# Forum Home Renovation Stairs, Steps and Ramps  Repair/replace rotten, poorly designed deck stair

## direvus

Hello folks, 
My back deck stair is rubbish, to put it politely.  The bottom tread, the base of one stringer and the base of the post have rotted, the top tread has fallen out of the stringer and others are threatening to do the same. 
At first I thought I could get by with just replacing the treads, but on closer inspection the rot so significant, I figured I should replace the stringers and bottom posts too. 
Once I started looking into stair construction (AS 1657, BCA) it became clear that the design of the stair is fundamentally poor.  There are six treads, but the bottom tread is absurdly close to the ground -- each rise is nominally 160mm, except for the bottom rise which is 90. 
The stringers are actually resting directly on the ground, which (I presume) is how the rot got into it. 
Based on the total rise (from the top of the deck to the concrete landing pad) of 1055, I figure 5 treads is more suitable, but that would probably mean digging up the existing stirrups for the bottom posts, and placing new ones at the correct location. 
On the other hand, I could attempt to re-use the existing stirrups and make a 6-tread stair with 151mm rises, which would at least yield a uniform rise, but seems to me like it could be uncomfortably shallow.  It also means that the stringers will just be bolted onto the sides of the posts, not supported underneath. 
I have some slight experience with DIY, and I don't mind getting my hands dirty, but I have never built a stair before, nor worked with concete (rapid-set or otherwise), so this is a pretty steep learning curve for me.  I'd be grateful for any advice you forumgoers can offer.  In particular, whether it is more sane to remove the whole mess and do it right, from scratch, or try to make the best of what's already there. 
I've included a link to my stair calculator spreadsheet, in the hope that someone else might find it useful, and pictures of the existing shambles. 
Thanks for reading,
direvus  https://docs.google.com/spreadsheets...it?usp=sharing  Attachment 102699Attachment 102700Attachment 102701

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## SirMe

> Hello folks,   Attachment 102699Attachment 102700Attachment 102701

  Your three photo attachment link does not work....

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## barney118

you only need 5 treads, you will have 6 risers which gives 1055/6=175.8mm which is a good height and compliant with BCA. I suggest in some concrete pads at the bottom using stirrups. I made mine out of TP stringers (keep the weight down) and blackbutt treads.

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## phild01

> I suggest in some concrete pads at the bottom using stirrups. I made mine out of TP stringers (keep the weight down) and blackbutt treads.

  Yep, did the same.

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## direvus

Thanks for the replies guys.  I actually finished building my new stair about a week ago, and am now finishing up the handrails. 
The final result is made entirely out of treated pine, 5 treads and 176mm rises.  The stringers are rebated into the posts at the bottom, so they are supported directly by the stirrups.  It is comfortable to walk on, and very sturdy. 
I decided to re-use the existing handrails.  I have cut them down to the new size and attached them to the bottom posts with mortise-and-tenon joints.

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## shauck

Stair Calculator - Layout Stair Stringer, Headroom Rise Run - Metric 
The above link will give you loads of detail for stair construction based on some info you provide. Check it out, it's a really useful tool. I agree with the others about 6 rises and 5 steps at 175.8. Suggest two ways to do it - either laying the concrete landing first and then measuring your total run and rise after, just in case it changes things a little bit. Or constructing the stairs with stirrups hanging and prop stairs in place and then pour concrete, let it set and remove props.

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