www.constructioncalc.comExample Hot Tub Deck Design Using ConstructionCalc Software, v2.0Note: The following example assumes you are a beginner. You should expect this to goslowly at first. However, with a little practice, getting solutions with ConstructionCalc isabout a one minute job. Awesome.1) General. In all ConstructionCalc programs you can type in a name of the memberyou’re designing, job name, date, etc. in the three cells at the top.1 of 1

www.constructioncalc.com2) Joist Design. We have to assume a joist spacing to start. Let’s try 16” spacing.a) We need to know the live and dead load.i) Live Load: Live load will come from the tub and its occupants; in ourexample the manufacturer tells us the maximum load will be 8,000 lbs. Wewill assume this load is spread evenly over the tub’s footprint, thereby loadingthe joists equally (verify with tub manufacturer to be sure). The footprint is8’x8’ 64 square feet, so the “psf” (pounds per square foot) live loading is:8,000 / 64 125 psf.ii) Dead Load: Dead load for a deck is the weight of the decking material andthe joists themselves, say 15 psf approximately (check out ConstructionCalcGeneral Loads Calculator for more on this topic).b) Let’s open the ConstructionCalc Wood Beam Calculator and enter data:i) Span: This is the inside of bearing to inside of bearing dimension of a typicaljoist. If the joists bear on a beam at each end, span is the distance between thebeams. In our example: 8 feet. (Note: only enter numbers, no symbols,spaces, or units – the program does that for you.)ii) Maximum Allowed Deflection: This is the amount of deflection (sag) we’rewilling to allow for the joists (see red triangle note for more). Let’s use thedefault values of L/360 for live load deflection and L/240 for total deflection.iii) Load Duration: Since we’re designing floor joists which will have the liveload there all the time, let’s select 10 yrs.iv) Add Self-Weight? Since the joist’s self-weight is already included in the 15psf dead load from above, and we don’t want to add it twice, we’ll select No.v) Loads Other Than Uniform Loads? These joists won’t ever see a point(concentrated) load, or other unusual load, so select Uniform Loads Over the Full Length of Member: Our joist will feel its loadover its entire length, so this is our section to input load data. Our load is aFloor Load, so under that row enter:(1) 125 for live load(2) 15 for dead load(3) Tributary width will be the joist’s spacing in feet, which is 16/12 1.3(Cool tip: because you’re using a ConstructionCalc product, if you enterthe following: 16/12 and then press Tab, you’ll see 1.3 displayedautomatically. In other words you can do math right in the cell by startingwith an equals sign. Try it. Very cool, very powerful.)vii) Done. Click on Calculate Now and let’s check our results.c) Allowable Solutions2 of 2

www.constructioncalc.comi) This section shows all the types and sizes of members that will work. We’reonly interested in 2x material, so that section is all we’ll look at. Certainly ifwe wanted to use a TJI or any other type of member shown we could.ii) In the Section 4x and Smaller (Lumber), let’s select the type of lumber wewant. Since this is an exterior application which will get rained on, we wantto use Hem Fir, pressure treated. (Note, there is nothing that specifically says“pressure treated”, but that’s okay. Pressure treated lumber has slightly lowerstrength values than non-pressure treated, but as long as we make sure ourfinal selected design is okay by at least 10%, we’re fine.) We know thelumber yard has lots of No 2 grade in stock, so we’ll select No 2.iii) Repetitive Member Use? We’re designing joists which will be spaced lessthan 24” apart and will share the applied load, so we want to select Yes.iv) With Hem Fir, No 2 selected, we see that 2x10 will work (we could also usedouble 2x8’s and some other odd sizes that show up in the table). Remember,our joist spacing (tributary width) from above is 1.3’, or 16”.d) Final Selection. We could stop at this point knowing a 2x10, HF #2 works, butlet’s continue and see how efficient that member is.i) Final Member: We want to use Hem Fir No. 2, which is Sawn Wood.ii) Final Size: 2x10iii) Minimum Bearing Length: Upon making the above selection, the minimumbearing length (to avoid crushing of the joist at the bearing point) is calculatedand displayed. In our case, the joist must sit on the beam over a length of atleast 1.5 inches; or the joist could sit in a hanger with a minimum cup lengthof 1.5 inches.iv) Reactions. This section shows the force applied to the bearing beam at eachend of the joist.v) Efficiency of Member: this section shows by how much the selected memberis over-designed for the three code-required design criteria. Usually, I justlook at the bottom sentence that says in our case: This member makes it by18.0%. A good safe design, even if we use pressure treated Add’l Detail – Not Including Self Weight. This section shows a bunch ofengineering information that may or may not be of interest to you.e) Printout. You may want to print this design. Because this ConstructionCalcproduct is nothing more than a fancy Excel spreadsheet, you have tons of printingoptions via File, Page Setup. Also, you can hide various parts of the display viathe ConstructionCalc Hide / Show Loads and Miscellaneous dropdowns towardthe top of the page.3 of 3

www.constructioncalc.com3) Beam Design (This example will go a little faster because I won’t repeat the basicstuff learned in the joist design above.)a) Let’s input the required data into the Wood Beam Calculator:i) General: Change Beam ID from Joist to Beam (optional).ii) Span: Inside of post to inside of post is 8’ (pure coincidence that this turns outthe same as the joists span; it usually doesn’t work this way).iii) Deflection: Use L/360 and L/240 defaultsiv) Load Duration: Ten years livev) Add Self Weight? Yes we want to add the beam’s self weight to the designbecause the 15 psf dead load we’ll use in a minute does not include thebeam’s self-weight (though it does include the weight of the joists anddecking).vi) Loads Other Than Uniform? No, because the loads applied to this beamcomes from uniformly spaced joists of equal length and loading. In otherwords, the beam’s load is uniform across the beam’s length – there’s no pointloads or other weird loads.vii) Uniform Loads Over Full Length of Member: Let’s use the same Floor Loadrow as before:(1) Live: 125, same as before(2) Dead: 15, same as before(3) Tributary Width: This is the only loading criteria that changes. This beamgets its load from the joists, and in particular half the span of the joistsgoes to this beam. The other half of the joist’s load goes to the beam onthe other side of the deck. So the tributary width for this beam is half ofthe joist’s span: 8/2 4’.viii)Done, now let’s check results.b) Allowable Solutions.i) We need Hem Fir, pressure treated again, so let’s give ourselves a coupleoptions:(1) Tripled 2x. In the 4x And Smaller section; first, this beam gets no helpfrom another member, i.e. it acts alone so we select No to RepetitiveMember Use?. Make sure Hem Fir, No. 2 is selected in the drop-downsand you can see that (3) 2x10’s work.(2) Single Beam. In the 5x and Larger section, select Hem Fir, No. 2 and a6x12 or 8x10 are all that will work.4 of 4 But Wait. Back in the 4x and Smaller section we see that a 4x12 alsoworks. This may come in handy if we want to use 4x posts.c) Final Memberi) I like the 4x12 because I want to use 4x posts and want my beam to match upwell. Selecting it shows it makes it by 14.8% - okay, even for a pressuretreated member.ii) Minimum Bearing Length is 1.58” – okay. This beam will sit on posts of atleast 4x4 dimension, so there will be plenty of space to accommodate 1.58”bearing length.iii) Print the results if you wish.iv) Check your work. If you’re worried you may have goofed something on theinput and want a rough check, first, look at the Load and Span Diagram in theupper right of the sheet. The span is shown in feet on the horizontal axis andthe loads on the vertical. A uniform load will look like a rectangular box overthe entire beam.Now take a look at the Reactions at the bottom of the sheet. We know the tuband occupants weighs 8,000 lbs; plus the deck itself (dead weight) will be acouple or few hundred pounds. So the beam we just designed should carryhalf of this total weight or about 4,200 lbs give or take (the beam on the otherside of the deck carries the other half). Because our beam is loaded uniformly,we’d expect each end to have the same reaction, which should be half of our4,200 lbs 2,100 lbs, give or take. The printout shows reactions at each endof our beam of 2,240 lbs. Close enough; we’re good to go.5 of 5

www.constructioncalc.com4) Post Designa) Open ConstructionCalc Column Calculatorb) General Inputi) Beam ID, Job Name, etc.; similar as before.ii) Length: This is the length from the bottom of beam (applied load) to bottomof column (top of footing), in our example 6’. Note: to be conservative,always use the maximum probable length, particularly in cases where you’redesigning a typical column and some are longer than others. With columnsand studs, length has everything to do with strength: the longer the column,the more prone to buckling (weaker). Thus short columns and studs arestronger than long ones of the same dimensions.iii) Maximum Live Deflection: This is for columns or studs subject to windloading. Not applicable in our case, so stay with the default value of L/175.iv) Type of Column, Stud, or Post: Select the most appropriate. This has to dowith lateral bracing and resistance to buckling. If in doubt, Unbraced Columnor Post is the most conservative. In our case Unbraced Column or Post iswhat we have.v) Load Duration: Our post will be subjected to 10 yrs live, just like the beamand joist from which its load Off Center or Other Bending Loads: This is for columns or studs subjected tobending either from compression loads applied off-center from the middle ofthe member (such as from a nailed-on ledger) or other means, such as a kneebrace. In our case, the post will be loaded only from the beam which will sitdirectly on top of the post, thus we select No.c) Applied Gravity Loadsi) This section can be used in several ways. You can input “psf” loads andtributary areas, or simply input previously known compressive loading. Sincewe already calc’d the beam which applies load to our post, we’ll simply inputthose known live and dead loads in the row called Other Point Load :(1) Description: From beam Reactions.(2) Live: 2000 (from beam design output under Reactions)(3) Dead: 240 (from beam design output under Reactions)d) Wind Load. This post will be subjected to no significant wind loading, thus weleave this section blank. It is important to note however, that diagonal bracingmust be installed on all four sides as shown in the sketch or the entire deck canfall over sideways.e) Acceptable Solutions. We can choose from any type of wood shown in the tables.6 of 6

www.constructioncalc.comi) Ours is an outdoor application, so we’ll choose Hem Firii) We know the lumber yard has lots of No. 2 grade on hand so we’ll select that.iii) We see that a 4x4 makes it. Good because this is an inexpensive member andwill match up nicely with our 4x12 beam. Certainly we could use anythinglarger too; the tables only show minimum sizes.f) Final Selectioni) Choose Sawn Wood, 4x4 and we see this member makes it by 77.4% - wayokay, even for pressure treated.7 of 7

www.constructioncalc.com5) Footing Designa) Open ConstructionCalc Square Footing Calculatorb) Applied Footing LoadsSimilar to the column calculator, this section can be used in several ways. Youcan input “psf” loads and tributary areas, or simply input previously knownloading. We can use the same loads we used for the post design except we shouldalso add a little extra dead load to account for the weight of the post itself, say 20pounds extra:i) Description: From beam Reactions 20lbii) Live: 2000 (from Beam design output under Reactions)iii) Dead: 260 (240 lb from Beam design output under Reactions plus 20 lbs forpost self-weight).c) Soil and Footing Input.i) Soil Bearing Capacity. Use 1,500. See red triangle popup note for typicals.ii) Permit Soil Bearing Capacity Increase for Size and Depth? The UBC codeallows the soil bearing capacity to be bumped up for large, deep footings.This toggle allows you to use that or not. It is conservative to select No,particularly if you don’t have a geotechnical report and aren’t sure how goodyour soils are. If your footings are small and shallow, either selection is okaybecause your design won’t be affected.iii) Depth to Bottom of Footing. This is the vertical distance from original nativeground to bottom of footing. We’ll use 2 feet.iv) Depth of Soil Over Top of Footing. If there will be soil piled on top of thefinished footing, input that depth here. For our example, use 0.v) Square Footing Width. Make a guess as to what you’d like the footing widthto be. You may come back and change this later, but for now just make yourbest guess. We’ll start with 1.5 Footing Depth. Make a stab at what thickness you’d like. You may wind upchanging it later. We’ll start with 8 inches.vii) Post or Bearing Plate Narrowest Dimension. We’re using a 4x4 post, so thenarrowest dimension will be 3.5 inches.d) Concrete and Rebar Inputi) Concrete Strength. Use standard 5 sack concrete 2,500 psiii) Steel Yield Strength. Rebar comes in two grades: 40 and 60. Grade 40 has ayield strength of 40,000 and grade 60 is 60,000. If in doubt use 40,0008 of 8

www.constructioncalc.comiii) Rebar Cover. This is the distance from bottom of footing to lowest rebar.Use 3 inches. Note, 3 inches is the code minimum for concrete placed againstground (an un-formed surface).iv) Rebar