24' yurt on a concrete pad? hydronic heat?

[turbotoyz]

Hello -- first post here but I've been reading a lot.

Getting ready to order our new yurt in the next couple of days. A few questions regarding my planned buildout:

I'd love to have someone shoot some holes in my plans or offer suggestions about what I may not be thinking of.

I want to pour a 30' by 30' concrete pad 4" thick and build my yurt on this platform.

Specifics:
* base -- 2 inches of compacted 5/8" minus gravel, which is on 3 inches of compacted 1 1/4" minus gravel
* 6 mi vapor barrier
* 25 psi dupont style insulating foam board
* 4" concrete pour on foam board (not looking for big discussion about this part; read lots about it on concrete forums and pours on foam board are awesome)
* pour will have lots of grid based rebar
* pour will have control joints to mitigate any settlement (there should be extremely little, however)
* pad will be protected by excellent drainage

I want to plumb PEX for hydronic radiant heat in the 24' diameter part of the pad where the yurt will live.

Questions...
* generally... is this a bad idea? why?

Has anybody done this? It seems like it should be excellent..durable, sturdy, and the concrete is an excellent conductor and thermal mass for the hydronic heat source.

What is the problem here? I know I'll need to factor in how to tie down the yurt...but what's wrong with this approach?

Thanks everyone! I'll post pictures as I'm building out over the summer. I got lots of fun stuff going on out on my land.

Edit: buildout site is about 30 miles east of Seattle...rainy but not particularly cold. expect maybe a week max in the 10-15 degree F during winter.

[Jafo]

Many of the state parks use concrete pads. You will have to anchor the walls to the pad, but with a masonry bit, no problem. Keep this in mind with your pex. You don't want to accidentally puncture the lines when running screws.

Consider the water runoff from the yurt. You will definitely want that water to run away from the yurt, so consider your grades AROUND the yurt base.

I think you have a great idea.

[cmwingfield]

If I had to do it again, this is what I would do. Good luck!

[mama23]

Not much to respond to, but just wanted to say Hi.

We are relative neighbors (20 mi N. of Sea) & we are receiving our 24' yurt in May & will be building around memorial day in e. wa.

We've got radiant heat in current cabin & feel hit/miss about it. our yurt will be wood stove heated, but not using it full time.

good luck & looking forward to hearing more about your project.

[Marshall Eppley]

Having installed lots of hydronic heat in slabs i would say you are on the right track. keep you heat lines at least 1 foot back off the edge.try and keep them at least 1 foot apart. keep your loops as close to 300ft as you can.this makes it easier on your circulater pump. the best way to keep your lines from floating up in your slab is to put roll wire in the slab the squares are about 6x6 and makes it easier to tie the pex down we used what we called a wee winder it winds those form tie wires to hook rebar together. hope this helps a little. (i am a Master plumber)

[Bob Rowlands]

My comment is regarding what Jafo mentioned about making certain water drains away from the yurt. You absolutely do not want rain water hitting the slab and migrating under the wall and into your yurt. It assuredly WILL in a heavy downpour unless the yurt is elevated above the surrounding slab. Even if the slab is sloping 1/4" per foot away from the exterior wall, some water will get in during a long term driving rain. This issue is normally checked by the wall cover draping over the edge of the platform. If your slab is 30x30, how will you stop water from entering?

[turbotoyz]

thanks everyone!! follow-ups below...really appreciate all the help!

NEW QUESTIONS:
I am close to buying a new yurt, but a seller just got back to me who has a Pacific Yurt that is about 10 years old. It sounds like it's in decent shape. I could buy this for less than half of a new one, and get a bunch of wood and extras in the process. Anybody bought a used yurt and regretted it? I understand top and sides have limited lifetime but I think I can replace the top on a 24' Pacific Yurt for around $1300 if necessary. Sound reasonable?

PEX:

Definitely will keep in mind what Jafo and Marshall say about

keeping PEX away from perimeter.

Originally Posted by Marshall Eppley

...try and keep them at least 1 foot apart. keep your loops as close to 300ft as you can.this makes it easier on your circulater pump. the best way to keep your lines from floating up in your slab is to put roll wire in the slab the squares are about 6x6 and makes it easier to tie the pex down we used what we called a wee winder it winds those form tie wires to hook rebar together. hope this helps a little. (i am a Master plumber)

Ok new information here for me here. I'll set back pex 18" from perimter of yurt to give myself a buffer.

Curious about keeping lines at least 1 foot apart... is this to keep my total run to about 300 feet? Is the 300 feet a target or a threshold? One complication that I haven't figured out yet is actually how I'm

heating

the water, and I know nothing yet about circulator pumps. Are the ideal target total length of pex runs for hydronics variable depending on on the

heating

and/or pumping mechanism?

I do not have utilities on my site yet, and I probably won't for a couple of years. The yurt will be used mostly as a "living room". I have a well-equipped Bluebird bus that will handle sleeping/cooking/showers/potty.

And I have is a large amount of deadfall wood (20 acres of mature second stage forest) I can cut up and burn. My perfect buildout would be to have some kind of thermosiphoning system in conjunction with a wood stove (ok we'd probably cook on this too sometimes), and I've read maybe an hour on it but I don't think it will work because I need to have my water tank above the wood stove. Awkward (and possibly dangerous if built incorrectly). I'm fine with a DC circulating pump if my pump stays under say 10amphour draw @ 12v. Pex can handle up to 200 degree F water. Regarding floating pex: good points and will consider. I'll be using your 6"x6" heavy wire mesh, and will secure the pex to that. Can't find "wee winder" on the internet. More details on this please. Can I just ziptie the pex to the wire mesh to prevent floatage? Pex should have enough rigidity to not kink when it tries to float.

WATER RUNOFF

Originally Posted by Jafo

Consider the water runoff from the yurt. You will definitely

want that water to run away from the yurt, so consider your

grades AROUND the yurt base.

Originally Posted by Bob Rowlands

My comment is regarding what Jafo mentioned about making certain water drains away from the yurt. You absolutely do not want rain water hitting the slab and migrating under the wall and into your yurt. It assuredly WILL in a heavy downpour unless the yurt is elevated above the surrounding slab. Even if the slab is sloping 1/4" per foot away from the exterior wall, some water will get in during a long term driving rain. This issue is normally checked by the wall cover draping over the edge of the platform. If your slab is 30x30, how will you stop water from entering?

Interesting...I hadn't realized this as a serious issue. Pad itself will be protected by excellent drainage...but yes water will land on pad.

So this pad will likely be used for my lifetime on my land. I don't know if I'll have a yurt there 15 years from now...but that concrete pad will still likely be there. This is why I was planning on building it as a square:
* more future utility
* i get a "deck" now
* i like concrete
* i don't like warped rotting decks and that's what pretty much always happens in Seattle area
* i like to do it once now for good, and move on to my next project

So I could do a couple of things:
* create like a 1" 24' diameter circular form and when I do my pour, I'll pour an extra inch around the most of it. if in 10 years when i'm no longer using a yurt and want to do something else, i can grind down the edges and have a slight incline.
this is easiest
* something fancy with a more gentle incline to 24' circular diameter
* ideas anyone??
* or I could set and plumb driveway style drainage (but find some curved pieces or do something clever in the concrete around the perimeter...wouth this be preferable to having the pad elevated
* or i could cut PVC in half and set this in with drains... this would look kind of ghetto though


SALUTATIONS

Originally Posted by mama23

Not much to respond to, but just wanted to say Hi.

We are relative neighbors (20 mi N. of Sea) & we are receiving our 24' yurt in May & will be building around memorial day in e. wa.

We've got radiant heat in current cabin & feel hit/miss about it. our yurt will be wood stove heated, but not using it full time.

good luck & looking forward to hearing more about your project.

Hi Mama. Where is your land at? Curious about what you don't like about your existing radiant heat?

Most people seem to love systems if they're installed correctly and functioning well.

Originally Posted by cmwingfield

If I had to do it again, this is what I would do. Good luck!

Hi there -- thanks. I'm only planning on doing this once so trying to get it the best I can.

[Marshall Eppley]

The reason you try and keep the loops a foot apart is so you don't have cold spots in your floor. Wee winder is just a handle with a hook sticking out that swivels. you hook the hook into the holes on the rebar ties and just winde it like a bread tie. and yes cable ties will work just fine. Loops longer than 300 ft don't circulate well,and it makes it harder on the pump. i have seen pex installed without tie downs and it wasn't a pretty site after the trowel machine was done with it.

[Marshall Eppley]

One of the down falls to radiant heat is it heats the surroundings and it takes a long time to get up to temp.its not like you are going to turn up the heat and in a couple minutes get it where you want it might take days to warm everything up .but once you get it where you want and keep it there it's great. So if you are not planing on running your heat all the time you will have to use antifreeze instead of water.

[Bob Rowlands]

You are detail oriented, and that is a good thing friend. Now is the time to think things through.

Once you are absolutely certain of the yurt diameter you are buying-- and I'd most definitely verify the yurt diameter with the builder or seller for sure before the central concrete 'yurt pad' is placed, making a 1" heigth raised concrete 'footprint' would help keep rain water out.

However if I was considering doing the raised radiant slab thing, I'd follow common construction practice and install a curved redwood/pressure treated 2x bottom plate the diameter of your yurt atop the poured slab. Cover the first slab with plastic so the interior yurt slab poured atop it doesn't bond to the lower slab (for future removal if necessary) It would easily bust loose, and no weird raised area to be ground down or whatever. You'd have to be a carpenter to foolllow details but suffice to say just shoot the plate into the slab with powder tool, or tapcons.

Use the 2x mud plate as the screed for the heat slab in the yurt. It will define exactly where the piping goes, and be the same depth-1.5"- just as in residential construction atop a subfloor. The pipes and the whole schmeer sit atop the first slab and can be removed later at will. Plus you'd have a good attachment point for the wall cover around the perimeter.

Good luck.