Dale's 53 year old green roof.

Dale's 53 year old green roof.

This roof stands as a great example of a low maintenance green roof.

I got called to check out the gutters on the low slope, tar and gravel roof of this house that was built in 1960. Nothing significant has been done to it since it was built. A home inspection and declaration from the original owner, stated that this is the original roof. The present owner, a lady with limited construction knowledge, had never even cleaned the crap away from the downspout screens in the 11 years that she has owned the house. I was called because water was washing over the top of the flashing and running over the edge. This roof has no regular gutters. Instead it's more of a swale with downspouts at both ends. A layer of moss averaging 4 inches deep covers the entire surface and remains green all year, although it looks a little more yellowed in summer. I held the ladder from the top and the owner came up for a look. She said it looks the same as it did 10 years ago. Many fallen branches have slowly decayed on the roof. There has never been a leak. Even the water washing over the edge has caused no problems, since there is a generous overhang and the metal flashing is bent on a proper angle to shoot water away from the fascia and walls. An almost maintenance free design and really high quality construction have preserved this marvel, despite years of neglect.

I started by clearing the crap from the wire screens that keep large debris from going down the downspouts. After 53 years, I expected them to be rusted away. They are made of copper and after some cleaning and straightening, it looks like they'll do for a few more decades. The pipe leading to the downspouts is also well preserved copper. All were covered deeply by a couple inches of well rotted leaf mold and slow growing moss.

First 2 photos are on my phone. The third photo is from my camera. The color is more accurate. It's like a miniature landscape with hills and valleys.

. Once you see 12 photos and some more story, I'm done.

In order to allow water to flow to the downspouts, I cut trenches through the moss and scooped out buckets of soil. Trenches were also cut along the gable ends. Half an hour of high pressure hosing made the mucky mess look like gravel again.

The steel flashing is corroded and will be painted and tared next summer. The asphalt goes up to the top of the flashing. The only real problem is one that is not easily fixed. The drains sit about 2 inches higher than the lowest portion of the swale. This means that some water always sits in the bottom portion and cannot drain away. In the summer, it evaporates and that is the only time that this area ever dries out enough for painting or tarring. This dip collects lots of composted leaf litter, and is probably the reason that the slightly higher downspouts weren't clogged much sooner.

The lower chimney was absolutely engulfed in moss. The metal flashing has lost most of it's zinc coating and is rusty. I cleared around it and made some slots for water to flow to. The metal will be painted in the summer.

The only other work needed on this roof is the removal of some unused radio antennas and replenishing of pea gravel in the newly formed, moss free trenches. The gravel is to protect the area from sun damage. I think it's safe to assume that the thick layer of moss which blocks the sun and moderates temperature has contributed to longevity. The home has never needed air conditioning. 80F is a pretty hot day for Victoria and it seldom goes below freezing. I dug down to the tar layer using only my fingers. The tar is not super brittle. I was able to dent it with my thumb nail. The decayed litter layer beneath the moss is about 1 1/2 inches thick. The moss is well rooted in this but doesn't seem to be trying to root in the tar. Big sheets of moss are easily lifted up like a big soggy carpet. My best guess is that this roof still has a few decades of useful life left in it. The owner will get me to check it out every couple of years, to clean the screens and keep the trenches open.

Fantastic post Dale!

Wow - what an interesting roof! Thank you for being able to see it with "permaculture eyes". I shudder to think what some folks might make of this roof.

Lovely.

Pretty cool Dale, so was it built with this moss on the roof or did the moss just grow over time on the leaves and such that accumulated there?

Amedean Messan wrote:Fantastic post Dale!

Thank you Amadean and Jennifer. When I first looked at the roof, I told the owner that I had good news and bad news. The bad news was that some serious maintenance of the metal parts is overdue. The good news is that there's not one person in 100,000 who is as keen on learning all about the construction and maintenance of gravel and moss covered roofs as I am.

Miles --- I don't think it was planned this way. If you ignore a roof in this environment, moss will find it's way there. If the roof is flattish and covered in a nice substrate of gravel, a layer of leaf mold/humus will develop. I've seen several others that are on their way to this state.

The surface of this roof is humpy bumpy. The leaves, needles and twigs tend to stick to where they fall rather than being washed to the edges. As time passes, the surface becomes more irregular. Twigs become leaf dams. Rather than developing as a thin layer that slowly thickens, this moss starts out as little clumps that grow to eventually cover the whole roof. I've seen roofs that appear to be half somewhat bare gravel and half islands of moss.

Moss destroys regular asphalt shingles, often causing them to have a much shorter service life. For this reason, many people go to great lengths to kill or remove moss. But on roofs that have a layer of pea gravel, the rhizomes seem to go for the gravel and I believe that the moss performs a protective function. The effects of daily and seasonal temperature swing, sun, wind and rain are buffered. Falling objects land on a sort cushion. Branches up to 2 inches in diameter have rotted into this roof and added to the layer of humus.
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This sort of roof management aligns well with a few other roofing ideas that I've been pursuing.

This thread concerns growing grapes on the roof. Leaf and fruit drop from grapes would cause nothing but problems on a regular asphalt roof but on a rubber roof covered in gravel, their presence should speed the whole process of getting a nice soil layer and moss thrives in partial shade. link -- https://permies.com/t/29143/permaculture/Growing-Grapes-Green-Gravel-Covered#227653

Love those pictures. I"ve been wondering if someone could use moss for a green roof. I loved the idea of a green roof, but was concerned about the weight load. Then I saw an episode of "Growing a greener world" and they discussing using moss as landscaping. They mentioned how moss doesnt root, so it wouldnt need soil, just something to cling to. Do you think someone could activly creat a roof like you"ve shown, and if so, how would you recommend it? We currently live in an old OLD double wide, that has a roof built over it. The pitch isn"t very steep (have to ask mate, if you needed specifics, as he's done roofing: most of my experiences have been as the " beer B**ch"). I loath putting more money into this place, but it"ll be a few more years until we will be able to move to our land/ homestead on a permenit basis. The roof needs to be replaced and there already exists plenty of moss on the existing asphalt. lol Would it be possable to remove the shingles, put down a liner and somehow glue a fine layer of sand? The tar and pea gravel looks to me as if it would be as heavy if not heavier than the asphalt singles. We live in the twin tiers region of WNY so, yeah lots o' snow. If not sand , something light wt. you might recommend? Thanks for any insight you might have.

Hi Dale,

This was an outstanding post to share with folks. Thanks so much for presenting it.

This really does demonstrate what green roofs can be like, even if they are not planned for. If you have a solid roof frame, and build your layers up properly (many different ways to do that) any low pitch roof can sustain a "green layer." Moss for the wetter climates like yours is great and sedums for the dry ones.

If you actually design the roof to be a "growing roof," you can plant even more.

Thanks again!

jay

Jay C. White Cloud wrote:Hi Dale,

This was an outstanding post to share with folks. Thanks so much for presenting it.

This really does demonstrate what green roofs can be like, even if they are not planned for. If you have a solid roof frame, and build your layers up properly (many different ways to do that) any low pitch roof can sustain a "green layer." Moss for the wetter climates like yours is great and sedums for the dry ones.

If you actually design the roof to be a "growing roof," you can plant even more.

Thanks again!

jay

Thanks Jay. I've been following your posts in green building and have seen that you've often injected some good sense when it's needed.
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I was talking with my dad on Sunday, about green roofing and the need to get away from disposable asphalt, which both of us considered an obsolete technology. He died yesterday. For the last couple years we've talked much more about my property and building inventions than about his failing health. He was a very smart and tough old guy, and really enjoyed helping me to think these things through. Moss, underlain with gravel was the last thing that we talked about. It was a bit of a eureka moment. Millions are spent getting rid of the very plant that makes the most sense to promote in my climate. I hung up the phone feeling more confident than ever that this is the way to go.
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Ray--- You're in an area where your roof may be designed for 75 lb. per sq. ft. or more of snow, so the weight of the liner and some gravel (15 lb. per sq. ft) doesn't seem like so much. Many trailer type homes get really hot in the summer. An insulating layer of moss will help a lot. It's always best to prevent heat entry rather than worry about getting rid of it later. One of the best ways to get extra strength in a roof is to have a large cantelevered overhang. Trailer homes have almost none. Suppose that a rafter spans 10 ft from the center beam to the wall. If you had a 3 ft. overhang, it effectively cancels 3 ft. of that span. The span is now effectively 7 ft. and can be loaded much more heavily than a similar span that has no overhang. If your building is near the end, I wouldn't go to the trouble of creating a high end roof. Instead I'd clean it and apply a coat of tar, if it only needs to last for a few seasons.

Good Evening Dale,

I am sadden to read of you losing your Father, my prayers are with you and your family...

I was talking with my dad on Sunday, about green roofing and the need to get away from disposable asphalt, which both of us considered an obsolete technology.

His wisdom will be missed, I am sure, and you both are very correct about the obsolenty of asphalt roofing systems in general in all their permutations.

Moss, underlain with gravel was the last thing that we talked about.

I know it is a small consolation at this time, but I could not think of something (at least to me) more comforting and pleasing to discuss before a passing. Moss has always been one of my most cherished living things to be around, to grow, and nurture. Moss and lichen gardens are some of the most enchanting gardens I have ever been part of.

It was a bit of a eureka moment. Millions are spent getting rid of the very plant that makes the most sense to promote in my climate. I hung up the phone feeling more confident than ever that this is the way to go.

As you should, and you are correct in your thinking. To not try and make the mosses and lichens a focal point of "pacific northwest" planting systems is obtuse. With little effort they will naturally enhance any space or surface with little nurturing. Your notion is wonderful.

Warm Regards,

jay

Dale - sounds like you lost a good friend and we all lost someone with a lot of wisdom and knowledge to share. Really great to know that you spent your time engaged in pondering inventions and other worthy pursuits - sounds like a damn fun time.

My thoughts are with you.

Jen

Thanks Jay and Jennifer. I know that many of us pursue unusual or uncommon interests in relative isolation. The forum is very important in linking people with unorthodox interests. My family contains a few free thinkers and innovators. Dad was always open to innovation and seldom a naysayer. He participated in the industrialization of farming in the 50s and 60s. By the seventies he was sure that all of the poisons and soil erosion meant that change was needed. I remember when I was about 10, a neighbor offered to spray our sweet corn patch with Atrazine, claiming that "it kills everything but corn". Dad shook his head and said, "We're not corn". I was a kid and understood what this meant.
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Back to moss covered roofs. We have plenty of glacial till on the west coast. The mixture of dozens of types of rock, gives moss all of the nutrients that are needed. Lichens grow in association with it and add nitrogen. Both moss and lichens can get all of their nutrients in this way. Small ferns and other plants are sometimes part of the mix. All of these plants can survive months of saturation, followed by months of baking in the sun with no rain at all. Rooftops are extreme environments. These plants have been around since the Earth had a much less hospitable environment for living things. All of the leafy things that we commonly think of as plants, evolved eons after these pioneers began forming the first soils. If your roof is in good shape, the best thing to do is stay off of it. With a covering that thrives on neglect, there's no need to do much up there. Check it out a couple times a year to make sure that nothing has blocked drains and you're done. Leaves, needles, sticks, bird feathers and oyster shells will feed the little ecosystem without interference. The home will be easier to heat in winter and will stay cooler in summer. And it looks really cool.

I a so sorry for your loss, and deeply humbled that you still took the time to answer my questions. Thank you so much. May your fond memories bring you
solace.
You are right. It would be foolish to invest more money in our place. The roof isn't even leaking, it just looks neglected. Which it is. I am still hoping to go
with moss when I build on our homestead. Thank you again.

It's been three months since the roof maintenance. This Rolling Stone is gathering plenty of moss and using it for roofing, wall covering, and flooring (outdoor shower). This thread is about using moss and ferns in the bathroom --- https://permies.com/t/32710/green-building/Dale-living-bathroom#254831

This thread is about moss art --- https://permies.com/t/13614/art/Moss-art

I've found several other roofs with moss, but none as deep as this. One wind swept site had a few spots on a flat roof that were rolled up like carpet. I'm trying several methods of making moss live on, in or around human habitation. On a recent pruning job, I worked on fruit trees that had thick mats of moss, ferns and lichen growing together. When pulled from the tree, it comes with some dead bark attached. It seems like an easy plant community to transplant to baskets or pots.

Dale, lots of great photos and info on this post. I have been wanting to replace an existing asphalt shingle roof with a green roof.

Located in Ontario, Canada we can get lots of snow load. It is a simple A-Frame cabin, we get water seeping through now in several locations during heavy rains or when lots of snow build up starts melting, so time to replace.

The cabin is shaded by pines and hemlock, so the roof naturally becomes covered in evergreen needles, with moss growing on the shingles. I would like to maintain the current look but with a roofing strategy designed for the purpose.

What I would like to do is to:

1 - remove the asphalt shingle
2 - repair any roof decking that is required.
3 - Lay down a protective barrier, cardboard, newspaper or filter cloth
4 - lay down epdm membrane
5 - lay down a protective layer for the membrane
6 - Allow roof to be covered with evergreen needles, sticks and moss.

I am looking for comments on materials noted above and any potential alternatives. I would also be looking for some installation details ie how to best attach the membrane and different layers.

Below are a couple of photos. Thanks in Advance.

I think these are the photos.

Any idea what is going wrong with my image insertion. I tried photo bucket and some other program?

Preview is not working for me, so i don't find out images aren't included until it is submitted. Thought I followed instructions I saw posted elsewhere.

P Lyons wrote:Any idea what is going wrong with my image insertion. I tried photo bucket and some other program?

Preview is not working for me, so i don't find out images aren't included until it is submitted. Thought I followed instructions I saw posted elsewhere.

You need to right-click on the image itself and select 'copy image url' then post that url into the little box that appears when you click the IMG button, not the URL of the whole page. I snuck into your post from behind the scenes and cheated a bit to find out what you were trying to post.

P Lyons wrote:Dale, lots of great photos and info on this post. I have been wanting to replace an existing asphalt shingle roof with a green roof.

Located in Ontario, Canada we can get lots of snow load. It is a simple A-Frame cabin, we get water seeping through now in several locations during heavy rains or when lots of snow build up starts melting, so time to replace.

The cabin is shaded by pines and hemlock, so the roof naturally becomes covered in evergreen needles, with moss growing on the shingles. I would like to maintain the current look but with a roofing strategy designed for the purpose.

What I would like to do is to:

1 - remove the asphalt shingle
2 - repair any roof decking that is required.
3 - Lay down a protective barrier, cardboard, newspaper or filter cloth
4 - lay down epdm membrane
5 - lay down a protective layer for the membrane
6 - Allow roof to be covered with evergreen needles, sticks and moss.

I am looking for comments on materials noted above and any potential alternatives. I would also be looking for some installation details ie how to best attach the membrane and different layers.

Below are a couple of photos. Thanks in Advance.

Sorry for the delay P Lyons. I just now saw this. The only thing I would change about this plan is that I would use recycled, tight weave carpet as the protective layer beneath the membrane. Sometimes as wood ages, sharp splinters can separate and poke upwards. Foot traffic on the roof can force the membrane against hazards. Don't use carpet that has been stapled. You will miss one. Use stuff that used carpet stripping along the edge. This is a free product, so cut out any questionable areas.

If the roof can handle the weight, a very thin layer of pea gravel could be added. Battens 3/4 inch thick, run horizontally across the roof would create little dams that could hold the gravel in place. They won't hold much gravel or water, just enough to prevent the liner from blowing up and to work as needle dams. Hopefully moss will take hold and spread from these moist lines. Dust, bird poop and sticks will accumulate. Don't try to cover the whole roof with gravel if weight is an issue. The 3/4 strip will easily back up a strip of gravel of that thickness at it's bottom edge and becoming progressively thinner going up. The roof will appear to have a dozen little terraces. Walk only on the clear areas immediately below battens where gravel does not gather. Use only nice round pea gravel. A misstep could cause sharp crushed gravel to puncture the membrane.

Don't try to stretch the membrane out. We don't want the weight of the organic layer to hold the membrane in perpetual tension.

I wouldn't glue it except possibly along the edge. weight alone should hold it in place.

Sun is the enemy of rubber. I would rake up plenty of needles and apply them before a rain and during a period of little wind. Moss can be gathered from the woods or from other areas. Try seeding a little. A small amount of grass clippings might help things to get started.

Once it is established, stay off of it. Pop up for inspections regularly, but mostly it should be admired from the ground or from the ladder.

What surprises me about this roof, and some other seriously mossy roofs I've seen in this province, is that there are no tree seedlings taking off in it, which I have seen in some locations in moss and in needle debris. I would think that with that much debris, and moisture retaining moss that hemlocks, spruce, pines, and other acid lovers would be all about inhabiting this niche as it progresses.

I have considered this to be the ultimate roofing solution for a long time, and the only maintenance being the gutter/swale/drain rock and drain screens, as well as the rooting out of the tree seedlings. Maybe the rooting out of the trees wont be necessary after all, if this is an indication.

Being a rainforest child myself, I wonder, considering the vast amount of water that the mosses can hold, just how much more the roof weighs in the Victoria winter, as opposed to the driest part of the summer.

Also, I thought instantly that such a roof, if watered in the dry part of the summer, could produce a massive cooling effect (swamp cooler) for the house (in addition to the one caused by it's insulation).

I really enjoyed this thread and the living bathroom thread that brought me here. Thanks Dale. You and I think a lot alike.

This is one of those fascinating projects that amaze me, and I have no idea how one would go about doing this.

Thank you so much for sharing these pics!

Roberto pokachinni wrote:What surprises me about this roof, and some other seriously mossy roofs I've seen in this province, is that there are no tree seedlings taking off in it, which I have seen in some locations in moss and in needle debris. I would think that with that much debris, and moisture retaining moss that hemlocks, spruce, pines, and other acid lovers would be all about inhabiting this niche as it progresses.

I have considered this to be the ultimate roofing solution for a long time, and the only maintenance being the gutter/swale/drain rock and drain screens, as well as the rooting out of the tree seedlings. Maybe the rooting out of the trees wont be necessary after all, if this is an indication.

Being a rainforest child myself, I wonder, considering the vast amount of water that the mosses can hold, just how much more the roof weighs in the Victoria winter, as opposed to the driest part of the summer.

Also, I thought instantly that such a roof, if watered in the dry part of the summer, could produce a massive cooling effect (swamp cooler) for the house (in addition to the one caused by it's insulation).

I really enjoyed this thread and the living bathroom thread that brought me here. Thanks Dale. You and I think a lot alike.

I think the lack of trees has to do with 3 months most summers with no rain at all. Sometimes as early as June, the roof will be bone dry. The surface of the moss gets hot. It can stay that way until September. None of our trees cane take that unless they are is soil which has a reserve of moisture.

On weight --- Water runs through moss pretty well. This one is really thick with a soil layer. It was maybe 4 lb. per sq. ft. Our roofs must be designed for maximum snow loads. During colder winters when it all comes down as snow, the weight is much higher. Saturated moss is a free draining material that will reach a level of saturation and then hold steady.

I don't think it would be advisable to use the roof as a swamp cooler, unless it was done consistently. Moss goes dormant when it dries out in summer. When a dry layer of moss intercepts all of the sun that strikes the roof, the first little bit gets quite hot and radiates that heat back to the sky. Four inches down, it's much cooler.
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Thinking like me can get you into trouble. I've been punished 4 times in a month.
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Natalie --- In the right environment this will naturally happen on it's own. It then needs only a minor amount of tending.

Much as I suspected you might answer Dale. I do recall that when I did see trees growing on roofs it was usually in deeper material and on the North pitch of a gabled roof, often shaded as well by dense conifers with large low branches. The swamp cooler idea basically rose out of my childhood where we would run a sprinkler on the roof of the house to help cool it down. I grew up in Terrace, lived on Haida Gwaii, and spent many years in Vancouver, so I do have a fair knowledge of what moss does. That said, I can appreciate what you do for work, and how much experience you have in regards to such things. It's great to bounce some ideas around, and I'm grateful for your insight. Although thinking like you might get me into trouble, I think that considering we have somewhat similar plans for our homestead homes (greenhouse/spa as a beginning) that I will do well to take heed of at least some of your thoughts, and those which spring in my own in regards to it! cheers.

We should share photos and plans for the spa. I hope to have it functional by fall. All will be welcome to try it out.

When I first moved here, I liked the idea of a house under the trees. Now, I want 150 ft. Between important buildings and big firs and cedars.

Well pruned maples and fruit trees could shed a branch that breaks a window or scratches the siding. Big firs don't stop until they reach the basement.

I hear ya. Long ago I dreamed of a little cabin in the woods, and then I saw one with a large tree THROUGH it. Later still I learned that First Nations people, despite the massive efforts involved (using stone tools and fire) on the Northwest Coast, would clear all timber within falling distance of any of their longhouse structures. Trees near the house are completely out. The orchard will be behind the house to the north so that they don't spring out of dormancy too early, But the house will eventually have a berm between it and the orchard. I have nothing built yet, so no photos. Plan is basically to build a sauna, solarium combo and then build to the north of that, and the greenhouse/gray water swamp monster that will be to the west of the sauna. The berm will hold root cellers, and rain water cisterns and be accessible from the house and outside. The south of the house will be a pond system with the hugulkultur kitchen garden. It's a grand project of epic labor and I will start slow.