Spindle Spacing

Mike604

just wondering what is the easiest and simple solution for finding out eqaul spacing of spindles on interior railings and do the trade master calc, help you and will figure this out....

any help would be great

Teetorbilt

Code here is >4". They have a ball that they use.

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concretemasonry

I think there is also a 6"(?) ball for stairs between the bottom rail and the tread/riser.

Despite the formulas and methods, the thing that will catch you is the real world when the inspector's ball slides through.

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Engineer, designer and consultant recently active domestically and internationally on construction and design in about 35 countries.

WilsonRMDL

What teetor said. 4" sphere cannot fit between spindles.

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wallmaxx

see if this works

span = 36'
spindles = 1 1/2"

4" min code plus 1 1/2" = 5 1/2"

36 / 5.5 = 6.545454 (7 sets that's 6 spindles and 7 spaces)

Take 36 - (6 x 1 1/2") then divide by 7

each space is 3 7/8"

zzzzzzzzzz monster is nearby so use this info at your own risk

send_it_all

I think I understand what you are asking. It's not the code but a formula to figure out equal spaces, right?

Here's my attempt. Take the total distance between newel posts...say for instance it's 10'...or 120".

Then measure the thickness of each spindle at their base...say it's an inch and a half. Multiply that measurement by the total number of spindles...say there are 30 spindles.....so 30 times 1.5" is 45". Subtract 45" from the total span which was 120"...so you have 75". Now you divide that number by the number of SPACES you will have between spindles....that will be 31 (always one number higher than the number of spindles). In this hypethetical example (I pulled numbers out of my a**) the correct spacing would be 2.42" or about
2-3/8"+.
Hope this helped...it's harder to explain than to do. If you don't get this, come back and give me the numbers and I'll figure it out.

send_it_all

Damn you wallmaxx and your fast typing.

JLTrim

Hey, I haven't done railings in a while, but just to clarify for future reference, the 4" rule applies to the narrowest part of the spindle, correct?

AtlanticWBConst

It applies "center" to "center": "Center" of the spindle/balluster - to the "Center" of the next spindle/balluster.

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skymaster

Atlantic; yes centerline, therefore using 1.5" spindles the MAX center to center distance will be 5.5". For real comfort I use 5 1/4 MAX, since the real test is that " a 4" diam ball cannot pass thru the space between the spindles"
The real "gotcha" is to make very very sure you have LESS than 4" bwtween them at their SMALLEST dia!!!!!! IE tho the bottom of the spindles may be fine CHECK AT THE TOP WHERE THE SMALLEST PART OF THE TAPER IS If the ball passes thru there no matter that it doesnt at the bottom you fail. You may find that you have to go down to maybe 3 1/2 or 4 on center at the base to comply

genecarp

3.5

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A.T.H.I.

Around here according to code we are allowed a 4" space between each spindel (ballast) edge to edge. I always make sure that I place my ballasts 4" O.C. that way they is no way I will get a code violation. I might have to use a few extra ballasts but it makes a stronger railing and allows me some extra room to make my railings look evenly spaced.

pfloyd

Is that 4 on the slope or horizontal?

The Woodtick

I know that the baluster spacing is 4" on a landing and 4 1/4" up the stair. That is the UBC code. I just had to look it up for a job I'm going to do. I found the best way to space balusters is using their centers not the sides, that way I can use a compass. I bought a cheap one at the hardware store. I set it to 4" plus the thickness of the thinest part of one spindle. I then walk it along the path of the rail. I can use this system on curved stuff and straight. You have to make allowances for either end, ei. the start and end points. It seems kind of confusing but man it works great. I don't do well with making computations and they never really work out that well for me. I'm better at laying it out on the work and messing with it from there. I was shown this technique a year or so ago by a guy that was doing a work shop for a local lumber yard. What a character. He called him self the Stairguy and wow did he build some incredible stairs. Most of the stuff he was teaching was real primer print for him but a God send for us. I should try to find out if he has a website. He said he was working on a stair build video. I wonder if he ever got it done? Any body got ideas on good newel post fastening hardware? I could use some.

Railman

It's SIMPLE!
All codes that refer to 4" max spherical spacing are referring to the largest space between components. On turned balusters (spindles) that point would be at the smallest spindle diameter. It's common for a baluster to have a 1 3/4" block at each end, & a 7/8" minimum turning diameter. In such a case, you may as well have a 7/8" dowel rod as far as bals spacing is concerned. The same applies to the newel post also.

It's kinda interesting that LJ Smith still gives faulty formulas in their installation literature. This is because it's still based on old code, on center methodology. It don't work for spherical spacing, because it doesn't take into account the turning diameters.

I prefer to keep the layout simple, & use a the SAME BURY values whether dealing with a turned newel, or dieing into a wall.

Example:
5015 taper (3/4" pin top bals)
4040 nl = 3/4" deep center cut (3" block, 1 1/2" dia center)
code = 4" spherical
On center = 4 + 3/4 = 4.75 oc (max value, use less for error margin)
safe bury value = 1/2 bals min + newel cut depth
(1/2 x 3/4) + 3/4 = 1 1/8" BURY ( @ each end of run)

Spaces = overall run / OC
If wall to nl block = 100" , then oa run = 100 + (2 x 1 1/8) = 102 1/4
102.25 / 4.75 = 21.53 (round up to whole number) = 22 spaces
102.25 / 22 = 4.64 OC ( apx 1/8" less than max code )

First center will start buried in wall or newel 1.125, & then 4.64 OC from there. So 1st center would be 4.64 - 1.125 = 3.52 from wall or nl block face.
Balance of layout is 4.64 OC.

For slope runs, I do the same thing with a converted OC value.
I use a slope conversion factor = to the hypotenuse/base of stair section, or the hypotenuse of the tread rise to run triangle, div by the tread run.
Example:
8 rise , 9 run: sq rt of (64 + 81) = 12.04
12.04 / 9 = 1.34
slope conv fact = 1.34
So, take 1.34 x 4.75 oc = 6.37 OC max on slope run.
You also need to convert the bury value using the same conversion factor.
1.125" x 1.34 = 1.50 slope bury

Note: This conversion factor is actually a secant value of the stair slope angle.
Secant t = hypotenuse/adjacent, where t = the measured slope degrees of the stair.
Tread rise run values are plenty accurate for this conversion factor, but I use the measured slope degrees in my job spreadsheets, since I need the measured degrees for rail assemblies anyhow.
On site, the basic triangle math is simpler using the rise run of a stair tread.

Slope stair layout example, using same 100" between newel blocks, on same 8 rise x 9 run stair :
slope bury = level bury x slope conv fact = 1.125 x 1.34 = 1.50
100 run + 1.5+1.5 = 103" total run.
max slope oc = level oc x slope conv fact = 4.75 x 1.34 = 6.37 oc max
103 / 6.37 = 16.17 , round up to whole number of 17 spaces.
103 / 17 = 6.06 oc ( well below max oc )
1st center buries 1.5" into newel, so from nl face,
so 1st center is 6.06 - 1.5 = 4.55
Balance is 6.06 OC.

The slope conversion factor may seem confusing at first, but is very easy & accurate once you do it a few times.
It's also easy to generate a degree chart on a spreadsheet.
As starting point for stair slope deg and slope conv fact:
42 = 1.34 slope factor
41 = 1.33
40 = 1.31
39 = 1.29
38 = 1.27
37 = 1.25
36 = 1.24

Piece of cake!
Joe

wallmaxx

Okay then. I think that about covers it.

We can put this one to bed

wink

if you put the square bottom part of your balluster lined up with your riser,below your tread then space the next one on the tread so that it meets code, the spacing should be the same on all of your treads. given your treads are all the same size. some railings may even need 3 ballusters (spindles), to meet code. then lay your railing on the treads and you can mark your railing and get the angle to drill all at the same time, if your newel post is plum it will even let you mark your length and the angle of cut.i know i don't always explain myself clearly, but this system works out for me, and i don't have to do halucinagenics to figure out some formulas like were given earlier. no offense. if you look at a well built stairway, the ballusters all land on the same spot on the tread. thanks for letting me ramble wink

Railman

Wink,
Your right about open tread stairs. For them, std layout is 1st bals block face lined up with the lower riser, & then divy up tread run dimension for the tread O.C, while still meeting 4" spherical code. For the rail OC layout, try marking the top, & bottom baluster onto the rail, & then dividing up the overall by the space count. It's easier than trying to transfer every bals center to the rail, & is less likely to have big space errors.

My "hallucinagenic" post referred to cap wall stair rails, which are probably more common today than open tread. Open tread stairs cost more, & hence are used less on most high volume builder homes. If I had gotten into open tread stairs at the same time, it would have just made it more complicated. I doubt anyone would have even read the whole thing!


If anyone has any questions about my posts, please ask away.
Joe

wink

Joe, I mean you no offense, but i can put the rail up before i figure out wtf you said.

Railman

Wink,
If you draw a rise/run right triangle, & measure the long side, you can find the slope conversion the same way. Just divide the longest side (hyp), by the base (run). That'll give a multiplier to change level on centers 's to pitch on centers. It's just a simple ratio. It's not that hard!

I've seen similar techniques with Norm Abrams, drawing full scale rail layouts on sheets of plywood. This method is light years easier than that.

If all you do is open tread stairs, then it probably won't do anything for you.
Joe