kenora
Basic Member
Posts:145
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| 09 Nov 2014 08:55 PM |
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Building in Kenora Ontario....zone 7. I plan 4" EPS on the exterior of the concrete walkout basement walls. I have purchased 4" EPS to use under the concrete floor of the walkout (800 sq/ft) and want to know if I should add an additional horizontal 4 ft of 4" as a frost block like in a shallow monolithic slab since the basement floor will be only be buried 4 ft deep on the west side and nearly level with grade on the east side.
Is 4" horizontal (4 ft ft out) enough, is it required at all?
I can add more under the basement floor, if so how much?
Thanks... I am purchasing the additional foam this week if needed....
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jonr
Senior Member
Posts:5341
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| 10 Nov 2014 10:20 AM |
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A drawing would be helpful. Putting foam directly against a surface is more effective than wings of foam that extend the path length that frost needs to travel. |
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kenora
Basic Member
Posts:145
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| 15 Nov 2014 08:06 PM |
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Page 55 of Joseph Lstiburek's book (Builder's Guide to Cold Climates) shows a diagram with rigid insulation extending horizontally a distance equal to frost depth; its about 8 ft around here. Since the walkout portion (eastern and southern sides) in particular are like the diagram while the rest of the basement is more like a conventional wall I wondered if it (horizontal rigid) was required or recommended... a- at all, b- only when basement slab will be buried less that 8 ft c- it can't hurt so do it everywhere...  |
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jonr
Senior Member
Posts:5341
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| 15 Nov 2014 09:59 PM |
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If the bottom of the footing is below frost level, just use the right density foam and and put it under the footing. Then you aren't trying to heat up the ground with heat from from the room flowing downwards. On the other hand, if you aren't below frost level, then you also need to block the cold from the outside surface and for that, foam wings are useful.
It sounds like you are making a frost protected shallow foundation. Use Google and look for the unheated building FPSF designs. |
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nooboo
Basic Member
Posts:136
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| 16 Nov 2014 12:49 AM |
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Posted By jonr on 15 Nov 2014 09:59 PM
It sounds like you are making a frost protected shallow foundation. Use Google and look for the unheated building FPSF designs.
Yep, half the building looks like it is a FPSF
Remind me, isn't extra insulation required at the corners of this system? And the minimum insulation depths are described in the system
Given that heat flows from hot to cold... outside of the building line, 4" of EPS seems generous.
How much insulation would you place outside of the building line, @ corners? |
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kenora
Basic Member
Posts:145
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| 18 Nov 2014 01:04 PM |
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Posted By nooboo on 16 Nov 2014 12:49 AM
Posted By jonr on 15 Nov 2014 09:59 PM
It sounds like you are making a frost protected shallow foundation. Use Google and look for the unheated building FPSF designs.
Yep, half the building looks like it is a FPSF
Remind me, isn't extra insulation required at the corners of this system? And the minimum insulation depths are described in the system
Given that heat flows from hot to cold... outside of the building line, 4" of EPS seems generous.
How much insulation would you place outside of the building line, @ corners?
jonr... I am building heated home.. nooboo... extra insulation at the corners...I am trying to find a reference to that but can't... what did you mean please |
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jonr
Senior Member
Posts:5341
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| 18 Nov 2014 01:35 PM |
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jonr... I am building heated home.. Yes, but many heated building FPSF designs use/waste building heat to prevent freezing under the footings. Avoid this and look for ones with foam on all edges. |
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krom
New Member
Posts:58
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| 22 Nov 2014 10:41 AM |
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4" is only R16, doesn't seem like enough for a walk out, unless you are putting more on the inside??
Wouldn't you want the wall insulated to the same as the rest of your above grade walls?
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jonr
Senior Member
Posts:5341
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| 22 Nov 2014 12:35 PM |
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I suggest that you never want things insulated to the same R value. It's all about cost vs energy saved and that varies with every method of insulating. For example, you would always use more R value where cellulose can be easily used and less where you need to use rigid foam. |
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kenora
Basic Member
Posts:145
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| 22 Nov 2014 03:13 PM |
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Hi..I guess I wasn't clear...I'm speaking Canajun eh! The walkout wall will be2x6 framed with 4" EPS on the exterior (sitting on top of the insulated footing), so 4" from the bottom of the footing to the roof-line. The diagram shows what I think is just the concrete floor and footer details with foam all around. My wall will have R20 dense pack cellulose in the bays and 4" EPS on the exterior. Jonr ... forgive me but I don't understand... ---Yes, but many heated building FPSF designs use/waste building heat to prevent freezing under the footings. Avoid this and look for ones with foam on all edges. --- Can you tell me where the "additional foam should go? Thanks Because this house, like most walkouts I would assume, has about 1/2 the wall buried in the earth on one or two sides and the other walls exposed to the floor level I thought it would/should be treated as a illustrated.. I AM NO EXPERT; I AM LIKELY WRONG  Please correct me. I gotta do this right the first time! I think the 4" EPS is a given, its the wings of foam that confuse me most, how much foam, how far out and how to handle the corners? |
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jonr
Senior Member
Posts:5341
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| 22 Nov 2014 04:17 PM |
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Around here, code spells out exactly what is needed for a FPSF in terms of foam sizes. Page 29 here only needs edge insulation to have foam on all sides. |
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FBBP
Veteran Member
Posts:1215
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| 11 Dec 2014 10:45 PM |
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Kenora - first, while you might experience frost to 8 feet under certain circumstances, from a building perspective your frost line is likely 48 inches. I don't have an Ontario code handy but I don't think you have more frost then we do in Alberta.
Therefore you would be required to have a footing depth of four feet or to put it better, you would need four feet of cover over your footings TO PREVENT FROST HEAVE. Note that the code is only protecting the structure from damage. You may substitute material have a higher insulation value the dirt and then have less cover.
Also you should consider that frost penetrates at an approximate angle of 45 degrees.
So in your case, if the slab is at grade and you place the wing insulation at grade, you would have to go out 48 inches. This is not practical as the insulation needs some protection for the elements. A better way is to place vertical insulation down 2 feet from the slab and then 2 feet of insulation horizontally away from the building and back fill it with what ever fill you have. This will give you the frost protection you need but you would probably do a bit better from and energy use point of view to extend that wing out 48" at 24" deep. This is what Joe shows in your example diagram. |
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tjetson
New Member
Posts:52
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| 12 Dec 2014 06:04 AM |
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if you have 2x6 walls in our climate you want R-15 of insulation on the outside of your house. I just finished building my place with only r8 on the outside with some worries.
i think your 4" of eps will do nicely i would look at using membrain by certainteed also as the interior barrier seems like you cant go wrong with it |
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kenora
Basic Member
Posts:145
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| 13 Dec 2014 05:57 PM |
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Posted By FBBP on 11 Dec 2014 10:45 PM
Kenora - first, while you might experience frost to 8 feet under certain circumstances, from a building perspective your frost line is likely 48 inches. I don't have an Ontario code handy but I don't think you have more frost then we do in Alberta.
---I'm an ex-patriot Albertan myself (High River, Red Deer, Grand Prairie and Zama.... yup...series of flying jobs  .. I smartened up in 1980 and got a Gov job in Manitoba  ) I imagine you are right about the frost depth since I believe that's the rule in Winnipeg (48" deep) just across the border.---
Therefore you would be required to have a footing depth of four feet or to put it better, you would need four feet of cover over your footings TO PREVENT FROST HEAVE. Note that the code is only protecting the structure from damage. You may substitute material have a higher insulation value the dirt and then have less cover.
---The existing portion of this project has footings built right on granite (this resulted in a crazy crawlspace floor as its wavy granite covered with concrete)... the expansion will be partly on soil and I likely partly on granite.... I won't know for sure till I excavate in March whether I will be on rock or soil or both..... I imagine that makes things more complicated  ---
Also you should consider that frost penetrates at an approximate angle of 45 degrees.
---I didn't know or consider that.---
So in your case, if the slab is at grade and you place the wing insulation at grade, you would have to go out 48 inches. This is not practical as the insulation needs some protection for the elements. A better way is to place vertical insulation down 2 feet from the slab and then 2 feet of insulation horizontally away from the building and back fill it with what ever fill you have. This will give you the frost protection you need but you would probably do a bit better from and energy use point of view to extend that wing out 48" at 24" deep. This is what Joe shows in your example diagram.
---I like that idea....however going two ft down from the slab (or footing) could be a challenge depending on the granite situation!!---
---just a thought...
If I'm going to have to build on granite (it can't frost heave in Kenora without toppling the CN tower in TO  ) does that change the need for insulation under/around the footings?---
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kenora
Basic Member
Posts:145
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| 13 Dec 2014 05:58 PM |
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Posted By tjetson on 12 Dec 2014 06:04 AM
if you have 2x6 walls in our climate you want R-15 of insulation on the outside of your house. I just finished building my place with only r8 on the outside with some worries.
i think your 4" of eps will do nicely i would look at using membrain by certainteed also as the interior barrier seems like you cant go wrong with it
Thanks |
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jonr
Senior Member
Posts:5341
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| 13 Dec 2014 08:41 PM |
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If you build 4" of EPS + slab on granite, you don't need to worry about depth, frost or wings of insulation. And if there are small amounts of dirt, it can be removed and replaced with non frost susceptible fill (like crushed gravel). Gravel is also useful for leveling the granite. |
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FBBP
Veteran Member
Posts:1215
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| 14 Dec 2014 11:49 PM |
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If you build on granite, obviously you won't have frost heave. On the other hand, you won't have energy efficiencies either.
Care needs to be taken with building half on granite and half on soils as there will be varying rates of settlement.
Great care must be taken when placing gravel or stone between a foundation and granite. One, it will migrate out from under the footing if not contained. Two, it will acted as marbles to roll the foundation downhill. The higher the seismic zone the higher the risk. |
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goddog
New Member
Posts:4
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| 18 Dec 2014 09:08 PM |
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i think they just removed all the seismic stuff from the code in manitoba/nw ontario no risk of earthquakes
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