New Building Foundation/Floor advice

[InlineDieselFan]

WVBill,

Forgot to add that over the concrete you can then add laminate flooring linoleum, carpetng or what ever the little lady wants.

Again if she is happy you will be happy.

steve

 

[jayhaitch]

Ditto on the concrete slab. Best would be infloor radiant heat. But......

You can get ceiling/cove radiant electric panel heaters. Heats the object, not the air, so the floor will stay warmer. I don't know your electric price, but heating a well insulated 400 sq ft building won't cost too much no matter what you do.

Also, another way to insulate the concrete floor is to Hilti 2x3's onto the floor on the flat, 16" on centre. Fill the spaces between with 1.5 inches of XPS (extruded polystyrene) panels, Styrofoam or Celfort are two popular ones up here. R5 per inch equals R7.5 under the floor. Lay a T&G 5/8 or 3/4 plywood floor overtop.

 

[dholly]

WVBill -

A while back I posted a few pics of a 24'x34' monolithic slab prep and pour that might be helpful. Also, a cross section diagram of the slab design. They are early on (pg. 1 or 2) in this thread:

So I got a good deal on some trusses...

Although my uninsulated slab works great for weekend use, if I were expecting to heat and use it daily during wintertime, I think insulating under ther slab and piping for radiant heat makes a lot of sense.

FWIW, I had a cabin with you #2 construction. You can't keep critters out with that, they will find a way in. Just my .02, HTH.

 

[Jagmandave]

Another way to heat/cool such a small building is with one of those motel heater/a/c units. They work well and are not expensive to buy, and that way you only need one unit.

 

[EddieWalker]

When I priced out wall units, I found there was a considerable savings buying seperate units. Several hundred dollars difference.

Eddie

 

[midlf]

WVBill - You best ask the CFO what kind of floor she wants. My SO has bad knees and cannot tolerate a concrete floor. She needs something with some give to it. A properly done crawl space will keep the critters out. You are lucky if you can get away without a toilet. Mine will have to have one because when she gotta go she gotta go NOW.

 

[patrick_g]

Radiant floors are wonderful but radiant in a concrete slab is not practical if you don't want to heat the space all the time. The time constant of a hydronic (or electric, or other in-floor system) is so long that you can't turn on the heat and be ready to occupy the space an hour later. It takes H O U R S to get up to temp. If the lady stands much or walks around much then concrete is very tiring and you can't put thick pads or most heavy rugs over a radiant floor without ruining the system response. Radiant floors can be easily made with other than concrete slabs.

I would recommend a floor with much less thermal mass if you want radiant floor heat in a space that is not occupied most of the time.

If you do want slab floors in a space that you don't want to have to heat all the time then consider a radiant ceiling. With a radiant ceiling you can carpet the slab for comfort and the R-value of the carpet is a good thing instead of bad (as it would be with radiant floors.) I have three rooms with radiant ceilings, two are tiled and one heavily carpeted with heavy pad (master bedroom.) The all have significant insulation under the slab so the floors tend to take on the average room temp and aren't chilly. I also have about 1200 or so sq ft of in-floor hydronic heated tiled slab floor. This is my great room and master bath.

I am "INTO" energy conservation so I have programable setback thermostats. These are used to control hot air distribution (back up heat) and the A/C. Separate T'stats are used for the hydronics and have no setback ability as it is useless with radiant slabs in continuously occupied spaces. The only programable radiant heat I have is the shower which turns on in advance to warm the floors and walls prior to our typical showering time. and off again till a few hours ahead of bed time so a evening shower is comfortable. The shower walls are cement backer board covered with tile and backed with batting, pretty low thermal mass compared to a slab and the automatic system turns on the hot water to the shower 3-5 hours in advance. There are aluminum heat sinks to spread the heat from the pex tubing to the tiled wall.

I would be happy to try to answer any specific questions about radiant heating in general or specifically why I think radiant ceilings would be a good thing for a quilting room.

Radiant is terrifically comfortable and needs no ducts and does not have an air handler so it is super quiet and draft free. NO dust is circulated as there are no ducts or fans. The heat is well distributed. Radiant ceilings do warm the floors with their infra red radiation so you should insulate the floors, slab or otherwise.

Radiant ceilings with normal sheetrock have a low thermal mass and begin to make the room comfortable fairly quickly, way faster than heating a slab.

Finally... I don't want to pick a fight with anyone but RADIANT systems heat the air very little. Eventually the air will warm by contact with warm objects like the radiant panel itself (ceiling or floor) and things heated by radiant energy. Air, being virtually transparent to IR, doesn't intercept the radiation and get heated in the process. This is OK as comfort is much more dependent on the radiant environment than the air temp.

Pat

 

[monkeymonk]

WV

I just started digging my foundation for our 24x16 guest cabin "quick cabin". For quickness and monitary reasons we are going with cement poured piers. Less work,rebar,and cement....The tops of the piers wil be 6in-12in off the ground with a 1 1/2ft foot print and 8in tower(rebar of course). The building is near a creek and on a hillside i leveled out the best it could be, (No Fill) if we could have gone all the way the whole building would be 6in off the ground all 4 corners.

There will be 4 piers on the 2-24ft sides and 3 piers down the middle. we will be setting brackets into the cement piers.
on top of the piers will be our main beams 3 in all, running the 24ft length of the building.
The main beams wil be "Built up beams" 3 eco groovy pressure treated 2x8's 1 1/2x7 1/2)nailed together to make a 24ft 6x8. The building is near a creek and close to the earth in spots so we are choosing to buy pressure treated lumber instead of using our milled beams.

The sub-floor will go on top of the beams
The subfloor will be 2x8' on 2ft centers running the 16ft width of the cabin(16ft 2x8's).
on top will be the sub-floor..floor.. 1 1/8 Tongue and Groove.

Then walls so on so on..

We will most likely buy the wall lumber 2x6's as this is an "un-planned" "quick cabin" and our milled lumber is "planned" for the barn 50x60....but thats another thread

You can use 4x6 beams and 2x6 subfloor with 3/4 T&G but we like to go overkill......Why...? Slab floors are cool and all, but cement ain't cheap and getting a truck out here is another story. We will be using slab radiant heat, wood floor for our main house and lodge...But that two is another thread...much later

Quick cabin, inspector? code? out here? Foundation may or may not be to code where you are but here it will suffice. Very strong.

Good Luck!!

 

[WVBill]

Thanks again for all of your ideas.

A concrete slab sure would make the rest of the construction easier (firm, fixed, level starting point), would eliminate the under-floor critter issue, and could be softened with sleepers and underlayment (she has a quilting machine that she stands at for hours at a time).

But a concrete slab would mean I would have to dig a four-foot deep trench for footers all the way around the perimiter, re-bar the edges, etc. etc. All of which is beyond my diy capability. Wouldn't the footers-foundation-slab could cost more than the rest of the building?

We have propane for central heating in the house and a vent-free propane fireplace that heats the finished basement so I'm thinking a vented propane fireplace for heat in the new building. It would be functional plus give a nice "homey" feel for the quilt studio. A window A/C (mounted in a dedicated space in the wall vice taking up a window) should be sufficient for summer cooling.

Construction will probably be next Summer so I have lots of time to plan this out.

Thanks again

WVBill

 

[dholly]

But a concrete slab would mean I would have to dig a four-foot deep trench for footers all the way around the perimiter, re-bar the edges, etc. etc. All of which is beyond my diy capability. Wouldn't the footers-foundation-slab could cost more than the rest of the building?

Are you required to dig full footers by local code? Code in my town says a building less than 1000sf can be built on a floating monolithic slab, i.e., no footers below the frost line. This construction technique is fully approved in upstate NY and I'm guessing we have more frost heave than you in WV, so I'd be surprised if you didn't have this option as well. It was significantly cheaper in both labor and material cost than digging and pouring full depth footers. I use a propane wall heater and ceiling fan in my garage/shop, works fine. Link is to the slab cross section I referenced earlier.