Looking for ideas for new shop

[chevynut]

I'm settling on the design of my new Montana shop. I've decided to make it 50x90 and I have room for that. It's divided into three sections, 36, 25, and 29 feet wide. I designed an upper level that will be part living area and part storage. There's about 1800 square feet there to work with. We wanted a small living area about like a tiny home, (399sf) but it's turned into more like 800 SF. Here's the layout I have now.

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Yeah, it's a monster place but I need a lot of storage room because I don't want stuff out in the weather.

I have a guy lined up to do the foundation and sent him plans. I want to do a monolithic slab using the MonoSlab EZForm system. It's a shallow frost-protected foundation and the forms stay in the ground. One pour, no need to strip forms. It's a way cool idea invented and patented by a guy in Idaho. A traditional foundation would take three pours......form footings, pour, and strip forms, then form walls, pour, strip forms, then pour slab. All the forms cost more than the EZForms. Labor is very much reduced but the concrete is about the same. I'm planning on a 5" thick floor. Here's the current plans....

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I have the SIP guys chomping at the bit wanting me to get a contract and deposit to them. They require 10% up front for the design phase, 40% when the design is complete and production starts, and 50% on delivery. Not a bad way to do business. The entire frame, less trusses and interior walls, is about $50K. The SIPs can be erected in 2-3 days and the walls are already insulated and sheathed inside and out. Insulation value is great with these.

I was holding off on the project until I got a bid on trusses, because several of them are 50' long and 14' tall. I wanted to make sure someone could build them AND get them up to the property. That looks like it's not a problem and the price was less than half of what I budgeted for them. Part of the roof will have to be framed but it's not much work.

I plan to put a green metal roof on it, and metal "log" siding (TruLog) made in Colorado. There is a rock ledge on the front where we'll put about 3 feet of stone on to complement the house. The living area will have a living room, kitchen, bath, pantry, closets, and 1-2 bedrooms. The mechanical room will be below in the shop area along with another bathroom. There will be a deck on the north and west sides of the living area. I'll have around 1000 square feet of storage area next to the living area.

I originally had a small, narrow roof over the living area but after some analysis I found out that the snow loading required a huge steel beam in the floor. So I made the trusses wider to span the entire 36 foot area, carrying the snow load to the exterior and interior walls in the shop, and taking the load off of the beams. I don't want any posts in the shop to support it. The SIP company structural engineer is going to help me size the steel beams for the upper floor.

I hope to get started in late May and get it closed in by winter. We're planning to move there full-time next year.

[chevynut]

Here's a good video showing the MonoSlab EZForm installation.

https://www.youtube.com/watch?v=uQM7LTarQgw&t=16s

[Custer55]

In floor heat is by far the most efficient way to heat a building. If you are worried aboug it freezing just use anti freeze in the system and maybe use the heat pumps for ac and back up heat.
In a building that large you would need several zones anyway so you wouldn't need to keep the whole thing at a certain temp. Even 50 degrees is comfortable with warm floors while you are working.

[Custer55]

That's a good way to pour a concrete slab for a shop. Around here we call that a grade beam slab where the concrete around the edges is poured thicker with rebar reinforcement.
When I did the slab for a 28 x 40 pole building about 10 years ago we did it that way with lots of rebar throughout. It has held up perfectly with no cracking at all.

[chevynut]

In floor heat is by far the most efficient way to heat a building. If you are worried aboug it freezing just use anti freeze in the system and maybe use the heat pumps for ac and back up heat.
In a building that large you would need several zones anyway so you wouldn't need to keep the whole thing at a certain temp. Even 50 degrees is comfortable with warm floors while you are working.

We have in-floor hydronic heating in the Montana house, 8 zones and 38 loops. It froze three winters in a row when the owner stopped going there and paying his bills before foreclosure. They turned off the power and pulled the propane tank. There was glycol in the system but the freezing broke PEX lines in the floors and actually ruptured the concrete in the basement floor. We had to chisel all of this up and fix it after locating the breaks. We also had to replace the boiler and the water heater and a bunch of copper lines in the mechanical room because they also froze. Miraculously, none of the water plumbing broke but faucets were trashed. It gets down to around -50F in Lincoln every winter. We hit -45F this January and -53F in the area last year. Rogers Pass which is only about 20 miles from us holds the record for the coldest temperature in the lower 48 states at -70F in 1954. The cold doesn't last long, but the house could easily get well below zero with no heat.

The more glycol you put into the system, the worse the heat transfer. Pure glycol freezes at -39F. I put around $1000 worth of glycol in the system after rebuilding it, and it's at about 25% now. If the house stays warm, above 32F, you don't need any glycol at all.

In-floor heating is nice, but it has it's drawbacks. One, you can't really use a set-back thermostat to save energy. The house changes temperature too slowly. When we're gone for weeks at a time I turn the house down to 50 degrees. I have to turn up the WIFI thermostat in the house at least a day ahead of time before we get there, more if it's really cold outside. We have log walls, and many tons of rock and concrete in the house. It's great for thermal mass, but it takes a long time to heat up. The basement heats up faster, but still takes many hours. The garage has in-floor heat too, but it's all broken up from freezing. There are seven loops in the garage, and two were never hooked up so I could use them. But then I'd have to always heat it so I'll probably abandon it.

I wouldn't recommend in-floor heat in a shop or garage. For one, you'd have to keep the heat on all the time. I may not even heat the storage area but I plan to install a heater. You can't shut it of in winter unless you have enough glycol to prevent freezing. Two, you can't turn it down to save energy because it takes too long to heat up. In my current shop I leave it at 50, and I can turn it to 65 and it will be there in 10 minutes. It would take hours for in-floor heat to heat up 15 degrees. Lastly, it costs at least 2-3 times as much to install in-floor heat as a heat pump or gas unit heater.

I will be insulating under the slab, which should really help with heating. The floor won't get cold from the ground. I'm not sure what kind of heating system I'm going to install in the shop. I may use a mini-split heat pump in the living area, and just propane unit heaters in the shop. My brother is installing a 45KBTU heat pump in his 2600 SF shop so I'll see how that works out for him. The problem I see with it is perhaps slow heating, especially when it's very cold. Heat pump efficiency drops dramatically when you need it the most. The nice thing is that you also get A/C for "free" but I doubt I'll ever need A/C in Montana with a well-insulated building. The house doesn't even get hot in the summer when it's 90+. I think a ground-source heat pump would be ideal for heating and cooling. I have a 75KBTU NG heater in my old shop in CO and a 125KBTU one in the new shop area. They work great and heat up quickly.

[Custer55]

We have in-floor hydronic heating in the Montana house, 8 zones and 38 loops. It froze three winters in a row when the owner stopped going there and paying his bills before foreclosure. They turned off the power and pulled the propane tank. There was glycol in the system but the freezing broke PEX lines in the floors and actually ruptured the concrete in the basement floor. We had to chisel all of this up and fix it after locating the breaks. We also had to replace the boiler and the water heater and a bunch of copper lines in the mechanical room because they also froze. Miraculously, none of the water plumbing broke but faucets were trashed. It gets down to around -50F in Lincoln every winter. We hit -45F this January and -53F in the area last year. Rogers Pass which is only about 20 miles from us holds the record for the coldest temperature in the lower 48 states at -70F in 1954. The cold doesn't last long, but the house could easily get well below zero with no heat.

The more glycol you put into the system, the worse the heat transfer. Pure glycol freezes at -39F. I put around $1000 worth of glycol in the system after rebuilding it, and it's at about 25% now. If the house stays warm, above 32F, you don't need any glycol at all.

In-floor heating is nice, but it has it's drawbacks. One, you can't really use a set-back thermostat to save energy. The house changes temperature too slowly. When we're gone for weeks at a time I turn the house down to 50 degrees. I have to turn up the WIFI thermostat in the house at least a day ahead of time before we get there, more if it's really cold outside. We have log walls, and many tons of rock and concrete in the house. It's great for thermal mass, but it takes a long time to heat up. The basement heats up faster, but still takes many hours. The garage has in-floor heat too, but it's all broken up from freezing. There are seven loops in the garage, and two were never hooked up so I could use them. But then I'd have to always heat it so I'll probably abandon it.

I wouldn't recommend in-floor heat in a shop or garage. For one, you'd have to keep the heat on all the time. I may not even heat the storage area but I plan to install a heater. You can't shut it of in winter unless you have enough glycol to prevent freezing. Two, you can't turn it down to save energy because it takes too long to heat up. In my current shop I leave it at 50, and I can turn it to 65 and it will be there in 10 minutes. It would take hours for in-floor heat to heat up 15 degrees. Lastly, it costs at least 2-3 times as much to install in-floor heat as a heat pump or gas unit heater.

I will be insulating under the slab, which should really help with heating. The floor won't get cold from the ground. I'm not sure what kind of heating system I'm going to install in the shop. I may use a mini-split heat pump in the living area, and just propane unit heaters in the shop. My brother is installing a 45KBTU heat pump in his 2600 SF shop so I'll see how that works out for him. The problem I see with it is perhaps slow heating, especially when it's very cold. Heat pump efficiency drops dramatically when you need it the most. The nice thing is that you also get A/C for "free" but I doubt I'll ever need A/C in Montana with a well-insulated building. The house doesn't even get hot in the summer when it's 90+. I think a ground-source heat pump would be ideal for heating and cooling. I have a 75KBTU NG heater in my old shop in CO and a 125KBTU one in the new shop area. They work great and heat up quickly.

All very valid points. We installed in floor heat in our house (staple up so not near as efficient as in a concrete slab) and love it. Wish we had gone that way when we built the house but it was 1992 and budget was a concern as well.
We have just distilled water in our system as we have back up heat. Also used the better pex that is far less likely to break if it freezes as it can expand quite a bit before bursting. You actually have to use an expanding tool to install the fittings.
Obviously it's your decision to make but my thought is that if you are spending that much money on a shop the extra cost wouldn't be a big deal. Also you could just keep the building at 50 degrees with the infloor and use the covetional heaters to warm it up when needed.
Anyway, it will be an awesome shop when you get it done.

[BamaNomad]

Wow... That looks like a 'half million dollar' shop (or more).. With winter temps that get as low as you stated, I doubt a mini-split heat pump is going to work very well for heating (although it should work great for cooling)... For heat, I'd think you're going to need to 'burn something'... ?

[chevynut]

Wow... That looks like a 'half million dollar' shop (or more).. With winter temps that get as low as you stated, I doubt a mini-split heat pump is going to work very well for heating (although it should work great for cooling)... For heat, I'd think you're going to need to 'burn something'... ?

Not quite "half million" I hope . I don't need to get any permits except electrical and septic so that saves a bunch. The slab is around $65-75K including forms, under-slab insulation, vapor barrier, bolts, rebar, concrete, and labor. SIPs are around $55K plus labor, trusses around $16K plus labor. That's about half of it. Total is expected to be a little over $300K just for the building. I plan to put a metal roof on it and drywall most of the interior. This will add a lot of value to the property too.

Clearly the heating requirements depend on insulation value. I think the 6.5" SIPS are around R25 and the ceilings will be at least R50. Newer heat pumps work good at lower temperatures than the old ones. They make special units for use in cold climates. I'm still skeptical.

[BamaNomad]

Taking heat from a frozen ice cube is a difficult task.. But I haven't dealt with temps that low (except on a couple of 2 week trips@)..