Author Topic: 1 and 1/2 Story 20x30 Alberta Cottage (Read 112281 times)

Alberta Curt · « **on:** February 24, 2008, 07:32:12 PM »

Hello everyone - I've added pics at the bottom of the thread

MountainDon · « **Reply #1 on:** February 24, 2008, 08:01:23 PM »

4. IIRC, the plate nailed to the bottom of the PT post is used on the crushed rock footing. That would be to spread the load out. (I don't have those actual plans)

3. not certain about that

2. Concrete vs. wood. Using concrete you'll never have any doubts whether or not the PT wood was properly and thoroughly treated. No need to replace, ever.

1. My thoughts on this is that a hybrid method may be best. Concrete footing, concrete blocks to above grade by one block or so, blocks filled with concrete and rebar. Then PT piers secured to the concrete using post bases that are secured to the concrete via anchor bolts embedded in the concrete when poured. This way the posts can be trimmed to exact length/height needed.

The same thing can be done using the round cardboard tubes. The tubes can also be cut to length once the lower end is firmly supported and the tube braced in place. I'm not sure of my own ability to get these right to within the 1/8 inch I'd like to aim for. $:-\$

I also like the idea of having wood piers as it seems to me they would be easier to brace with diagonal bracing, wood pier to wood beam/joists,

Keep in mind IRC code requires the beams to be 12" above grade and the joists to be 18" above grade, unless PT wood is used for the beams and/or joists. For installing insulation in the floor from the bottom you also want to have at least that much working space. Ditto for plumbing, etc.

Others may have other ideas.

EDIT: As I have learned more, I have changed my tune on my comment on 1. above. Transitioning from concrete to PT wood in the pier, with the beam on top is actually poor engineering. Doing s creates two "hinges", two potential areas where things canmove. The beam can hinge or turn on the top of the PT pier, and the PT pier can rotate or hinge on top of the concrete. That results in a less stable foundation. Better would be all concrete up to the beam or one continuous PT pier from the concrete footing up to the bea. And a 6x6 pier, not a 4x4.

glenn kangiser · « **Reply #2 on:** February 24, 2008, 10:55:43 PM »

I think you need to find your depth of frost and plan a plastic pipe around the footings or Big Foot footings unless you put adjustable pier bolts at the top and have the good drainage to prevent frost heave. I'm pretty sure it could be a problem in your area.

Concrete around the post will lift with frost easier than well drained crushed rock.

n74tg · « **Reply #3 on:** February 25, 2008, 05:23:39 PM »

Where are you in Alberta? I wintered over in 1985 working for the oil industry; worked out of Grande Prairie.

Alberta Curt · « **Reply #4 on:** February 25, 2008, 05:38:02 PM »

I'm in Edmonton. Land is at Mayerthorpe - just a couple hours SE of Grande Praire.

Alberta Curt · « **Reply #5 on:** February 25, 2008, 06:59:43 PM »

Thanks for the information everyone. I'm on to the joists. I'm looking at my plans and it appears that the joist ends are flush with the edge of the beams.

I thought there was always some overhang?

Does anyone have experience with insulating the joists? I'm assuming this can be done and the bottom covered with OSB.

glenn kangiser · « **Reply #6 on:** February 25, 2008, 08:30:30 PM »

Overhang on the small ones only to stiffen the floor. Too much wall weight on this one to overhang.

We have talked of various solutions - that could be one. Usually done after the place is dried in to prevent filling the insulation with water.

miman · « **Reply #7 on:** February 26, 2008, 11:30:37 AM »

i used the over-hangs, but i only went one foot. however, the bathroom area is bumped out two feet. my daughter is physically impaired, and i have tried to add as much space possible. i have a double the problems, building and building accessible, hard to do in 745 sq feet. by the way my footings are 24x24x12 wood boxes, fill with concrete. each pier is dry stacked, fill with concrete. each pier has two blocks, from 5-6 block high.

Alberta Curt · « **Reply #8 on:** February 26, 2008, 03:29:48 PM »

Thanks miman. Any pics of your place?

lonelytree · « **Reply #9 on:** February 26, 2008, 10:38:56 PM »

Quote from: miman on February 26, 2008, 11:30:37 AM

i used the over-hangs, but i only went one foot. however, the bathroom area is bumped out two feet. my daughter is physically impaired, and i have tried to add as much space possible. i have a double the problems, building and building accessible, hard to do in 745 sq feet. by the way my footings are 24x24x12 wood boxes, fill with concrete. each pier is dry stacked, fill with concrete. each pier has two blocks, from 5-6 block high.

Do you have any pics of your footings?

Alberta Curt · « **Reply #10 on:** February 27, 2008, 05:27:35 PM »

One the items I have planned for my cabin is solar power. Being fairly new here, I'm not sure if this has been a topic of the past. Are there any experiences with solar power that people want to share with a newbie? I'm looking at solar water heating and running a few lights in the cabin.

MountainDon · « **Reply #11 on:** February 27, 2008, 06:05:58 PM »

Yep. Solar electric more than water heating.

The place to start is to make a detailed list of everything electrical you intend to use for certain. Sit down and make a realistic estimate of a typical days use for each item (time in hours).

Depending on cabin size and power uses, some folks can make it work on 12 VDC only. But a system that uses a bank of batteries wired for 24 VDC and uses an inverter to provide 120 VAC can be much more versatile.

In our cabin to be built this summer I am planning on having a couple or so 12 VDC lights, but we are mostly going with 120 VAC lights and such via an inverter. Reason; IF the inverter craps out we'd still have a few lights that would work until we made the trip into town to look after the inverter problem. Not a real likely thing, but I have a tendency to look for backup systems if I can.

There has been some past discussion here...
Solar Electric System Sizing Calculator

Off-Grid Power Systems

Battery Bank Charging

Some of the info in those threads may be of some use to you.

Also you could continue your thoughts/questions here or begin a new topic of your own separate from this. We have opinions and ideas and some of them even have merit.

MountainDon · « **Reply #12 on:** February 27, 2008, 06:16:45 PM »

A quick search on "solar water heating" here brought up...

I didn't read 'em all carefully so can't guarantee the relevance...

http://countryplans.com/smf/index.php?topic=2429.msg23803#msg23803
http://countryplans.com/smf/index.php?topic=1349.msg11381#msg11381
http://countryplans.com/smf/index.php?topic=780.msg5811#msg5811
http://countryplans.com/smf/index.php?topic=90.msg292#msg292
http://countryplans.com/smf/index.php?topic=336.msg11516#msg11516

MountainDon · « **Reply #13 on:** February 27, 2008, 06:22:57 PM »

We place a microwave oven high on our list of items to have and use in the cabin. Having to run a generator for that is a real drag, IMO. Hence my own desire to run 120 VAC. Having 120 VAC available also means it's easier to add things that are nice or convenient to have. Of course as you add appliances, etc the battery bank size goes up, so there's some horse trading to be done. Wiring 12 VDC may need heavier wires to avoid significant voltage drop...

I've said enough for now. Somebody else's turn or questions please.

glenn kangiser · « **Reply #14 on:** February 27, 2008, 07:50:20 PM »

My underground complex is off grid -- entirely - we have a phone line with DSL -- that's it.

I have to take off now -- illness in the family, but a search will bring up lots of solar information.

Alberta Curt · « **Reply #15 on:** February 29, 2008, 05:41:43 PM »

What kind of siding did Mike use? I like it!!! Thinking of the same style for mine.

http://www.countryplans.com/cgi-bin/yabb2/YaBB.pl?num=1115136283

Alberta Curt · « **Reply #16 on:** March 02, 2008, 11:10:58 AM »

Quote

1. My thoughts on this is that a hybrid method may be best. Concrete footing, concrete blocks to above grade by one block or so, blocks filled with concrete and rebar. Then PT piers secured to the concrete using post bases that are secured to the concrete via anchor bolts embedded in the concrete when poured. This way the posts can be trimmed to exact length/height needed.

I see some pictures of beams attached to the side of the 6x6 foundation post, as opposed to resting on top with a bracket. Any thoughts on the pros and cons of this?

MountainDon · « **Reply #17 on:** March 02, 2008, 12:59:47 PM »

Quote

I see some pictures of beams attached to the side of the 6x6 foundation post, as opposed to resting on top with a bracket. Any thoughts on the pros and cons of this?

A beam side mounted to a post would have the total bearing weight on the fasteners used. While this is frequently done when constructing decks and gazebos (sandwiching the post with a 2x on each side and then through bolted with 1/2" bolts), it is not best building practice for a cabin or a house. The entire weight of the structure, from the roof down, along with any snow loads, plus the entire contents, would be on those fasteners. Not a good idea at all IMO.

Did you see that side attached beam on here? Each and every owner posted picture is not reviewed by an architect or engineer so there may be the occasional posting illustrating something that is not completely kosher. Asking questions before you do something is always the best policy.

Alberta Curt · « **Reply #18 on:** March 02, 2008, 01:29:16 PM »

Hey Mountain Dion. Thanks for the reply. Yeah, I think I saw a picture of it on the Michigan Cabin. After all the feedback from you folks, and discussion with Larry the Lumber Guy (Home Depot), I have a plan for my foundation.

1. Concrete piers with rebar. I'm going to use 15 instead of the 12 in the plans. Aot of the feedback I've received mentioned the possibility of bounce if I went with the 12.
2. Anchors for beam cemented directly into pier. This way, my beams will not have to sit directly on the 6x6 posts and potentially sacrifice stability. The challenge as I understand it, will be to align the tops of the piers on a gradually sloping terrain, and to also align the anchors of each pier in a straight line.

28 days until I start digging.

John Raabe · « **Reply #19 on:** March 03, 2008, 03:45:03 PM »

The key to getting the beams and anchors right is to attach the brackets to the beam first. Level, support and square the beams and finally pack or pour the concrete piers around the bracket pins. If you get the Bigfoot forms you can do pier and footer all in one. Otherwise pour footers first (if needed).

Alberta Curt · « **Reply #20 on:** March 07, 2008, 07:03:20 PM »

What kind of siding did Mike use?

http://www.countryplans.com/cgi-bin/yabb2/YaBB.pl?num=1115136283

Alberta Curt · « **Reply #21 on:** March 08, 2008, 08:08:55 PM »

I was thinking of using 3 beams instead of 2. Could I then use 2'x8'x10' for joists instead of the 20' I-joists or the alternative 2x12's? Wouldn't have to overlap, just join at the center beam, with 3 inches of beam on each side of the joint. I could even place them at 12 oc.

Thought it was an opportunity to save some money, but I don't want to sacrifice structural integrity.

Any advice?

glenn kangiser · « **Reply #22 on:** March 08, 2008, 08:22:00 PM »

I think I recall John mentioning that as an option on some designs.

You may want to weigh the savings against the extra labor, footings and beam cost to see if you really save.

MountainDon · « **Reply #23 on:** March 08, 2008, 08:51:04 PM »

You would have to run the numbers. I compared the cost of two foundation variations for my planned little house. Two beams. I don't have all the actual dollar calculations handy but here's the gist of it.

The first was using two built up 6x12 beams with 4 piers per beam spaced 8 feet apart. The other was using 6x10 built up beams spaced on 5 piers piers per beam 6 feet apart.

The pricing included all the rebar, concrete, concrete blocks, post bases, anchor bolts, piers, post to beam connectors and the built up beams with 1/2" plywood spacing. The second option came out costing less. The wider 12" lumber cost more per board foot than the 10". The extra concrete blocks were quite cheap in comparison. However, not enough was saved to warrant the effort of extra digging IF I had to dig the footing/pier holes by hand. Since we're going to use my neighbors small backhoe we're going to opt for the second option (more footings).

So, run the numbers, consider your labor, and go from there. Or guess.

Back to the 2x8 x 10 ft span. No problem there as far as being strong enough. In fact that looks like it would be stiffer than 2x12 w/o the center beam.

John Raabe · « **Reply #24 on:** March 10, 2008, 11:15:36 AM »

Yes, the costs may favor one method over another. Then you should also consider the labor issues and the time involved. Either one will produce a strong solid structure. 20' of width is about the limit of cost-effective single span floor joists. For a 24' width you would likely go to a centerline beam and go back to shorter joist spans (unless you have access to cheap web trusses or the like).