Cost for heated slab?

[SPDMETL]

I'm getting close to starting on a Building, and hoping those of you that had someone construct their heated slab will share the approximate cost. I'll take any advice those who have gone before me can give...Thinking along the lines of 30x45x14 high.

Anyone here near Lowell, MI?

If you have a contractor you recommend for this, word of mouth referrals are way more comfortable than "eenie, meenie, miney moe" in the phone book...

What's more cost effective, post building or stick built? I aim to attach to the house, so it has to look right.

Sorry if this has been covered before, and thanks for your answers

 

[mopar440_6]

SPDMETL, the shop I just built is 50x60x14. Build thread >HERE<.

It cost me right around $6500 to have the radiant tubes and insulation installed. This is in addition to the cost of the building and concrete. Also, that figure doesn't include any of the plumbing, pumps, manifolds, boiler, etc (hoping to have that quote back this week).

My building is post frame as a stick built this size would have been cost prohibitive. Post frame is definitely going to be more cost effective but if you want to attach to the house, stick built may be your only option.

Hope that helps. Feel free to PM me if you have questions...

 

[SPDMETL]

Thanks for the reply. Pretty sure it's gonna be expensive!

So one more question...this will be at least partly a bodywork garage, and that means vapors that explode. What kind of boiler is safe
?

 

[Highbeam]

Thanks for the reply. Pretty sure it's gonna be expensive!

So one more question...this will be at least partly a bodywork garage, and that means vapors that explode. What kind of boiler is safe
?

That's a loaded question. If you are using the entire shop as a paint booth then no boiler is safe. Even a light switch can trigger an explosion.

Lots of bodywork involves sparks and flames at floor level and if you're comfortable with that then any boiler with the lowest point located the appropriate 18" above the slab will be equally safe.

 

[mopar440_6]

While I'm no professional HVAC guy, what I have gathered is that the absolute minimum is to have the boiler at least 18" above the floor height. A wall mount, high efficiency unit should be able to be mounted plenty high enough. Also, I chose to build a small mechanical room to house the boiler and that room will be externally vented allowing enough air circulation that should prevent any flammable vapors from building up to a dangerous level. I think your best bet would be some combination of the above and determining a way to externally ventilate a separate area for doing paint work. Nothing is 100% safe, but if you understand the risks and how to mitigate them you should be fine.

 

[mustangfan]

The additional cost to buy the insulation and the tubing for the concrete is about $1.25 per square foot. This is based on using 1/2" pex 1' on center. The labor cost will vary by area, and you can do it yourself. It is not difficult to put the insulation down and run the tubing.
You can wait to buy all of the stuff to hook it up to the boiler if you want. BUT if you don't put the tubing in the concrete when you pour it, you can forget about having a warm floor to work on.

 

[buildingup]

The additional cost to buy the insulation and the tubing for the concrete is about $1.25 per square foot. This is based on using 1/2" pex 1' on center. The labor cost will vary by area, and you can do it yourself. It is not difficult to put the insulation down and run the tubing.
You can wait to buy all of the stuff to hook it up to the boiler if you want. BUT if you don't put the tubing in the concrete when you pour it, you can forget about having a warm floor to work on.

Before concrete is poured I assume the tubing is pressure tested to insure no leaks and also maintain that pressure during pouring to validate pipe isn't damaged?

 

[rburke65]

That is how it is usually done....maintain pressure during the placement of the concrete.

 

[MScott]

The additional cost to insulate and put pex in my 28x38x12 floor was only $1035 although I got a real deal on the foam insulation ($500 on Kijiji.) This does not include hooking the pex to my outdoor wood furnace system. Worth every penny.

 

[86turbodsl]

If you think you want a heated slab but don't want the full cost now, it's not that bad to just put the tubing in. Only 2 things you need to remember, put down 2" rigid foam under the entire floor, and use 1/2" pex loops 250'-300' MAX length, spaced about 12" on center. I put mine 6" on center at the outer edges to keep the heat even. Everything else you can do later.

 

[Crazy68Dart]

Sounds like you are looking to contract it out. Just be sure you pick a good one. Otherwise, the question is a little hard to answer. You should be able to calculate material cost very close to reality, but the labor costs (and experience) is going to vary.

I almost *didn't* do radiant, but decided I could do it all on my own for not a ton of money. My system is terminated to a manifold and has been under pressure for months (also during the pour). Like most things, it is the prep work and detail that will make a good finished product.

 

[finn]

If you think you want a heated slab but don't want the full cost now, it's not that bad to just put the tubing in. Only 2 things you need to remember, put down 2" rigid foam under the entire floor, and use 1/2" pex loops 250'-300' MAX length, spaced about 12" on center. I put mine 6" on center at the outer edges to keep the heat even. Everything else you can do later.

Also, make sure the edge of the slab is insulated from the backfill with 2" foam along the slab and footings

 

[Randy in Maine]

And worth every nickel. My floor keeps the air temp right at 55º. I can work out there all day and be very comfortable.

Make sure the base is well compacted. I re-compacted after every 6" of fill was brought in.

 

[buildingup]

And worth every nickel. My floor keeps the air temp right at 55º. I can work out there all day and be very comfortable.

Make sure the base is well compacted. I re-compacted after every 6" of fill was brought in.

What temp do you have the floor set at? Any fans running to push great back down?

 

[Randy in Maine]

The thermostat on the wall is set for 55º F. I turn it on around Thanksgiving and turn off around April.

The floor runs about 62º or so. About 1000 feet of 1/2" pex. Shop is around 1200 square feet 28x40x12 using SIPS. Cold roof just trusses and soffit & ridge vents. The warm water comes from my propane house boiler so there is no flame in the garage.

The ceiling is actually a little cooler at about 48º or so (when measured with my lazer gizmo). I don't normally run the two ceiling fans in the winter. My heat radiates from the 46 tons of concrete floor + the building + what is in the building so it stays pretty stable.

 

[koditten]

I think I got about $2k extra in foam board and pex tube. 1' centers for the middle, 6" for the 3 rows on the perimeter. I did it myself.

3 loops at 270' each.

I cheeped out for my boiler. I found a used boiler on CL. People bought a house and didn't know that hot water heat does not have A/C. The mostly new boiler came out and a forced air unit went in. $200.

I got lucky. I had wanted a standing pilot boiler for the shop. Only reason was because of reliability. Relay, thermocouple and a gas valve and pilot light. Parts can be found anywhere if needed.

The savings of buying a 96% efficient unit could not be justified. My 84% efficient unit works just fine. Shops are not as efficient as a home. The difference in cost was about 35 years to break even.

Ceiling fans are not a benefit for in floor heat. I experimented and found no gains running a ceiling fan. Found out later that it actually makes your system work harder. You do not want convection with in floor heat.

I keep the shop set to 50*. It costs between $110 and $130 per month to heat my 1400 sqft. Depends on how ruthless the winter is. I only heat October thu March.

 

[Voi]

The floor runs about 62º or so.

The ceiling is actually a little cooler at about 48º or so...

This is one of my favorite things about in floor radiant heat. Friends of mine run a cabinet building shop and I sometimes go over there and crawl around up in their loft looking for stuff I can use. It's nice that it cools off a bit as you go up vs sweating as you're digging through stuff.

The thermostat on the wall is set for 55º F. I turn it on around Thanksgiving and turn off around April.

The floor runs about 62º or so. About 1000 feet of 1/2" pex. Shop is around 1200 square feet 28x40x12 using SIPS.

Do you ever have any issues with the shop being uncomfortable on somewhat warm days following cool nights?

We get a lot of those swings here in the Black Hills and I do find the warm slab a bit overbearing on those days.

Some former clients of mine built a SIP house with a walkout basement and their basement could be nearly unbearable on those days.

My friend's shop is the same way, although their building is just fiberglass insulation between bookshelf girts.

Guy who did some work on my house has the same problem. Pole barn with flash and batt insulation with in floor heat. Says his shop can be uncomfortable on days like that. But I'm guessing Maine doesn't have weather patterns like that. At least not to the degree we do.

Cold roof just trusses and soffit & ridge vents.

Just curious why you didn't use SIPs on the roof?

 

[akpolaris]

Spend the time to compact it at each lift and wet it down then compact it again and again. I did mine myself and spent a lot of time compacting prior to laying down the insulation. It isn't a technically challenging task. Put in the tubing when you pour the slab and even if you do not do a boiler now the tubing is always there if you decide to do it in the future.

And worth every nickel. My floor keeps the air temp right at 55º. I can work out there all day and be very comfortable.

Make sure the base is well compacted. I re-compacted after every 6" of fill was brought in.

 

[Randy in Maine]

We ended up building the building and then pouring the floor due to the weather.

My excavating contractor left the plate compactor at my house and I did a lot of the compacting at night. Almost every night.

I opted to go with a flat ceiling in my shop that is 12' tall. The ceiling panesl are SIPS. My roof is help up with trusses.

I live right at the beach and it only gets "sultry" about 10 days a year. I do own a dehumidifier and 2 great window fans. My shop is divided into a 12'28' wood shop and a 28'x28' 2 bay "car shop". Just for me and my stuff though.

 

[Rockcam]

Try Kentwood Plumbing and Heating.

I am in East Grand Rapids, and they did an amazing job for me in our old 1920's Tudor in replacing the old, oversized and inefficient boiler with a new condensing unit. They are really into what they do, and their pricing was really reasonable.