Is stud wall in loft room load bearing?

[stickyneep]

Hi

I have a 1960 chalet style semi detached bungalow and want to remove a stud wall forming an upstairs cupboard to make the room bigger.
I wouldn't mind a second opinion that the room wall isn't load bearing...

The chalet style bungalow has a room upstairs that is part of the original structure, taking approx half of the "loft" space. Roof construction is traditional, with the collar ties forming the room roof and stud partitions forming the walls.
There are large (approx 25cm x 10cm) purlins running the whole length in a single piece; these are supported by the gable wall and party wall. The purlin is supported midspan by a single leaf brick wall at halfway along its length, onto a supporting brick wall below (not shown)
The roof rafters are 10cm x 3cm approx on 45cm centres.
Roof pitch is approx 45 degrees.

Attached is the side view, from the gable end. Its a sketch, so not to scale

I would like to remove wall 1. It is constructed from 10cm x 3cm stud, with 12.5mm plasterboard. Top of wall is nailed directly to each rafter (no top plate) and the bottom is via a spreader plate that crosses the floor joists at 90 degrees. The nearest support to the base of this wall is approx 1m to the right (of the picture), where there is a brick wall forming the downstairs hallway.
Under the purlin is another large (25cm x 10cm) joist, with J hooks joining the bottom joist to the floor joists.
So wall 1 is floating on the floor joists (approx 7cm x 3cm) approx 1m away from the nearest support.
Finally, at the edge of the roof, is another large joist, attached to the exterior wall.

Approx 75cm behind wall 1 is a second stud wall, same construction method, forming a cupboard.
The length of the part being removed is just over 2.5m.

The only issue I can see is that the amount of unsupported rafter (2 on diagram) will increase between the collar ties and cupboard wall adjacent to the purlin, to about 1.7m.

Does anyone see any problems with what I'm proposing?

Many thanks

Neep.

 

[freddiemercurystwin]

Hey tony1851, did you draw this? It's the door that gives it away.

 

[tony1851]

@FMT; no, it's better than mine - if only I could draw like that.

@op; If the rafters are continuous over the purlin (ie in one long unbroken length from ridge to wall-plate) and being that sort of pitch, you won't
have an issue with the rafters over the 1.7m length.

 

[CambridgeBrummie]

Looking at your sketch, I would suggest that the roof rafters span from external wall to ridge, with the purlin acting as support to the mid length of rafter. You don't say how long the purlin is, but you say it is supported mid-way between gable end and party wall, so that would be pretty typical if the gable to party wall is about 5m. The purlin is classically supported at mid way by either dropping down to the floor joists and then spreading the load out over 4/5 floor joists.

So I don't think Wall 1 is loadbearing.