Historical residential roof composition

[BECT]

Hello,

I am not into wood construction but just come across a drawing where new solar panels are going to be installed . I am looking into the historical drawing (1980 house)and the roof is composed of cedar shakes,15#felt , 2x6 spaced strapping , 2x 12 roof joists @16" oc ,insulation and 6 mil poly and 1/2 gypsum board( see attached) . if somebody can help me understanding 2X 6 spaced strapping . I am not seeing 15/32 ply wood or 7/16 OSB over the joists. Are these 2x6 straps are place next to each other perpendicular to the joist like i.e. 2 inch deep and 6 inch wide beam over the joist. Just want to under the composition.

There is special type of mounting called Roof Mini II by roof tech which can be wither screwed into rafter/joists or decking. Just trying to under the roof composition before i go any further into anchorage details.

Regards

 

[bigmig]

1980 is not historical by any means, but the construction you are describing is similar to pole barn construction....no sheathing. The 2x6 runners (flat, perpendicular 2x6's) create the gap bewteen the roofing and the 2x12 joists. I'm not a pole barn expert, but I have seen people build like this. I will be interested to see others take on this.

 

[BECT]

Thanks bigmig, I am interested also to see others take on it but if these 2x6 runners are placed next to each other over the joist creating a gap that would make lot sense to me.

 

[hokie66]

The 2x6 "spaced strapping" would be spaced to suit the length of the shakes. Often called battens rather than strapping.

 

[IRstuff]

When cedar shake is replaced with, say, concrete tile, like Cedarlite or Eaglelite, or similar, installers usually put down something like plywood over the entirety of the roof

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[hokie66]

I suppose the support for concrete tiles varies with location. In Australia, concrete or clay tiles are typically supported on discrete spaced battens, not continuous sheathing. In much of Europe, traditionally clay tiles have been supported on battens. Not sure how extensive concrete tiles are in Europe. But I am sure IRstuff is correct about cedar shakes being replaced by tiles. With sheathing, you don't have gaps to contend with. As well, the sheathing provides lateral stability.

 

[SWComposites]

As others said, the 2x6s are not placed adjacent to each other; there are gaps between them. And there is no plywood/osb sheathing. See images here:

https://inspectapedia.com/BestPractices/Wood_Roof_Sheathing.php

 

[SWComposites]

And frankly, I would not install solar panels over a shake roof; not sure how one would seal the mounting devices that would penetrate the shakes.