beam spacing and pier hight on 24x16 cabin

[highplainsdrifter]

I am following the 14X24 plans and am making some changes so as to actually build a 16X24.

For this foundation, I am going to dig down to hard soil, back fill with crushed rock, and the use the pier pads on the pavers just like the plans suggest.

first question:

I had spoken to John and he said that I should increase the size of my floor joist from 8 inches to 10 inches to accomodate the added 2 feet.

Would it be equally strong to instead, add a middle 4x8 beam (and also a middle row of pier and pads) and then stick with the 8 inch floor joist?

I am sure the strength is there, but doing it this way, I would not have the cantilevered floor joists, and I am not sure if that is an important part of the design.

second question:

I am going to be building on a slight slope. The piers (4x4 PT) at the low side of the slope are going to be about 2 feet tall. I plan on cross bracing them, but wanted to make sure that 2 feet is not to tall for these.

I'll be taking pictures along the way, and once I get a few, I'll start posting them up.

Thanks for the help,
Russ

[John Raabe]

If you are using the 14x24 Little House plans and will do an interior centerline beam and piers, I would set the outside beams to the outside of the platform. That would leave an 8' span for the joists. At 16" o/c you could use #2 Doug Fir 2x6 or go to 2x8 to get more depth for the floor insulation.

If you are in an earthquake or high wind area consider concrete tube footings as they will provide better anchorage against uplift.

[highplainsdrifter]

Hey John, thanks for the response.

Yeah, I am using the 14X24 little house plans.

I live in northern california in the foothills of the Sierra Nevadas at about 2100 feet.

We do not get earthquakes. During the winter there may be one or two really bad storms that will blow up to 50mpg gusts, but that is unusual. I would not consider where I live to be overly windy....and when we do get real heavy winds, it is few and far between and not for a long duration.

given that, do you think I will be OK with the piers and pads, or would you recommend that I use the concrete tube footings?

Thanks for the help,
Russ

[John Raabe]

If you use the anchor brackets in the pier block configuration using PT posts that are cross braced on crushed rock footings you should have no problem with 24" high posts. For better anchorage into the soil and more resistance to uplift use 8" concrete tube piers. However they are not easy to cross brace so you don't want them to be taller than about 3'.

Look at this discussion: http://countryplans.com/smf/index.php?topic=8531.20

While no foundation is totally guaranteed, tall piers in clay soils and unsecured posts can sometimes fail.