Help.! The purlin is in the way of the stairs.

[Jml]

Due to doors etc. there  is only one place for the position of stairs to our extended loft conversion.  All was going well with the design of the stairs until I realised the purlin, will create a head cracking problem, as it means the 2.0 m headroom cannot be met on the stairs.  
 

The green line on the diagram shows the 2.0m line.  The stairs are at a max. of 42 degs.
 

Any easy / simple ideas to get around the purlin?
 

Other half thought of replacing part of purlin with steel or cable, not sure how it would work or if practical.  

 

Otherwise thinking of something like this

 

.But as we are removing normal stairs from elsewhere, not sure how building inspectors would view it.

 

Any ideas welcome.

 

Cheers Jenny.

 

[Mr Punter]

Can you pitch the stairs at 52 degrees or get rid of one of the winders at the bottom?  I appreciate it will throw the top landing forward 240mm.

[Jml]

  On 18/06/2020 at 12:21, Mr Punter said:

Can you pitch the stairs at 52 degrees or get rid of one of the winders at the bottom?  I appreciate it will throw the top landing forward 240mm.

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Max. pitch per Part K building regs.  is 42 degrees unfortunately,  unless use ladder or alternative tread stairs for loft conversions. 

[Mr Punter]

  On 18/06/2020 at 12:59, Jml said:

Max. pitch per Part K building regs.  is 42 degrees unfortunately,  unless use ladder or alternative tread stairs for loft conversions. 

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Doh! I meant 32 degrees - the same as the roof

[JFDIY]

38 degrees would match the roof.

 

But I would say the same, shallower stairs or could you fit a supporting wall either side of the stairs under the purlin and then chop the purlin out, probably cost more in structural engineers calcs than its worth

Edited June 18, 2020 by JFDIY

[Jml]

  On 18/06/2020 at 12:21, Mr Punter said:

get rid of one of the winders at the bottom?  I appreciate it will throw the top landing forward 240mm.

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  On 18/06/2020 at 13:17, JFDIY said:

 

But I would say the same, shallower stairs or could you fit a supporting wall either side of the stairs under the purlin and then chop the purlin out, probably cost more in structural engineers calcs than its worth

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Have tried to work on shallower stairs, but top landing position is fixed due to doors etc. 
 

Wall probably not suitable  but could you have a supporting beam or steel?  

Edited June 18, 2020 by Jml

[the_r_sole]

by the time you have properly insulated the ceiling to current regs it's going to sitting somewhere in line with the purlin anyway?

Do a quick uvalue calc to see how much insulation you're going to need, and then revise the stair layout

[Temp]

On your line drawing (black background) what's that at floor level below the purlins? Are they going to be steel beams? If so it might be possible to support the purlin either side of the stairs on that beam and remove a section of purlin. However it's not quite that simple. The rafters without a purlin may need doubling up for example.

 

You could also consider a dormer or velux in that area which would also require a section of purlin to be removed and possibly a rafter or two.

 

You will need to discuss with an SE if you want to go down any route that cuts or removes the purlin.

 

And as @the_r_sole says the purlin might not be the limiting issue.

[Jml]

  On 18/06/2020 at 14:28, the_r_sole said:

by the time you have properly insulated the ceiling to current regs it's going to sitting somewhere in line with the purlin anyway?

Do a quick uvalue calc to see how much insulation you're going to need, and then revise the stair layout

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  On 18/06/2020 at 15:44, Temp said:

On your line drawing (black background) what's that at floor level below the purlins? Are they going to be steel beams? If so it might be possible to support the purlin either side of the stairs on that beam and remove a section of purlin. However it's not quite that simple. The rafters without a purlin may need doubling up for example.

 

You could also consider a dormer or velux in that area which would also require a section of purlin to be removed and possibly a rafter or two.

 

You will need to discuss with an SE if you want to go down any route that cuts or removes the purlin.

 

And as @the_r_sole says the purlin might not be the limiting issue.

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Many thanks.  Will look at it from an insulation thickness viewpoint, I think we will have to resort to stepped stairs.

[Mr Punter]

If you post floor plans someone may suggest a stair configuration that will work.

[Jml]

  On 19/06/2020 at 12:19, Mr Punter said:

If you post floor plans someone may suggest a stair configuration that will work.

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Proposed ground floor plan

 

[Mr Punter]

I still cannot see without the upper floor.  Can you take out a tread from the winders at the bottom and add a step at the top?

 

Also, veering off, you seem to be demolishing a lot of what was there and building a very large footprint of over 200m2. Could you demolish and rebuild to gain exactly what you want, saving 20% VAT in the process?

[Jml]

  On 20/06/2020 at 14:02, Mr Punter said:

I still cannot see without the upper floor.  Can you take out a tread from the winders at the bottom and add a step at the top?

 

Also, veering off, you seem to be demolishing a lot of what was there and building a very large footprint of over 200m2. Could you demolish and rebuild to gain exactly what you want, saving 20% VAT in the process?

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Unfortunately don’t think it’s practical to add a step at the top, diagram attached.

 

The budget would not run to demolition even with the VAT saving.  We. are making as few alterations as possible and “reusing” lintels with a new floor area of approx. 60 m2 and a bit of demolition.

 

[DevilDamo]

Not sure if it helps, but the headroom can be reduced to 1.9m for a new loft stair.

 

Assuming a small dormer window to just achieve the required headroom is not possible, could you look to install a rooflight as that will provide you some additional height within the recess of the rooflight itself?

 

If you’re going down the route of upgrading the rafters to meet u-values, etc... you’d normally bolt the new rafters to the side of the existing and therefore probably eliminating the need for the purlin. But even without it, the increased rather sizes and insulation requirements may end up brining you back to square one.