Decks, Patios, Porches and Docks - Angled Stringers

Hi,

I'm planning to rebuild a porch on our semi-detached house (my side as well as the neighbors). Our old brick columns are completely falling apart. Anyway, we'd like a stair case that spans both sides and flares out from top to bottom. I've attached a picture below to give you an idea what I'm talking about.

My question is: How do I build the stringers for the 90º angle corners? I'm assuming I'd need a stringer on a 45º angle, and then another running parallel to the porch to support the short steps on the side, but I'm having a hard time picture how it would all fit together.

Any suggestions would be greatly appreciated. Thanks!

Nick

http://joose.ca/porch.jpg

NickTodd,

Welcome to the forums.

As drawn, the simplest way to achieve the steps would be to biuld a series of boxes (one for each step) that get progressively narrower and shorter to keep the rise and run consistant, and attach the boxes to each other as you build your way up.

Hi Nick, lefty has got the method, if you want to review the numbers just give us the total rise you have to deal with. The only issue I see is Toronto, and frost. Your porch I assume is resting on supports that extend below the frost line. Your steps will probably be floating, so they will rise and fall with the frost. That's ok, as long as you don't attach the back of the steps to the deck. Happy to provide details, just let us know.

Bud

When you ask your building department about frost heave, also remember handrail questions. By my local IRC code would require one for 4 and more risers. Be safe, G

Yes, as drawn, the IRC would require a handrail for this. Attach it to the center post at the top and to a post directly below that at ground level.

Attaching to the center post and to the bottom of the steps brings the frost issue back into play???

Bud

I would cut a stringer on the 45 degree angle. The rise would be the same but the tread would be longer and you would just use (a*a) + (b*b) = (c*c) where c would be your new longer tread width and a and b would be your regular tread width. For example, if your tread is 10", you would have

(10*10) +(10*10) = (c*c)

100 + 100 = (c*c)

c = square root of 200

c = new tread width = 14 1/8"

Now just use your framing square and mark your stringer using that number keeping in mind how you are attaching to your ledger.

The way it is drawn, the boards on all of your treads are parallel. There is no reason to have an angled stringer. Frame each box so that it will catch the ends of the short deck boards at the end of each step.

NickTodd is showing 3 steps -- he has 4 rises. Divide the total height from where the largest step sits on the ground to the top of the porch by 4 and that becomes the rise for each of the steps. Make the largest box that tall minus the thickness of the decking. The middle and smallest box are the height of the rise and sit on the box below them. Once you deck everything, all of your rises are equal.

If frost is an issue, that determines what size you'll need for footings for the steps as well as for the handrail.