Hi,

I'm about to build the access stairs to my new raised deck which will go up to approximately 1400 mm and have 8 steps.

The rise will be 180 mm and the going 260 mm and I intend to have three stringers (the width of the stairs will be around 870 mm).

Locally the largest size of treated timber readily available seems to be 225 x 47 and I was going to use this to cut open stringers from but it would only leave around 75 mm of timber at the bottom of each cut out. I have seen some pre-cut ones like this but they were only 5 steps high.

On-line a lot of US sites seem to recommend using 12" x 2" timber which would obviously be much stronger but I can't seem to get it.

So my question is will the readily available 225 x 47 be OK or could I either glue and screw say two lengths of 150 x 47 together before cutting the steps or make up the stringers from say a length of 150 x 47 and then fix separate triangular pieces to this to form the stringer? (I have seen pictures of ones made like this but can't see how they attach the triangular pieces and if you were to screw through the 150 x 47 piece you would need something like 200 mm long exterior screws ).

Any advice,

John.

Any reason for the long going? Standard private stair case would be about 220-235 going.

Probably the going could be shorter but I'm using 150 mm wide composite decking so to avoid too much cutting or wastage I was intending to cut the 2.9 metre lengths supplied into three and use one piece for the rise and two for the going. Sitting the riser on the going makes the total rise 150 mm + 25 mm (the thickness of the decking) + 5 mm clearance for expansion.

With a little overlap (which should give a nice shadow gap and make look more 'open' you should be able to get 100mm
Stick some decking lights in the riser should enhance the overhang also.

Think you may have mis-read his original post loggy, he says 225, not 247.

You could double up on all three stringers, but only cut the inner ones on the outer stringers (if you get my drift). From the side the stringers would then appear full depth throughout ?

[Edited on 21/9/17 by Mash]

[Edited on 21/9/17 by Mash]

quote:

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Originally posted by Mash
Think you may have mis-read his original post loggy, he says 225, not 247.

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OK, I have now found a supplier of 245 width so, as suggested, with a little alteration I could probably get around 97 - 100 mm below the notches but would this be OK? (The overall length of each stringer will be around 2450 mm). I guess I could fix some additional 75 x 47 to the inner faces of the stringers below the level of the notches but obviously that does increase the cost slightly.

What do you think?

John.

100mm, even 75mm is decent size - spread over a fairly narrow width on (what im assuming is) a fairly low traffic area. To be sure maybe use 3 of them across the width, although if it was me 2 would satisfy me.
Stringers used on a internal stair would only be 25mm thick, (with only have a 12.5mm bearing on the tread), only have a 50mm waist/throat and span would be full width of tread.

Thanks for all your advice.

I've now decided I'm going to use 3 stringers made from 245 x 47 timber and also slightly reduce the going (even though I will have to cut the composite to width to achieve this) as it helps get the steps within the available length and also very marginally increases the material left below the notches.

Once it's built, if it seems a bit flexible in use, I'll add some 75 x 47 timber to the insides of the outer stringers and possibly to both sides of the middle one but I'm now much more confident it won't be necessary.

John.