This is in conjunction with my Tesla Solar install thread.

The pre-install site survey for my solar panels indicate that the underlayment of my roof is sufficiently deteriorated that Tesla will not proceed with install unless the underlayment is repaired.

My roof is the original concrete tile roof, built with the house in 1999 (21 years old).

The quote from Tesla is to pull the tile, remove and replace the felt underlayment, inspect for and replace any deteriorated roof decking (at additional cost), reinstall everything, and rebuild/replace all flashing and water diverters as necessary.

So, here are my questions:

1) Can the roof experts here confirm that 21 years is a reasonable replacement time frame for the underlayment?

2) Would you replace JUST the needed portion of the underlayment for the solar install, or would you replace ALL of the underlayment throughout the roof due to age?

3) The roof is 21 years old. The tiles are in otherwise good shape. Is there any need for me to seek a quote for tile replacement too?

When I bought the house, I knew that many things would need replacing due to age, so I'm not overly upset by the additional roofing costs. I just want to know that I'm not selling myself short by replacing parts of the roof too early.

Thanks in advance Sigforum!

I'm curious to know the answers to your questions. I have little experience with tile roofs but I know for shingles, we have always replaced the dry in and drip edge before shingles are installed.

I really don't see any benefit in trying to save money by not replacing the underlayment. It just seems like leaks waiting to happen.

I just spent $32k on a reroof in SoCal and I did all that research and then some.

30 lbs. felt only lasts in prime functioning condition for about 15-20 years. It will still work after that but not perfectly and is prone to curling and drying out. Two layers of 30 lbs felt is part of the Uniform Building Code (UBC) that Orange County adopted.

You can go with two 40 lbs. layers that will add 5 years to the above numbers but even then, you may want to consider something else.

I went with concrete tile with a 50 year warranty. But since felt only lasts 15-20 years and perhaps a tad more, the felt will need to be replaced and that means taking off the solar roof and that's not cheap and there's the risk of damage. That's all going to be at your cost.

Instead, consider a synthetic underlayment. It's not that much more expensive but it comes with a 50 year warranty. I have 50 on the tiles and 50 on the underlayment so the roof isn't expected to be repaired for faiured underlayment like you have to plan on doing with felt.

Why do people go with felt? Because it's less expensive and they think that if the felt needs to be replaced then they might as well put on a new roof too.

Also, consider where you live, the hot months and the Santa Ana winds. Ask for elevated battens which raise the tiles off the roof about 2 inches (you don't see it) and this creates a boundry layer of air. On hot days the air flows up and out the peak of the roof and helps cool the house without expensive AC. You can drive around all throughout mid-OC in Mission Viejo, Laguna, RSM and see a hybrid of sorts that has metal squares in the roof. This is another form of venting that is cheap but looks like a checkerboard, IMO.

The UBC will require you to have some roof venting and raised battens meet the code requirements and give you an extremely nice looking roof. You could do solar mushroom fans but they only come with a 10 year warranty and require that nice roof to come apart to replace.

Raised battens have no moving parts and there's nothing to replace.

1. In a hot climate, ABSOLUTELY. Here in South Florida tile roofs with 30/90 felt (FL minimum Code) underlayment go about 25 years. I can't believe CA allows 30/30. 30 lb felt for the second layer is pretty thin stuff.

2. ABSOLUTELY NOT. Replace all of it (entire roof, flat roofs too). No easy way to tie in just the solar part of re-roof, to existing old roof that's going to be replaced soon anyways. Tiles get destroyed when removing them and new ones won't match old ones. And, upgrade to a premium underlayment. It only adds 5-10% to the cost of the roof and will extend the life from 25 years to 40+ years. and also some will give you a hurricane discount on your insurance IF you're in hurricane country.

3. You cannot do the underlayment without replacing the tile. Unless you want to spend a million man hours removing the concrete (most likely) underneath them that was used to glue them down and the time removing them. They now use a 2 part 3M system of foam that mixes at the gun and has superior adhesion. A complete re-roof with good concrete tile and premium underlayment (as well as replacing all drip edges/flashing etc. and tear off and throw away of the old roofing materials) runs about $600 per square (10'x10' area) here in South Florida. You also want color thru tiles, not ones that are a slurry (slurry is baked on finish over grey concrete tiles, color really pops but slurry wears off before time to re-roof and you have ugly grey showing through, color thru means the entire tile is the same color concrete.)

Thanks for all of the info guys. I'll collate some more data here before I proceed.

^^^^^^^^^^
He is correct. Replace it all. Leaks are a nightmare.

Frick. If I’m in the same situation and the roof is going to add $18k to cost of doing solar, then that puts BE at about 10 years. That might be a deal breaker for me.

My concrete tile roof is 100 years old +/-

It is now just starting to have problems.

There are few people around here that can and will work on them. It is a two year wait for them to show up to do the work.

The nails are rusting out and some rows are moving.

I will strip the tiles and replace everything underneath and go with asphalt shingles.

I will not be alive in another 100 years.

quote:

Originally posted by jimmy123x:
1. In a hot climate, ABSOLUTELY. Here in South Florida tile roofs with 30/90 felt (FL minimum Code) underlayment go about 25 years. I can't believe CA allows 30/30. 30 lb felt for the second layer is pretty thin stuff.

2. ABSOLUTELY NOT. Replace all of it (entire roof, flat roofs too). No easy way to tie in just the solar part of re-roof, to existing old roof that's going to be replaced soon anyways. Tiles get destroyed when removing them and new ones won't match old ones. And, upgrade to a premium underlayment. It only adds 5-10% to the cost of the roof and will extend the life from 25 years to 40+ years. and also some will give you a hurricane discount on your insurance IF you're in hurricane country.

3. You cannot do the underlayment without replacing the tile. Unless you want to spend a million man hours removing the concrete (most likely) underneath them that was used to glue them down and the time removing them. They now use a 2 part 3M system of foam that mixes at the gun and has superior adhesion. A complete re-roof with good concrete tile and premium underlayment (as well as replacing all drip edges/flashing etc. and tear off and throw away of the old roofing materials) runs about $600 per square (10'x10' area) here in South Florida. You also want color thru tiles, not ones that are a slurry (slurry is baked on finish over grey concrete tiles, color really pops but slurry wears off before time to re-roof and you have ugly grey showing through, color thru means the entire tile is the same color concrete.)

There's a lot of truth in this post.

In CA we don't have FL type of driven weather so 30/30 is the code minimum but you can ask the contractor for 40/40 although most do 30/30. The reason is that a lot of older homes can't do the heavy tiles without a structural engineer to determine load factors but you can do light concrete that most any home can handle but they are more expensive than standard concrete hence, people go with asphalt.

The part about tiles breaking is very true and if down the road you need to order new ones, who knows if the manufacturers exists or even makes them anymore. Instead, I have an extra 150 tiles, 50 for the ridge and overhang.

Tiles here aren't glued down. Just an airgun and pop-pop. The UBC code here doesn't require all tiles to be nailed down once you meet certain nailed margins however no contractor puts them up unsecured.

Through and through is the only way to go. You can get them with the slurry color that looks good but it starts to lose the gloss (depending on texture and color and product rating) over a few years, seems to hold and slowly lose color but the through color will make it good looking for the entire time.

The OP should make this reroof and solar project a once in a lifetime thing. There's no long term upside to not putting down a synthetic underlayment as part of the project. IIRC, the synthetic added about $600 more than felt but ' have to look at the paperwork.

Flashlightboy, did you like your roofer? Could you recommend him?

Here in San Diego I found out that a "lift and relay" is a very standard thing for roofers. The tile will last indefinitely, the underlayment maybe 25 years. Our roof was redone by the original owner in 2004 shortly before a devastating fire in Scripps Ranch; he replaced cedar shingles with tile. Hence the house did not burn down as those around it did. We had underlayment looked at before our solar system was put in last year, and it was OK.

I don't think it's necessary to replace the tiles, but is to replace the underlayment. If synthetic is available with 50 year warranty, I would go for that.

quote:

Originally posted by konata88:
Frick. If I’m in the same situation and the roof is going to add $18k to cost of doing solar, then that puts BE at about 10 years. That might be a deal breaker for me.

To be fair, the roof is the roof, and solar is solar (in my opinion). If it's time to replace the roof, I'm chalking that up to home maintenance costs. It's not the solar panel's fault that the underlayment is at its end of life.

quote:

Originally posted by sjtill:
Here in San Diego I found out that a "lift and relay" is a very standard thing for roofers. The tile will last indefinitely, the underlayment maybe 25 years. Our roof was redone by the original owner in 2004 shortly before a devastating fire in Scripps Ranch; he replaced cedar shingles with tile. Hence the house did not burn down as those around it did. We had underlayment looked at before our solar system was put in last year, and it was OK.

I don't think it's necessary to replace the tiles, but is to replace the underlayment. If synthetic is available with 50 year warranty, I would go for that.

Lift and relay seems to be the recommend procedure here.

I'll look into the synthetic underlayment and see what the price delta is. A 50 year underlayment might exceed the lifespan of the roof tiles though.

Gonna make some calls tomorrow and see if Tesla's bid to replace the underlayment is competitive.

Jimmy has good points. I supervised the construction of one of my boss’s bank buildings in ‘98-‘99. We used the polyset adhesive foam system to secure the barrel tile roof. It was the first job up here using that system. The manufacturer had to send a team up here to train the roofers on the system (long story, builder should have read the specs). Basically, conventionally nailed down tiles will vibrate in high winds until they crack at the nail holes and then they start to go. The foam system eliminates this issue. To date, we have lost zero tiles through several storms.
I also recommend a self sealing, adhered underlayment(I.e. peel and stick). This should give you some break on your insurance.
I had my roof done in 2017. Complete removal, replaced 17 sheets of decking, all decking nailed to current code, self sealing peel and stick underlayment and architectural (6tab) shingles. After inspection my insurance dropped 60%.’i

quote:

Originally posted by Aeteocles:

To be fair, the roof is the roof, and solar is solar (in my opinion). If it's time to replace the roof, I'm chalking that up to home maintenance costs. It's not the solar panel's fault that the underlayment is at its end of life.

Yes, generally agree. But, unless conditions improve here (socioeconomic politically speaking), I’ll likely be seeking greener pastures without breaking even as I believe the roof will last that long. It may not last the extent of the solar warranty but should last for the current BE period.

It may not be financially sound to do both unless I plan to stay for >> 10 years.

No decisions yet but a $20k roof expenditure will give me pause. If it’s due for replacement before I intend to leave this location regardless of solar is one thing. But if replacement is indicated only because it won’t last the life of the solar panels, that’s different.

Grace Ice and Water held up to a 165mph Cat. 5 hurricane on a house we were having built. The roof had yet to be installed when Ivan hit it.

quote:

Originally posted by jimmy123x:
Unless you want to spend a million man hours removing the concrete (most likely) underneath them that was used to glue them down and the time removing them.

Concrete tile roofs here in AZ (and they are ubiquitous here) are laid on furring strips to keep the rows parallel. The tiles have a projection on the back side that hooks over the furring strip. Some rows are nailed down (the tops an bottoms, and some in between), but otherwise one row holds down the one below it. There is no concrete used in applying the roof tiles.
 
I had a particularly nasty dust devil pass directly over a corner of the house. It ripped off two tiles and broke a couple of others. I went to my "saved tiles" pile, got 4 replacements. On the roof, all I had to do was lift an undamaged tile above the broken one, lifted just a couple of inches, and I could pull it out and replace the damaged one.
 
The tiles are quite heavy. IIRC correctly, the roofer told me 11 lbs each. Anyway, at that time when he was roofing it, I calculated the total weight of our roof, based on the number of squares he used. The concrete tiles on a 2300 sq ft house plus 3 car garage, with a 6/12 pitch, weigh 44,000 lbs. The roof is "stacked" before laying the tiles. Piles of 4 or 5 tiles each are laid all across the roof, including all the tiles that will be used. The roof is left stacked for a couple of weeks to let the house settle under all that weight. This is done before the stucco sub comes in, for obvious reasons.

Replace underlayment with a modbit type, have tiles put back on unless they are damaged. The tiles are concrete, new ones will not be any better than the old ones. Or get a new metal roof installed, it’s only money.

quote:

Originally posted by henryaz:

quote:

Originally posted by jimmy123x:
Unless you want to spend a million man hours removing the concrete (most likely) underneath them that was used to glue them down and the time removing them.

Concrete tile roofs here in AZ (and they are ubiquitous here) are laid on furring strips to keep the rows parallel. The tiles have a projection on the back side that hooks over the furring strip. Some rows are nailed down (the tops an bottoms, and some in between), but otherwise one row holds down the one below it. There is no concrete used in applying the roof tiles.
 
I had a particularly nasty dust devil pass directly over a corner of the house. It ripped off two tiles and broke a couple of others. I went to my "saved tiles" pile, got 4 replacements. On the roof, all I had to do was lift an undamaged tile above the broken one, lifted just a couple of inches, and I could pull it out and replace the damaged one.
 
The tiles are quite heavy. IIRC correctly, the roofer told me 11 lbs each. Anyway, at that time when he was roofing it, I calculated the total weight of our roof, based on the number of squares he used. The concrete tiles on a 2300 sq ft house plus 3 car garage, with a 6/12 pitch, weigh 44,000 lbs. The roof is "stacked" before laying the tiles. Piles of 4 or 5 tiles each are laid all across the roof, including all the tiles that will be used. The roof is left stacked for a couple of weeks to let the house settle under all that weight. This is done before the stucco sub comes in, for obvious reasons.

I was not aware of the fact that tiles are only nailed down. Here in South Florida tile roofs date back to at least the 1930's (clay barrel tiles), then at least as early as early 1950's the vast majority of homes had 1/2" thick flat concrete tiles and both of those were just sent on top of the tar paper with a handful of concrete and pressed down. Many still have those roofs but have a bunch of coats of that elastomeric sealer goo people paint over them to stop the leaks, which create their own leaks and issues because people are too cheap to re-roof. When re-roofing they have to basically break them all loose by sliding a large shovel under them and breaking them free and then they're not re-usable. Our tiles are glued down and 1/2" concrete in 3 styles, flat, S, and Barrel.

I've seen the furring system used in the Carribbean, but down there they use 4'x8' (I think) sheets of stamped metal that looks like S-tile screwed down to it.

Wasn't aware they nailed tile down in your area. I still don't know if I'd re-use it, as I feel it would get a little brittle over time baking in the sun with the heating and cooling cycles. I'd also think they'd break some of them pulling the nails out. From my experience the tile colors vary a little, even from one batch to the next batch from the same manufacturer.

YES, they're heavy. They do the same on a re-roof here, leave them in piles of say 12 tiles every 2' feet along the roof for a few days.

A premium underlayment is not that much more money, and I'd highly recommend it.

This message has been edited. Last edited by: jimmy123x,

quote:

Originally posted by Aeteocles:
Flashlightboy, did you like your roofer? Could you recommend him?

I like the roofer but I'm a bit hesitant to pass on his name. He's fine, his crew was fine and all the good stuff you'd expect however we have some cracked plaster from the increased weight of the house settling and he's already said he'll take care of it on his dime, as he should.

Until it's done I don't want to pass on a name. His workmanship was great, the roof is great and all the things you want to hear were true. I just need him to address the plaster. This isn't a reflection on him but rather a fact of having a heavy roof where it was cedar shakes before.

The roofing contractor didn't guide me per se but when I pointed out what I'd found about the underlayment, he said most people don't do research or mention it since they want the cheapest new roof and that usually means asphalt and 30 lbs. felt.

For people who have half round clay tiles, he said most people will still go with the 30 lbs. and rely on the tiles for addtional protection to save going with 40 lbs.

When I asked about warranty, concrete tiles, battens and synthetic underlayment, that elevated the conversation to places the vast majority of people never consider and that's when he pulled out the really glossy brochures.

Now that it's up, I would do it all over again just like I did, even with the cracked plaster.

The plaster cracks are minor but the problem is that all the good contractors are very busy and scheduling 2-3 months out because home owners are working from home, looking at their home projects and deciding to do them. This includes concrete, masons and painters.