Modifying a staircase

6 Jan 2010
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United Kingdom
Hi - first post this so here goes.....!

To allow the a first floor bathroom to increase in size I’d like to modify the existing staircase we have to incorporate a 3 step winder at the top of the flight. There is already a 3 step winder at the bottom). The ground floor substrate is slate flags on top of earth, there is ready access to underside of both staircase stringers which is a boxed in cupboard. I can almost picture how it will fit together, i.e where the newell posts will go, the framing necessary to support the kite boards etc. The existing balusters and containment all fall short of building regs. So there is plenty for a joiner to go at. Cost effectively is it feasible to modify a staircase in this way versus a install a completely new staircase?


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Joiner 1 who looked at job was not not comfortable with cutting the stringer however he has promised to return with a colleague. It was interesting visualising how the stringer changes direction and height compared to a straight run as it winds around.

Rough estimate is 2 x men for 2 days plus materials for to drop new treads on top of existing to form the kiteboards. Additional treads would then be fixed on top of the lower treads so the rise and going on the steps is maintained. I'm going to go and get a price for a 17 step double winder staircase for comparison.
are both strings supported by walls or how do they plan on supporting the cut string!!
Good point - for the existing straight staircase, one string is against a party wall, the other is open. this one is the intended inner string of wind. There is a boxed in rsj adjacent to it to support the newell post. I will try and post a photo later when not constrained by company firewall / photohosting sites

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Top of flight where I want to adda a 3 step winder:

View on area where I want to turn the stairs - towel is where I want to access landing

View of underside of stringer<a

3 step winder at base of stairs

i think i now understand exactly what you are trying to do !!!
are you trying to turn the stairs into the top landing 1tread width quicker and use the landing as part off the bathroom!!
is that correct!!!

if it is you wont need to cut the strings but will need a different set up to support the winders as they will interfere with the stairs they are replacing
Thanks big-all - thats exactly what i'm trying to do!

I envisaged some framing to support the kite boards / winder fixed to the existing stringer. Joiner 1 when he visited did not wish to remove existing treads but wanted instead to put the kite boards on top of the treads, however I think the existing treads will interfere with smooth passage up the new stairs!

I received a quote from stairplan for replacement stairs, this was £900 plus £100 delivery. I guess add a couple of days to strip out existing and install new plus some making good...
officialy you cannot just lay on the old as the risers need to be equal all the way up
in other words at the same height as the old ones

by planning on "sitting" on the old treads means the last 2 [the kite winders] will be around 21mm to high[the thickness off the tread they stand on]thus a trip hazzard

another reason it wont work is because a kite is wider than a single tread as it has to cover 1/3 the combined tread width and length so all 3 top treads need to come out
so if your carpenter hasnt worked that out he hasnt realised whats involved ;)
When I drew it all out on paper I saw that if the 'old' treads remained they would interfere with the 'new'.

Since I saw 'Joiner 1' last week he has re-worked his plan and the working proposal is to remove the top three treads, insert a newell post against the rsj / beam, build the framing under the stairs that will support the replacement the treads and rebated risers. These new treads will be pegged rather than rebated into the new newell post. So I'm please he has since gone away and thought about it

I'm almost sold as he has independently come to a prosal that i saw as possible but I'll need to work on the missus :confused: big-all's posts have reassured me that its feasible too, so thanks :D

If I go through with it I'll post some photos....

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