Changing stud spacing on internal wall in loft conversion

[Del-inquent]

Just been asked if I can help with something but I'm not sure on it, so looking for a bit of guidance.

In their loft conversion, a stud wall runs from the purlin down to a plate on the floor joists. Half the wall has studs at 400mm centres, half has 600mm. All studs are 4x2's

They'd like them all to be 600mm so they can put storage in. 

I'd assume the wall is spreading the load out, but why they have a mix of centres is what is concerning me. Can those 400mm centred studs be replaced with 600mm?

[Redbeard]

Hi, You say 'They'd like them all to be 600mm so they can put storage in'. Do you mean so that they can have 600-wide 'modules'/doors? If so, assuming the eaves are 'cold', how will they insulate the back? Or are the eaves 'warm'?

 

Probably only a structural engineer can respond definitively, but the section of the 'plate on the floor joists' may have a bearing (sorry) in deciding whether one thinks it is load-bearing or not.

 

If you know the size of the purlin there may be some span tables assuming given loads (such as the roof covering) which would give you an idea of whether the purlin is 'doing it all itself' or is being supported by the stud wall (in which case what supports the stud wall? etc. etc.)

 

 

[Del-inquent]

21 hours ago, Redbeard said:

Hi, You say 'They'd like them all to be 600mm so they can put storage in'. Do you mean so that they can have 600-wide 'modules'/doors? If so, assuming the eaves are 'cold', how will they insulate the back? Or are the eaves 'warm'?

 

Probably only a structural engineer can respond definitively, but the section of the 'plate on the floor joists' may have a bearing (sorry) in deciding whether one thinks it is load-bearing or not.

 

If you know the size of the purlin there may be some span tables assuming given loads (such as the roof covering) which would give you an idea of whether the purlin is 'doing it all itself' or is being supported by the stud wall (in which case what supports the stud wall? etc. etc.)

 

 

Yes, they'd like all the modules and fronts to be the same size. 

Cold eaves, yes. Modules are clad with 150mm PIR on the backs, and 50mm stuck between each as they go in, so pretty snug.

The plate (I can't remember the name for it when it's used like this! Binder?) is just a 4x2, there isn't anything below at all. I'm going to try and get a proper look at the Purlin, at the moment I can only see an edge of it!

[syne]

I had exactly this on my loft.

Steels directly below purlin timber upright every x apart, boarded front and back with osb.

When widening the distance between the uprights the timbers were to be doubled either side with a caveat of no opening to be larger than x times 2.

As for insulating I did it the hard way; the void was formed using the triangulation timbers at the eaves as the back wall- just enough vertical after insulation to put a skirting on-

Stapled breathable membrane on the timbers fully filled gaps with wool, encased in pb and plastered insides.

It's awfully awfull to do Plastering laid on your side in a trangular coffin.

If your going to do it this way, do the awkward work in the eaves before before you make the purlin wall up. 

 

If you want to leave the void as a Cold space then just insulate the walls and any doors and use a good seal on the opening edges.

 

[Del-inquent]

On 20/10/2023 at 14:15, syne said:

I had exactly this on my loft.

Steels directly below purlin timber upright every x apart, boarded front and back with osb.

When widening the distance between the uprights the timbers were to be doubled either side with a caveat of no opening to be larger than x times 2.

As for insulating I did it the hard way; the void was formed using the triangulation timbers at the eaves as the back wall- just enough vertical after insulation to put a skirting on-

Stapled breathable membrane on the timbers fully filled gaps with wool, encased in pb and plastered insides.

It's awfully awfull to do Plastering laid on your side in a trangular coffin.

If your going to do it this way, do the awkward work in the eaves before before you make the purlin wall up. 

 

If you want to leave the void as a Cold space then just insulate the walls and any doors and use a good seal on the opening edges.

 

very helpful, thank you!