How do I do an asphalt shingle to concrete tile transition?

[omgwtfbyobbq]

Hi! I'm looking to install some panels on a two story house and noticed that in addition to stand-offs that fit underneath the existing tiles, some installers just install asphalt shingles and then place the panels over them, more or less flush with the existing tiles.

This seems preferable because it...

• Gets me some surplus tiles
• Is easier than stand-offs that sit under the tiles
• I don't need sign off from a civil engineer on the roof load
• Aslphalt tiles under panels will probably be as durable as concrete tiles

The transition from concrete to asphalt seems pretty easy. Just drop the last layer of tiles over the shingles with a little flashing. I imagine the sides are also pretty easy. Just flashing to make sure the water is channeled to the bottom.

I found this post, which suggests some custom flashing. I don't think that's too hard, but I'm unsure of how well it will prevent water from getting under the tile. I think the second solution, installing asphalt all the way down and then placing tile over it, is better, but still pretty labor intensive.

http://www.solarpaneltalk.com/showthread.php?14290-Remove-Tiles-on-RooF&p=101221&viewfull=1#post101221

Are there any other methods I'm missing that might be easier than either of these?

[J.P.M.]

Hi! I'm looking to install some panels on a two story house and noticed that in addition to stand-offs that fit underneath the existing tiles, some installers just install asphalt shingles and then place the panels over them, more or less flush with the existing tiles.

This seems preferable because it...

• Gets me some surplus tiles
• Is easier than stand-offs that sit under the tiles
• I don't need sign off from a civil engineer on the roof load
• Aslphalt tiles under panels will probably be as durable as concrete tiles

The transition from concrete to asphalt seems pretty easy. Just drop the last layer of tiles over the shingles with a little flashing. I imagine the sides are also pretty easy. Just flashing to make sure the water is channeled to the bottom.

I found this post, which suggests some custom flashing. I don't think that's too hard, but I'm unsure of how well it will prevent water from getting under the tile. I think the second solution, installing asphalt all the way down and then placing tile over it, is better, but still pretty labor intensive.

http://www.solarpaneltalk.com/showthread.php?14290-Remove-Tiles-on-RooF&p=101221&viewfull=1#post101221

Are there any other methods I'm missing that might be easier than either of these?

Some of us think this is a very poor idea.

1.) Even if composition shingles are placed all the way to the eaves and tiles replaced on top of them, water and perhaps more importantly the bugs, bird crap, dead animal parts, leaves, etc. will be transported under the tile as the stream bed load of the runoff, stay there and start to build up. I'd grant that most of the water will run out the eaves, at least at the beginning, but not all of it, and less of it over time as the junk builds up. So, you'll have a nice warm, dark environment in warm weather, just sitting there growing stuff and smelling, not to mention real potential problems with rot and health. In freezing weather, any trapped moisture will freeze and cause expansion problems as nails and other things lift and move. Not something I'd want to take a chance on.

2.) Unless the roof slope is rather steep, any added flashing under the array at the bottom of the of the composition portion added to act as a transition to get the runoff over the tiles below the array and thus PERHAPS help prevent but not ensure the situation in 1 above from occurring, it would still act as a sump and then a junk catcher requiring cleanout or at the least, inspection as do gutters.

3.) Thinking long(er) term, at some point, the array will come off the roof for any number of reasons. Someone may not like it. Not everyone likes solar. In, say, 10 years, some new or current owner may want newer, better, cheaper faster stuff. Do you think the composition shingles will look a bit strange on a tile roof once the array is gone or in a different configuration ? For the thinking that goes something like : screw it - I'm outa here in 10 years: Thinking a bit more about it, do you think by then that all the corner cutting done with schemes such as this with attendant problems will become more common knowledge over time with more attention added to such concerns at time of sale ? Will that effect property values or appeal ? If not, roll the dice.

In general, using composition shingles in this way seem a shortsighted cheap out, usually tried by vendors who make money putting panels on roofs with a lot of concern about making the most profit, and with perhaps not enough regard for the long term integrity of the customer's property. I would not allow such a thing to be done to any roof I owned. The relatively small amount of money saved is truly not worth the long term risk of problems to me. Seems like a short sighted crap out to me. To reiterate, particularly for the relatively small expense in time and particularly money compared to the cost of most arrays. Penny wise and pound foolish.

BTW: roof loading will probably not be affected in any serious way. I'd suspect if a P.E. check on roof loading is required, tile/comp. weight diff. won't affect things much, if at all. And, you'll need standoffs or some other way to attach the array to the roof. Lastly, keeping a healthy space ( = or > ~ 6") will keep the array cooler and more efficient in terms of output.

[omgwtfbyobbq]

While 1) could be a concern with other homes, there shouldn't be any leaves or dead animal bits where I'm planning on installing the panels. There isn't even a whole lot of bird doo, mostly because the birds hang out in the smaller trees around the house. There's still plenty of dust/etc... But I'm not sure if that could gum up anything.

With that said, I could use acrylic strips as standoffs to minimize the buildup of crud under the tiles. Freezing temps around here are also very rare, and if we do see them they seldom coincide with rain. For 2), I could add a layer of mesh before the flashing to clean out periodically. If I don't see a whole lot there, I can either reduce the frequency of cleaning, or pull it entirely.

3) would only be an issue if everyone in my family passed away, and in that context I don't care what the next owners think. Short of some terribleness, we're keeping it in the family because the house has a very low tax basis here in CA, which translates into a ~$4k/year lower property tax bill compared to if the house were assessed at market value. Energy efficient upgrades/solar will only help with those cost reductions. I'll also keep the tiles I removed around, so if I really want to reinstall them later I can.

I have this idea in my head that if I were to install the panels above the tiles, that would require structural calculations from a PE (more $$$), but if I were to remove the concrete tiles, I wouldn't need the calculations because the weight of the panels/racking/asphalt tile is less than the weight of the concrete tile. But I could be wrong about that too. I'll need to do some more research.

Thanks for the advice by the way! Please include anything else you can think of. The more I can do/consider ahead of time, the less I'll have to deal with later.

[foo1bar]

I have this idea in my head that if I were to install the panels above the tiles, that would require structural calculations from a PE (more $$$), but if I were to remove the concrete tiles, I wouldn't need the calculations because the weight of the panels/racking/asphalt tile is less than the weight of the concrete tile. But I could be wrong about that too. I'll need to do some more research.

Most likely the extra weight of the panels is not a problem.
My panels are 37lb each, and cover 17.6 square feet.
That's around 2lb/sq. ft

concrete tile are around 12lb/sq.ft. and shingles 2-3lb/sqft.

If your roof was designed for concrete tile, my bet is that ~14 instead of ~12 is no problem.

My guess would be you have to be more worried about making sure that the feet for the panels are fastened down sufficiently because when there's a good wind, there will be *significant* uplift on those panels. (I was a little suprised how many lbs of uplift would be at each foot when I was using the ironridge online design tool)

[J.P.M.]

While 1) could be a concern with other homes, there shouldn't be any leaves or dead animal bits where I'm planning on installing the panels. There isn't even a whole lot of bird doo, mostly because the birds hang out in the smaller trees around the house. There's still plenty of dust/etc... But I'm not sure if that could gum up anything.

With that said, I could use acrylic strips as standoffs to minimize the buildup of crud under the tiles. Freezing temps around here are also very rare, and if we do see them they seldom coincide with rain. For 2), I could add a layer of mesh before the flashing to clean out periodically. If I don't see a whole lot there, I can either reduce the frequency of cleaning, or pull it entirely.

3) would only be an issue if everyone in my family passed away, and in that context I don't care what the next owners think. Short of some terribleness, we're keeping it in the family because the house has a very low tax basis here in CA, which translates into a ~$4k/year lower property tax bill compared to if the house were assessed at market value. Energy efficient upgrades/solar will only help with those cost reductions. I'll also keep the tiles I removed around, so if I really want to reinstall them later I can.

I have this idea in my head that if I were to install the panels above the tiles, that would require structural calculations from a PE (more $$$), but if I were to remove the concrete tiles, I wouldn't need the calculations because the weight of the panels/racking/asphalt tile is less than the weight of the concrete tile. But I could be wrong about that too. I'll need to do some more research.

Thanks for the advice by the way! Please include anything else you can think of. The more I can do/consider ahead of time, the less I'll have to deal with later.

You're welcome. But respectfully, you're also naïve. Think 10+ years and think what can happen over that time. Believe it or not, some bird will dump on your roof, some material will spall off, and mixing materials and covering systems on a roof will provide an opportunity for ingress of foreign material under the tile where most roofing systems are designed specifically to keep moisture and foreign materials away from. Your idea of structural calculations for both static and dynamic loadings is equally uninformed.

Suit yourself. Not my house/money/life. I do know that most arrays I've seen on roofs keep the same roofing material under the arrays. I can see/think of no long term benefit to replacing tile with shingles under the array. I can see lots of potential and probable problems in the long run that will likely go undetected, only making the damage worse and the fix more costly.

I'm not sure how much money will be saved up front with those savings mostly coming as a result of less labor and time.

I am of the opinion that a roof and it's integrity are not the place to cut corners either in materials or good design. The few bucks saved up front by doing something that just looks like a bad idea and cheaping out via the blow and go style for reasons mentioned doesn't seem worth it to me from any angle I look at it. I won't even call doing it the right way - that is, keeping the roof material uniform over the entire roof - insurance, because that's the right way to do it in the first place.

To reiterate, I see no advantage to mixing roof materials and a lot of drawbacks that, to me anyway, are a real invitation to problems down the road.

However, I'm open to learning how mixing materials will increase the integrity of a roof and increase its service life.

As you write, you could be wrong. I agree you'll need to do more research.

No hard feelings and no skin in the game. Take what you want of the above. Scrap the rest.

[omgwtfbyobbq]

I wouldn't say naive, but inexperienced is I think accurate.

Concrete's durable, but getting the flashing/bird stops to the point where someone can go decades without water intrusion is apparently tough, especially on a tract home. On the flip side, asphalt is great for water proofing, but takes a beating from the sun and needs to be replaced every decade or few. My mom's second house has asphalt shingles under concrete tiles on the ridge (maybe the eves too) and it's held up better than any roof I've seen with one or the other. The asphalt shingles last a lot longer when there are a row of tiles above them, and they do a great job keeping out water if there are problems with the bird stop weep holes and/or other flashing.

With that said, I'm taking your advice and plan on keeping the tile and using prosolar's TileTrac (Unless there's some reason I shouldn't). I like being able to drill through the peak of a tile instead of the valley. If drilling out the existing weep holes and fixing the flashing doesn't fix the problems with water intrusion, I'll just put some asphalt shingles under the tiles in those problem areas. The California Solar Rights Act has really streamlined permitting too, so I don't think I'll need to bring in any engineers for drawings/calcs as long as the install conforms to the standard plans.

Thanks for the advice!

Edit - I just realized this was in the wrong forum. Mods, feel free to move it.

[solarix]

Yes, carry the shingles all the way down to the eave. This is common in the roofing industry in areas that use evaporative coolers. They just run shingles below all the way to the eve. Try to arrange the solar array so that it goes near the eves as well if you want to minimize the shingles seen. Really looks good to recess the array into the tile roof.