Pole barn vs. Steel Building

[Raspy]

There is always a lot of advice on how to do radiant heating. There is no reason to over think this, but try to get advice from someone that has actually done it before.

The underslab insulation, if you choose to use it, must be waterproof. Blue board styrofoam is the common material and probably the best. Some foams are not waterproof. Insulation under the center of the slab has questionable value. I chose not to use it on mine, but insulated the perimeter with 2" blue board. Remember, it will be supporting your slab for the rest of the time it's there and must have high integrity.

A foil faced board does not provide a radiant barrier because it is in direct contact with the concrete. The foil faced insulation boards I've seen are isocyanerate and not designed for direct contact with moisture or to support concrete floors. There may very well be others I haven't seen, but be careful. Blue board is your friend if you want insulation.

In a concrete slab, the PEX gets tied to the rebar directly with rebar ties spaced at about 1 1/2' and closer on the bends. Even with that, you don't really don't know how close it is to the surface after the pour. NEVER saw cut a slab with radiant heating lines in it.

Later, when you need to drill in for some reason, refer to your many photos and compare them with landmarks like anchor bolts and plumbing vent lines. Then simply turn on the heat and "look" for the lines with your hands or a radiant thermometer. Draw the lines with a crayon or pencil to confirm the pattern and drill as far from the heat line as you can. It's a strait forward procedure.

Hold the heat lines back a foot or so from the exterior. Use separate loops in each room for balancing and zoning purposes. Space the lines closer in the bathroom and in front of the exterior doors or in the mud room. 6" spacing for the closer lines and 12" spacing for the rest of the areas works well. 12" rebar spacing allows for this and you can add a few bars at 6" for the closer spacing. The tubing should run with the top bar and be tied directly to it. This minimizes the chance of damage during the pour.

Try to make the loops approximately the same length, if it's convenient, and limit 1/2" PEX (5/8" OD) to 300 linear feet. 3/4 PEX (7/8" OD) works great in slabs because it is much stronger and you can make the lengths up to 500' if needed. Shorter lengths are better. You can have one manifold per thermostat if you'd like, or you can have one central manifold and control the loops with thermostats and telestat valves. Whichever works out for your floor plan is fine.

Don't plan on joints in the slab, but the reality is that sometimes tubing gets damaged and must be fixed. I have never had a repair fail in a slab. Use brass barbed fittings and copper crimp rings if this occurs.

Code says a 100 PSI hydrostatic test is required. If you are getting inspected, fill the system with a garden hose to full house pressure and top off with air to 100 PSI. Leave it pressurized during the pour. If no inspection, air pressure to 50 PSI or so is fine.

Expect to get some cracking. Cracks will not hurt the PEX.

Look at the Watts stainless steel manifolds with flow meters and isolation valves. Very nice equipment! Easy to work with and zero problems. Where the tube enters and exits the slab, you should have it in a PVC electrical conduit 90 for protection. Slip it through a 3/4" 90 for 1/2" PEX or a 1" 90 for 3/4" PEX. Works great.

I'm wondering what you are planning for a heat source and your control strategy.

I put in all of the post footings, then put up my steel building and did the roof. Then I did all the underslab infrastructure of conduits, waste lines and water pipes. Then I did the final leveling, vapor barrier, bar, radiant heat and poured the final slab at 8" thick. During the pour we wet set the J bolts. Then I glued and bolted down all the pressure treated plates for the exterior and interior walls. My building is 60X60 including a 12' overhang the full length for a covered porch. The house area is about 1800 sq ft and the garage is about 1100 sq ft. It has 12' high eves and a 4 and 12 pitch roof with two 10X10 garage doors. I then added a 14X10 front porch. It's just two steel trusses on 4 H posts, roofed with the ridge running the opposite direction as the main house. Then I built a 5' X 8' steel frame front door out of 4" box tubing and double paned it with two sheets of 4'X5' tempered glass.

I've done many slabs with 1/2" PEX, but on my own home, I went with 3/4" ox barrier PEX (oxygen barrier is pretty much standard now, not necessary, but is the best choice). I tied it to number 3 bar on 12' centers that run in both directions. Some extra bars were added to prevent cracking and to facilitate 6" spacing where needed. I have two layers of 6 mil plastic for vapor barrier and radon protection. I have four thermostats and three manifolds.

The earlier comments that prompted my comments were about tying the tube, saw cutting and insulation. Be careful where you get your advice!

 

[newbury]

Y'all realize this thread was almost a year old and the OP hasn't been around since October?

 

[Raspy]

Looks like the OP hasn't been around for over 4 years. But the conversation has resumed and it's a good topic. Cool.

 

[Underdog57]

Looks like the OP hasn't been around for over 4 years. But the conversation has resumed and it's a good topic. Cool.

Yes! Very valuable info posted by Raspy!!!! Thanks

 

[motoguy]

Looks like the OP hasn't been around for over 4 years. But the conversation has resumed and it's a good topic. Cool.

Very much so. I'm investigating the pole barn vs steel option as well, for a 40x60 shop I plan on installing at our new home. It seems to be a very back and forth thing. Personally, I just have an issue dropping wood in the ground for a long-term structure. I'm sure it would be fine for as long as I live...but...it bothers me. lol

An excavation buddy of mine has 40x60, 30x50, and 30x40 shops, all pole barn. 40x60 is used for the dump trucks, skid steers and mini-x. Has a 2 post lift. 30x50 for plow truck and one of his race cars (general storage, it appears). The 30x40 is race car/toys only, it has a 2 post lift as well. All of his buildings are pole barns, and when visiting, I can't help but think that I'd be happy with any of them. To quote him, "Everybody wants steel. It looks more professional. I wanted it too, but not for twice the cost."

My shop will be housing a few CNC machines (mills/lathes/plasma table), some computer stuff, etc. In my dreams, I'd also have a 2 post and 4 post lift in there, as well as a crane/gantry of some type. Insulation / humidity control is a concern for me. I plan on using this shop for the next 30 years or more, so I'm hesitant to save a few $ up front, if I'm going to regret it later.

The above friend visited my home yesterday. His calibrated eyeball says there's about a 4' drop across the area I want to use. He estimated $7500 for dirtwork, levelling, trenching for foundation, and fill. He estimates $250/finished yard for concrete. At 45 yards for a 6" 40x60 slab, we're at $11,250 for concrete, not including 4' retaining walls. $11250+7500= $18,750 for a leveled, filled 40x60 slab (excluding vapor barrier and insulating foam) before we can put a building on top.

He says his 40x60 bole barn was roughly $24k, constructed. FWIW, he says his 30x40 was only about $6500 constructed. This includes the thin foil-backed insulation, 2 man doors, and 3-4 14' doors for his dump trucks. Based on those rough numbers, we're looking at about $43750 to get a 40x60 shop up and enclosed. I would like to have better insulation than he has. That does not include electrical stub, water stub, water drainage, etc. We'll stub services to the shop, and I'll be handling interior completion myself (wiring, water, wall treatment).

I'm in contact with General Steel and Worldwide Steel to get quotes. I like the steel truss, hybrid (wood purlins) aspect of the Worldwide Steel option. My last shop was a 24x35 Versatube structure, and I ran into a LOT of moisture issues. I'm assuming this was due to the vapor barrier'd slab, as well as the directly exposed steel of the structure (sheet metal screwed directly to steel structure, insulation in between). I purchased a $1200 professional dehumidifier to keep the humidity down in the shop, in order to keep from rusting the ways on my CNC mill!

I'm curious of these numbers sound in-line with your recent experience in constructing your shop/shops. The friend above said to budget $50-$60k for an installed 40x60 shop (insulated, but otherwise unfinished interior), and I believe he was talking pole-barn construction. I'm assuming metal would add to that, but I'll know when I get the quotes.

If these numbers are correct, we're blowing our budget, and I may have to settle for a 30x40 shop for now. He said that a 30x40 should be able to fit on my preferred area, with minimal fill, no retaining walls, etc. "I bet you'll cut the ground/concrete work in half by going to a 30x40." I understand that's a personal/individual decision, and not a construction issue that carries over to each person wanting a shop. It's just a function of the lay of my land.

My main issues with a pole barn, are 1) I loathe the idea of setting wood into the dirt. My friend mentioned that the wood won't actually be in dirt, it'll be in gravel fill, so rot should be a minimal (to nonexistant) concern. I could mount the posts to the top of the slab, but then you've lost a TON of wind rating/stability. 2) sealing the shop op. I do not want wind, water, or critters getting into the shop. I could probably alleviate this by running a treated sill plate between the posts, and attaching the drip edge/bottom of wall to the sill plate. A "plus" of a pole barn would be 1) cost, and 2) lack of 'sweat' that I ran into with my previous steel shop. I think the sweat issue could be overcome in the steel building by simply using wooden purlins and girts, vs steel, when attaching the metal siding.

Anyway...I know this is a small book, but I'd be most appreciative on any insight you guys may have on the matter.

 

[ultrarunner]

The nicest shop I have ever visited is 40 by 96... basically four 24 x 40 deep bays with a roll up door for each bay and a huge gable end roll up for the dump truck...

Stick construction and with skylight, hardie exterior for fire and sheetrock inside... all on a 8" slab....

No moisture problems, good light and sturdy with double rebar for the CNC lathe.

 

[Creamer]

Motoguy - i am planning the same thing (40 x 60 x 16) for a project this summer. here is what I have found.

Materials for kit are roughly the same whether it is steel or pole barn - maybe $2000 difference if you compare similar grade materials
Erection of insulated shell with floor is slightly higher for the pole barn because you have to set the poles.
Concrete for a metal building is much more critical because your building is attached to it.
The $50-60k is a good estimate if you have it built for you and it has a good concrete floor.
I have found the truss type steel buildings for this size to be more expensive than the steel beam buildings by about $6k.
I know of many buildings that have no problems with moisture/sweating if there is the visqueen barrier layer under the concrete and standard "pole barn" fiberglass insulation elsewhere that was installed properly during construction. I also know of a few buildings that have had moisture problems and they were not built this way.
I would not put in eaves and overhangs as they are a lot of cost and labor and create more potential issues. (A complete lean to is a different and not an issue like a 12-24" eave)


having a good concrete floor is a major cost driver for the pole barn but a necessity for the metal building because if the floor moves the building twists. The nice part about the pole barn is that the floor is independent of the building. For the metal building in my area you have to put a footer down 3.5' all around - which is a major cost driver - to get below the frost line and to keep the frost from under the slab to keep the floor from heaving. With a pole barn if you have a problem with the floor you can just tear it out and replace that section.

I would not be concerned with having wood in the ground - especially if you have some of the laminated posts for the pole barn because then the treatment is completely through the wood and you will never have an issue. In fact some companies will warranty their pole buildings against pole rot for 50 years.

With your grade issues a pole building may be much lower cost because you can put one side below grade and use treated lumber fore the retaining wall - much lower cost than the grading or concrete.

Dollars wise here is what I have found:
Steel building kit with one OH door frame and one walkout door delivered to the site - $21k. Pole barn equivalent $20,200
Windows for building with frame for steel building $500 each. For pole barn $300 each (less framing needed for pole barn construction)
Concrete in my area for 6 bag mix is right at $100/yd so about $5k for a 6" floor and another $3500 for footers and columns
Labor for concrete - digging footers, forms, trowelling, etc. $18k
Erection - metal building $8-10k, Pole building - $10-13k
Grading costs are site dependent but I am planning on doing most of it myself but I will need to haul in some fill.
I have no costs for having one side of building subsurface.

Hope this helps. Please share what you find as I am still looking.

 

[prestigesteel]

Has anyone ever tried spray foam insulation on their steel building? I know up here in Ontario if the wrong foam is used the expanding and contracting cracks it. Most people use a fibre spray insulation that is flexible. Any experiences to share?

Jason Gullett
Prestige Steel Buildings
(888) 314-5751