Tar + paper?

I was wondering about the feasibility of creating wofati roof without plastic sheeting if we were to use layers of newspaper brushed with "tar paint".

Tar from coal or other fossil fuels has carcinogenic VOCs, but natural tar/pitch from the process of making charcoal (anaerobic heating of wood for dry distillation) is considered safe. It can be cut with linseed or tung oil and turpentine to make into a liquid varnish that could be spread on newspaper. If layered, I could see making an effective water-shedding material for Wofati/PAHS building.

Thoughts?

In short...yes...yet look to the actual logistics and application. Is it cost effective in both fiscal and physical application. Do you have other resources that may be better? Do you have flat stone? Do you have large slabs of recyclable concrete?

The concepts of Wofati are not new...they are ancient...look to the past for foundational understanding then apply a current metric. This, perhaps, will yield the most germane system to current needs.

Regards,

j

Flat stone is easy to come by in Missouri. We don't have land yet, but there's a good likelihood of having some limestone we could quarry.

Stone as waterproofing? Are you thinking that quarried stone will have less environmental impact than polyethelyne sheeting?

If it's sourced on site, possibly.

It depends on how much of the labor is done by fossil-fueled machines versus human/animal muscle.

Agreed. How do you propose sealing between stones?

I believe that traditional slate roofs overlap and are not sealed.

At least, that's how I remember them.

I don't know. I'm more apt to try the tar on newspaper method, since it's such a work-saver. The tar can be locally sourced, too. We could build an anaerobic char pit and cook out the tar/pitch from local wood.

Shingling flat rocks works great above grade when gravity can do its job. The steeper the roof, the less risky. Everything changes underground when capillary forces are at play. Perhaps a lot of gravel, geotextile and drains to daylight would do the trick for bulk water.. water in its vapor form not so sure.

Where would the vapor come from, once the soil under the umbrella is adequately dry? For there to be vapor, there has to be moisture.

If the ground-water is sufficiently deep, and an non-capillary gravel matrix kept it from rising, we don't need to worry about that.

Humans and plants in the living environment put out moisture, as does cooking and bathing. However, with adequate ventilation (which you would want, anyway), this is controlled.

I suppose the question is-- how did primitive builders keep their homes snug and dry without impervious plastic sheeting and vapor barriers like Tyvek?

One answer to that question is fire-- many primitive homes had a central fire, without a chimney, and just a smoke-hole in the roof. The constant heat source in the center of the dwelling would cause the moisture in the walls to bake out and then ventilate with the smoke.

We can do similarly today, with a radiant heat source centrally located. Our heat source would be ducted to safely remove combustion exhaust, as well as provide fresh combustion air without creating a draft in the house. Active or passive air exchange can be created, such as the PAHS air tubes. So long as those air tubes are properly sloped to drain away condensation, they might work fairly effectively.

Underground, water vapor and other soil gases come from all directions. Unless you are completely encapsulating an area of earth (and somehow drying it out), there is no guarantee that making an "umbrella" above will mitigate underground water vapor. On the east coast, depending on the site, its common for bulk water to come straight up from below, from the side or wherever else is a path of least resistance. If those conditions did not exist or were mitigated for, and the umbrella was not a vapor barrier, then bulk water from above could easily make its way through the umbrella in its vapor form.

Tyvek is not a vapor barrier and technically not even a vapor retarder. Its a highly permeable Weather Resistive Barrier meant for above grade applications. https://permies.com/t/31490/green-building/Vapor-permeability-material-suggestions-humid#252351

In my opinion, primitive builders used whatever they had at hand and if placed in today's modern world, 99% would use whatever available technology that made the most sense. To say that all primitive homes were sufficiently dry is a pretty big assumption. Certainly, open fires helped with comfort but not so good for health. I think that homes are less risky and more healthy with ALL combustion sources removed from the conditioned space, even if properly vented.

Even properly sloped earth tubes will grow mold and mildew if the walls of the tube are not kept clean which is why my vote is in favor of providing a means of mechanical ventilation. Passive ventilation works great when the weather is nice.. windows!

Sorry, I had stepped away from this conversation for a while to deal with some other matters.

First and foremost, I can't say enough Kevin how pleased I am to see others thinking through this process. This is the key thinking steps I try so desperately to trigger in students I have taught. Approaching this from the mind of..."it had been done by my ancestors...now who do I ask about it...and/or how do I figure out how it was done." is Excellent!!

Brian Knight wrote:Shingling flat rocks works great above grade when gravity can do its job...

YES it does...very well indeed!

Brian Knight wrote:Everything changes underground when capillary forces are at play. Perhaps a lot of gravel, geotextile and drains to daylight would do the trick for bulk water.. water in its vapor form not so sure.

One of the primary issues I have with information on the internet...is way to much of it (usually to counter a less than typical perspective) all to often is extrapolated from "bits and pieces" of information, not the actually in depth study of vernacular forms, and even fewer that have actually built/restored and occupied such traditional dwellings. "Everything," does not change underground...only some of the factors are minorly adjusted...like not have to deal with driven rain. As many here have already read the work I started on Raised Earth Foundations, I will not again go into this misnomer of water vapor in the ground NOT being the issues many believe (or claim) it is. Nor the other misnomer of "capillarity"...cohesive diffusion, yes...capillary action not so much, as stone and gravel do not contribute to this to any great degree as it has neither "capillary structures" (only some very rare crystals do) nor does it create in its macro and microstructure enough interstitial voids to carry moisture very far. This is even more true when these elements are understood by traditional builders of today and ancient times...all of which further mitigate these effects in there fossorial building practices.

Even with an open spring within a subterranean home (which I have seen more than one of)...if built properly...still will not have an overburden of moisture. Often less so than n many modern homes "wrapped up in plastic" as to virtually make them airtight and dependant on mechanical ventilation, which must always be working to have the architecture function within healthy parameters. So if the location for such a dwelling is well selected, the biome moisture cycles and flow patterns are mapped, and certain principles adhered to, the "umbrella," effect can be created...even with all natural materials. This is not theory, speculation or conjecture...its archaeological evidence and the understanding that many have done this with good success over the millennia...even today. Many of these successes. describe in the writings of this forum or its links. The principles described in "Raised Earth Foundations," apply for this style of architecture as well...just augmented and taken below grade.

I like that the open hearth had been thought of...which indeed is a tradition within many cultures. Never the less this often added more moisture to the atmosphere then took out not only through cooking, but the fact that wood was not always as dry as it could be. The venting did, however facilitate the movement of air, in certain designs, which contributed to the drying effect by convection. In some designs this rapidly moved into "closed hearth" or "furnace" style heating some even moving under the floor in sections before allowing those gases to escape.

Please continue to read, think and research Kevin. I will answer as many direct and/or technical questions I can. Please do not be discouraged by assumptions and concepts to the contrary about how many cultures successfully did build architecture within this format. Look to literature about these modalities, speak with those that have done it, and focus on what target goals are set down. I will add that most "subterranean" architecture is probably much harder (and more expensive) to facilitate than above grade...especially if trying to not use any modern materials in the construction (which I would as well.) Some building sites, nevertheless, can create the perfect combination to make this really easy as well...it all depends on what the land will gift the wise builder.

Whatever the final choice for architecture, I am glad to see someone else striving to build a natural home that is not dependant on technology to make it function...and function well.

The difference of driving rain and water or moisture in the ground is seen as minor? Perhaps, but they could also be argued as different as meteorology and hydrogeology. I do largely agree with much of that though.

Sometimes straining to use more natural materials can work against you. Other times the natural environment or situation at hand provides exactly what one needs wether natural or not. I think the used billboard vinyl that people often point to in this forum is an excellent example of an un-natural/traditional material filling a natural role as it relates to this thread's goal. It may not be all naturale but it keeps materials out of the waste stream, is readily available, does a better job than many commercial alternatives, doesnt contribute to pollution as much as some natural materials might and is cheap or free.

In a different spin on that concept, at our construction projects we often re-use the polyethelyne plastic left by the lumber supplier for rain protection of building materials. Rather than send it to the landfill, we first use it as a temporary groundcover and/or swale liner under the rooflines to help with drainage and erosion control before final grade. We then use it when backfilling foundations as an underground umbrella or more of an awning or shed you could say in the top layer of earth that slopes away from the foundation. Ive noticed a difference in the moisture levels above and below the plastic in instances of rework or adding utilities. I actually just used the same technique on my personal house after insulating the above grade portions of my CMU basement. I like to think its contributing to keeping the bulk water out of my once leaky basement.

Surely used vinyl or plastic could be considered as friendly and more stable than tar paint..

How about an oiled cloth tarp?


A cloth tarp made of canvas or similar, soaked in a drying oil such as linseed and used as the waterproof outer barrier. I've done a few searches...Has this been discussed before?



Ideally you'd have cotton or flax or hemp growing on the land for your cloth source, and then walnut or linseed or similar
growing onsite for the oil source...

How about wax?


The real question here is how long can an oiled canvas tarp last underground--anyone? Can it be made to last a bit longer? How long would it need to last in order to make it worth while? Let's say it lasted ten years. Hell yeah, your house just lasted ten years. Cool, right? And then really....I wonder if you new the tarp was reaching the end of it's life (ten hypothetical years) you just do some careful digging, pull out both sheets and relay with soil layers. Maybe it would even be feasible to just replace the topmost layer of tarp, once every xxx years. Or even, watchout I'm crazy, what if you just left the old tarps in place, merely added a new layer of waxed tarp, plus a few inches of new soil, once ever xxx years.?

Kevin : There is a fair Wikipedia article about Pine Tar Which does contain creosote, which is regarded as a carcinogen ! a Google search looking for information on
how to make ''Stockhom Tar'' should lead you to related articles, and a discussion about the frequency of massive earth moving explosions from the techniques of
our Colonial past!

In this situation I would tend to go for the surest material to make a skin for your Umbrella, Here in the North East, we can generally count on loosing most of our
snow cover with flooding events, followed by several more weeks of winter whether the groundhog sees his/her shadow Or Not !

A bad leak that develops in february would saturate the soil, remove the Thermal battery, and be a major mess to live with for as long as several months, until you
could start to uncover your roof, my experience is the place the water shows up inside the structure is never where the leak is ! Most of the soil removal will have to
be done by hand!

This does not mean that I would not use a covering of as much as an inch of paper/cardboard, and even Carpeting to reduce the danger of punctures to the final
membrane !

There are many 'natural materials' that have a health risk as do seemingly all man-made materials, but Unless your research finds you a working technique for a
durable 'natural membrane' for your Umbrella skin, (and there may be such a thing !) The caliber of disaster resulting from that membranes failure would weigh
heavy on my mind!

For the Good of the Crafts ! Big AL

hmmm...I really considered starting a new thread v's bringing back this one. Whatever.

Hey allen, how about oiled cloth? Oiled or waxed canvas....like an old sail, or tent kinda thing.

How about an oiled cloth tarp?


A cloth tarp made of canvas or similar, soaked in a drying oil such as linseed and used as the waterproof outer barrier. I've done a few searches...Has this been discussed before?



Ideally you'd have cotton or flax or hemp growing on the land for your cloth source, and then walnut or linseed or similar
growing onsite for the oil source...

How about wax?


The real question here is how long can an oiled canvas tarp last underground--anyone? Can it be made to last a bit longer? How long would it need to last in order to make it worth while? Let's say it lasted ten years. Hell yeah, your house just lasted ten years. Cool, right? And then really....I wonder if you new the tarp was reaching the end of it's life (ten hypothetical years) you just do some careful digging, pull out both sheets and relay with soil layers. Maybe it would even be feasible to just replace the topmost layer of tarp, once every xxx years. Or even, watchout I'm crazy, what if you just left the old tarps in place, merely added a new layer of waxed tarp, plus a few inches of new soil, once ever xxx years.?

Unfortunately it will rot on you...I have tried and it just didn't last.

Now few methods I have been saving as a "secret" are as follows.

If you don't have a lot of flat stone, use old recycled concrete sidewalks and/or slabs.

The other trick that seems to have a lot of promise in the way of "recycled materials" is a layering system of cardboard, newspaper, clay, felt carpet padding, etc and maybe oil some of the papers and or lime wash the carpet padding. Just the carpet padding by itself really does an amazing job and just does not seem to rot even when exposed to uv for years at a time. I have some piece that have been out for over a decade still solid, though you can see it as it also forms a great growing matris for mosses. I even shingle a small out house with a steep pitched roof and it did really well till it got burnt down...

Regards,

j