The dilemma is that this is a garage and will often be as cold as the outside.
Surprisingly not true. The new garage is better insulated then my current garage and attached to the house so it will get some lost heat from the house. My current garage is detached and with engine heat alone it stays around 0 all winter long. Right now it is -20C outside and there is water sitting on my garage floor(unfortunately drainage sucks in my current garage)
I lived in Oregon where I was a general contractor and did some interesting slab on-grade construction. One method is to actually create a slab that has loose fill (such as un-compacted gravel or sand ) under it when poured, and then the gravel/sand eventually subsides to create an air space. You still provide insulation under the slab, and you provide a good moisture barrier - but the slab is engineered to actually support itself over a dead air space by the perimeter that has extra rebar. In some cases, with a large floor, you need an additional footing running down the middle of the slab with extra rebar. This results in much less problems with ground water below the slab and adds significant insulation as dead air space. Plus the floor is much better reinforced than the usual 6 x 6 wire mesh. It is engineered as a suspended concrete floor.
I have worked on buildings like this. Though I am sure it can be engineered to support the weight it is not an approach I am willing to take. One of the reasons the garage doors are so big is so I can drive my work truck inside which is extremely heavy.
For a moisture barrier under the slab, I used 50 pound roofing with glued seams on top of the loose fill and under the footings continous.
With icing and wet/dry situations, sealing the top of the slab after it is poured with a water seal will get rid of spall and may actually eliminate the need to heat the slab unless you just want that for occasional use of the space.
I will look into this for under the slab. I am also now planning to pain the garage floor with the rubberized paint thy make for garages.
What a worthless project.
Heating the door sill? really?
I live in Minnesota, I have had a garage door here for a heck of a long time >40 years, and have never had a problem with ice.
Not to say I don't get ice under the door. I have many times, pools of the stuff.
and the effect? nothing. you push the button, the door opens. Not an issue.
The trick is to have a rubber door seal at the bottom, it doesn't stick to ice.
People do have heated garage floors, but they put a thermal break inside the door AFAK, not outside
Now...If you keep your concrete under the sill at just above freezing, the concrete just outside the door will be cycling from above to below freezing as the temperate changes. You will destroy your concrete pretty quick.
Parking cars outside in the winter is hard on the concrete due to the engine heat...
as far as PWMing the heater? O.M.G. what a waste of effort, a simple thermostat is more than enough.
PWM for heaters is for when you need to control the temperature cycling to an absolute minimum for accuracy
What a worthless project.
Heating the door sill? really?
I live in Minnesota, I have had a garage door here for a heck of a long time >40 years, and have never had a problem with ice.
Not to say I don't get ice under the door. I have many times, pools of the stuff.
and the effect? nothing. you push the button, the door opens. Not an issue.
The trick is to have a rubber door seal at the bottom, it doesn't stick to ice.
People do have heated garage floors, but they put a thermal break inside the door AFAK, not outside
Now...If you keep your concrete under the sill at just above freezing, the concrete just outside the door will be cycling from above to below freezing as the temperate changes. You will destroy your concrete pretty quick.
Parking cars outside in the winter is hard on the concrete due to the engine heat...
as far as PWMing the heater? O.M.G. what a waste of effort, a simple thermostat is more than enough.
PWM for heaters is for when you need to control the temperature cycling to an absolute minimum for accuracy
I suspect good weather stripping in the door rather than heating the sill is a better solution. There are mechanical weather stripping that goes down when the door is closed and retracts upward when as the door is opened. That may be more expensive than the normal exterior door, but it does get out of the way of ice and doesn't require puling wire and heating anything
About rubberized paint on concrete floor..................
No, absolutely not. It is a rather worthless product that will peel or at least come up with scratches.
Either use an epoxy paint for a tough surface that grips concrete or a low-viscosity water sealer that sinks into the porous surface of the concrete (I have very good luck with a US product - Thompsons WaterSeal).
The biggest problem with garages in such cold climates is the garage doors themselves. When a vehicle goes in or out you dump a lot of heat. That cannot be helped. But the door between the main house and a garage can be rather annoying in the winter as people going in and out of the garage let in a lot of cold air. If you can affort the space, having two doors and an interim buffer space (like an airlock) would conserve heat in the main house. But this is a luxury that a lot of people cannot afford.
Though I enjoy electronics and microcontrollers, there are passive solutions that just work better and last longer than anything electric.
will definetly be using good weather striping and a rubber bumper on the bottom. I use the garage as my air lock. Drive in close the door then go into the house. In this way there is no window and the garage temperature is no where near as cold as it is outside. Will look into the water sealer.
Well, here is Thompson's web site. You might ask around and Google to see if this product has a proven track record with spalling of concrete due to freezing.
The doctrine is that all concrete is porous as extra water that is included to help it pour and cure creates capillary voids as it sets up. The Thompson WaterSeal is low viscosity and is soaked up and fills those voids. So water should not get in and freeze, especially is there is an adequate moisture barrier under the concrete slab.
Dry concrete with reinforcement should hold up just fine as the thermal gradiant of expansion and contraction are nearly the same for concrete and steel. The real damage is caused by water going to ice as the water expands and produces tremendous leverage as it freezes.
You may have to wait a bit after the concrete is set and the weather is dry to use the WaterSeal.
Here is a quote from another web site http://www.concretenetwork.com/fix-spalled-concrete/fixing-a-spalled-driveway.html
"On new concrete, you can dramatically reduce water-induced spalling by applying a penetrating waterproofing sealer 28 days after concrete placement and every few years thereafter. To address the problem after it has occurred requires covering the entire affected area with a polymer-modified cementitious overlay in a color matching the existing driveway. Once the overlay cures, apply a waterproofing sealer to prevent the problem from reoccurring."
Comments
Surprisingly not true. The new garage is better insulated then my current garage and attached to the house so it will get some lost heat from the house. My current garage is detached and with engine heat alone it stays around 0 all winter long. Right now it is -20C outside and there is water sitting on my garage floor(unfortunately drainage sucks in my current garage)
I have worked on buildings like this. Though I am sure it can be engineered to support the weight it is not an approach I am willing to take. One of the reasons the garage doors are so big is so I can drive my work truck inside which is extremely heavy.
I will look into this for under the slab. I am also now planning to pain the garage floor with the rubberized paint thy make for garages.
You mentioned passive solar heating. I found the link below looks interesting.
http://www.builditsolar.com/Projects/SpaceHeating/SolarGarageCollector/garcol.htm
Thanks for resolving that
How do you feel about being moderated ?
Heating the door sill? really?
I live in Minnesota, I have had a garage door here for a heck of a long time >40 years, and have never had a problem with ice.
Not to say I don't get ice under the door. I have many times, pools of the stuff.
and the effect? nothing. you push the button, the door opens. Not an issue.
The trick is to have a rubber door seal at the bottom, it doesn't stick to ice.
People do have heated garage floors, but they put a thermal break inside the door AFAK, not outside
Now...If you keep your concrete under the sill at just above freezing, the concrete just outside the door will be cycling from above to below freezing as the temperate changes. You will destroy your concrete pretty quick.
Parking cars outside in the winter is hard on the concrete due to the engine heat...
as far as PWMing the heater? O.M.G. what a waste of effort, a simple thermostat is more than enough.
PWM for heaters is for when you need to control the temperature cycling to an absolute minimum for accuracy
I suspect good weather stripping in the door rather than heating the sill is a better solution. There are mechanical weather stripping that goes down when the door is closed and retracts upward when as the door is opened. That may be more expensive than the normal exterior door, but it does get out of the way of ice and doesn't require puling wire and heating anything
About rubberized paint on concrete floor..................
No, absolutely not. It is a rather worthless product that will peel or at least come up with scratches.
Either use an epoxy paint for a tough surface that grips concrete or a low-viscosity water sealer that sinks into the porous surface of the concrete (I have very good luck with a US product - Thompsons WaterSeal).
The biggest problem with garages in such cold climates is the garage doors themselves. When a vehicle goes in or out you dump a lot of heat. That cannot be helped. But the door between the main house and a garage can be rather annoying in the winter as people going in and out of the garage let in a lot of cold air. If you can affort the space, having two doors and an interim buffer space (like an airlock) would conserve heat in the main house. But this is a luxury that a lot of people cannot afford.
Though I enjoy electronics and microcontrollers, there are passive solutions that just work better and last longer than anything electric.
The doctrine is that all concrete is porous as extra water that is included to help it pour and cure creates capillary voids as it sets up. The Thompson WaterSeal is low viscosity and is soaked up and fills those voids. So water should not get in and freeze, especially is there is an adequate moisture barrier under the concrete slab.
Dry concrete with reinforcement should hold up just fine as the thermal gradiant of expansion and contraction are nearly the same for concrete and steel. The real damage is caused by water going to ice as the water expands and produces tremendous leverage as it freezes.
You may have to wait a bit after the concrete is set and the weather is dry to use the WaterSeal.
http://www.thompsonswaterseal.com/
Here is a quote from another web site http://www.concretenetwork.com/fix-spalled-concrete/fixing-a-spalled-driveway.html
"On new concrete, you can dramatically reduce water-induced spalling by applying a penetrating waterproofing sealer 28 days after concrete placement and every few years thereafter. To address the problem after it has occurred requires covering the entire affected area with a polymer-modified cementitious overlay in a color matching the existing driveway. Once the overlay cures, apply a waterproofing sealer to prevent the problem from reoccurring."