Rotten roof?

[snowjim]

Feels like you're taking the "boring" tips as personal attacks, Snowjim. You don't need to do that. You also don't need to do anything mentioned here in the thread. If you want to let the roof stay for another 20-40 years, you're absolutely allowed to do that.

Just note that eventually, the roof will reach a point where it becomes more expensive to delay the replacement than to keep the old one, so to speak.

Well, I'm not taking it as attacks, but I want to learn about this; I want to understand what indicates that the roof should now be written off. I do see that the tiles are worn, but there are no damages except the unfortunate tile that has slid down. If it hadn't slid down, this would never have been a discussion, and I feel pretty confident it would last at least another 5 years. I'm not a builder, but I have looked at MANY houses before we chose this one, and many roofs looked far worse than this; the most common issue was moisture in the attic, which we fortunately don't have at all.

The main idea of the thread was to hear what should be done about the damage. It does get interesting when people write off a construction that's been there for 48 years without explaining exactly why it needs to be replaced now.

 

[TheGame]

There was a lot of bickering in the thread now. I believe what's happened is that you have a very small gap between the battens and the plywood because the counter battens seem to be very thin. This has caused debris from the trees or something to get stuck there, then water that's run, for example, dripped from condensation or bounced unfortunately during heavy rain hasn't been able to flow down but got stuck. It has then swelled and become a permanent blockage there. So, it probably has been going on for a while. Local repair, then you'll manage for a while longer

 

[Kurtivan]

Stop bickering now, fix the undersarking and the lath, put the tile in place. End of discussion.

 

[justusandersson]

what has become markedly worse in the construction that makes it need to be replaced now?

The technical function of the panels has deteriorated. It's not that it couldn't last another 5 years, but the risk of damage increases. When the fine surface of the panels has eroded away, the drainage gets worse. For roofs with low slopes, this is an issue. Then I think you could try lifting a part of a ströbräda and see how it looks underneath. It can provide an important indication.

 

[garvin]

Probably holds for a few more years. My roof is from 1953, no paper, masonite, tiles.

 

[irihenke]

All roofs must have a waterproof layer. There's nothing wrong with plywood, but it needs something waterproof on the outside. If the plywood looks like in the top pictures, it must be replaced. All tiles and battens must come off, rotten plywood replaced, and everything covered with a membrane or roofing felt. The tiles are also ready for retirement. You probably need to use a tarp as a temporary measure. What is the roof pitch?

but no tarp. better as it is now so it can dry out

 

[irihenke]

lift down tiles on one side. remedy by removing all moisture-damaged.
råspont or new plywood. roofing felt on. fresh battens and laths. put back tiles.

 

[findus42]

What bothers me as a professional with TS's reasoning is that he only has one line of defense and doesn't seem worried that rot and mold will immediately occur as soon as a tile cracks or shifts.

My view is that TS's house is parked on a steep hill without a gear in place and the wheels are turned in the hill's direction. The only thing preventing an accident is the handbrake / roof tiles. The hill becomes steeper every year.

The plywood may look healthy to a layman's eyes, but not to me. It is completely dry but with surface cracks (indicating it's wet periodically) and absorbs every drop of water that finds its way in. It acts like blotting paper. A leak can seep for quite some time. When it becomes noticeable, it's because the plywood has turned into a cracker. It doesn't show on the underside until it's too late.

You can't see from the ground when an old concrete tile has cracked. You have to climb around and feel them. One in ten tiles might break when you try to lift it. That means it was cracked but you couldn't tell.

Take the advice about the roof celebration a bit seriously. Just changing tiles won't feel good. You'll find more rotten parts when you take everything down. If you're replacing all the battens (recommended), it would be negligent not to also replace the plywood. In that case, board planking and underlayment felt is the strong recommendation from the professionals in the thread. Probably cheaper than plywood if the plywood is meant for outdoor use. Russian-made K-plywood is a complete scam and shouldn't be sold at all. If you're considering that, I'd claim that OSB is safer and better outdoors on a roof.

NOTE: No recommendation of OSB as a roof. But it would be a step up for TS at the moment.

If you replace the roof seriously, you'll get a roof that is watertight without tiles. The tiles protect the felt from sunlight, so a simple underlayment felt lasts as long (almost) as the tiles. Bitumen and stuff that makes the felt waterproof will eventually evaporate, making the felt look like old desktop lining. I've seen it on old roofs. Not making this up.

Best regards, Findus

 

[AndersS]

But it has been like this for 48 years? How can this suddenly be a higher risk than before? What do you see that has become so bad that it needs to be replaced now?

As long as the roof shingles do their job, this is not a problem? Or have I missed something?

This is where the difference lies. Concrete tiles, as they age, start to allow moisture/water to seep through, and their lifespan is about 40 years. They may very well be intact and still have decent thickness, but their function to redirect water via the surface layer has significantly deteriorated (do not compare with clay tiles). Concrete ages/degrades over time, unlike clay tiles. And even their tightness at overlaps between them worsens.

So the answer is that the tiles are no longer doing their job as their function to be watertight and allow water to run off has deteriorated. So you will experience more and more moisture/water seepage from the concrete tiles.

For many houses, it's saved by the fact that the underlayment can still prevent moisture intrusion to some extent, even though it is also now starting to become dried out with a risk of cracking. However, your house lacks this extra protection and only has a wooden underlay. Our roof expired after 38 years, where after rain, you could see wet sections on the underlayment, so it had to be replaced. Our builder, who did the roofing work, lived in the neighborhood and after checking his own house, which was the same age, it also got a new roof a few months later.

So your roof leaks moisture/water after rain/snow, and the deterioration is not linear, but logarithmic. This means that the function of concrete tiles deteriorates significantly more towards the end of their lifespan. So what worked well after 25 years is now completely inadequate after 48 years. The risk now is that water can begin to penetrate the load-bearing parts of the roof structure.

 

[Freddedan]

I agree with Findus. Some of our 40-year-old pans just split apart when we lifted them. And the plywood looks a bit cracked. What happens if you press/scrape with a knife? In the cabin, we had plywood in the wall behind tretex, and they had delaminated completely. It reminded me of TS's ceiling panels but not as bad.

Personally, I would replace it a.s.a.p because if there's one thing you can rely on, it's that things go wrong at the worst possible time. Suddenly the roof starts leaking when you're going to Thailand for two weeks, and no company has time until six months later.

 

[snowjim]

Now we're getting somewhere! You can dislike reasoning as much as you want, but for me, it's fundamental to understand why I need to replace something. Just saying that a roof that hasn't had problems for 48 years should be replaced immediately due to poor underlying construction or simply due to age doesn't hold for me.

1. The underlying construction is outdated and inadequate according to today's building standards.

- Since the construction relies on the tiles not letting any moisture through, the roof's lifespan should largely depend on the condition of the tiles.

According to retailers and construction companies, concrete tiles last at least 40-50 years, while clay lasts twice as long.

2. The surface of the tiles wears down and becomes rough, which in turn makes debris stick more easily, especially when the roof has less slope. This also means that moss and similar can gain a better foothold.

- Sounds reasonable, but it's not really a problem until moisture penetrates the tiles.

3. Concrete tiles are not classified as waterproof and will over time leak more and more moisture onto the underlying construction.

- I also have the understanding that normal concrete lets water through, but to what extent is the question? Shouldn't I see leaks in the photos showing the other sections? And if water gets into the concrete and then freezes, wouldn't the concrete tiles break apart? And if I walk on tiles that are frost-damaged/cracked, shouldn't they give way? Above all, shouldn't I at least see a little moisture penetration into the attic if the concrete tiles are absorbing water significantly?

4. Rising can be seen in the plywood, indicating that it has been exposed to moisture.

- It's quite obvious that the plywood rose when the tile slid down, but I don't see these tendencies in the other sections? Which pictures are you referring to? And sure, wood can rise from high humidity which can occur between the tiles and the untreated plywood? It doesn't necessarily have to be water that has run over the plywood. On rainy days, the humidity easily rises to 80% according to my meter, i.e., it quite closely follows outdoor humidity.

 

[AndersS]

According to retailers and construction companies, concrete tiles last at least 40-50 years, whereas clay tiles last twice as long.
.

That claim certainly applies to today's concrete tiles in general. Our concrete tiles that were replaced were from 1960, and when I compared a new one that was in reserve, it was significantly thinner than the new ones that are now on the roof. And the old worn ones that were on the roof were even thinner and like 40 grit sandpaper on the surface.
Furthermore, when it comes to additional damage, your roof underneath is already in such bad condition that it needs to be addressed; it's not enough to just lay new underlayment and battens. In the normal case with decking, it's sufficient to roll on new underlayment and battens, but if you do nothing, you risk rot in the decking. So this differs with your roof where the substrate is already finished.
My philosophy is to maintain our houses before major problems arise; then you can think about addressing when real/major problems appear.

But your roof is finished and should be addressed, then you can twist and turn different arguments, but it becomes more of a philosophical discussion based on the concept of how bad it should be before it needs to be replaced.

 

[Plupp 122206]

I'm not a big fan of changing things before it's necessary; I replaced the entire roof this summer when it started leaking water.

What happens is it suddenly becomes damned urgent, which is rarely a pleasant situation to decide on a roof replacement. You'd rather plan in advance.

The other thing that can happen if you wait until you see leakage is that it leaks somewhere you can't see and where it doesn't dry up. Suddenly, you have mold in the bathroom wall or somewhere else; in our case, with a low-slope roof, it turned out that several of the rafters around the chimney were destroyed by rot; I honestly don't understand what was holding the roof up. Water has a very nasty ability to penetrate and get through structures, causing maximum damage.

Patch up your roof, then start inspecting the attic after every rain, when the snow melts, when it's stormy, and so on. You can live like this, or you can listen to all the wise people here on the forum who advise you to plan for a replacement before something goes terribly wrong. Consider how much you think the insurance company will support if the fault is due to a 48-year-old roof with known deficiencies.

Invite your friends and make a thing of it. It cost me 100,000:- to replace the roof, including new rafters, two layers of roof decking, new chimney caps, metalwork, food and beer for all my friends, and last but not least, we went from 3cm insulation to 39, with loose-fill insulation. It took a week from when we started tearing down until the surface felt was in place.

 

[snowjim]

That statement surely applies to today's concrete tiles in general. Our concrete tiles that were replaced were from 1960 and when I compared one such new that was kept in reserve, it was significantly thinner than the new ones that ended up on the roof. And the old worn ones on the roof were even thinner and felt like 40-grit sandpaper on the surface.

Aha, interesting, so what you're saying is that the material is thinner on older tiles?

This is what one from storage looks like versus one that has been on the roof for 48 years:


https://i.imgur.com/gJzqUf9.jpg

If you look closely, you can see that those that have been on the roof are a few mm thinner, and that's also what makes the surface similar to sandpaper.

How thick are your new tiles?

Then when it comes to further damage, if your roof underneath is already in such poor condition that it needs attention, it is not enough just to lay new underlay and battens.

There we are again, what is considered poor condition? Apart from the areas affected by local leakage? Can you point out the pictures?

In the normal case with tongue and groove, it is enough to roll on new underlay and battens, but if you do nothing, it risks getting rot in the tongue and groove.

Yes, roofing underlay is a good solution as long as it doesn't disintegrate. The durability seems to be around 50 years, which should mean that if you use clay tiles, you will have to replace the underlay at least once before replacing the tiles.

But roofing underlay can also cause problems; if it leaks somewhere, the risk of rot is much higher because the underlay traps the moisture. There are membranes that breathe one way, but I don't know how good they really are in the long run.

This is how it differs on your roof where the underlay is already worn out.

Again, in what way is the underlay worn out? And we of course don't refer to the local damage that can be relatively easily fixed.

My philosophy is to maintain our houses before bigger problems arise, though one might instead think of addressing them when real/bigger problems arise.

Bigger problems yes, that's exactly what I've been trying to sort out with this thread. It's not exactly like the roof tiles just give up one day. It is said that the process happens gradually, but so far we can't see any signs of leakage? So what are the big problems we're talking about?

But your roof is worn out and should be addressed, then you can twist and turn different arguments, but it becomes more a philosophical discussion based on the concept of how bad it should be before one must replace it.

Well, it's actually quite simple, I want to figure out how to determine that a roof is worn out and what risks exist? Just saying a roof is worn out without detailing is quite pointless. It's easy to see that the tiles are worn, but what says they wouldn't last another 5-10 years? If we had tiles that had frozen or cracked in other ways, I would be more convinced, or for that matter, if we had moisture penetration in the attic.

However, someone mentioned that a concrete tile opens up much more towards the end of its lifespan; is there evidence for this? Are they suggesting this happens in just a few months? Otherwise, the water getting in should frost damage the tiles during the winter months? And that should then be apparent when walking on them.

Now we have a roof where we can see that all the tiles are worn a couple of mm but are whole. We cannot see any alarming moisture in any compartment other than where the tile slid down, nor can we see any moisture penetration in the attic. So how can one see that it is worn out?

 

[irihenke]

Aha, interesting, so what you're saying is that the material is thinner on older tiles?

This is how one from the storage looks compared to one that has been on the roof for 48 years:

[bild]
[link]

If you look closely, you can see that those that have been on the roof are a few mm thinner, and that is also what makes the surface resemble sandpaper.

How thick are your new tiles?



Here we are again, what is considered poor condition? Apart from any localized leakage? Can you point out the images?



Yes, roofing felt is a good solution as long as it doesn't disintegrate. The durability seems to be around 50 years, which should mean that if you use clay tiles, you will have to replace the felt at least once before you replace the tiles.

But roofing felt can also cause problems; if it leaks somewhere, the risk of rot is much higher because the felt traps the moisture. There are membranes that allow for one-way airflow, but I don't know how effective they are in the long run.



Again, in what way is the underlayment worn out? And, of course, we're not referring to the localized damage that can be repaired relatively easily.




Major problems, yes, that's exactly what I've been trying to figure out with this thread. It's not as if the roof tiles will suddenly give up one day. People say the process is gradual, but so far we can't see any signs of leakage. So what are the major problems we're talking about?



Well, it's actually quite simple; I want to determine how you can tell a roof is at the end of its life and what the risks are. Simply stating that a roof is finished without detailed reasoning is quite pointless. It's easy to see that the tiles are worn, but what indicates they wouldn't last another 5-10 years? If we had tiles that were cracked by freezing or split in another way, I would be more convinced, or for that matter, if we had moisture penetration in the attic.

However, someone mentioned that a concrete tile opens up significantly more at the end of its lifespan, is there evidence for this? Are they suggesting this happens in just a few months? Otherwise, wouldn't the water that enters cause frost damage to the tiles during the winter? And that should also be apparent if you walk on them.

Now we have a roof where we can see that all the tiles are worn by a few mm but intact. We cannot see any alarming moisture in any other section than where the tile has slid down, nor can we see any moisture penetration in the attic. So how can you tell it is finished?

you don't see any difference between those that have been on the roof and the one you've had in storage?
it's not always the thickness you think of when something thins out.