Confused by gable masonry detail where it meets the roof.

[epsilonGreedy]

My garage includes a lean-to brick shed extension 3m x 2.4m under a shallow pitch (21 degrees) slate roof. The outer wall of the shed is only 7 blocks high e.g.chin level and the small 1/2 gables rises 4 blocks to the wallplate height of the main garage at 11 blocks high. The gable is a cavity wall and the main garage has a hipped roof.

 

I do not think the gable wall contributes to supporting the "brick shed" roof.

 

Should I:

1. Leave the gable unfilled until the roof is on.
2. Build it up to just below the expected finished height.
3. Build it to a precise full height so that the roof gable-end carpentry can be cut snugly around it. 

 

 

[RichS]

Usual way is to build up with full bricks to no more than top of rafter level but don't do any cuts. When the roof rafters are on, but before felt/lathing run a short length of tile lath over  the last two rafters top and bottom, projecting out to face brickwork. String a line between these to give the desired line for the cuts and then infill.

[epsilonGreedy]

  On 29/09/2019 at 14:48, RichS said:

Usual way is to build up with full bricks to no more than top of rafter level but don't do any cuts.

 

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Relieved to read this because yesterday on the spur of the moment this is what I decided to do. With the main garage rectangle two blocks higher than the lean-to, I clamped a batten to the main garage wall projecting up to the future 11th course. I then ran a line down to the inner block wall of the lean-to tied to a brick dangling over the edge. With this in place I started filling in gable blocks by eye.

 

The rafters will be 150mm x 50mm minimum and even with a birdstooth notch they will be higher than my simple profile line hence a comfortable extra clear space margin. And oh forgot the extra height of the wall plate at 50mm = bigger margin.

[ToughButterCup]

  On 29/09/2019 at 14:48, RichS said:

Usual way is to build up with full bricks to no more than top of rafter level but don't do any cuts. When the roof rafters are on, but before felt/lathing run a short length of tile lath over  the last two rafters top and bottom, projecting out to face brickwork. String a line between these to give the desired line for the cuts and then infill.

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Thats almost exactly what we did. Some cutting (but more infill) was needed because of the size of the Durisol block: it projected just a little too far  in places.

 

We also needed to match the pitch of one section of the building with  (in this case) some external steels. Needless to say, with my luck, the two pitches did not match. Matching the two might not be important to you (the image appears to show two different pitches).