UKC

We're going to get our roof replaced this summer. Currently it is made up of concrete tiles and we are getting integrated solar panels. When a neighbour did this a couple of years ago we were surprised to find the roof was just resting on top of the walls, not fixed to a wall plate . Concerned that the new roof would be much lighter than the old one he fixed the roof down as shown in the picture. This involved drilling 1 metre holes through the capping block into the internal wall. The resulting vibration meant that a significant internal  plastering was required. I also have two windows that are over 3m wide with just the cappping blocks above a concrete lintel. At the moment I'm planning to secure the four corners to a depth of 1 metre and points between each window. Any thoughts that I'm not doing enough or ideas as to how it could be done differently welcome. 

Roof straps would normally be fixed to the internal face of the wall, and then cloaked by plasterboard / plaster. If access to do this is an issue I can understand why your neighbour decided to drill deep holes for fixing instead. Do you know if those are dense concrete blocks, or the lightweight ones? Lightweight blocks won't hold as much shear force but without researching the numbers I don't know if that's significant. I would check whether the neighbours ceiling is showing any signs of moving with respect to the wall.

On the other hand, if the drilling is likely to 'pop off' some plasterboard / plaster, you might be as well to cut some out neat strips of it to allow face fixing of some straps and then simply fill over them.

Fortunately they are dense ones. 

I think I might go for  a mixture of both. The front of the house is a bathroom between two bedrooms. Two holes to fix four of the rafters above the bathroom and keep my fingers crossed it doesn't affect the tiling. The other issue with the bedrooms is they both have 10ft windows with just a concrete lintel and the capping blocks above, so for several rafters the best I can do is attach them through the blocks to the lintel ( I think any metal work should be in the bottom part of the lintel?) I'm thinking if I take your advice and attach straps to the rafters above the corners of the bedrooms. I'm thinking I could also use something similar to hold the lintel down as well. Bits of walls that are hidden by wardrobes and or curtains are the sort that Mrs J allows me to plaster. Using some straps on the gable ends would be easy to do as well.

Thanks Rob