Purlin scarf ... sister it / steel plate it, not sure

[Anstiss Ltd]

I'm starting a loft conversion on my 1929 semi detached bungalow.
Architect/SE and BCO have approved plans to remove purlin (shown with the red line on my photo) and replace with structural stud wall on to new ceiling joists 195x75 c24. Two dog house dormers going in to.

Currently there is not a wall separating the loft space with next door (obviously will be all to regs).

On to my problem.

The photos attached will help with the explanation.

I want to cut the purlin supporting my side of the roof along the yellow line on my photo. The blockwork support for the purlin is staying and is built on the party wall.

The blue arrow shows a scarf joint in the purlin, this is on my neighbour's side of the roof.

If I cut the pulin on my side of the roof this scarf won't be supported will it?

Looking for suggestions thanks in advance.

Going to ask the architect/SE but he's on holiday for four weeks without his work phone (he is semi retired).

The other side of the roof is opposite to this, i.e. scarf on my side so I can cut that with out issue. This is also the side architect looked at when he drew the plans hence sorta why he missed this side.

 

[blup]

Your architect/SE (is he both?) will doubtless advise on the options when he returns from holiday, and is introduced to the side of the house the loft conversion is to be built on. If you can't wait, make an appointment with BC who may be prepared to offer some informal advice in the meantime.

Blup

 

[Anstiss Ltd]

Yes he is the same person.

Extension to rear so other side is being converted to.

I'm sure he will have some solution.

Other thing is how do I stand as technically that's my neighbour's roof/property

 

[tony1851]

Use a length of steel channel (150 x 50 - ish) coach-screwed (not bolted) to the purlin, in a length sufficient to reach the block, and equal length the other side of the scarf - prob. around 5 - 6ft?

 

[^woody^]

12mm ply glued/screwed both sides, or a large truss connector plate.

You'll need the owners express permission though, else its a trespass. And if I were him I would want a proper structural engineer's confirmation in writing that it is adequate.

Unless the Party Wall Act applies for the other work you are doing and you invoke it, then without some sort of agreed survey of the neighbours roof and ceiling and wall condition, then you remain vulnerable for a future claim for anything remotely connected to movement of the purlin.

 

[Anstiss Ltd]

All ready got party wall agreement in writing for all other work that involves the party wall.

The new loft partion is detailed
the steel work that is now resting in the wall at the rear of the property.

No issues there.

Possibly could leave some of it on my side of the party wall approx 1000mm as that's when the dorma window starts

Would this be sufficient support my side an addionatal structural stud could go directly under it.

Possibly tie it in to the dorma framing to anchor it
Just thinking of different solutions.

 

[^woody^]

Tony's or my suggestion will be OK. Its not a big issue, it just needs something across the joint

 

[Anstiss Ltd]

Tony's or my suggestion will be OK. Its not a big issue, it just needs something across the joint

Ok will speak to SE so he can put something in writing and then get permission from the Mardy arse next door

 

[John D v2.0]

Ok will speak to SE so he can put something in writing and then get permission from the Mardy arse next door

Id be a Mardy arse if I knew my next door neighbour's SE was away and they were asking for advice from random people online about how to stop my roof sagging!

 

[Anstiss Ltd]

Id be a Mardy arse if I knew my next door neighbour's SE was away and they were asking for advice from random people online about how to stop my roof sagging!

After plenty of non registered reading I can pretty much sort wheat and chaff.

Plus not cut anything yet so no sagging.

Woody echoed my own thoughts maybe I would have used 18mm not 12 prob still will.

Affirmation of my own thoughts.

 

[tony1851]

A decent length of ply both sides would be ok structurally, but the space behind that purlin looks a bit tight and maybe difficult to work in - the joiner might be tempted to skimp on the fixings on that face?
Personally, I'd prefer to see a chunky piece of steel on the inner face where it's easier to work, and where all the fixings are visible and easy to check.
Just my humble....

 

[Anstiss Ltd]

A decent length of ply both sides would be ok structurally, but the space behind that purlin looks a bit tight and maybe difficult to work in - the joiner might be tempted to skimp on the fixings on that face?
Personally, I'd prefer to see a chunky piece of steel on the inner face where it's easier to work, and where all the fixings are visible and easy to check.
Just my humble....

You can get to the other side fairly easy it's the angle of the photo

I'll be doing it so I'll be sure It's right.

Not done roof work with structural changes before. For example I've striped back to rafters and refire the membrane and tiles etc. Ki

I buy at auction repair and sell on houses. I wouldn't call my self a DIY'er I am far more competent than that.

I also do small works for people.

In essence I leave the big stuff I've not done for my own house.

If I do something the long way and costs a little more than it should it's my house not a customer.