tag:blogger.com,1999:blog-1252950587209456779.post1668346219451490805..comments2024-03-02T00:58:18.681-08:00Comments on The Path to Sustainable Living?: XPS vs. EPS - Which holds up better in a below grade environment?SENWiEco Designshttp://www.blogger.com/profile/16191232750350097838noreply@blogger.comBlogger39125tag:blogger.com,1999:blog-1252950587209456779.post-3974876577684845862019-12-15T19:12:44.921-08:002019-12-15T19:12:44.921-08:00Yes the test results are available here: https://t...Yes the test results are available here: https://thepathtosustainableliving.blogspot.com/2014/08/sub-slab-insulation-eps-vs-xps_31.htmlSENWiEco Designshttps://www.blogger.com/profile/16191232750350097838noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-83501151337487086422019-12-15T17:46:33.260-08:002019-12-15T17:46:33.260-08:00Are the results of this anywhere?Are the results of this anywhere?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-22075519466226126232018-04-25T13:00:31.761-07:002018-04-25T13:00:31.761-07:00Hi GravelID,
Thanks for visiting.
The XPS was F...Hi GravelID, <br /><br />Thanks for visiting.<br /><br />The XPS was Foamular C-300 from Owens Corning. http://insulation.owenscorning.ca/assets/0/188/58cb329e-6ca2-4e54-a8cf-b4e7cf4586ea.pdf<br /><br />The EPS was PlastiSpan 30 from Plasti-Fab https://www.plastifab.com/products/insulation/plastispan30-US.HTML<br /><br />Both of these actually exceed the compression strength of the 20 lb or less material typically placed under slabs.<br /><br />I am just about finished installing a full time lab that will test below grade insulation solutions. https://www.theenclosure.ca/slab-happy-revisited/<br /><br />Let me know if you need any further info<br />Anonymoushttps://www.blogger.com/profile/11893465015266900051noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-35834350584775589442018-04-25T12:03:37.070-07:002018-04-25T12:03:37.070-07:00Can you tell us more about the EPS/XPS used?
E.g....Can you tell us more about the EPS/XPS used?<br /><br />E.g. density, any added fillers (graphite EPS etc - assume not as it appears white)?gravelldnoreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-21068244178399922472015-03-16T08:46:38.522-07:002015-03-16T08:46:38.522-07:00Demetris - For info specifically on your climate z...Demetris - For info specifically on your climate zone and for assemblies that use rigid foam - see http://www.buildingscience.com/doctypes/enclosures-that-work John and Joe are masters at building science and you can be rest assured that the assemblies listed will work for you. I personally just feel they are not a sustainable option and still prefer the safety of a more permeable wall.SENWiEco Designshttps://www.blogger.com/profile/16191232750350097838noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-17303476643195766912015-03-15T23:18:49.276-07:002015-03-15T23:18:49.276-07:00Hi Demetris - Thanks for visiting my blog.
I am...Hi Demetris - Thanks for visiting my blog. <br /><br />I am a firm believer that a wall should be highly vapour open to the low pressure side of the assembly. This is why I would not utilize any type of rigid or spray foams for above grade assemblies in my designs. This is regardless of how good the air barrier is. I instead prefer a mineral wool insulation on the cold side of the assembly. <br /><br />I am comfortable with my climate zone (heating dominated) but not cooling dominated zones, so really cannot comment definitively on your conditions. In heating dominated zones you want the majority of insulation on the exterior side of the sheathing but in your zone, it may make more sense to do a 50/50 split to ensure neither side of the sheathing will ever reach the dew point.SENWiEco Designshttps://www.blogger.com/profile/16191232750350097838noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-29501944543679527862015-03-15T22:45:12.388-07:002015-03-15T22:45:12.388-07:00Hi. I leave in Cyprus. The climiate here is quite ...Hi. I leave in Cyprus. The climiate here is quite hot during summer reaching up to 40 degrees celcius. During winter the temperatures could fall down to 5 celcius but this is just for a few days. The rest of the winter temp is around 15 -25 celcius. We also have a lot of days during the year with quite high humidity.I read so manu information about xps vs eps and i cannot decide which one i should install for external insulation of the walls of my house. What do you suggest?Anonymoushttps://www.blogger.com/profile/04470206498815623355noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-2934679582365450302014-03-26T22:31:13.041-07:002014-03-26T22:31:13.041-07:00Well I dug up the samples today and delivered to B...Well I dug up the samples today and delivered to BCIT for testing. I first weighed them and it is very clear that EPS absorbs a LOT more water than XPS. The samples were continually wetted for the last 8 months. The XPS samples all were 130 grams when buried and came out at 158/173/180 grams. The EPS went in at 139/133/133 grams and came out at 511/447/494 grams. So proof is in, XPS is more appropriate for below grade. I will post the results of the official testing from BCIT when available. <br /><br />Also an update on the density of the below slab insulation. My structural engineer did not really have any concerns and basically indicated what ever I wanted to use was OK as even the lower densities would have more than enough resistance.SENWiEco Designshttps://www.blogger.com/profile/16191232750350097838noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-34182120005440066942013-10-22T08:27:25.452-07:002013-10-22T08:27:25.452-07:00You are very welcome - I knew you would appreciate...You are very welcome - I knew you would appreciate it. He is very knowledgeable and is considered the guru of hydronic heating.SENWiEco Designshttps://www.blogger.com/profile/16191232750350097838noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-63082257591527011642013-10-22T06:20:12.221-07:002013-10-22T06:20:12.221-07:00I got the book. Didn't realize it was a "...I got the book. Didn't realize it was a "textbook". But now I understand why it could be so expensive. Reminds me of university.<br /><br />Anyways, just wanted to thank you for pointing me to the book. It's very good. I've learned a lot just in the first chapter and a half. I believe I will build a better house, with a better HVAC system because of it.Anonymoushttps://www.blogger.com/profile/15805229787872391765noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-44436760306411255832013-10-18T11:23:15.639-07:002013-10-18T11:23:15.639-07:00The book is worth every penny and should be requir...The book is worth every penny and should be required reading for anyone in the hydronic heating industry (and quite frankly the forced air as well)SENWiEco Designshttps://www.blogger.com/profile/16191232750350097838noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-11266064717890588822013-10-18T10:04:37.263-07:002013-10-18T10:04:37.263-07:00I ordered the (expensive!) book, so I will read up...I ordered the (expensive!) book, so I will read up on it - especially the ceiling option.<br /><br />If one thinks of radiant heat transmission as "the warming of things", then it makes sense that slab edges would transfer a lot of heat, because they have a big "thing" right next to them. Especially if you also think of heat as a bit of a fluid that finds the paths of least resistance and exploits them with flow.<br /><br />In the meantime, I still haven't done any experimenting with Perlite (which was pertinent to the topic) as an under-slab insulation alternative. I'll let you know when I get a chance to play around with it & talk to the local tree-huggers who have used it. I may mock up a little section of floor, complete with concrete, and see more clearly what I'm dealing with.<br /><br />All the best with your permits! Great news about your engineer!Anonymoushttps://www.blogger.com/profile/15805229787872391765noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-53046380215598590252013-10-17T19:36:08.974-07:002013-10-17T19:36:08.974-07:00Zenon - I am afraid that the responses needed to a...Zenon - I am afraid that the responses needed to address your questions are getting more involved than I really have time for based on my need to finish my design and get my permits. The train of this discussion has also veered way off the original topic.<br /><br />Please continue posting, but try to post on similar topics as the content I am posting and contacting me privately for other stuff. I will answer as much as I can when I have time (on or off line) or at least point you in the right direction.<br /><br />Re your last post, you really need to read the Modern Hydronic Heating book I recommended. You comments indicate a lack of knowledge as to how radiant heating performs as it is a totally different animal than convective heating. Radiant heating heats objects not air and as long as the object can 'see' the heat source it will be warmed (even the floor from a ceiling panel will be warmed). Think how the sun works for an understanding of radiant heating. This is not an east coast/west coast thing.<br /><br />Also, note the zone that is most important for human comfort is around our head not our feet. And in fact our feet do not like to be that warm, just not cold. So ceiling heat is closer to the intended target and what I am utilizing on all floors of my house.<br /><br />Re the direction of heat - this is just physics. Not sure I have the technical information to provide you. It is just taught. For instance, the air film that attaches to all surfaces has completely different values depending on the direction of interest (see http://goo.gl/e6Ptlu for some technical info).<br /><br />This is why slab edge around a house with a slab @ grade is so much more important to address than sub slab insulation. It is also why insulation levels prescribe by code throughout the world have the highest levels in the ceiling and the lowest levels below grade, with the walls being in between. So - strongest drive Up, next strongest drive out to the side, and last is down (believe conductive air currents and stack effect also are part of this equation). <br /><br />By the way - hot air does not 'rise' per say. It floats on top of cold air sinking. SENWiEco Designshttps://www.blogger.com/profile/16191232750350097838noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-62451215295015316142013-10-17T12:05:25.855-07:002013-10-17T12:05:25.855-07:00I guess I don't understand the physics behind ...I guess I don't understand the physics behind the assertion that "heat likes to go sideways more than down". I know that heat moves through conduction, convection and radiation. I'm pretty sure that radiation emanates outward in all directions equally (like the sun). And that conduction chooses the most conductive route & exploits it (and if there are no conductive routes, then the movement via conduction is negligible, by definition). And then convection is blowing air around, and the "hot air rises" thing.<br /><br />So I don't see how any of the methods automatically mean that "sideways" is the path of choice for heat. Yes, if the side has an obvious conductive bridge, then it will have the greatest amount of energy moving through it. But otherwise, I don't understand. Where did you get this principle?<br /><br />I will look into the book - thanks for the tip.<br /><br />I'm not discounting the ceiling, but I find it hard to understand why I would want to heat a ceiling that's 9' away from my feet (which are the coldest part of me). And then the heat will convectively stay up there, so the floor will be the coldest part of the assembly. Which is exactly what makes basements around here suck so much. Because their floors are freezing cold (and usually uninsulated in tract homes).<br /><br />It defeats the point of radiant heating, IMO. I may as well just stick with forced air in the basement, because a heated ceiling is almost the same thing. Again, I must be missing something, because the stuff you are saying is just way, way different than what I'm reading or expecting. So something is amiss. I wonder if it's an east vs west/climate thing. Maybe your winters are just so much milder, and maybe your underground temperatures are just so much warmer. I didn't think it was that big a difference, because cold feet are cold feet no matter where you live. But I'm obviously mistaken.Anonymoushttps://www.blogger.com/profile/15805229787872391765noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-10928349349020471612013-10-15T22:22:39.276-07:002013-10-15T22:22:39.276-07:00Zenon - you are right re wall. You can compensate...Zenon - you are right re wall. You can compensate. My reaction was more instinctual because heat likes to go sideways more than it likes to go down, so the conduction forces are larger going through a foundation than a slab. <br /><br />Any reason you are not considering the ceiling (where I will put mine). Heat lost will just end up in the main floor where it can be used anyway, and now you are not increasing thermal conductance through the slab or foundation. (Main reason I am using this method throughout the home is that it is fast to react which is important in a HP home where solar gain is encouraged and will be used to lower energy needs - stay tuned as I will blog about this topic in the future if you want to discuss further).<br /><br />Let me be clear - slab edge losses are huge regardless of where the slab edge is. Above grade, grade, or below grade - does not matter. <br /><br />Heated slabs will be a lot warmer than 72 or 73 on average. You will typically be running 110-120F water through them (even hotter for wall or ceiling panels)and their surface will be in at least in the 80's. I suggest you buy "modern hydronic heating" by John Siegenthaler as a primer on hydronic heating. It is an excellent book that I have pretty much read cover to cover. I am also a certified Residential Hydronic Designer having completed the local TECA week long course, but I got a lot more out of reading the book. It will answer all of the questions you have (sorry, I am rusty and would have to research the answers which I do not have time to do right now, I will look at the subject in the spring when I design my hydronic ceiling panels and will blog about that activity then). HWT's used for space heat are hardly ever a good idea.SENWiEco Designshttps://www.blogger.com/profile/16191232750350097838noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-80660035066299350902013-10-13T15:39:43.830-07:002013-10-13T15:39:43.830-07:00You say that running hydronic tubing inside a wall...You say that running hydronic tubing inside a wall is a much worse idea than putting it in a floor. Because it makes the wall hotter than it would otherwise be, and increases the delta T. And that one would have to insulate the wall much more to compensate. I understand that.<br /><br />But the thing I don't understand is how the floor is automatically a better choice. There will be much less insulation under the floor. Maybe R-15. However, on the wall, I can easily put many layers of relatively cheap Drainboard/Rockboard/Comfortboard on the lowest part of the wall. Even without extra layers of drainboard, I was always going to get higher R-values in the wall than in the floor. At the lowest part of the wall, the delta T between the earth under the slab and the earth adjacent to the lower part of the wall will be similar.<br /><br />For clarity, I would only put the tubing in the lower half of the wall anyways - as recommended by the local contractor who builds with Durisol. He says it's a nice heat, and you can choose between the walls and the floor, or both. And it radiates its way up the wall.<br /><br />Yes, it also radiates its way down to the footings where it can/will thermally bridge its way out. A matter that can more easily be controlled within the floor.<br /><br />You said that the presentation you saw about slab edge losses was talking about slabs-on-grade, where the delta T would be much higher.<br /><br />I guess ultimately the question is: "would I rather have a higher delta T in a (large) area with lower R-value (the floor), or would I rather have a higher delta T in a (smaller) area with much higher R-value, but with a built-in thermal bridge (in an area with similar delta-T)"?? <br /><br />Maybe it's smart to rough in both, and at least have the options for the future?<br /><br />And a follow-up thought - the only experience I have with in-floor heat is in our bathroom, with an electric system. We keep it at 74. That makes the floor warmer than the rest of our house and is a perfect temperature, if you ask me. So I'm expecting the slab in the basement will also be pleasantly comfortable at 74, or even a bit lower. Maybe targetting 72. If the earth is 55-60, then I'm only trying to keep the slab (or walls) somewhere between 12 and 19 degrees warmer. Which is vastly different than keeping an interior at 72 when the above-grade temps can be -20 to -40F (delta T of up to 112 degrees).<br /><br />I understand that a hydronic system uses water off a boiler or water heater tank. And the lowest output would probably be around 120F if the system was combined with domestic hot water supply (although our current tankless system is set to only about 108). So I'd be pumping 120 degree water through a slab, trying to get the slab to maintain 72 degrees. Does that mean that the walls/floor will temporarily exceed 72, until they reach equilibrium - or until an in-floor sensor placed between tubes will hit 72? So my delta T will actually be a mix of 120F areas and 72F areas?<br /><br />I wonder if I can modify the system to output 72 (or 80, or whatever) degree water, and to keep the circulation running longer. I wonder if the energy consumption is mostly the heating, and not so much the pumping. I assume the pumping can be very efficient. Maybe even buy a "cheap" hot water tank, and keep it at the minimum temp for the hydronic system. And then have another tank do the domestic hot water. Would that decrease my delta-T problems??? Maybe it's extra smart because I could eliminate heat-exchangers, and just have the hydronic be completely isolated. Maybe even change the fluid to be something even better than water. Just thinking out loud here.Anonymoushttps://www.blogger.com/profile/15805229787872391765noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-11390904457993799362013-10-10T14:13:04.953-07:002013-10-10T14:13:04.953-07:00Got to keep this short as I really need to get som...Got to keep this short as I really need to get some work done.<br /><br />Planning on using standard drywall. I am managing my moisture by using a fully adhered membrane on the exterior of the ICF and VB paint. This services raceway will also not be air tight anyway.<br /><br />The Clay is not a durable product based on my research, it cannot handle any humidity without becoming soft and rubbing off. Plus is more $ than drywall and paint. It also is not a qualified VB. <br /><br />The studs will probably be reused from the house I am tearing down.<br /><br />Routering out the ICF may be close to the cost of framing a wall when using conventional labour. Hove you done it? It is not straightforward. You typically have to mount straightedges to the ICF to run the router against for each run. Mounting the boxes is also a pain. You then have to foam up the channels so you are no loosing R value. PITA<br /><br />As far as running conduit - major PITA. Have you placed either conduit or ICF before. When combining, you have long pieces of conduit you have to thread the ICF blocks over (on vertical run conduits). At close to 50 pounds a block, this is no easy matter. And have you ever run cable through conduit? At least some of the runs are going to fight you and have a reversed lab exactly where you cannot get at it. I have spent hours trying to run cable the last 5ft through a conduit. Again - a PITA. <br /><br />I am all about reducing carbon footprint, but not to the point of reducing the durability and flexibility of a dwelling. I tend to go with the best product for each use taking into account many factors including carbon footprint. <br /><br />I do not make low embodied energy the driving force in my decision and instead concentrate on much larger carbon footprint reductions based on how I live. I drive a vehicle that burns WVO and I typically go on vacations within a 3 hour drive. I am building a house that will significantly reduce our energy load and will be built with many materials that are low VOC. I do not get hung up on the minutia of 'green' products such as programs like LEED. Many of these 'green' products I have found are not durable and therefore not suitable for purpose. <br /><br />It does not matter how 'green' a product is if it does not stand up to its intended use and must later be replaced or repaired.<br /><br /><br />Looks like we may have different priorities. Just make sure you understand the implications of your choices and try speaking with people that have had both good and bad experiences with those products.<br /><br />I have just signed up my structural engineer so will need to concentrate on design for the next couple of weeks.SENWiEco Designshttps://www.blogger.com/profile/16191232750350097838noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-23853642296155475932013-10-10T12:58:11.329-07:002013-10-10T12:58:11.329-07:00The hangers - are you using Simpson ICF hangers? ...The hangers - are you using Simpson ICF hangers? The ICFVL?<br /><br />I'm planning on coating the walls with plaster. Either natural hydraulic lime, or American Clay. And maybe paint. Or maybe just leave it natural. Still have to figure that out.<br /><br />Another full studded wall inside the Durisol sounds like a waste of trees and drywall to me. And you're probably not going to want paper-faced drywall in a basement, so now you are also into expensive fiberglass based material. A little anti-sustainable.<br /><br />I don't see how a full studded wall, with full drywall coverage, could be cheaper than passing a router over the face of the Durisol, and then plastering it over. I find that baffling.<br /><br />And what's wrong with incorporating conduit inside the cavity (other than future accessibility - I can understand that)??Anonymoushttps://www.blogger.com/profile/15805229787872391765noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-84406540455250260762013-10-10T12:38:57.509-07:002013-10-10T12:38:57.509-07:00There are many reasons for a service wall:
- Stud...There are many reasons for a service wall:<br /><br />- Stud wall is much faster and cheaper to frame compared to routing out ICF or worse incorporating conduit into the ICF. Both of these approaches also mean you have to perfectly plan your needs and will be reducing your future flexibility. <br />- While I plan on some utility areas (HVAC room) to 'showcase' the exposed Durisol finish, I definitely will cover the rest with drywall. An exposed Durisol wall will suck the light out of the room and will build up dust and be hard to keep clean.<br />- But most importantly, you still need SOME form of VB on the interior of the wall space. You do not want poly, but you want some resistance to outward vapour flow. Best approach is VB paint so would need drywall anyway.<br /><br />Don’t forget, my basement will be ‘living area’ and not just storage and utility. I do not believe I would go through the cost of putting in a basement if only for storage and utility. You can stick utility into a closet on the main floor and old always build an accessory building for storage. As far as leak detection, without poly in the wall, any significant moisture coming in the foundation will be easily identified on the floor.<br /><br />Re thermal break – yes when dealing with such a small gap, you want the biggest bang per inch. 2” becomes harder to cover with wall and still have wall sitting on enough of the slab for support. An important note is that this service wall in my dwelling will not be ‘bearing’. My floor joists will be attached by hangers to a ledger that is attached by anchors to the ICF. This allows me to put more edge foam in because the service wall just has to hold itself up.<br />SENWiEco Designshttps://www.blogger.com/profile/16191232750350097838noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-80473116635770139552013-10-10T12:09:05.917-07:002013-10-10T12:09:05.917-07:00By "services wall", it sounds like you ...By "services wall", it sounds like you plan to frame a stud wall inside the Durisol wall. Is that correct? Why would you go through that extra effort and expense when electrical can be run inside the Durisol (or routed into the face)? Part of the appeal of Durisol is that it's done as soon as the concrete is poured. At least that's what I was thinking - at least for utility space. The other appeal is that if it's finished with plaster, then what you see is what you get in terms of the foundation wall. If there ever is any leaking, it will be readily apparent right on the wall. Why cover that up with another wall?<br /><br />I could see using XPS for the vertical break. Even with 1", you get R-5, and then something like R-2.5 with the Durisol material, so a total R-7.5. Also easily boosted to R-12.5 with 2" of xps.Anonymoushttps://www.blogger.com/profile/15805229787872391765noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-16550872361898214612013-10-10T10:55:48.228-07:002013-10-10T10:55:48.228-07:00I will use rigid foam for this because I want as h...I will use rigid foam for this because I want as high a r value per inch as possible. <br /><br />Chamfering this insulation is a really bad idea. You will loose a majority of your thermal break. There is also no reason to do so as your services wall inside of the foundation will cover the gap. The only issue is when you have areas of the ICF exposed without a service wall (this is limited because of the need to run electrical outlets). In these areas, I plan on either having flooring above the concrete slab which would easily bridge the gap or figuring out a S.S. cover plate. The other problem with chamfering is that the concrete in that area will be weak and crack anyway if any load is applied.<br /><br />Goo luck with the perlite. Hope it works out but suspect the PSI will not be high enough and then by the time you figure out a way to protect it, you will be at the cost of EPS (common choice).<br /><br />Be careful of the straw heads. There is a lot of these designs that do not meet best building science practices. Construction method only appropriate in dry regions. You also NEVER want a dirt floor. You want the concrete slab.SENWiEco Designshttps://www.blogger.com/profile/16191232750350097838noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-51189534865553181312013-10-10T06:44:51.050-07:002013-10-10T06:44:51.050-07:00You know the perimeter insulation you are proposin...You know the perimeter insulation you are proposing - to reduce slab edge loss? That stuff could be ComfortBoard, right? There is no weight on it. And if one wanted to have the floor topping come right up close to the wall, one could cut the ComfortBoard on a 45 degree angle and the slab edge could at least appear to go right to the wall - with minimal heat loss. Correct?<br /><br />In other news, I found a local sustainable building group that apparently buys lots of Perlite from the local co-op for use as insulation. So I've got a call in to them to see what their experience is with the product, and what they use it for. And also questions about compressive strenght, and protecting from crushing during a concrete placement (if they even use concrete - these guys are straw-bale types), etc, etc. I'll let you know what I learn.Anonymoushttps://www.blogger.com/profile/15805229787872391765noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-65878731762381936282013-10-09T11:56:50.101-07:002013-10-09T11:56:50.101-07:00It is expected that there will be times where wate...It is expected that there will be times where water will come up to the perimeter drainage pipe and build up some head in the pipe. This will typically be after a heavy rain but can also be when underground springs are present or your pump fails. Point is you need to design for failure. If you can convince your engineer to allow the pipe to be buried in the granular layer below the footing, all the better.<br /><br />I am very aware of houses that lower their slabs (dig down) without lowering the foundation and footings. I see this in my home inspection practice many times on teh older 100yr old specials. It is a very POOR practice that leads to water ingress as now your slab will be below the perimeter drain pipe. These eventually all need to be fixed by lower external drain or adding an internal drain. The slab belongs above the footing and their is no reason to build any other way as it is easy to lower footing to right height.<br /><br />Water tables change all the time. All it takes is construction nearby to dramatically change the table on your site. It is much easier to just pump the storm water than to restrict your design to a perceived water table depth. Pumps are cheap, easily provided with back up power, and alarms. A very high percentage of homes have pumps in my region, and as long as some basic due diligence (backup/alarms/regular service), there have been few problems with these installations.<br /><br />My advise is to make the depth what you need/want and pump the perimeter storm. You should be separately piping the roof storm runoff anyway and this can be gravity fed. Then you only have to pump ground water which hopefully is limited and seasonal.<br />SENWiEco Designshttps://www.blogger.com/profile/16191232750350097838noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-2593682207199881012013-10-08T19:34:47.395-07:002013-10-08T19:34:47.395-07:00You are expecting to have events that overwhelm yo...You are expecting to have events that overwhelm your drainage plane? Does that mean you expect your drainage system as a whole to be overwhelmed (I'm thinking they are one and the same)? Because that sounds like a flooded basement to me. Please explain.<br /><br />I'm not suggesting undermining footings - that would be ridiculous, and never pass inspection. I'm just considering all the options when it comes to where to place the slab. I only meant below the top of the footing. Like they do in old houses when they "lower the floor" without underpinning. Again, this isn't decided yet. This is just exploring options and gathering information.<br /><br />My excavation limit is self-imposed so that I can have gravity/daylight drainage and not rely on sump pump(s). Our site has unique features, so it's more complicated than just digging deeper. And we have a very good idea of where the water table is through the year.<br /><br />I will investigate perlite in more detail, as I was going to do anyway. And it does have a tried and true track record in many applications. Just because it's not common to see it underslab doesn't make it a poor choice. Especially if it can perform as well or better than XPS at half the cost.<br /><br />A "drainage plane overwhelm event" would be a much bigger problem than a loss in R-value because the perlite got wet. But yes, of course, if it was underwater, it would have negligible R value. But R value isn't everything.Anonymoushttps://www.blogger.com/profile/15805229787872391765noreply@blogger.comtag:blogger.com,1999:blog-1252950587209456779.post-46673028775072868122013-10-08T13:04:20.341-07:002013-10-08T13:04:20.341-07:00Need to keep this fast as I need to get some work ...Need to keep this fast as I need to get some work done. You cannot make your floor lower than your footing. Doing so would interrupt the bearing surface of your fitting which is not allowed. There is also no reason to do so, just make your footing deeper if you want your floor deeper. Just deal with the water issues, it is easy to do so. Use a fully adhered membrane on the outside of the ICF and install proper perimeter drain. Besides, how do you 'know' where the water table is throughout the season. What is the sense of limiting your excavation to say 7ft if the water table can come as high as 4ft. Just deal with the water. Stick with common and best practices for your construction to save yourself a lot of aggravation. <br /><br />DO not presume anything. There are many many examples of people building in a certain way to later on find that that may not have been the best way to build. For instance in my region, we built literally 100's of thousands of homes with faced sealed stucco to later find out that was a very poor idea and that we really need to build with a rain screen assembly in an area that has the volume of rain we do. Just because someone who is trying to sell you a product shows a site where their product is being used as below slab insulation does not mean it is appropriate. Don't forget their are many areas even in the USA, where building codes are either not present or not enforced. Just logically, Perlite sounds fishy, if it needs protection during installation so it is not crashed, what do you think is going to happen when concrete is poured on top of it. My advise is to stick to materials that have a tried and true track record.<br /><br />My point about getting wet, is what happens to the R Value when the field of Perlite becomes saturated during high water table events that overwhelm your drainage plane. I would suspect it drops significantly. This is not a problem with sheet stock as there is no where for the water to go except very minute layers at seams and between layers. <br />SENWiEco Designshttps://www.blogger.com/profile/16191232750350097838noreply@blogger.com