Longterm durability of Youker system 1.5″ thin slabs
DIYJester
| Posted in Green Building Techniques on
John Seigenthaler describes thin slab concrete systems that can be used as thin pour slabs over subfloors. There is a specific mix (which I intend to follow) along with some control cracks.
Gypsum is not preferred due to thermal conductivity and cost.
Does anyone he any long term experience in the longevity of these pours? I was more concerned with making sure my subfloor was designed with little deflection of L/480 or L/600 to minimize the root cause of the cracking, floor the subfloor not supporting the floor evenly.
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Replies
Michael ,
Sounds like you are designing for a radiant floor job . You may want to explore other options that don't contain all that weight . There are several above floor systems that work really well . The best i have found so far is Sunboard with graphite . Very even heat distribution due to the graphite , costs 2/3 of Warmboard , lower water temps due to 8" spacing as opposed to 12" . Much less weight and being a wood product also will actually not effect deflection one bit .
Another question is what type of finish floor are you planning ? If it is tile Sunboard makes an even more attractive product that certainly is within budget while still being superior and more effective . Slabs are difficult to control and are not very responsive , these other methods are far better . John will attest to this . Your mass should be at your source , another thing John would agree with .
Richard, this floor will meet up with a slab on grade hydronic system. The majority of the southern walls are windows so thermal mass is attractive. I understand the response as I already have a poorly designed system that barely responds. I also understand this may have a tendency to overheat the home. I know that there will be large solar gains possibly, but I intend on using some sort of programmed hysterisis or something similar. Currently I've seen temperature rises of about 8-10 degrees but do to lack of insulation under the original slab, the boiler is useless, and the house will cool rapidly as my average floor temperature is in the low 60s at best (as low as 40 near exterior wall, like my side of the bed when I get out of bed in the morning).
What kind of cost per sq.ft. are these products. I believe they will not be cost effective compared to the extra framing members. I have figured an extra 300 or so board feet of TJI will be nothing in cost compared to plates. I've seen costs.of around $4-5 a foot for the joists.
For the sq. footage I'm cover, I'd have to be able to get them at about $3 per sq.ft. to be cost effective. I also have varying OC spacing currently from 6" in the bathroom to 9" and 12" in other rooms.
I will try giving you a call this afternoon Richard. We've already been talking back and forth via email about the same project, but different details.
My 10 year old Youker floor looks like the day after I stained and sealed it.
In my opinion, it's the fiber that reduces the cracking. Put in the maximum amount of fiber that the suppliers recommend. The pour might be hairy at first, but the hairs can be burned off with a torch if necessary. It's quick.
You also have to know where to put in your control joints.
Here's a little more info: http://greenbuildingindenver.blogspot.com/2014/10/slabs-vs-crawlspaces.html
Awesome thanks Kevin. Do you know the details of the subfloor? I have calculated 11 7/8 TJI 16 O.C. with Advantech or similar sheathing, that will end up with spans of about 16 ft. I've read some people going with same O.C. spacing but only 10 ft spans.
You may want to look at the LVLs Michael . A whole lot more there structurally .
Please elaborate on finish floor material . This actually CAN determine between a 5.30 / foot product and a 3.25 / foot product. Plus an added bit of insulation .
As far as your existing radiant install , are you interested in doing some forensics and possible determination if it may be made better ?
Richard, I'm taking a concrete saw and a skid steer with forks into the house to demo the slab. Installing 2" XPS vertically 2' down on perimeter and 2" over the rest.
Final floor coverings are still somewhat in Limbo. The baths and kitchen will either be tile or stained concrete, I'm trying to decide if I want a laminate or stained concrete for bedrooms and other areas.
The finish material is not my concern in cost. I was comparing cost of extra joists and concrete to the radiant plates. I'm still waiting on the quote for that mix, but I anticipate it to only be about $1500 for the mix based on the coat to do the slab beneath it. A 36 x 32 9' pour with walkout was about 22k with 4k of that flatwork.
So you are re plumbing tubing under the bad slab ? That's a good thing . The rest of this that is framed is new if I remember correctly ? Is someone designing this for you or are you going it alone ?
If the framed part of the home is new , have you thought about radiant ceilings , They work just as well if not better than floors (they'll receive BTUs from above) . At that point you could skip the additional framing , lose the overpour and use Sunfoam panels with graphite (< 4$ / ft /sq) and rock right over . Lower water temps , less resistance and responsive to beat all hell .
That does not get rid of your slab dilemma but it sure saves Michael alot of first cost while providing a more comfortable , efficient system . Then you can do whatever you want to the floor . Is it a must that you use something cementitious in the new area ? Maybe we could discuss if you'd like . I can talk better than type as we all know .
Richard, slab is not a 100% needed deal. That portion of the house will also benefit not nearly as much as the original slab from solar heat gain as the main slab has nearly 300 sq ft of windows on the southern face.
I am all ears. I know hydronic may not be the best solution, but I don't want to have to buy another heating system (boiler or heat pump, although a hest pump would suffice to a point. I am also much more confident in fluid flow and dynamics over air flow based on my background in nuclear power.
Michael - 10 years ago I built a super insulated house that had 11/2" concrete floor over 3/4"plywood in the upstairs bath and hallway over 2X8's 12"o.c., 10' span. The 3 bedrooms had wood floors. I put tarpaper over the plywood, laid 3/8 rebar over that lifted by small scraps of the rebar, and pex tied to the rebar.I used regular mix for floors, but with 3/8 stone. The hallway was stained and the bath was tiled. I hired my teenage son and a few of his friends to carry up the concrete from the truck in drywall mud buckets. The floor turned out great, had control joints, never cracked, and heated the whole upstairs if we kept the bedroom doors open. The nice thing about all the heat in a small area was that the heat came on more often, so the bathroom floor was often warm. Downstairs, was a 31/2" slab over 2"xps that was rarely warm as the heat rarely came on. I also poured 11/2" concrete stair treads, also acid stained. Reinforced concrete, even at only11/2" works amazingly well. Use a dry mix. It seems to stiffen the floor, and I never had cracks, not even in the control joints.
Ok, one of the contractors bidding the job has gotten back to me wondering if they could substitute pea gravel/torpedo gravel (never heard of torpedo gravel) for the #1A 1/4" max crushed stone.
Anyone have any thoughts against this?