10'X14" Little House

[daverave]

John et al,

I'd like to build your 10X14 cabin. I'll be building in South-Central Wisconsin about 20 miles south of La Crosse. The soil (based on the USDA link provided on this site) is silty clay loam, Fayette silt loam FuD2. Do you think I'll need a post foundation using 6x6s and a gabled roof? Both of these add quite a bit of time and cost to the cabin. I'm not looking forward to digging the 16" dia. post holes, especially.

Of course, if they're needed I'll dig and so another question is: Any advise from anyone on how to dig a 16" dia. hole? Are there post-hole diggers that large that can be rented?

Dave

[Redoverfarm]

 

John et al,


Of course, if they're needed I'll dig and so another question is: Any advise from anyone on how to dig a 16" dia. hole? Are there post-hole diggers that large that can be rented?

Dave

Dave I am pretty sure they have 18" augers.  If not you will probably not have that many that you can't use a 12" and widen it with a digging iron.  Check you local rental centers to see what they have. Don't know anyone with the electric company?

[glenn kangiser]

There are pretty nice trailer mounted diggers that will handle that at some rental companies - or a Bobcat with an auger.

[John Raabe]

If you are in clay and silt soils then there is a high likelihood of expansive soils (stick a jar of wet soil in the freezer to see). If that is the case then you do need to be down at the frost depth if you want a foundation that won't move.

If you are building this as living space then I would not suggest the shallow footings that can work in low frost areas or dry low-clay soils. The main problem with frost heave movement is that it will likely cause windows and doors to stick. If you don't use drywall but a wood interior and are using it more as a shed then a bit of movement may not cause problems. But, the more money you plan to spend on it the more you will want a good foundation.

In terms of the roof you could do the shed roof plan that is part of the Little House Plans. If you have a high snow load you might want to deepen the rafter a notch or two. Once you have the plans post a question on the Plan Support forum with your design snow load and I'll check the rafters for you.

[daverave]

Concerning low-sloped roofs, has anyone tried "KoolSeal" black elastomeric roof coating, sold at Menard's?

[daverave]

John et al,

Code in Southern Wisconsin requires 30 PSFsnow loading. So, I am going to use 2X8 SPF rafters on the cabin. Sound OK? I think I will shorten them to 12 feet because I don't think I need quite the overhang you have designed, plus they're easier to handle and the roof snow weight will be lower. 

Also, you mentioned that the deeper the post is into the soil the less the load will be on the soil. This makes sense but is there a rule of thumb for estimating the additional soil load bearing capacity due to this? Suppose a 6x6 beam is used 48" deep with sand and gravel backfill.

Thank you,

Dave

[John Raabe]

I assume you have the Little House plans and are building the 10x14 shown on P-1 of the plans. A 2x8 rafter at same spacing as the plan should be fine for your snow load. (The one shown is for a 25# load.)

The primary bearing of your post foundation will be determined by the diameter of the gravel or concrete footing at the bottom of the hole. For a lightweight house like this an 18" dia by 9" deep crushed rock footing will provide plenty of bearing. See more information here: http://countryplans.com/foundation/index.html (bottom of page).

On the roofing I do not have any specific brand information - we used standard roll roofing over tar paper and it is now on its 9th year with no leaks.