Ceiling Joist Construction

[nero44]

Hello All,

I am looking for some advice from someone familiar with the construction of old victorian terraced houses. I have posted my question in another forum already, but have not gotten quite the response I was after yet.

Long story short:
I want to know how the ceiling of my outrigger is constructed/supported, as I want to use the loft space and am concerned about weight. The loft is already fully boarded up, and I am looking to get some insights (educated guesses are fine at this stage) as to how the timber frame is constructed and supported.

I found a random video here, from someone who is doing a full loft conversion but a similar setup to my property. Below screengrab is from minute ~13.30


This is the outrigger/annex roof, not the main roof. I would like to know how the joist are supported on the (Party)Wall side highlighted in yellow. On the other side, the joists will obviously sit on a wall plate connected to the outside brick wall. From the video it looks like there is a timber running parallel to the wall and the joists are attached to it. But what is this resting on below?

Let me know if you need me to clarify anything.

Depending on how this is supported, it would help me to decide where the strongest loading capacity is. I thought it would be closest to the wall, but that was assuming that the joist are going into pockets into the actual brickwork, which I don't believe is the case.

 

[JohnD]

How about some photos and dimensions of your own roof?

 

[nero44]

Some more info here...

 

[JohnD]

.

 

[cdbe]

Keep them spread along the right hand wall, but away from the chimney breast. The weakest areas of that ceiling is mid span, and the area where/if a joist is trimmed round the breast. Ideally they should be stacked directly on top of the masonry wall between the middle room and the bathroom.

 

[nero44]

Thanks that's helpful.

Keep them spread along the right hand wall, but away from the chimney breast. The weakest areas of that ceiling is mid span, and the area where/if a joist is trimmed round the breast. Ideally they should be stacked directly on top of the masonry wall between the middle room and the bathroom.

Agree, unfortunately that is not possible, as the middle room is 4 steps higher. The floor level of the outrigger is offset by a bit, so that brick wall actually just goes straight up all the way.

 

[nero44]

Just to close this out... I've opened the floor and the joist are indeed supported by a ledger board/joist that is nailed to the wall, but also supported from studs below. The joists measure 100mmx50mm and weirdly are spaced 360mm centre to centre instead of 400mm.


So should be okay to support some permanent load spread over two 1sqm areas away from the chimney breast as suggested. Thanks all.

 

[tony1851]

That timber is known as a runner, and it would have been supported off a large timber (purlin) vertically above it via a few strips of thin timber hangers.
The runner is there to support the ceiling joists midspan, otherwise they would have been over-spanned..