Foam under slab details
New residential construction, Zone 4A, slab on grade with attached garage. Three questions:
1. Most builders around here pour the entire slab flat; in other words, no slope to garage door and no step up into the house. Is this an okay practice?
2.我打算将2½英寸的泡沫纸放在板下方，以进行R-10。是否有任何令人信服的理由继续在平板的车库部分下继续泡沫（不会有热中断，平板将是连续的）。
3. What is the detail for continuing the foam below bearing walls that will be supported by a thickened slab?
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Replies
大卫，
1) I don't know which code you are under but ours mandates that attached garages have both a slope to the overhead doors and a sill between the garage and house.
斜坡的原因是显而易见的，因为您将大型湿物体带入其中，并且它们流失了很多水。
除了防止水进入房屋的其余部分外，门槛还是许多代码要求的一部分，以限制排气气体的扩散到住宅中。在这里，包括空气密封和自闭合铰链在连接两个空间的任何门上。
2) Is answered above. A continuous slab isn't a good idea.
3) Foam is available which can withstand a variety of compressive loads. You can run it continuously under the thickened parts of your slab. Some people are uncomfortable placing the load-bearing portions of their house on foam. If you feel that way, the energy penalty for leaving out the foam under a couple of walls is very small.
大卫，
Malcolm gave you good advice. The garage slab should be poured separately.
某些车库平板不是将平板倾斜到门上，而是设计到板块中央的地板排水沟上。
When I built my garage, I placed the slab on a solid base consisting of compacted gravel (with fines), followed by 4 inches + of crushed stone. The crushed stone was raked and shaped for a thickened-edge slab. The rigid foam was installed on top of the crushed stone, conforming to the slope creating the thickened edge. I though this would be trickier than it was; it was fairly easy. You can use some tape to hold the foam in place if needed.
因此，我的平板边缘下有泡沫。您可以做到 - 但是如果您担心，请与工程师交谈。
Another reason for a step up from the garage is that gasoline fumes are heavier than air. In case of a spill or leak, you don't want fumes flowing under the door and into the house.
马丁，
我正处于在格洛弗（Glover）的房屋和半独立式车库中完成混凝土的边缘。我的挖掘机为车库提供了一个增厚的边缘板，我想将其隔离以调节内部的温度。我喜欢您对车库的描述，您是否可以详细说明您使用的泡沫厚度以及是否还有外围泡沫？
Thank you,
Caleb
Caleb,
我的车库在混凝土板下面有2英寸的水平刚性泡沫，在平板周长时有2英寸的垂直刚性泡沫。
请澄清。
马丁，how do you keep the trap in the floor drain from drying out, especially during dry seasons?
Secondly: Malcolm and Martin, I would of course install a good exterior threshold (I prefer bumper thresholds); the question is whether a riser is necessary?I.e. is it necessary to have a step up from garage to house; and if so, how high?
大卫，
My floor drain is not connected to a septic system or city sewer system, so there are no smells to bother me. A dry trap causes no problems.
The two methods I have heard of for keeping traps from drying out are:
1. Pouring a little water down the drain when it begins to smell.
2. Pouring a little water down the drain, followed by a few tablespoons of mineral oil or vegetable oil to reduce the evaporation rate of the water in the trap.
大卫，I'll reiterate: you need to first check your building code to see what it mandates as far as separation, slope and sills between the garage and house. For the reasons I mentioned there should be a difference between the height of the garage and house slabs. If the code doesn't prescribe a certain height, I'd use three inches.