Should I put insulation under and on top of a concrete slab floor?
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Should I put 2" foam board under, around, AND on top of concrete slab?
Insinuendo Insinuendo
Aug. 5, 2022
嘿。我有一个似乎没有人能回答的问题:我们正在一个整体板上建造一个1100平方英尺的牧场，板下有2英寸硬泡沫隔热层(+碎石和eps蒸汽屏障)，板和地板上的底部/边缘垂直有2英寸硬泡沫隔热层。在楼板的顶部将是一个木质地板网桁架系统，其中包括带PEX管的电力、管道和水循环地板采暖板，因为它们不会埋在混凝土中(从楼板顶部到地板底部的地板空间高度约为18英寸)。我的问题是:我们还需要另一个2英寸硬泡沫板在板的顶部?或者在楼板下的2”泡沫板+楼板和底板两侧/边缘的垂直2”泡沫板是否足以抵消上面的热量损失，与上面直接位于地板下的PEX循环加热管的热量结合在一起?请让我知道你的意见，因为我不确定是否真的有必要在平板顶部再加一个2”的泡沫板绝缘。非常感谢。期待你的回答!
That sounds like an unusual way to build a slab, and I can't see any reason why you would want insulation under and on top of the slab, also not sure why you aren't putting your hydronic tubing right in the concrete, why is that? I think the best way to help you through this is to describe how we'd do it, and you can let me know why you're doing it the way you are.
简而言之，我们会用1/2到3/4的透明石把基础层弄平，钉住楼板的边角，在透明石上铺设管道(水线装在绝缘套管里)，铺设完之后再重新铺设，铺设绝缘/网格/蒸汽屏障，浇筑混凝土。
So I'd be putting 4 inches on the stone rather than 2 under and 2 over, I'd do my wiring in the concrete (you can put it in conduits so you can always pull them out, pex tubing in the concrete, and engineered wood right on the concrete. I'm not getting the purpose of the web truss is all, so if there is a reason I'm not grasping let me know, but I think its cheaper and more effective for heat distribution to omit the web trusses.
Here on this page abouthow to build a slab on grade on problem soilsyou can see some photos of a slab being assembled as mentioned, the only difference is that it has anair heated radiant floor instead hydronic.
Happy to help more, I just need to understand why you've got the web trusses in the equation.
Thanks for your amazingly fast reply Emmanuel. I'll do my best to try & explain.
Web truss subfloor reasons are 2 fold:
(1) We've lived in 3 different places w/ concrete floors and hated how hard it felt to walk on (yes, they all had carpet w/ extra thick padding under). Plus, in one place in Mt. Desert Island ME that had hydronic radiant floor heating imbedded in the concrete slab itself, the floor was unfortunetly more cool than anything in winter even though we never expected to actually feel the heat w/ our feet anyway. So by having pex radiant panels installed directly under the floor itself as opposed to being buried in the concrete, we're hoping to actually feel that lower register heat a bit better (we know it won't actually feel warm to the touch except maybe on REALLY cold days). Additionally, aren't we heating the structure more now than putting that energy directly into the slab?
2) Conduits for electric, septic, and well water will be poking up through the concrete slab. However, the remaining plumbing, etc., will be installed within the subfloor structure and consolidated in the utility room so that if any worst-case-scenario happens (ie. serious leaks, etc.), it should be easier to have to only pull up the utility room floor to do the work (or even worse - more flooring inside the house) instead of going into the slab itself. Also, in 20-30 years, if the hydronic floor heating tubes/panels need work or replacement they'll be more readily available under the floor.
I'm sorry if I didn't explain correctly above - it's hard for me to articulate when I'm not an expert :) So I'd bullet point the 1st reason as the 'comfort when walking factor'; 2nd as the 'feel the heat a bit better', so to speak; and 3rd as the 'fix/replace/worst scenario' potential. Below is a summary:
2" horizontal foam board below slab; 2" vertical foam board around sides of slab (plus up 18" to cover subfloor); 2" horizontal foam board 'wings' set just under the ground surface extending 2-4' out around perimeter of slab. I'm really sorry but I just realized I forgot to include the perimeter 2" horizontal foam in my original post,
Awesome! Only you and ZEP have responded, and all at once too! FYI: Zero Energy Project also just replied to my question, and they suggested 2" foam board under slab w/ 3" of vertical foam board around sides/edges of the slab and the 18" of subfloor. They thought the 2" foam board on top of concrete slab was unneccesary. You're also sayig the 2" of foam board on top of the concrete slab in not necessary, right?
我希望我已经涵盖了所有的内容，这样你就能得到所有可能的信息。再次抱歉，我忘记了2“水平泡沫板翅膀周围的周长，因为我不想扭曲你的答案。感谢艾曼纽!