vaulted and hipped roof

[RonBowater]

hi guys ... this is my first append to what seems to be a useful forum. Hope that you can help me with a issue relating to the design of the roof for a small single storey extension.

I am in the process of drawing up the plans for a small 4.5 x 3.5m single storey extension which is intended as a family room. Details are as follows

- East facing .. abuts to house
- South facing .. glass (wooden frames with double windows) apart from pillars at either side.
- West facing ... solid block/brick cavity wall
- North facing .. 1/3 abuts to house, 2/3 block/brick wall with window
- 4.5 dimension runs N-S
- Pitched roof (30 deg) to run N-S
- South pitched end to be vertical
- Roof to be hipped at N end i.e. slopes to E,W and N with a vertical section and small window up to ridge height on N face (reason for the hipped roof at the N end is to join in on N and E with the house which is a 'cottage style' with eaves about 3.5m above ground level).
- Roof to be totally tiled apart from N face vertical section and window

I reckon that I can figure out how to do most of this and draw up structural plans for everything up to roof level.

However, what I am unsure about is the best way to brace the roof so that that weight of the roof does not apply a spreading pressure to the walls on W and N sides. Should I have bracing timbers (or steel of some sort) at eaves height or part way up the rafters ? How many braces will be required ? I assume that E-W braces will be required but will the N walls needs to be braced ? Could I get away without braces and a steel frame ? How does one go about designing such a roof ? Or should I bite the bullet and see an architect or structural engineer ?

Any advice much appreciated.

Thanks
Ron

 

[freddiemercurystwin]

Bite the bullet and get a struct eng, will be about £300 for some sketches and calcs which building control will likely demand from you anyway.

 

[noseall]

If i am picturing it right, then the majority of the roof is lean-to, no?

If this is the case then the pitching plate/pole plate (bolted to the wall), will counter spread.

 

[RonBowater]

Thanks Guys ... I think that I will take 'freddymercurystwin' advice and get a structural engineer involved although I am still of the mentality that it should be able to do it all myself given enough book and web reading.

I am still interested in how to solve this problem and in response to noseall's append, the roof is not a lean to (sorry but it is hard to describe in words).

Image a rectangular building 4.5m x 3.5m with a roof which slopes from a 1 metre ridge in all 4 directions. Now lift up one of the 4.5m ends so that the ridge extends to the front of the building. We now have a roof which slopes in 3 directions : one side which joins into a valley gutter against the house wall and the other two sides which end on block/brick walls.

Apart from a small window on one end, the roof is completey tiled and I would like it to be vaulted and as open as possible (fully insulated to current BS, of course).

Actually, just found this on the web which contains a picture of a roof which is very close to what I want ... http://quick-calcs.net/designs/vaulted-roof-p-32.html

These folks seem to offer a reasonably priced service and they do mention a ring beam as one solution.

As a matter of interest, would a ring beam have to be steel and could it just replace the usual wall plate timber ?

Comments anyone ?

Ron