Building Confidence

Volume 16 Issue 6
ISSN 1923-7162

Welcome to Dave's Shop Talk's Home Improvement Newsletter of questions from our members on their construction projects, a Tip of the Month and a home remodeling article, both from our website at

Tip of the Month

Formica is applied to the plywood top with a solvent based (not latex) contact cement on both surfaces applied in an area with lots of fresh air.

And a Bonus Tip:

Erecting batter boards is a good idea to help get an excavation square and accurate.

Ask Dave!

Dave, this is Ken from Denver hope you are having a good day... I have a question to ask you when setting up the stair gauges I know you set yours up at 7 1/2 for the risers and 10 1/2 for the run when I put my rise measurement from the ground to the top of the deck my riser dimension is different from the 7 1/2 its at 8" is this ok??? And should I set my gauges at 8" and 10 1/2" . Also do I need to subtract an 1 1/2 in from the bottom to compensate for the material 2x4 for the run which is not a true 2" thick but 1 1/2 thick or has the stair calculator all ready do this for me???? Thank You

Hi Ken,

An 8" rise is not really according to the Building Code, 7 3/4 to 7 7/8 is acceptable. Can your raise the ground up a bit to give you a bit less rise?

Yes, at the bottom of the stringer you need to cut off 1 1/2" for the thickness of the tread, then drop it down 1 1/2" from the top to make all the rises the same with the treads on.


Editor's note: The Stair Calculator will show the bottom of the stringer with the thickness of tread to remove, if you input the thickness of tread in the correct box.

Here are the standard code measurements from 2015 International Residential Code-Stairways, Section 311.7

Width of stairs36914
Width handrail to wall31 1/2*787
Width between 2 handrails  27*698
Rise between landings1473734
Riser height7 3/4196
Variation in risers3/89.5
Tread depth10254
Variation in tread depth3/89.5
Nosing radius9/1614
Nosing projection3/4191 1/432
Handrail height on slope3486438965

    * this length in inches is different from the milimeter length in the original document.

Hi Dave, I just found you and do a lot myself around the house. I hope you answer my first question before possible becoming a member. I had to redo my deck and want to tie together the front and left stairs together at the corner creating a wrap around. Definitely does not seem like an easy task. I was able to use pre-cut 5 stair stringers for the faces that are 7" rise and 11" run and know the 45 needs a special cut somehow. Can you help me with the best way to connect the 45degree part. I would be in much debt if you could give me a direction to go in. I can send pic to if needed. Thank You in advance, Jim

Hi Jim, Yes, please send me a pic or two. Dave

Hi Dave Here is a pic. Putting on side stair stringers today. Then it's brainstorm how to connect corners together for a good wrap around where rake is. Was going to use white 1by for risers I think I appreciate any input. Thanks Jim

Photo of backyard deck stairs from a member of our site.

Hi Jim, Thanks for the pic. I notice you have the first step even with the deck. Usually we start a set of stairs 1 riser down from the upper floor or deck. Our Stair Calculator works with the 1st step dropping down a riser, but you can trick it to work with the step even with the deck by adding 1 extra riser. The stringer will then have the same number of risers as runs. Checkout this article on our website: Are you familiar with building a hip roof? If not check out this article for the correct terms: Let me know how you make out on the stair return instructions. Dave

Thanks Dave I will check out the links. The runs should be longer on the 45 stringer correct? I usually start one down but trying to gain that extra foot.

Yes, runs are longer on the 45 stringer.


Feature Article of the Month

(taken from our website:

Tables 4: Common Conversions

Here are some of the more common conversions that are used in the building trades.

We also have a handy conversion calculator

To ConvertToMultiply By
°C (degrees Centigrade)°F (degrees Fahrenheit)1.8 and add 32
kg (kilograms)lb (pounds)2.205
kPa (kilo Pascals)lbf/in² (pounds of force per square inch)0.1450
kPa (kilo Pascals)lbf/ft² (pounds of force per square foot)20.88
L (liters)gal (imperial gallons)0.2200
L/s (liters per second)gal/min (imperial gallons per minute)13.20
lx (lux)ft-candle0.09290
m (meters)ft (feet)3.281
m² (square meters)ft² (square feet)10.76
m³ (cubic meters)ft³ (cubic feet)35.31
mm (millimeters)in. (inches)0.03937
m³/h (cubic meters per hour)ft³/min (cubic feet per minute)0.5886
m/s (meters per second)ft/min (feet per minute)196.9
MJ (megajoules)BTU (British Thermal Units)947.8
N (Newtons)lbf (pounds of force)0.2248
RSI (insulation)R-value (insulation)5.6818

Slope Conversion

There are two ways to measure a slope and each method of measurement can be converted to the other. The two ways are: ratio of rise to run or degree of angle.

Measurement One

Most carpenters are familiar with the ratio of the rise and run for stairs and rafters. The rise is vertical and the run is horizontal. A typical slope of the roof is 5:12, so the rise is 5" and the run is 12". Another way to look at this is the ratio of a slope when the rise is one compared to another value. 5:12, or 5 in 12, becomes 1:2.4 or 1 foot in 2.4 feet. Road builders refer to the gradient of a slope as a percentage. It is still a ratio but the rise is figured in 100 units of run. For example, a 10% gradient is 10 units of rise in 100 units of run, where the units are the same. 5 in 12 becomes 41.67% (percent which means per 100) or 41.67 feet rise in 100 feet or 41.67 inches in 100 inches or 41.67 metres in 100 metres. No matter what unit you use you must measure both the rise and run in the same unit.

Example: To calculate the slope of a roof (referred to as a pitch) of 5:12 to a percent of slope: Divide 5 by 12 = .4167, then multiply by 100 = 41.67%.

As a ratio to a rise of one: 5:12 becomes 1:2.4. (12 divided by 5 = 2.4). To convert 1:2.4 to a percentage, simply divide 1 by 2.4 = .4167, then multiply by 100 = 41.67% - the same as 5:12.

Measurement Two

The second way to measure a slope is by the angle of the slope (in degrees). If you know the angle of the slope you can convert that angle to a rise to run ratio.

This is done by using the tangent, which simply means the rise divided by the run at any given angle. The tangent of a known angle can be looked up in a table or by using a scientific calculator (a calculator that has a tangent button and usually lots of others). You can also find the angle of the slope if you know the rise to run ratio by using the inverse tangent on your calculator (the tangent in reverse, usually looks like this: tan-1) or by looking up the angle in a table of tangents where the angle corresponds to your known slope ratio. That's all a tangent is. It's just the ratio (fraction) of rise over run for any angle of slope.

One important note about angles in calculators. There are three ways to specify an angle (and you only need to know one of them unless you're an engineer): degrees, radians and gradians. You guessed it: degrees is the one to use. You can skip the other two and I won't bother you with their definitions!

The reason the above note is important is because you MUST set your calculator to degrees (instead of rads or grads) otherwise the results of your calculations will NOT be useful to you. There are many types and models of calculators. You want one that can calculate in degrees and has the tangent key (tan) and inverse tangent key (tan-1).

Using your Scientific Calculator to get the rise to run for any known angle of slope:

  1. Set calculator to Deg. (Not Rad or Grad.)
  2. Tan 22.62 degrees = .4167. (On some calculators you need to enter the angle first, then press the tan key. On others you press the tan key first, then enter the angle.)
  3. To convert this to a rise to run ratio multiply the answer by 12. So, in our example .4167 x 12 = 5. The rise to run is 5:12 (5 inches of rise for every 12 inches of run. A typical and useful slope for roofs.)

Using your Scientific Calculator to get the degrees of a slope from a known ratio of rise and run:

  1. Set calculator to Deg. (Not Rad or Grad.)
  2. Divide rise by run. (Example: 5:12 or 1:2.4) 5/12 = .4167
  3. Click the inverse tan button (tan-1). In our example, you will get 22.62 degrees as the result.
  4. Or on some calculators you need to click the inverse tan button first, then enter .4167 to get 22.62 degrees as the result.

You can also check out our Conversion Calculator at our Construction Conversion Calculator and set the Convert field to Slope.

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(Ask Dave) (About Dave)

Your source for building tips, woodworking & furniture plans, house plans and building advice directly from Dave...

Hi, I'm Dave Osborne. With over 50 years experience as a journeyman carpenter, foreman and contractor in heavy construction I enjoyed working with apprentices and sharing the tricks of the trade that others shared with me. Now I get emails from Members all over the world and we include many of my answers in our Free Monthly Newsletters. Some of my answers include drawings and instructions specific to a project, but may also answer your questions. I use correct construction terminology, so you can confidently inform your building supply dealers or contractors exactly what you need.


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