Aussie Stairs American Style

Hofmann

After an attempt at hyjacking one of Macs threads and getting a firm but fair warning, I've finaly started my first thread. All the stairs I've built so far, and I've done a few, have been closed stringer, open riser but I've just won a job to build a 26 foot wide staircase so I'm going to have to jump onto the american side of the fence for this one. 6 treads 12" wide and the risers will be somewhere round 5" and raked back 8 degrees. both treads and risers lined with 4" Australian hardwood decking with 4mm gaps. The decking only spans about 20 inches so there's going to be tons of stringers. By the way, the architect drew it up to be framed up in 4x2. It'd be a bloody spaceship by the time I was done. Anyway, I haven't worked it out properly yet but if I use 12" stringers there will only be say 4" left in the narrowest parts. Stringers are pine. I'll obviously have a bearer running the full length to pick up the bottom of the stringers and I'm wondering if I should run a purlin through the middle of them too. Or is it easier to lace lengths of 2x4 to the side? I should also point out that this leads onto a massive deck and then to a cafe/function center so I have to assume that they could have a fat camp before photo on it. Of course, to make it a challenge, it narrows substantially on your way down the stairs so my two end stringers are going to have to be at an angle of, say 20 degrees. I'm looking for ideas to mark these out. At the moment all I can come up with is running a straight edge over the normal stringers and marking it on the angled stringer which would be in position. Bit clumsy. I'm probably going to have to have a creeper stringer too. Any ideas and comments appreciated. By the way, I'm converting to imperial to keep you yanks happy so if you've seen the light and are using metric, don't convert back to your crazy measurements on my behalf

neolitic

This part, I understand!
Gonna have some really hefty folk
on the stairs.
The rest?
It ain't just the metric system, we've got
some terminology issues here too.
Can you post a drawing?

__________________
Put your location in your profile!
(Sorry....it seems there really are dumb questions)

Hofmann

Yeah just reread that and had trouble understanding it myself. Basically just a very wide staircase with decking for treads and risers and about 8ft narrower at the bottom than the top. Is there any terminology in particular? I can try and scan the plans but its my first crack at it so have patience. and risers will be more like 7". Cheers

MALCO.New.York

Then go back and edit it!!!!!

__________________
Something to One may be Nothing to another!

Ultimate Wisdom---------
http://www.youtube.com/watch?v=OW-cnizLDEE

BuiltByMAC

Is this what the top down view looks like? (Not to scale)

Mac

Attached Images

 

Joe Carola

To start off with, if your using 2x12 stringers with a 5" rise and 12" tread, you will have 6-7/8" left after the cut out on all the string but the first one. The first one cutting out rough 1" for the thickness of the decking making your first riser 4", you will have 4-5/16" left, but that will be sitting on a pad, so that's alright.

Tell me if this is close to what you're talking about.

Attached Thumbnails

 

__________________
Joe Carola

neolitic

When he says risers "raked back",
I think they are battered risers
(out of plumb)?

__________________
Put your location in your profile!
(Sorry....it seems there really are dumb questions)

BuiltByMAC

Joe, you're on the ball this morning! Here's another view, using (266.7mm) 10 1/2" cutout for (292.1 mm) 12" treads (leaving (38.1 mm) 1 1/2" for nosing over riser).

Hofman, you got lots of meat left in that stringer w/ only (127 mm) 5" risers.

Mac

Attached Images

 

Joe Carola

Neolitic,

Thank you for picking that up. You think this is what he's talking about?

Attached Thumbnails

 

__________________
Joe Carola

BuiltByMAC

Wouldn't it go the other way to prevent a poss. trip hazard?

Mac

Joe Carola

Mac,

I don't know. Either way, back or forward you would have to lay out the tread if going back 1" bigger at 13" and going forward 1" smaller at 11".

Attached Thumbnails

 

__________________
Joe Carola

BuiltByMAC

Since he's only got a (292.1 mm) 12" tread, you wouldn't cut the stringer anymore than that. You can have the rake angled backward (bottom is further back than top), notch the stringer (266.7 mm) 10 1/2", have your tread overhang the notch (38.1 mm) 1 1/2" which would give you a (12.7 mm) 1/2" nose while covering the top of the (25.4 mm) 1" thick riser.

ETA: Check my diagram in post#8 for a pic of what I'm talking about...

Treads would sit all the way back in the notch and risers would sit on top of them.

Mac

neolitic

If Joe's last drawing looked like Mac's
last description, I think that's his stringer.
Maybe he'll be back in a bit.
I think it's some where between 4:30
and 6:30 Sunday morning there now???

__________________
Put your location in your profile!
(Sorry....it seems there really are dumb questions)

Hofmann

Ok Im back Im back. You guys are machines. You seem to have made sense of my post. I knew you would. Mac, your top view is bang on and Joe, your elevation is right except for the raking risers. I buggered up the conversion Joe, the risers will be 7". The risers are raking back the way Mac has shown.

Hofmann

Couple of things Mac. Firstly our decking boards are only 18mm (7/8" ?) thick. Also because they are only 4" decking boards, I have to be carefull how far I overhang the nosing. It can't really be more than a 1/4" or the nail will have to be too far back. To be honest it will probaby be more like 1/8" and I think thats why the architect raked back the risers. Also,while your nosing and notch comes to 12", I don't think you allowed for the 18mm of riser board at the back of the tread. I'm pretty sure my notches are going to be 12"x7" except for the bottom one.

wallmaxx

The sloped riser cut is easy...I guess y'all have similar codes. This was an ADA requirement for a multi-family in Ocean Shores, WA.

If Mac, Joe or Neo are assisting you...you are in good hands.

Hofmann

Sorry Joe, just had a look at your diagram in post 11 and that's it. So it leaves me 5 7/16". Is that enough to span the 6 treads. To be fair there's a lot of stringers, every 18". I aso need to work out how to support the bottom of the stringers. I don't really want to put every one on its own post foot plus I'd need a strip footing. so I was going to use a doubled up 2x4 as a bearer with post feet at 4' centres. Problem is, 4" of bearer plus post feet is going to bring me pretty close to the top of my first tread. I can use joist boots but I don't like it plus I would have to spend hours with a plane raking back my bearer to match the other risers. Ideas? If I gotta do the strip footing I will.

Hofmann

Thanks for that Wallmax. Now you guys have got the terminology on me. Whats ADA and whats a multi family. I am sure that if the stairs are strong enough for you guys they will be strong enough for us. ( You guys have more mcdonalds than we do. ha ha) Your template has fewer treads than mine will though so I've gotta span a bit further. By WA I assume you must be talking about Western Australia.

Joe Carola

If your finished notches have to be 7"x12", I would layout the stringers 7"x11" and come back 1" on the bottom and that will give you a finished 12" tread. First step cut the rise to 6-1/8".

Attached Thumbnails

 

__________________
Joe Carola

Hofmann

Yeah, that looks awesome joe. I need to sort out that first tread detail though. I assume you guys don't cut your stringers hard to the ground. We have the joy of whiteants which you probably don't have in your temperate climates. Although they won't touch the treated pine stringers, they'll make mincemeat of the hardwood decking. I've seen them eat an entire home in a couple of years. So I will have to keep the stringers at least 2" off the ground so the post feet can be inspected for their little mud trails. If I want to use a bearer as well you can see my dilema. ( I think thats how you spell it. I wish this site had spell check. I've seen people shredded here for bad spelling)