Not sure if this is best here or in Roofing........
Outline- twin ridge roof, ridge heights about 2 metres above eaves, 30 degree ish pitch, purlin/rafter construction.
Problem- both chimneys in the gable end wall are in poor condition, as is the brickwork of the parapet wall between them (lean on the parapet and it moves). The chimneys at the other end of the roof came apart in my hands (the place is nearly 200 years old) so I expect these 2 to do the same, and possibly the gable end wall as well (it has been rendered but it is quite exposed).
I'm getting scaff put up to do the chimneys (and the rest of the roof) so access isn't a big problem but if the gable end wall does come apart then I need to put temporary supports under the purlins if I need to rebuild below them.
My cunning plan is as the sketches.
View media item 77596
First one is just what's there (purlins are 8 x 4 set at 30 degrees, rafters are 3 x 3 ish. Purlin span from gable end wall to next support is about 3 metres. Slates are off back to the supports- they're only Marley so not a massive load there.)
Second one is meant to show my support scheme. In words it is
A lump of 6 x 2 set vertically under the purlins as near the wall as I can get (in practise that'll be more or less flush with the inner face of the chimney) with wedges fixed to it to maintain the purlin angle and to maintain the gap between the purlins.
Ends of the 6 x 2 will be screwed to the nearest rafter (to prevent any lateral shifting) once I've jacked up the support beam (to make sure the beam is taking the load rather than the walls. Only by a millimetre or so, nothing radical), then leave the Acros in to support the whole job from the bedroom floor (and probably another pair to support the bedroom floor from the concrete ground floor if I get any significant deflection in the bedroom floor.
View media item 77598
Any thoughts?
Outline- twin ridge roof, ridge heights about 2 metres above eaves, 30 degree ish pitch, purlin/rafter construction.
Problem- both chimneys in the gable end wall are in poor condition, as is the brickwork of the parapet wall between them (lean on the parapet and it moves). The chimneys at the other end of the roof came apart in my hands (the place is nearly 200 years old) so I expect these 2 to do the same, and possibly the gable end wall as well (it has been rendered but it is quite exposed).
I'm getting scaff put up to do the chimneys (and the rest of the roof) so access isn't a big problem but if the gable end wall does come apart then I need to put temporary supports under the purlins if I need to rebuild below them.
My cunning plan is as the sketches.
View media item 77596
First one is just what's there (purlins are 8 x 4 set at 30 degrees, rafters are 3 x 3 ish. Purlin span from gable end wall to next support is about 3 metres. Slates are off back to the supports- they're only Marley so not a massive load there.)
Second one is meant to show my support scheme. In words it is
A lump of 6 x 2 set vertically under the purlins as near the wall as I can get (in practise that'll be more or less flush with the inner face of the chimney) with wedges fixed to it to maintain the purlin angle and to maintain the gap between the purlins.
Ends of the 6 x 2 will be screwed to the nearest rafter (to prevent any lateral shifting) once I've jacked up the support beam (to make sure the beam is taking the load rather than the walls. Only by a millimetre or so, nothing radical), then leave the Acros in to support the whole job from the bedroom floor (and probably another pair to support the bedroom floor from the concrete ground floor if I get any significant deflection in the bedroom floor.
View media item 77598
Any thoughts?
- around 18 inches from rear face of gable end (its only half brick) to where the collar (?) will be. Pediment is all stretchers, only half brick so nowt to bond to except the chimney where there is some keying in.
