New Building Foundation/Floor advice

[WVBill]

I'm getting ready to design/build a small 20 X 20 foot building as a quilting studio for my wife. the enclosed floor area needs to be a free span with no internal supporting posts/walls. I live in the northern Shenandoah valley and will want to insulate/heat the building for winter use.

My foundation/floor choices (and some of my concerns) seem to be:
1) Concrete footers/concrete slab floor - (concrete floor would be uncomfortable and cold in winter) (?)
2) post-and-beam foundation with insulation between above-grade engineered lumber floor joists - (how to keep "critters" from taking up residence under the building)
3) pole building type foundation with concrete slab floor - (same concern as #1)
4) pole building with insulation between above-grade engineered lumber floor joists. (same concern as #3)

I will be building this myself with my son in law's help and don't want to break the bank doing it. I think #2 is my preferred approach except the building will be less than 50 feet from a 200 year old rock wall and a sometimes corn field on the other side meaning we have lots of squirrles, skunks and woodchucks who will be more than happy to take up sheltered residence under the building. If I keep my floor joists 6" up off the surface grade and fill that 6" gap with crusher run topped by heavy plastic sheeting do you think that will be enough to deter the critters? Any other ideas?

Oh - I plan to have a gambrel roof with a loft in the upstairs area.

Thanks

WVBill

 

[srossman]

How about running radiant floor heating in the concrete slab. That should make it much more comfortable to work in in the winter as well as take care of your heating.

-Scot

 

[RonMar]

You could build concrete slab like a garage(without the rollup door). Should be no problem getting a 20' span without any internal support. Many building supply houses and truss manufacturers sell garage buildings nearly pre-fab, just place the pad and provide the doors windows and trimmings. It should be no problem replacing the garage bay door with a stud wall as no real engineering would be required like for accomidating that large opened span for the door, just copy one of the other walls.

On the slab, you can build up a raised box floor, IE: 2 X 4 or 2 X 6 frame with plywood or plank floor sheething and carpet or linoleum floor cover. You could also add insulation. If doing it from the beginning, you can raise all the door sills and windows to match the raised floor. The raised floor would allow you to add floor electrical recepticals for plug in work lighting around the quilt racks or for sewing machines out in the middle of the space without having to run cords across floor or down from ceiling. Depending upon your conditions, you might also be able to add a bathroom or sink without having to go into the slab.

 

[bbabineau]

I too like your number 2 and as for critters I would put wire in a trench all around the building just like for a chicken coop. You could even lay wire on the ground under the building to keep out the possiblitly of gophers with crushed rock on top of the wire.

 

[mikim]

I think I'd go with a perimeter concrete beam ~6" below grade footer then up 18" or more above grade (concrete or blocks), then set a treated sill plate on that and build your floor off it. If you used piers in the middle with a build up beam level with the perimeter sill plate, you could use 12' joists lapped on that center beam to span the 20'. fill, insulate, or whatever you wanted to do with the crawl space. Certainly lay a plastic moisture barrier down. That would give you the softer warmer floor and the beam would keep the critters out --- unless you get a very enterprising one that will dig under the footer beam.

 

[EddieWalker]

WVBill,

Based on the fact that this is a specialized building to be used for quilting, and you don't want to spend allot of extra cash on it, I'd advice pouring a concrete pad. It's the simplest, cheapest and if done well, one of the strongest foundations you can get for your money.

20x20 is only 400 square feet, so heating can be easily and cheaply done with a few heater units. You can get two real good ones from Sams for less than a hundred bucks each and they will make the room too warm to be comfortable if you turn them up.

Cooling can be handled with a large window unit for another couple hundred bucks. I'd put a small one on each side of the building if it was me.

I like Ron's idea of building up the floor with some 2X4's with insulation inbetween and plywood on top. This will give you as much insulation as you'll get with Pier and Beam, but without the expense or labor.

Before I did that, I'd just through out some area rugs adn see how it works. I bet you don't even need anything else with the space heaters.

With a slab foundation, you can stick build the frame and fab your truss's on site. This will keep it simple and easy to get materials from the Box store.

Insulate the walls and especially the ceiling. Heat rises, so the ceiling is your most important area to insulate.

If your not familiar with building, it's pretty simple and there's allot of members here who enjoy helping you along if you get to a point your not comfortable with.

Have fun,
Eddie

 

[schmism]

id go concreet floor. you could always do a radiant floor heat or at least keep the slab at 60 deg instead of 40.

otherwise you could cover it with simple floating wood floor

baseboard heat and a window A/C unit

 

[WVBill]

Thanks for all the ideas guys,

If I went with the concrete slab, I think I'd have to go with footers all the way down below the frost line (4 feet here). Or is that not a requirement for a 400 square foot non-living-unit space? I'll have to check the code.

WVBill

 

[EddieWalker]

Code will dictate what you do no matter how you do it. If you go pier and beam, then you will still need to go down the same depth.

The footing depth will be the same either way. The savings and advantages to a slabfloor is in materials, labor and maintenance. Without any plumbing, it's evey easier.

You did mention the idea of pole construction. The advantage of poles is they don't need a floor. This is a huge savings for a building that is just used for storage, but when you put down a floor, it looses it's apeal. Pole construction is cheap and easy, but it's not the best way to build a small building or shed. Stick framing and/or a metal kit are far better choices.

Have fun,
Eddie

 

[InlineDieselFan]

WVBill,

If you are in an area that get cold, (on been ack to WV once and it was 80 degrees), and this is a specific for the wife, and I am sure some of here friends I would find a way to do the radiant floor heating. She wil be happy and her friends that come over will be happy and tell her how wonderful you are to build such a nice quilting room.

If the wife is happy you will be happy.

Put lots of plug-ins around for sewing machines, and lights. Also put in good overhead lighting also.


steve