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Small Cabin Forum / Cabin Construction / cabin foundation pier height - Why?
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DaveBell
Member
# Posted: 17 Feb 2019 01:36
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I see pictures of cabins on piers on a flat grade that are 2 or 3 feet above the ground. Is there some reason for this? I don't want to hear any guesses. Did you do it for some good reason? Is there any published discussion you know of?
Thanks,
Dave

Fanman
Member
# Posted: 17 Feb 2019 08:09
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You want it high enough so you can get under it to make repairs or clear out debris.

beachman
Member
# Posted: 17 Feb 2019 08:25
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We were going to set ours down about 9in less but realized our composter toilet wouldn't fit so raised it. And what Fanman said. 2 to 3 ft is usually good IMHO.

toyota_mdt_tech
Member
# Posted: 17 Feb 2019 12:14 - Edited by: toyota_mdt_tech
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I know crawl spaces require 18" minimum, might be more for maintenance now with bigger Americans, add plumbing, waste drains, insulation, service later...

Just
Member
# Posted: 17 Feb 2019 13:41
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if you have no central supports you can go lower , but anything lower must be PT lumber. IMO.. It is important to have good drainage and good air flow under there...

DaveBell
Member
# Posted: 17 Feb 2019 14:41 - Edited by: DaveBell
Reply 


A++
Thanks, all good posts.

Edit: I did find some published studies today at APA.
Moisture and critters was mentioned.
I could also add it puts windows higher out of easy reach of burglars.

NorthRick
Member
# Posted: 17 Feb 2019 17:36
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Quoting: DaveBell
I could also add it puts windows higher out of easy reach of burglars.


And bears. That's also a factor to consider around here.

rockies
Member
# Posted: 17 Feb 2019 18:17
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There's flooding to consider. Also, piers tend to require a lot less concrete than a stem wall, full basement of concrete pad, which is an important consideration (especially for larger cabins).

KinAlberta
Member
# Posted: 17 Feb 2019 21:13 - Edited by: KinAlberta
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I’d love to build a cabin on piers high enough to put some rails underneath and then build sealed boxes to roll underneath. Could hide away all kinds of things, and/or use it for winter storage. (Tools, kayaks, canoes, lawn furniture...)

Put skirting on that looks permanent and fixed in place but has hidden releases (maybe via cable and have the release handle hidden in the cabin itself).

ICC
Member
# Posted: 17 Feb 2019 23:38
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Here in the west a building on piers with open space under it is a bad idea. You may have noticed all the wildfires that make the news. A windblown wildfire spreads big embers that if blown under a cabin may set it on fire. Most of the fire suppression folks here in the west recommend skirting with metal if your cabin is on piers. And if there is a cantilevered floor hanging out to cover the underside with metal or cement fiber.

KinAlberta
Member
# Posted: 17 Feb 2019 23:45 - Edited by: KinAlberta
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And skirting would keep stuff from blowing or rolling under it. Higher up on piers would be beneficial in preventing the flames from grass from igniting the structure. The wood of our buildings would easily ignite if the grass burned. (Should probably run a wide gravel perimeter all around every building.)

For fire prevention wooden decks should be eliminated too and trees within something like 50 feet and a number of other fire prevention modifications like no vinyl siding.

Think of the heat a burning wooden deck might produce. I’d say that that’s a huge risk factor. And as they are often treated and coated with chemicals I’m not sure if I’d even want to be trying to put out a deck fire even if it threatened the cabin.


Lots of information here:

https://www.firesmartcanada.ca/mdocs-posts/firesmart-begins-at-home-manual/?mdocs-fil e=545&mdocs-url=false

sparky30_06
Member
# Posted: 18 Feb 2019 07:39
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Wood less than 18" to the ground should be pressure treated.

silverwaterlady
Member
# Posted: 18 Feb 2019 07:52 - Edited by: silverwaterlady
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We did it so we could get under the cabin to do maintenance work.

And for air flow. We didn't want our cabin to smell like a moldy, musty cabin. The old cabins around our area built on the ground smell awful inside.

KinAlberta
Member
# Posted: 18 Feb 2019 08:30 - Edited by: KinAlberta
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Pressure treated wood can’t be a universal necessity though if I were building myself, I might use it (with stainless steel fasteners due to the longevity needed.) I’d want to research PT and connectors before using it.

Our main cabin is just inches off the ground with the beam along one side being flush with the ground but not on the ground. (Overhang keeps water off it and it’s on the sheltered side from the prevailing wind and rain.) It is not likely pressure treated (definitely not the type of treating that punches holes in the wood), the perimeter wood is all good and dry and there is no mustiness in the cabin. (70+ years.) It was built in the 1950s so the beams may have been painted with something and the wood itself might be fir.

However towards the front/lakeside the land is slightly sloped and that slope is into the prevailing wind so I would guess that that has accelerated air flow under the cabin and helped expel moisture. Also here in central Alberta we don’t often have moisture problems at any time of the year.

woodspirit
Member
# Posted: 18 Feb 2019 22:09
Reply 


I've read that the Amish use cloth bags, like pillowcases, hanging underneath cabins. with calcium chloride in them. Then they put large buckets or containers under the pillow cases to collect the water that drips down from the calcium chloride. Of course the crawl spaces have sealed skirting sealing them in. They also lay down plastic on the ground in the crawl spaces and cover that with gravel. This is all done to collect the water in the air underneath.

smallcabin
Member
# Posted: 19 Feb 2019 15:07
Reply 


3 main things come to mind when I built my cabin 3ft off the ground.

1. Airflow
2. Future plumbing works
3. SNOW

FishHog
Member
# Posted: 19 Feb 2019 18:29
Reply 


There is also the requirement to have piers just to level unlevel lots.

rockies
Member
# Posted: 19 Feb 2019 19:43
Reply 


In addition to a layer of gravel under the cabin you should attach a fireproof product to the underside of the floor system (like Hardie cement panels or corrugated metal roofing panels). For extra fire safety you could add a layer of Roxul Comfortboard (mineral wool insulation) between the finish material and the cabin floor (mineral wool won't burn).

Wooden posts and beams should be painted with a fire paint that foams up when exposed to a flame.

Example:

http://www.fireretardantsinc.com/149/bb_149.html

Old and Slow
Member
# Posted: 19 Feb 2019 22:32
Reply 


Subterranean termites are not supposed to climb over 16-18 inches. This probably is not pertinent in the far north. Also if there is wiring, the inspector must be able to view any underfloor wiring for rough in.

Many old log cabins were built with the first log directly on the ground. Many of these lasted a long time. The bottom log was supposed to be oak. Some cabins were "painted" with off road Diesel.

Bob

Aklogcabin
Member
# Posted: 20 Feb 2019 10:55
Reply 


Our cabin is 4 feet off the ground. I wanted the windows 7 feet high because of bears. Also have the drip line over 3 feet out so that the snow that falls from the roof doesn’t build up on the walls . That also would help the bears out. Been a good snow year in this part of the state. Probably over 7-8 feet I suspect. Rick north may know.
Also found out that this places that view height. For lack of better terms right about at the bottom of the tree canopy 10 feet or so and above the flora that is 4 feet high. Great for a customized tree stand.

NorthRick
Member
# Posted: 20 Feb 2019 18:04
Reply 


Quoting: Aklogcabin
Been a good snow year in this part of the state. Probably over 7-8 feet I suspect. Rick north may know.


I'm not sure what the total is if measured right after each snow fall. Snow is a living thing that changes over time and with settling, melting, and sublimating, what you measure on the ground is less. However, we are probably close to 4 ft on the ground right now.
Cabin_snow.jpg
Cabin_snow.jpg


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