Fixing to Top of Unreinforced Masonry Wall
Fixing to Top of Unreinforced Masonry Wall
(OP)
Hi all,
Here in Western Australia, there is a plethora of residential buildings of unreinforced double brick construction (2 leafs separated by a 50mm cavity). The roof to wall detail typically consists of fixing rafters to a timber plate which is on top of internal leaf, which is strapped down into wall (900, 1200mm down etc..) with light gauge G.I. Straps. Further more either bolts into top of brickwork (top fixed, not face fixed) or nails into mortar joints are used to locate plate on wall (sorry scanner not working, will get sketch up as soon as I can). In my opinion this detail provides an unreliable mechanism in resisting In-plane and Out-of-Plane actions at the plate/wall interface. I personally don't get involved in the design of these types of houses and was seeking others opinions on this detail. The main reason I ask, is a client is looking at putting a timber framed second storey addition on a double brick house - my immediate concern is shear transfer in-plane of the walls from framed shear walls above and from timber floor diaphragm between the two types of construction. Has anyone dealt with this before? If so any information/opinion would be greatly appreciated.
Thanks in advance
Toby
P.S. - My initial concept was to bear joists/blocking on top of existing brickwork and then brick up between to "wedge" them in.
Here in Western Australia, there is a plethora of residential buildings of unreinforced double brick construction (2 leafs separated by a 50mm cavity). The roof to wall detail typically consists of fixing rafters to a timber plate which is on top of internal leaf, which is strapped down into wall (900, 1200mm down etc..) with light gauge G.I. Straps. Further more either bolts into top of brickwork (top fixed, not face fixed) or nails into mortar joints are used to locate plate on wall (sorry scanner not working, will get sketch up as soon as I can). In my opinion this detail provides an unreliable mechanism in resisting In-plane and Out-of-Plane actions at the plate/wall interface. I personally don't get involved in the design of these types of houses and was seeking others opinions on this detail. The main reason I ask, is a client is looking at putting a timber framed second storey addition on a double brick house - my immediate concern is shear transfer in-plane of the walls from framed shear walls above and from timber floor diaphragm between the two types of construction. Has anyone dealt with this before? If so any information/opinion would be greatly appreciated.
Thanks in advance
Toby
P.S. - My initial concept was to bear joists/blocking on top of existing brickwork and then brick up between to "wedge" them in.






RE: Fixing to Top of Unreinforced Masonry Wall
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Fixing to Top of Unreinforced Masonry Wall
As far as the upper storey extension goes, configuration of lower storey wall openings is changing considerably from original, so I have just opted to remove outer leaf and inset steel bracing frame fixed to new floor over.
Thanks
Toby
RE: Fixing to Top of Unreinforced Masonry Wall
I'm not sure that I understand the steel frame bracing scheme but it sound as though you've solved your immediate problem.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Fixing to Top of Unreinforced Masonry Wall
Yes, nailing would provide load path, but as you mention, a method to reliably assess its capacity does not appear readily available - Anyone?
RE: Fixing to Top of Unreinforced Masonry Wall