Glenn's Underground Cabin Update

[MountainDon]

My comfort zone stops at about 35 C, which is why we have mountain property north of home.

[tiger0383]

lol then you would be no good in the outback here then. This is not REAL outback. If it was, expect to temps into the 50's 

But bear in mind, cause the ground is sand, and over here sand is cold when you get down low, i might have to look at some heating

this would get a few looks i think if i said that i was putting on my heater in the middle of summer when it is 40+ 

[glenn kangiser]

Thanks glenn,

It has given me more than what i wanted to know  

To give you an idea on what i will be working with, have a look at this album http://s626.photobucket.com/albums/tt344/tiger0383/karte/

It's easy to get more than you wanted to know from me--- I have to take every opportunity to spew my views for others to think about....  

Is that an ant hill in the second pic?  If they can do it, you can too.

I think Coober Pedy has the right idea...

[glenn kangiser]

The next step in readying the area here for the floor was to get the screed boards around the perimeter of the area.  At the left end of the retaining boards will be a storage area covered by a bookcase and a stair to the deck.



It is not necessary to compact the soil.  It only needs to be firm enough to hold you up as you work.  The piers will support it after the concrete is cured and then settling is desirable to allow an insulating air space below the concrete.

A layer of sand is added to finish final grading.  I screwed a 1" thick board to the screed to grade the sand to 1" below the top of the 2x4's.  This will leave room for the netting and 2 thin layers of concrete with fibermesh in it..

[tiger0383]

It's easy to get more than you wanted to know from me--- I have to take every opportunity to spew my views for others to think about....  

Is that an ant hill in the second pic?  If they can do it, you can too.

I think Coober Pedy has the right idea...

I dont believe so. There is a large native bird around that area which makes nests like that. Just cant think of the name at the moment

[glenn kangiser]

Gotta be a monster bird.  I was thinking of some termite mounds I have seen pix of that I thought were in Australia.

[tiger0383]

lol yep the ones that you are talking of are vertical pillars 

[glenn kangiser]

After the sand is screeded off to the desired level below the finished floor grade then I put the jute netting on it.

I find that one of the thin metal cutting blades - .045 I think - cuts the jute netting better than nearly anyhing.  Bad thing is that they can take a finger off in a split second too.  Yeah - I'm one of the guys that takes his guard off of his grinder for functionality.



The netting is cut to fit the space and the digging bar is dropped - driven  repeatedly through the loose fill to the solid ground underneath - recommended every three feet by CBRI as I recall - I do it closer around the edges and about every 2 feet in the middle for more support..  


This is about like doing stucco and since the floor is so thin, a wetter mix works well as the excess water is removed quickly even when the soil is dampened ahead of time - as I always try to do.  

I dampen the sand a bit to make it stay firm and open until the concrete -(sand up to pea gravel aggregate) is poured into the pier holes.  I drive the bar through the netting messing it up a bit but I also use fibermesh so a missed edge here and there is not critical.  This way it is pretty sure that the jute will get firmly anchored to the cement.  I also wet the jute to soften it and allow the concrete to stick better to it.



It is hard to see the pier holes but the bar is 1" dia and flat on the end.

We have many sections of floor made this way with no problems.  Repairs are easy if needed.  Bonding glue, sand and cement - color if needed and the repair will only take a few minutes.

[Ernest T. Bass]

Cool stuff! Thanks for taking the time to pictorialize...

[glenn kangiser]

Thanks, Andrew.  Nice to know someone is benefiting.  

After the piers are driven to undisturbed soil with the bar it is time to fill them with concrete (like strong stucco mix).  I probably put this in before but again, I mix 3 parts sand with a bit of pea gravel included, 1 part cement and about a half a handful of fibermesh for every three shovels of sand.  I mix it with a heavy duty half inch drill and a bucket mixer.  It mixes faster and easier with less cleanup than a cement mixer for this purpose I think.



Here is the first coat of concrete on the dampened jute netting.  I mix it a bit on the wet side to get it to grab the jute and work into the sand below it a bit easily.  I smooth it and work it in with a wood float only and do not trowel the first coat with a steel trowel.  This leaves the surface pretty rough for the finish/color coat.



This coat is just a little thicker than the jute netting averaging from 1/4 to 1/2 inch thick.  Try to work it into the pier tops well and fill the dips well - less to fill with the finish/color coat that way.

The jute is great to work with and lays right down when dampened and troweled over with concrete.  Much better than wire such as chicken wire which is great for ferrocrete but tends to pop up on floors.

The jute gets cemented together and becomes locked in place  when the concrete hardens, reinforcing it like steel does but a very slight bit of give to the floor.  Even the military has experimented with varying degrees of success with non-steel reinforcement for locations where steel is unavailable.  I read of them using bamboo in one instance.

When you step on the floor the jute spreads your weight through tension in all directions supporting you and keeping the concrete from sinking between the piers.  Pier to pier is like a little rope or fiber bridge holding you up even if there is an air space between the piers from the settling soil.

[glenn kangiser]

I got the chimney rigged for the great room fireplace today so I can continue on with the walls.  I had to jackhammer a small tunnel to get it out under the section between the foundation rocks that support that part of the roof.

Actually Mariposa rigged but Okie rigged sounds so much better.  It is made from a piece of 8" well casing uunder the wall section to get down to the 4'6" level where it meets the fireplace stove pipe.  On the outside I put a cleanout tee at the bottom as bare pipe collects a lot of creosote in the winter.  It falls to the bottom and needs to be cleaned out around 3 times for the season.  Insulated pipe would be better but costs about $1000 for this much.  Therefore it is Okie rigged.

I had to go 20 feet vertical outside so made the bottom 10 feet from well casing and welded brackets to support it over the tee and a standoff for the earth retaining wall of the roof.  I put a cap over it and 1/2 inch wire screen over the opening as I don't want to add the spark arrestor screen later.

I added bailing wire guy wires to screws with washers at the cap so I could guy it 4 ways.  It needed to be tall as it is near where the bedroom/bathroom pops out of the ground on the west. Lower pressurizes from the wind and causes smoke inside sometimes.

Now I can get back to the floor and walls.

[glenn kangiser]

Here is the bucket mixer I use for the concrete mix.  

I traded one I had that took a smaller drill for this one which takes more horse power but does a great job of mixing.



Here it is mixing the concrete and fibermesh in the bucket - the area in the picture above took two buckets for the second coat and 2.5 for the first coat, so very little is made to go a long way.

[glenn kangiser]

Just looking - love that drill cord in the second pix... 

[glenn kangiser]

I let the first coat of concrete set up over night then applied the second/final/color coat over it.  First I wet it lightly to keep it from pulling the moisture from the second coat.

Remember that the first and second coats are only around 1/4 to 3/8 inch thick in most places for a total thickness of 1/2 to 3/4 or so.  

I added white cement or stucco mix to the mix to lighten the concrete color and let the color finish be a bit more predominant.   I also put some fast setting high strength anchoring cement in the mix to speed up the setting, but only because I had some left from a job.



I just empty the bucket in an area spreading it enough as I dump it so that I can easily spread it around with the wood float to level the floor.  Since this is the final coat it needs to be pretty smooth but I don't get fanatical about it.  It has an interesting handmade if it is not 100% perfectly flat.  A swimming pool trowel, thin with rounded ends will still give a smooth easy cleaning durable finish.

Unlike the first coat, this coat does get troweled with the steel trowel.  This is your finish coat and will be what you see for as long as you use the floor.



Working concrete is always easier if you keep after it while it is wet then come back and improve your previous work after it has set a bit but was already close to where it should be.  Leave it too long before you knock it down and you could get a real hard job , especially in hot weather.

I trowel it pretty smooth then while I can still reach the extents of the area, put the color on the top in random splotches.  The powder or liquid will work, but I like the powder the best.  It leaves intense areas of color that can be smeared around giving areas that feather out into much lighter color.  Keep in mind that the color is dark when wet but will fade a lot when dry.  Whitlock says it looks like a leather floor when dry.  It does look like light colored tanned leather using the color called "Buff".  We like it because it is similar to the color of the earth around here making cleaning easier.

If the color gets hard to spread  a bit of water helps.  The powder will stick to the trowel on the first swipe but subsequent working will get it loose and spread around.

The point here is to not put the color on evenly and don't overwork it to where it all looks the same.  That is not interesting.  For a different scheme, mix other colors in random spots working them together  but not overworking them.  It gives it a natural look if not overworked.  A blah concrete look if overworked.  A trick I learned from my brother when he did work with Bomanite- a stamped decorative concrete.  This technique will work on full thickness normal concrete slabs also.

[glenn kangiser]

Hmm My postings here are actually going slower than the work because the floor has been done for a bit now.  Better get on with it, eh?

Here is the section of floor as finished and hard troweled for a smooth surface.  Sorry about the poor pix.  



So after the floor was complete and set over night it was hard enough for me to cover it with plastic and plywood and get after the trough for the chimney of the fireplace to go out.  I over dug it a few inches to allow room for insulation.



Always six things to do before I get anything done around here.  Had to pick up a few logs so I would have wood for completing the deck and walls - bookshelves etc.  Yeah - right -- right after I put the sawmill back together - with it's new shaft.

[Mike 870]

Really neat stuff, I would love to do this instead of pour a floor if I have a basement in my imaginary cabin.  Do you think there would be any problems with doing this technique on top of high psi blueboard?

[glenn kangiser]

I think you could do it anywhere, Mike.  Just leave out the plunger piers and do it flat like a concrete carpet.  I would still use at least 1/2" or so of sand on top of the blueboard under the jute.  The sand allows a bit of movement but compacts 100% when you dampen it lightly with water before putting the netting and concrete on it.  In other countries they use hessian which is more like a burlap sack but the netting works great and is cheap.  If for some reason you wanted to use the piers you could do them right through the blue board but it will work fine without them I think.

I used this around the pool as I mentioned with no piers.  I did not expect it to hold up perfectly as I did not compact the ground well.  It held up very well though and is about 1 1/2 years old now.  It has a few very small cracks but no separation and still looks good.  There was a crack along the place where I experimented wit chicken wire instead of jute.  It is not a problem either.  The purpose of that concrete carpet there was to have a cheap floor that would keep the wet clay soil off of th swimmers feet.  Looks like it wil be good for years to come.  If you can give it about a week to cure before you get on it you will have less cracks, however I put the stove on the angled slab in about 5 day.  I added high strength grout and made the stove area slightly thicker with closer piers for the weight but likely that was not necessary if I waited the 7 days.

We got one small hole where a bench leg broke it by an edge where the soil underneath settled.  Patching is easy with fine sand, cement and color if desired.  Put concrete bonder  (like Elmer's glue - Elmer's will work) on thinned with water.  Add some to the patch - trowel it in - add color - blend it to your liking.  You are done.

I am sure it would even work over a wood floor.

[Mike 870]

Thanks for the info.  I was trying to fugure out how to get the most out of a small cabin, and with a low cost way to do the floor it makes more sense now.

[glenn kangiser]

Glad I could help.

We will probably eventually do this over our soil cement floors -it will only add about a half inch to the height of the FF and they will be durable then.  They are currently a bit too soft for good durability and we have a tree root growing through cracking them a bit.  Some day I will cut it off and fix the floor but it is kinda cool...

We just finished digging a couple yards of dirt and claystone out of the area to the left of the wall.  There will be a storage area there and a stairway in front of it.  Sassy did a lot of the shoveling as I was jack hammering and running the wheelbarrow.  The floor took the weight of a contractor wheelbarrow heaped to the top.  Almost a quarter yard I think - probably a good 400 to 500 lbs.  No problem.

[glenn kangiser]

Don't forget that for a small cabin you could scrounge burlap sacks and use them cut open and flattened out.  That would eliminate the cost of a roll of netting at about $80.

Thinking about this a bit more, I think I would cut down the loose sand a bit on a smooth surface floor or possibly eliminate it to prevent lumpiness as you move around.  A small amount - maybe 1/8 to 1/4 or so would elevate the jute a bit but not give too much problem with lumps.  I think it would be successful no matter which way you do it. 

Be sure to add the fibermesh for additional strength.  It's cheap and a bag goes a long way.  I get it at the local concrete company for about $6.50 per bag.  About 1/4 bag or so is enough to do an 8x10 area at about 2 small handfuls or large pinches per bucket of cement mix.  I think a bag is a pound.

When they pour the inch and a half floor over wood they use an asphalt building paper (much lighter than tar paper, but #15 would work) between the wood and the concrete.  That would be a good idea.  Just staple it to the wood if necessary to help hold it down.  It may lay flat on it's own without stapling.