MartinPL
New Member
Posts:10
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| 09 May 2013 07:37 PM |
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New house is being designed and will be built in the Seattle area. Due to slopes on the lot and ease of access to plumbing etc a crawlspace is taken under consideration rather than the slab. No basement. Standard 3 to 3.5 foot high crawler. Due to some terraces and patios only approx 60% of the perimeter length will be exposed and could have crawler vents. Radiant heated floors in gypcrete will be used so no floor ventilation holes (and I DO NOT want any ever). What will be better from the standpoint of cost and comfort considering I will live in this house for a longer period of time:
fully insulate the crawler walls and seal the bottom (how), do not do vents and condition it (how?)
standard crawler with vents along 60% of the perimeter, and standard insulation (foil on the ground, maybe foam in the floor bays along the foundation walls, and whatever pinky\yellow\white\... stuff is used under the floor
Also, do the King County, WA codes now allow enclosed, insulated and conditioned crawlspace? I do not think they did some years ago.
Cheers
Martin
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jonr
Senior Member
Posts:5341
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| 09 May 2013 07:55 PM |
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codes now allow enclosed, insulated and conditioned crawlspace? I do not think they did some years ago. Perhaps the trick is to tell them it's just one big room with an raised floor. Or a really short basement. What are floor ventilation holes and why don't you want them? |
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MartinPL
New Member
Posts:10
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| 09 May 2013 08:04 PM |
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Posted By jonr on 09 May 2013 07:55 PM
What are floor ventilation holes and why don't you want them?
What I call the floor ventilation hols are the forced air vents for heating or cooling. I like to have my floor continuous with no holes, grills, ... For me one of the big advantages of radiant heated floors is the elimination of these vent holes. AC air goes through ceiling vents.
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Dana1
Senior Member
Posts:6991
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| 10 May 2013 11:37 AM |
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I'm not sure what's the real point of going with a crawlspace rather than slab on grade, if you're going with a gypcrete radiant floor? (It's not as if plumbing issues haven't already been solved in slab-on-grade.) Even though the pipe freeze-up risk is low in Seattle, a vented crawlspace is just another point of heat loss.
If unvented, IRC 2009 requires either periodic air exchange with conditioned space air or exhaust venting averaging 1cfm for every 50' of floor space. A quick rundown of your options lives here:
http://www.epa.gov/indoorairplus/technical/moisture/1_4.html
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MartinPL
New Member
Posts:10
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| 10 May 2013 01:36 PM |
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Posted By Dana1 on 10 May 2013 11:37 AM
I'm not sure what's the real point of going with a crawlspace rather than slab on grade, if you're going with a gypcrete radiant floor? (It's not as if plumbing issues haven't already been solved in slab-on-grade.) Even though the pipe freeze-up risk is low in Seattle, a vented crawlspace is just another point of heat loss.
If unvented, IRC 2009 requires either periodic air exchange with conditioned space air or exhaust venting averaging 1cfm for every 50' of floor space. A quick rundown of your options lives here:
http://www.epa.gov/indoorairplus/technical/moisture/1_4.html
Thx for the info on the crawler conditioning. Topology makes slab not doable and I do not care about dark basement and additional square footage |
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jonr
Senior Member
Posts:5341
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| 10 May 2013 03:59 PM |
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You can avoid all issues with having anything underground by building on piers. Ie, ventilate the "crawl space" by have it completely free and open to outside air. Alternatively, you can seal and insulate a crawl space and pay to condition it just like a small basement. Any hvac installer can do that.
My preference is that space be clearly part of the outside or the inside. I'm not a fan of "in between" or semi-conditioned space. |
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DickRussell
Basic Member
Posts:182
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| 10 May 2013 04:07 PM |
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"Topology makes slab not doable and I do not care about dark basement and additional square footage."
Why not pour the "foundation" walls, fill it with dirt, cover with an insulated slab? It seems to me that an unvented/unconditioned crawl s inviting moisture issues, especially in that climate. |
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MartinPL
New Member
Posts:10
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| 10 May 2013 04:11 PM |
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Posted By jonr on 10 May 2013 03:59 PM
You can avoid all issues with having anything underground by building on piers. Ie, ventilate the "crawl space" by have it completely free and open to outside air. Alternatively, you can seal and insulate a crawl space and pay to condition it just like a small basement. Any hvac installer can do that.
My preference is that space be clearly part of the outside or the inside. I'm not a fan of "in between" or semi-conditioned space.
I think the crawler being a part of "inside" is very nice but I don't feel to comfy with just a layer of poly separating my inside from the ground. If I could better protect and seal this surface I'd be super comfy making it a part of inside. Pierec and so would look great for the modern structure: glass, metal, ... but not the Mediterranean house IMHO. |
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BadgerBoilerMN
Veteran Member
Posts:2010
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| 10 May 2013 04:51 PM |
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Slab-on-ground. I am literally comfortable with a vapor retarder under 2" of XPS or my new friend EPS. Crawl spaces are like basements; a vestige of the now obsolete root cellar. I have a root cellar but certainly don't miss the hundreds of crawl spaces I visited as a young plumbing and heating technician. |
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| MA<br>www.badgerboilerservice.com |
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sailawayrb
Veteran Member
Posts:2283
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| 10 May 2013 05:50 PM |
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Crawl spaces are far from optimal, but usually better than needing a jack hammer to gain access to the plumbing. |
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Alton
Veteran Member
Posts:2164
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| 10 May 2013 09:38 PM |
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I wonder how often concrete has to be removed to repair plumbing? I know from watching This Old House that older homes use poor quality materials that had to be replaced. But now with PVC waste pipes I have not heard about breaking up concrete to make repairs. |
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Residential Designer &
Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period .
334 826-3979 |
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jonr
Senior Member
Posts:5341
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| 10 May 2013 10:23 PM |
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Most of the breaking up I've heard about relates to basements and water problems, not slab on grade. |
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toddm
Veteran Member
Posts:1152
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| 12 May 2013 06:23 PM |
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I had an 11 degree slope graded level with terraces above and below the house. Then I built a frost wall with steps to reach undisturbed soil. I filled it to height with no 7 stone and compacted it. My slab on grade is perfect two years later. ICF is tailor made for frost walls, but warn your contractor that a low unbraced wall is more likely to float, and check for level before you do the flat work. |
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toddm
Veteran Member
Posts:1152
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| 12 May 2013 06:34 PM |
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Alton, I never had a problem in 20 years in Texas with PVC waste pipe through the slab and I built on very active clay. Code now requires sleeves through the slab for domestic water and electricity. |
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