10 beams - does not know what he is talking about - first of all 2x10's are never considered "beams" just joists. Good luck Er, a beam can be whatever you want it to be. It's just a term for a load carrying member. "A structural member, usually horizontal and narrow in proportion to its depth, which supports superimposed loads primarily by its internal resistance to bending. The bending effect at any point in a beam is found by calculating the bending moment. The principal structural materials for beams are: steel, light alloy, timber, reinforced concrete, prestressed concrete or composite materials. " And doubled "2 x 10"s can make a fine beam, depending on application, of course. btw, a joist is also a beam... BTW - you can also pull out your Simpson catalog and look up beam hangers - they start making them for 4x's but the joist hangers start at 2x's and ins fact if you double up your joists and get a Simpson hanger for it it is staill called a double joist hanger not a beam hanger. Quote Link to comment Share on other sites More sharing options...
cplarsen Posted September 5, 2007 Report Share Posted September 5, 2007 Yes, but the math is still the same. Anything vertical = column Anything horizontal = beam Unless you're into structural steel, then it's a girder. All trades have their jargon. Quote Link to comment Share on other sites More sharing options...
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