Building Confidence

Volume 21 Issue 7
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 We are into our 21st year putting out this Newsletter. Dan and I would not be able to do this without your input every month. Thank you and keep the questions coming!

Tips of the Month

Always miter the cap in the corner of the deck railing for a nice looking fit. Galvanized nails or screws should be used in any outdoor finishing work, such as backyard decks and deck railing.

When plumbing or framing a house always make the grade stamps on the pipe or lumber you're using, visible to the building inspector.

Ask Dave!

Hey Dave I am building a wrap around set of stairs for a deck and need to know how to calculate the center stringer for a 90 degree wrap around center stringer. Can you guys help me? Attached is a sketch of my project. I have figured out the stringers I need from your stair stringer calculator. I need help figuring the corner stringer, and any supporting stringers. Thanks. Ken Deck stairs corner stringer

Hi Ken, thanks for the sketch. What is the rise and run of your common stringers!

We need to treat the corner stringer similar to a hip roof, and the hip rafter.


Hey Dave, From your stair calculator my total rise is 25 and 1/4 inches and total run is 33 inches. Unit rise is 6 and 5/16 inches and unit run is 11 inches. It would be neat if your brother Dan could incorporate a hip stringer calculator in the program. I am thinking there are a lot of folks who would like to build wrap around deck stairs but are afraid of trying. Thanks. Ken

According to my calculation, the hypotenuse of 11, the 45 degree run is 15.56", 15 9/16". In other words, the diagonal of a square of 11. The rise is the same, 6 5/16"

I'll check with Dan to be sure.


Dan confirms the math!

Thank you. Can I plug these numbers in your stair calculator?

Hi Ken,

Yes, you can plug these numbers into the stair calculator. Choose the override option.

Will you have any overhang on the treads? If not you may need to slice the end of the stringer off to a 45 degree, about 3/4". With a nosing of 1" to 1 1/2" you would not have to 45 the stringer.


Dave, I love your site and newsletters and read every word repeatedly to learn new info and techniques. You also answered several of my questions when I replaced the staircase in my home. My current problem is at my daughter's home. She and her hubby bought a foreclosure and got a really great deal. The windows are all custom sizes (expensive to replace) and several are rotted at the bottom because of a poorly designed landscape irrigation system. Most have some good wood left at the bottom and only one can be probed all the way through. Can I repair the window bottoms in place with an epoxy product, wood filler, or some product you recommend or do we "bite the bullet" and special order ($$$) new windows? Thanks for all your help. You are a great resource for "jack-legged" woodworkers like me! Larry

Hi Larry,

I see from our records that you were with us for 2 years, thanks.

I would try to repair the window bottoms, if they are not too bad. Try to get all the rotted wood out, which is like a cancer and especially any bugs in there. I would try to repair the damage with a new piece of wood, if the damage is large, Otherwise, use a good epoxy body filler for cars for smaller repairs. I like the epoxy putty or filler that they have out now. I've used these quite a bit for repairing fiberglass, steel and wood. Just mix equal amounts and apply it to the surface, let it dry and sand it like wood. I would not replace those expensive windows, if you can make a decent repair on the sill or stoop. Don't use the plastic wood products, though, go with the two part epoxy.


Hi Dave, While I'm vaguely familiar with the concept of venting toilets and other DWV piping, the term mechanical vents is unfamiliar to me. I checked Dave's luck. I Googled it and came up with several medical (breathing) applications. So, what exactly is a mechanical vent in this context? Thanks, Trace

(Trace is referring to our weekly tip: "When retro fitting a plumbing fixture that requires its own vent, use a mechanical vent.")

Hi Trace,

This refers to a small check valve type of vent that opens only one way, when it senses pressure from a drain. It won't over flow, just provide venting so that the p-trap will not siphon out.

Here is a picture of one:

Photo of a check valve for a drain pipe.

It screws into a 1 1/2" ABS female adapter, has a small spring in it. It is allowed by the code under certain conditions:

Section 2.5.9 of the National Plumbing Code of Canada covers this. 2.5.9. Air Admittance Valves (See A- in Appendix A.) Air Admittance Valve as a Vent Terminal 1) Individual vents may terminate with a connection to an air admittance valve as provided in Articles and (See also Sentence Air Admittance Valves 1) Air admittance valves shall only be used to vent a)fixtures located in island counters, b)fixtures that may be affected by frost closure of the vent due to local climatic conditions, c)fixtures in one- and two-family dwellings undergoing renovation, or d)installations where connection to a vent may not be practical. 2) Air admittance valves shall be located a)not less than 100 mm (4") above the horizontal branch drain or fixture drain being vented, b)within the maximum developed length permitted for the vent, and c)not less than 150 mm (6") above insulation materials. Installation Conditions 1) Air admittance valves shall not be installed in supply or return air plenums, or in locations where they may be exposed to freezing temperatures. 2) Air admittance valves shall be installed in accordance with the manufacturer`s installation instructions. 3) Air admittance valves shall be rated for the size of vent pipe to which they are connected. 4) Installed air admittance valves shall be a)accessible, and b)located in a space that allows air to enter the valve. 5) Every drainage system shall have one vent that terminates to the outdoors in conformance with Sentence

Since the Canadian Code has this provision, it doesn't mean that Codes elsewhere are the same. Your local jurisdiction is what counts when codes are involved.

Notice that the code refers to these as air admittance valves, other names are auto vents, mechanical plumbing vents, etc.


Thanks, Dave.- now I've got the picture. I'm in the plumbing business but on the commercial / mechanical side and had not run into this - though I'm familiar with various bronze and iron check valves for water, glycol, steam. etc. Trace

I can understand that, since it is only for residential use, not in commercial installations.


Feature Article of the Month

(taken from our website:

Stairs 9: Answers about Stairs

Here's a list of Dave's answers about building stairs you might find of help. Click on a title to see its answer.

Angle of Stairs

How do we get the correct angles to cut the stair stringers and handrail posts?    [see answer]

Bouncy Stringers

I have straight-run, open riser stairs up two stories. Each flight has about 17 risers. I was planning on using 2x12s for the stringers, but once they were installed and the treads were put on, they were still very bouncy.    [see answer]

Building Deck Stairs

How to cut the bottom of the stair stringers so the steps of the backyard wood deck stairs stay level to make up for the unevenness of the ground.    [see answer]

Concrete Landing

I took the old concrete landing out from under the front steps because it was not level. How would you go about replacing it with a new one?    [see answer]

Cut Stringer

I'm pretty good with tools, but I'm concerned with getting straight cuts on the stair stringers with my circular saw. Are there any tricks or helpful hints on making straight cuts with a circular saw?    [see answer]

Dadoed Stringers

Some stairs are made by cutting a groove in the stringers for the threads to fit into. Is this done with a router? If so, what kind of jig does it require?    [see answer]

Different Length Stair Stringers

I have a 21 inch plumb from my deck to the concrete below. My problem is that the concrete is not even, it slopes away from the house. I'd like to use two stringers (2x10) and then bracket two steps between them. How do I measure the dist    [see answer]

Glass Railing

What would be the best railing and baluster combination for a glass pane?    [see answer]

Handrail to Newel

I am installing a handrail on my landing and down the stairs. Your instructions given on how to do this includes everything I need except how to attach the handrail to the newel posts. Could you explain how to do that?    [see answer]

Hardwood Stairs

How new hardwood should be attached to an existing stair case.    [see answer]

How to Build Deck Stairs

I just built a new backyard wood deck, which turned out rather well. I am however having difficulty making up deck stairs. My total rise from the ground to the top of the deck board is 20.5 inches.    [see answer]

How to Install Stair Spindles

How to determine an equal size spacing between stair spindles.    [see answer]

Newel Posts

What is the recommended distance between newel posts for a balcony?    [see answer]

Open Riser

With an open riser stair, how do you connect the stair treads to the stair stringer?    [see answer]

Pine Stair Treads

Is pine okay for stair treads or is it too soft a wood?    [see answer]

Risers and Treads

When installing stair treads and risers some people are telling us the riser goes on top of the tread. We prefer the look of it behind the tread and thats what it looks like on your page. We just want to know the correct way of installin    [see answer]

Splicing Stringers

I need to make stair stringers for a 10' rise. This will work out to the stringer being 18 to 20 feet long. I can only find 16' 2 X 12's. Is it okay to splice them to make them long enough? if so HOW?    [see answer]

Stair Landing

Should I add a landing in the middle of a 10' rise or use stronger wood for the stringer?    [see answer]

Stair Repair

One stair in my basement stairs is shorter than the rest by about 1/4 inch. I'm thinking of two solutions, but wanted to see what you say first.    [see answer]

Stair Risers

What size nails or screws would you suggest using for nailing/screwing the stair risers if I'm using 1/2 inch plywood for the risers?    [see answer]

Stair Rises and Runs

I want to build some stairs and I want the total rise to be 2 1/2 feet high, the rise 6 inches and the run 12 inches. Can you give a diagram of what it will look like?    [see answer]

Stair Runs and Risers

Why our Stair Case Calculator always gives one less run than the number of risers.    [see answer]

Stair Skirt

I want to replace the stair skirt boards with oak to match the stairs. Treads and risers were cut and installed to match the old fir skirt boards, and oak is thicker dimension. Where do I start?    [see answer]

Stair Stringers

I've got a nice stair case but it needs support stringers. How do I cut the stringers?    [see answer]

Stair Tread Thickness

If I cut 16 runs at 7 1/2 inches each, wouldn't my very first step be 9 inches?    [see answer]

Stair Treads

I used 2x12 non-pressure treated boards for the treads. A couple of carpenters told me the treads should be ripped into two 5 3/4 inch treads to avoid splitting and cupping of the stairs in a couple of years. Any advice on this?    [see answer]

Stair Trim

I'm going to be installing yellow pine over the stairs inside my house. They are between two walls and I would like to put trim boards along the walls on both sides, down the stairs. How is this typically done?    [see answer]

Stair Width

What width should indoor stairs be? They will be going to a master bedroom upstairs. I was thinking about 42 inches. They will be a straight run.    [see answer]

Stair Winders

How do you build winder stairs to save space?    [see answer]

Stairs Repair

The level of the concrete in my basement floor is off about an inch between where the ends of the stair stringers will be. This means the stringer height will be different. How should I fit and trim these two stringers?    [see answer]

Story Height

What are the measurements of one story or the total rise of a one story staircase?    [see answer]

Stringer Board

Dave what's the standard size board for a stringer?    [see answer]

Stringer on Concrete

The inspector said I have to protect my outside stair stringers from the concrete on the outside landing. What does he mean?    [see answer]

Stringer on Pavement

How do I secure the bottom of the stringer to the paving slab?    [see answer]

Stringer to Joist

What is the best way to attach the stair stringers to the floor joist?    [see answer]

Tile on Riser

I want to replace my existing painted wood risers with slate or some durable tile. Is this possible and if so, how do I remove them to replace them or should I tile right over the existing riser?    [see answer]

Tread Thickness

Does the thickness of the stair tread change the total rise?    [see answer]

Veneering Stair Trim

I need to put new treads and risers on my indoor entry stairs. How do I remove the existing skirt boards? Or do I just veneer the old ones?    [see answer]

Wood on Cement

The bottoms of my stringers are resting directly on cement. How can I maintain some sort of dry spacing so they don't rot out like the old ones did?    [see answer]


Almost the End

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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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