site survey found no plywood under tile roof

[newsol]

I just had my site survey and they found out the tiles under our 40 yr old roof has no plywood underneath. So it's just the tiles then the rafters that hold up the roof in place. Is it possible to install the solar arrays in the tiles without plywood without it leaking over the years? My neighbor has the same roof as mines but one solar company said they needed to put plywood and underlayment. So my neighbor went with another company that would install it without doing that. I'm just curious which is the better route. thanks for any info.

[inetdog]

I will assume that there is some sort of membrane (tar paper, etc.) below the tiles, even if there is no plywood. Otherwise it is very likely to leak in any wind.
And there have to be some sort of wooden support members perpendicular to the rafters, just not forming a continuous layer.
To my mind the biggest problem is that with only partial support the roof will flex so much as the installers walk on it that breaking tiles will be guaranteed.
Make sure that the solar installer is ready and willing to deal with that and will do a proper job of replacing broken tiles with matching new tiles instead of just trying to patch broken tiles.

Some installers will suggest removing the tiles under the footprint of the panels and putting in plywood sheathing, a waterproof membrane, and shingles for that area.
If you do not mind the looks and the projected lifetime, this is a valid approach.

[newsol]

I will assume that there is some sort of membrane (tar paper, etc.) below the tiles, even if there is no plywood. Otherwise it is very likely to leak in any wind.
And there have to be some sort of wooden support members perpendicular to the rafters, just not forming a continuous layer.
To my mind the biggest problem is that with only partial support the roof will flex so much as the installers walk on it that breaking tiles will be guaranteed.
Make sure that the solar installer is ready and willing to deal with that and will do a proper job of replacing broken tiles with matching new tiles instead of just trying to patch broken tiles.

Some installers will suggest removing the tiles under the footprint of the panels and putting in plywood sheathing, a waterproof membrane, and shingles for that area.
If you do not mind the looks and the projected lifetime, this is a valid approach.

I believe there is some kind of rubber or some sort under the tiles since I do not see any leaks under the roof and yes it does have wooden support perpendicular to the rafters. Would it leak over the years to come if I do the install without the plywood and the underlayment.

[Naptown]

The horizontal pieces are called Purlins. Pretty standard and old time for slate or metal roofs common in pole barn construction too.
You should not be attaching to only the purlins.
Where you should be attaching is to the rafter or truss at the purlin location or if this happens to be between the purlins then block at that location the thickness of the purlin and attach trough the blocking to the truss or rafter. All lag bolts need to penetrate at least 2" into the rafter not counting the purlin thickness.

[buellwinkle]

The solar racks are attached to the rafters, not the plywood, so I would not see why it would impact the install in that regard. The only thing that I don't know is how they would run the wire through the roof and keep it sealed, so it could be they will run conduit along the top of the roof and enter from the eave.

[Naptown]

Number of ways
A solar deck is the most elegant

[newsol]

The solar racks are attached to the rafters, not the plywood, so I would not see why it would impact the install in that regard. The only thing that I don't know is how they would run the wire through the roof and keep it sealed, so it could be they will run conduit along the top of the roof and enter from the eave.

My neighbor's setup was like that. They just installed through the tiles into the rafters. His initial company wanted to put plywood and underlayment under the tiles for their leak warranty. The company he went with still had the leak warranty without putting in plywood. So i'm just wondering if it would be more stable and less prone to leak later down the road.

[newsol]

attic.jpg

here is a picture of my attic.

[SunEagle]

[ATTACH=CONFIG]6093[/ATTACH]

here is a picture of my attic.

I hope those tiles are strong enough for foot traffic when the installer starts installing the rack and panels.

I guess that type of roof is acceptable but I would feel more comfortable knowing there was plywood beneath the tiles to help support a lead foot.

[Amy@altE]

Perhaps a flashing that replaces the tile, instead of drilling through it would work. It would be lagged into the rafters. http://www.ecofastensolar.com/store/...6#.VQmX847F8rU

I also am concerned about how the weight of the installers will be supported without breaking through. But I'm a New England gal, the whole idea of tile roofing is bizarre to me.

[newsol]

Perhaps a flashing that replaces the tile, instead of drilling through it would work. It would be lagged into the rafters. http://www.ecofastensolar.com/store/...6#.VQmX847F8rU

I also am concerned about how the weight of the installers will be supported without breaking through. But I'm a New England gal, the whole idea of tile roofing is bizarre to me.

They will not be drilling through these tiles at all. They most likely use a stype hook to the rafters or use a flashing instead of the tiles. i have 2 different neighbors with the same roof and they went through the same situation where one installer would want to put plywood underneath as well. but in the end they did end up with a different installer without doing that. Here is a picture of his install as well.neighbors roof.jpg

One of my neighbor's installer was a large company that does roofing as well, and have been around a long time. so i believe they did know what they where doing.

[newsol]

I hope those tiles are strong enough for foot traffic when the installer starts installing the rack and panels.

I guess that type of roof is acceptable but I would feel more comfortable knowing there was plywood beneath the tiles to help support a lead foot.

my roof is pretty sturdy to hold some foot traffic. the installer of my neighbors system did have some that broke but replaced them or glued them back together. we had a heavy storm back in december and he had no reported leaks in his roof and he inspected it thoroughly as he quoted.

[newsol]

So i have 2 installers now that are able to do it without putting plywood underneath. They are going to take the tiles where the rafters are and place hooks into the rafters for the mounts. 2 of my neighbors have this setup with my exact same roof. We did have a major storm that went by in dec and there were wind gusts up to 70mph, and their systems are still up and holding. So i feel it should be good.

[Stuntman]

The horizontal pieces are called Purlins. Pretty standard and old time for slate or metal roofs common in pole barn construction too.
You should not be attaching to only the purlins.
Where you should be attaching is to the rafter or truss at the purlin location or if this happens to be between the purlins then block at that location the thickness of the purlin and attach trough the blocking to the truss or rafter. All lag bolts need to penetrate at least 2" into the rafter not counting the purlin thickness.

I have the same situation with my 1975 home.. I was just told, at the last second, that the contractor I was going to have put my solar up won't do it as I don't have plywood to secure the risers to. I don't know if there is no way, or if they just were not wanting to do it 'differently' than the way they normally do it.

What do you mean when you suggest to put a 'block' at the location.. are you suggesting to simply attach a block of wood, a thick block of wood, to the side of the nearest rafter so that the penetration can be 'offset' by that amount? I don't know how spaced out the risers are versus the spacing of my rafters and if it is even possible to block out as far as would be needed to attach... maybe there is some standard and it wouldn't be an issue?

Thanks in advance for any input regarding this dilemma.

[inetdog]

The other form of "blocking" consists of running a piece of framing lumber (2x4 on edge would probably do) from one rafter to the next rafter to allow a tie down in between rafters.

Any contractor who plans to fasten the rails to plywood between rafters rather than directly to rafters is one to avoid. The plywood simply does not have the thickness needed to attach rail supports.
He might just be worried about how to support/attach his flashing around the supports though.
If he is concerned that there is no place to slather on the roofing cement around his supports, run away from that guy too!