I would run the loop from a thermal store - heated by a stove and other inputs.
I had imagined this approach would function like a trombe wall too - but perhaps I'm missing something. The wall is lacking the thermal mass in a trombe - but wouldn't the cavity heat up like a "bell" - and create a convection current?
Designing a single story long house with a solid fuel stove - looking for a way of getting heat to the rest of the building. There's an internal, non-structural wall that cuts through the centre. It could be double stud, with heated pex piping inside and adjustable top and bottom vents to create a convection current in adjoining rooms.
...any thoughts as to why this might be a bad idea?
Dillon Crew wrote:Neat design! I like the looks of that clay based membrane; do you have a notion of what it will cost you?
Thanks Dillon! Depending where you get it and in what quantity, geosynthetic clay liners can cost $2 a m2...
You're right - it's a huge amount of 8" logs. But these can be sourced at a reasonable price, the total for this structure would be around $10,000.
Interesting point about wind resistance, makes sense - thanks.
I hear you on the windows, there's plenty of tweaking to be done here. Thing is, we've amazing views out to sea in the North - with lots of light reflected back. It's a fairly mild climate, rarely drops below freezing - and there's never any real snow to speak of. Just have the wind to worry about, need some pretty bomb-proof glazing...
Glenn Herbert wrote:I have the same reservation about reciprocal roofs. They are an ingenious idea and very cool, but I wouldn't want to live under something that, if one part failed, the whole thing would fall on me.
I've been underneath a few structures and have noticed a disconcerting bounce in the wind... not to say that they can't be constructed safely - but I don't feel confident building a foolproof one myself!
However that design is not built to withstand the type of weight in a bermed structure. A circular building with the same window/glass placement would allow better light distribution without the walls. Of course any circular home would stI'll need interior walls that would block light.
Support for a living roof could come with a reciprocal roof, but I'm unsure of the diameter to bearing loads for round diameter timber.
It is a cool design, are there any real life examples of this anywhere you know of?
I should have mentioned our location - the Isle of Lewis. The occasional 130mph winds put the need for such a sturdy structure into context. I'm trying to draw upon the vernacular with all the stone and turf - see the following images for real life ancient examples. Here is a more modern take using shipping containers.
As a self builder I am wary of using a reciprocal frame roofs due the inherent issue known as progressive, or disproportionate, collapse. The structures rely on interlocking of the main members, which means that the accidental removal of one member can potentially mean the collapse of the entire structure. A corbelled roof is a simpler, more predictable approach which doesn't suffer from the same problem.
Daniel Ray wrote:What is the benefit of such a design over a simple circle or spiral? If the walls curved in a circle rather than cutting back in, the interior space would be much greater and the surface area of the walls would be much less meaning lower costs in materials.
Primarily to add a large amount of thermal mass, compartmentation and structural stability. These dimensions and spans permit the use of relatively small diameter timber in construction. A large amount of light is also able to enter the structure through large glass doors/windows from all six perimeter rooms.
I have struggled to find a way to build an equivalent with natural stone and timber using a circle or spiral. Are there examples you have in mind?
Part inspired by pictish wheelhouses, this is the latest in a long line of house designs. Keen for feedback and thoughts!
This approach relies on the generous use of foam glass aggregate - for all round insulation, drainage and use as rubble trench foundations for lime mortared walls. The entirety to be covered in a waterproof membrane, a "geosynthetic clay liner" and a good topping of soil and turf.
The space between the walls can be filled with more stone/gravel.
I'm trying to come up with simple flooring system that's concrete free, breathable and heated with good thermal mass. Something I can also get into easily enough if (when) the underfloor heating needs replaced.
Insulative compacted foam glass foundation:
Geotextile membrane on the foam glass. Joists spaced half a metre apart, in filled with compacted dirt/sand/clay. Electric underfloor heating mats rolled out, covered in sand, etc:
Any thoughts appreciated! I should say - we're on the Western Isles and are looking to make good use of all the wind here by generating a lot of leccy.
EDIT: Minor oversight, as the boards would be laying across the joists it would be in no way simple to access the heating mats, duh.
Is the following workable? Laying flagstones, (approx 600 x 300mm) over the joists, with sand/dirt packed underneath? Or am I asking for trouble and cracked flags.
The nights are drawing in here on the Isle of Lewis, I'm back to cooking up some house plans...
My aim is to design a simple house, one that takes inspiration from the vernacular here - something that requires minimum machinery and specialist expertise. Using as "green" material as is possible in our context.
Simple frame using big lumps of untreated graded 75mm x 300mm timber. Doubled up for the trusses. I need to rope in a Structural Engineer but I reckon they can handle an extensive turf roof - dead weight of around 200kg/m2. There's rarely snow here - but it's often fairly gusty.
Clad it out with MGO boards - these seem to be the bees knees and tick a lot of boxes for this build. Insulate inside with rockwool or similar. I'd like to get a good amount of thermal mass into the gable end walls somehow.
Big wrap around double skin dry stone/earth filled wall - as per Blackhouses. It's fairly low, at 1.2m high. I want to keep the overall profile low and tuck the building into the hillside.
Heavy duty liner (I've looked into geosynthetic bentonite liners as an alternative but I don't think they're cut out for roofing...) cover in turf from on site and let the grass grow!
In the future additional wee houses and structures can be added on and share the existing walls - as per Turf and Black Houses:
All sitting on a "raised earth" foundation - some form of slab/rammed earth floor, insulated with foamglass.
Electric underfloor heating (used as a dump load) and a masonry stove/oven/cooktop/water heater.
Back from the drawing board again. Seems like I'm progressively moving towards the vernacular - out with the round, in with the rectangular. Seems a bit simpler to pull off and to butt additional buildings on. If I keep going down this path I'll be doing away with the glazing and stretching Highland Coo' stomach over the window frames like they used to...
Again, the idea is to start with a small dwelling - internal measurements 6m x 4.5m. Big chunky wood frame to hold up chunky joists for supporting a heavy sod roof. I couldn't find a span table for joist sizes supporting up to 500kg/m2 - having a slab of timbers made up of 100mmx300mm would certainly do the job however.
Waterproof membrane and landscaping fabric to protect it on top. A layer of foamglas insulation or similar, another membrane and finally turf from the site.
Build second dwelling 10m away and join the two together! Central section to be split into greenhouse, kitchen, bathroom, living room, etc.
The finished build would require between 200 and 300 tonne of walling stone...
Criticism and thoughts, constructive or otherwise, encouraged!
Glenn Herbert wrote:If sealed with silicone or other good sealant, it would actually be double glazing, just without special atmosphere and fancy components. The secondary glazing is a good idea where there is already one pane of glass in a frame.
I have built a few of these as sealed, double-glazed panels that were then set into a custom wood frame.
I suppose it would be! Looking forward to giving it a go one day
Regan Dixon wrote:Re: double glazed windows. I'm asking partly out of my own ignorance, but I intend to do the following in my next project: Can one not get two panes of ordinary glass, and double-groove the wood one intends to use as a frame, and just seal it well, as one would for a single pane of glass? It wouldn't be vacuum sealed, so maybe some moisture between the panes, but it would be dead air space for pennies instead of pounds.
Glenn Herbert wrote:You certainly can do that. What would probably be better than double grooving the wood frame would be setting one pane of glass into a deep frame recess with a 1/2" x 1/2" strip of material, then setting the second pane in the normal fashion with putty. This would allow future disassembly for maintenance or replacement of a broken pane without destroying the frame. That is what my father did in the late '50s when he built the house I grew up in. It had no good sealing aside from tight wood joints, so moisture and even a few spiders did get in. With actual sealants in the construction (either putty or silicone if you are willing to go with modern tech), it could be quite tight. I would do the work in very dry weather to minimize the built-in moisture. Clean the inner surfaces painstakingly, as anything left inside will be there to look at forever.
Great! "Secondary Glazing" is essentially what you speak of. As you say - predates double glazing, is more user friendly, simpler/lower tech and less wasteful in that a misted up unit doesn't have to be "recycled" every 20 years or so. My dad says he's used cling film in the past at a pinch. My double glazing blues have subsided; thank you.
Glenn Herbert wrote:The sola-tubes (one brand name I believe) should work for you, but I would also want some sort of view out of every main room. The skylight, being at the highest point of the space, will cause the most possible heat loss. Windows low in the space will cause less heat loss. I would modify the design just a bit to lower the stone/sod wall at one point on the south side of the room to allow a window, which would also allow through ventilation when the windows can be open. You could have a bit of view out to a sunny garden space, or through flowers in the spring...
I would most assuredly have a window leading from each round room to the greenhouse space, as that would not even alter the drainage or exterior appearance of the structure.
Yes Glenn, in the name of simplicity I think I'm going to give the ol' skylight a rethink.
Good call on a window looking into the greenhouse. And a decent sized south facing window would be really nice. Though I found myself getting upset when considering double glazing! Such a limited lifespan for such an integral, expensive and energy consumptive item. Hopefully there may be a way of interpreting the building regs that permits single glazing with some shutters/a really decent curtain. Perhaps another topic...
I'm having a think about different approaches to the roof as I am no longer considering a skylight. The diameter of the roundhouses is 6m. I'm looking for something that doesn't necessitate any posts in the middle and can support a turf roof. The hunt continues...
Travis Johnson wrote:I am not an expert on this kind of housing, but I am VERY interested in it. I see no reason why it would not work.
I was originally going to say that building with rock takes a lot of time, but then when I look back at my own lavish use of rock, I got a lot accomplished in just a few years. The key is just to start. This applies to everything in life, but when you suggest doing anything, there are 15 people telling you why it can't be done. There is SOME value to that, but often just starting an ambitious project is enough. And the last piece of advice applies to everything as well. Finish. Always save drive, determination and funds for the finish.
It is kind of like a marathon runner. They can't win the race if they never start! And 15 people are going to tell him why he is not conditioned enough to take on the grueling challenge. And it certainly does not do any good to quit the race 80% of the way through.
I have found in the middle is where I get discouraged, for I see how hard it has been to get to the half way point and yet there is so much to do, but sticking with it achieves results.
So best wishes to you on this. I'll be following your progress for sure.
Thanks Travis for your advice and well wishes, I'm with you on all those points. I look forward to getting started, we need a plot first! All in good time. I'll be posting updates on the build once we get round to it.
Chris Knite wrote:Primarily I wanted to comment in order to encourage you. Fun looking project! Please keep us informed and updated.
As a possible input - when building my in-laws place, rather than put in a skylight we put in a "sun-tunnel" (not the correct word). He wanted the natural light into an interior room, but was afraid of heat-loss and exposure to leaking of a sky-light. Instead we put in a kit that had a small 12" round aperture on the roof - connected to shiny 8" ducting, connected to a glass opening in the room. We insulated the ducting so very little heat loss, but a surprising amount of light gets radiated into the room. It is not a window, but it brings in the natural light.
How in the heck you would install either that (or a skylight) into your type of roof I have no idea.
Thanks for the encouragement Chris. I've seen these before and they look very interesting. I'm sure we could find a way to squeeze a few into the design
Regan Dixon wrote:Aha! You're back from the drawing board! In my opinion, this take is looking more promising and feasible, and a plausible part of the landscape, with its historic precedent and scale. A couple of questions, and thoughts:
-What holds up the top of the roof? Presumably posts, but they're not shown. Or is the system more like a yurt roof, where the poles support the chimney ring, and the whole thing stays up in a conical shape, because of outward pressure on the unyielding wall?
-Your source of heat is up through the floor as described. Is the only source of heat?
-Have you a membrane between the wooden roof members and the sod? Near where I live, early settlers built sod roof log cabins, which today are all lovely and rustic, but eventually moisture passes through the sod, sits on the roof members, and rots them through. I've been on a roof-clearing team. It was dusty, dusty work, lots of sweating, and suitable for lightweight, nimble-footed people only. The room below was disused, but I imagine they had barrowloads of dirt to remove.
Back from the drawing board indeed, after some sage advice.
I'm scheming up an all singing all dancing rocket mass heater - there's a stove builder in Scotland who can commission it and sign it off against relevant regulations. Cook-top, oven, back boiler... interested to see how peat will rocket.
Very interesting to hear your experience of the sod roof cabins. We'll definitely opt for a membrane of some sort, and perhaps some appropriate insulation.
William Bronson wrote: Black houses and corbeled roundwood roofs,both are new concepts to me,and very cool!
The only thing I would weigh in on is the skylight- they leak and/or are noisy.
I like how the black houses used turf ,covered with thatch.
I like the ledge that allows for easy access for re-thatching.
Heating is a common dump load for excess wind energy. Water heating allows you to move the heat around.
A connected green house could give a yeild from excess heat/energy.
If there really is a lot of wind, incandescent lighting could give light and heat,and heat loosing glazing could be eliminated.
Happy to introduce you to the concepts! It's funky stuff. I shall take heed regarding the skylight - given the occasional 130mph gusts it may not be the best idea...
I'd be happy to live in a pretty much windowless dwelling much like the original Black Houses, but my partner thinks otherwise! The sun room/green house/glazing will be a fixture of whatever we end up building.
I'm sticking up some pictures of my current schemings of a home that will withstand the elements of the Outer Hebrides. Inspired by the Black Houses that were very much of the land and have stood the test of time.
The idea is to start small and build one independent round house so we can get moved in; then a second one - and then join the two together. Double skinned, earthen filled dry stone walls. Corbelled roundwood turfed roofs (less that can go wrong when compared to a reciprocal framed roof). Underfloor heating used as a dump load for turbines (plenty of wind!). Perhaps a nice geodesic skylight...
Finally a good amount of glazing for a south facing sun room.
Crispin Pemberton-Pigott wrote:The idea of using 'fencing' as a deterrent or structural element is good in that you can make by hand precisely what you need. For example if you are making Square Mesh on site, you can make a single sheet of 'fence' as wide as you want - no joints for example over an entire roof.
You may have seen the Diamond Stucco Mesh on the same website. This was specifically designed to make a wire product that could hold cob or plaster without and backing - sort of like a chicken wire that is sized to hold plaster. It has a thickness of about 5mm meaning if you push it against a mould, the cement still gets behind half the wires and onto the other half.
The purpose is to be able to add a very strong reinforcement to plastered things like hay bales without investing a lot of money.
The Diamond Stucco Mesh machine is also used to make stainless steel mesh for bird cages. Unlike chicken wire (rigid hexagonal holes) it is stretchy so it can form over complex shapes like barrels. The machine is not easy to learn to use it - it takes a few days. Experts make about 25 m^2 per day (14mm holes). There are no machines in North America.
The Square Mesh has been made by hand down to 30x30mm. It is used to make gabions with internal dividers. The usual size is 76mm (3") holes.
The savings over buying fence may not be much where you live - check the cost of plain wire in bulk per kg and fence per kg first. The difference is the available savings. Most places it is 40% but watch out. Same warning for barbed wire.
If there is any interest in making water tanks from cement and mesh I can forward drawings for making a mould based on a galvanised corrugated iron water tank. We made dozens of such moulds for thousands of tanks in Southern Africa. The finished tank is 40mm thick (1-1/2"). Sizes were 1000 and 2000 Imperial gallons (4500/9000 litres)
Just been checking out the other equipment, some really interesting stuff - I like the air-compressing ram pump. This house build is purely hypothetical at the moment - but should our plans come to fruition I will enquire further about the mesh machines. Would you be able to PM me with a quote for the square and diamond mesh machines and P+P to the UK?
Regan Dixon wrote:I appreciate maximizing sunlight and using cheap, plentiful local building materials, and I understand that a corbelled or monolithic ceiling might be a bit much work.
The traditional blackhouses seemed smaller than what you're designing, presumably limited in width by the timber available to support the roof. Though there is this picture/link I'm attaching that appears to be two houses parallel to each other, which may or may not be connected to one another. Are you married to the idea of a flat roof? I wonder if the idea of parallel traditional roofs over the different rooms would be practical, with interior gabions to support them, or whether that would pour water inside the house. (Hm, harvest fresh rainwater delivered right to point of use....) It rains in Scotland, doesn't it? For that reason, I would question having a flat roof.
(And, about a chimney--are you going traditional blackhouse, without one, or am I jumping the gun on details? )
Alas, all that my build will have in common is that the walls will be thick and partly built from the surrounding stone. The parallel roofs would be great but I think I'll try and keep things simple. The roof is at a slight angle to permit water catchment - I'm aiming to keep the profile of the build low so it can handle the wind, be easier to construct and not be too much of a blot on the landscape.
It'll have to have a chimney to comply with building regulations! The plan is to stick in a rocket mass heater/cooker. Some underfloor heating wouldn't go amiss as a dump load for turbines - no shortage of wind.
Crispin Pemberton-Pigott wrote:Gabion making by hand.
There is a set of hand operated equipment (two actually) for producing gabions from plain galv wire.
The idea is to make one of three types of mesh, then fasten it to a wire frame that is held on a large spindly jig. Then fold it up.
The three types of mesh are Diamond mesh (chain link) and Trinet which has triangular holes and Square Mesh which looks like diamond mesh turned 45 degrees. All three can be hand made under a tree.
The website is www.newdawnengineering.com under fence products.
The Trinet jig product was designed for Dam construction and bad be made with quite thick wire. The others are normally 11 gauge or thinner, 12 gauge being most common (2.5mm).
Thanks Crispin! Solid looking equipment. I'll have a look into it further and figure out if it will be cost/time effective.
Do any cob experts out there envision that putting gabions up against a cob wall would encourage pests to have a go at it?
It is a single story cob house with an outer skin of rock filled gabions to keep the elements at bay. I firgured gabion baskets are quick and cheap and once they start falling apart after 60 years I can leave it to future generations to do a proper job and throw up a dry stone wall...
You'll have to use your noggin and imagine doors, windows and glazing along the front of the house - big ol' greenhouse.
I'm stumped as to how to go about sticking a mono-pitch turf roof on this. The cob can be load bearing. I've been looking into a roundwood frame roof but can't work it without getting posts everywhere which messes up the design. Alas, I think this is too big a beast for a recipricol frame roof - approx 15m x 23m. Any suggestions welcome!
Had a reply from Mike Wye, natural builder and foam glass supplier in the UK - here are his thoughts:
Foamed glass would be an ideal insulating base - 100% recycled waste glass, low capillary, great insulation etc etc. I can see that you might need some lateral restraint to keep the foamed glass in place whilst compacting. For load bearing its usually 30% compaction but unlikley to need that in the case of a yurt where there aren't loadbearing walls. Perimeter dry stone walls would be quite time consuming and need a lot of stone but would finish off the yurt aesthetically
Making use of materials on site is good, it depends on your soil characteristics as to how effective lime will be as a binder. Ideally the floro would be based on the sub-soil. Some of the pictures on your link look like there's more lime and aggregate than earth in the earthen floor. In the UK ash was often added to the floor mix both as a cheap bulking agent and as a pozzolan - a material that reacts with lime to create water setting chemicals that harden the floor mix.
I'm never convinced about the boiled/double boiled linseed oil approach as
a. you need vast quantities of linseed oil to seal a porous earth floor
b. you can have an allergic reaction to the amount of oil vapourising into the room
c. these coatings take a long time to harden and dry.
A traditional UK finish was to have a more lime rich surface coat and trowel a source of the protein albumin into the surface. This was often egg white or blood, but there are many everday sources of albumin. Olive soap is another source thats readily available, its often called Marseilles soap.
The action of troweling in a material containing albumin produces a smoother, harder-wearing surface which is water repellant.
...and my reply:
The yurt living hinges on us getting a croft outside of Tighnabruaich in Argyll, Scotland. We've sent off an application and are waiting to hear back...
Glad to hear you're with me on the foam glass, makes a lot of sense. Regarding the lateral restraint, I'm now thinking of sticking the stakes in the ground before the foam glass sacks. This should give them some support - will have to make sure there's plenty.
I will get in touch with the folk on site and see what they can tell me about the sub soil, else I'll do some digging and take samples next time I'm up. Good to know about the ash - I'd seen the word pozzolan being banded about a few places...
Very interesting to hear your thoughts on the linseed oil and the alternative protein albumins. I remember seeing Kevin McCloud playing about with blood on an earthen floor. Always a good idea to christen a place with an animal sacrifice!
Had a rethink! Should save time and costs - part inspired by this article.
Level the area, lay perimeter of foam glass filled sacks:
Pack the inside with more foam glass:
Stake in some ply formwork:
Install some kind of lime-stabilized/soilcrete/rammed earth floor:
This way the yurt cover will drape over the raised earthen floor.
Earth can be bermed up against the side of the exposed poly sacks to protect them from the elements.
I have to determine what kind of earthen floor will be best to use - given that I'm unsure of the soil type on site and the climate is predominantly damp - we'd be able to stick a tarp over it but that's about it.