10 foot tall tree stumps to support a carport

We have a cabin that we have converted into a house. On one end of the cabin there are several trees, about 15 feet from the end of the building that we want to top off and leave approximately 10’ tall stumps to use as the supports for the roof of the carport. The other side will be 4X4 posts put in the ground with concrete and attached to the cabin. Will this work? The dimensions of the carport won’t be perfectly square but we are going to make a lean-to type roof so there won’t be any trusses

Maybe, possibly. If the trees are iron wood or locust, or maybe cedar/redwood.

But in general, using dead tree stumps is a very poor idea. The dead wood will continue to draw water up the stump. And the stump will rot fairly quickly. If you are only going to use the carport (house, barn, whatever) for a very few years, go ahead. But if you want to structure to last longer, put in a proper foundation. Stumps are not it.

Welcome to Permies, Deborah!

Would it be possible to not top the trees, leaving them alive? That way they protect your structural investment. You might need to drill through, mount a lag bolt and hang the roof the carport instead of just screwing it to the dying posts, but there's every reason to think you could make it last that way.

I hope you decide to stick around here -- I'd like to hear back from you in a few years about how the project is going.

I thought maybe your plan included coppicing the trees and using live trees.  Did I misunderstand?

If so I liked the idea.  Would it work?  I have no idea.

There are several threads on the forum for using live trees to make furniture and even a shelter.

Here is a book on that subject:

https://permies.com/t/122929/Powell-Hedges-Windbreaks-Shelters-Live

Some threads:

https://permies.com/t/45176/Standing-trees-building-supports

https://permies.com/t/27725/Photos-growing-eco-buildings

I hope I was right as this is a lovely idea.

i think we need to know the tree species and size/diameter of trunks.

Not the best idea unless you can keep the trees alive otherwise the stumps will be rotted out in a few years more than likely. There are a couple species of tree that don't rot as fast but the odds are not in your favor. I KNOW for a fact this doesn't work well with eastern red cedar!  

Beau uses a great low-tech method of joinery in the Grape Arbor PTJ project at Wheaton Labs. This trailer is nice in that he uses a small test version to explain his methods.

A friend of mine bought some property with a 1920s cabin built with a redwood tree growing through the middle of it.  Redwoods live to be a couple thousand...yes, thousand years old, they don't rot, no bugs bother them, he thought he had it made.

But....they keep growing, getting bigger and bigger, wider and wider.  And they sway in the wind like crazy.  He only had one and it just about ripped his roof off it was filling up the space and swaying so much.  Cost a fortune to have it removed.  

You are talking about 4 trees.

If you are going to top them, and it doesn't kill them, everything above can still apply....plus, if you have bark beetles, termites or any other kind of beetles, messing with those trees at all will stress them, and the insects will move in.

And, honestly, from my experience, you aren't going to want to do this again in 5 years, while at the 3-year mark you have to try to fix what is starting to go wrong with it. Wood for a carport will only get more expensive in 5 years.   It will just always be on the list, and in a rural situation it really is better to make the list shorter and shorter.

And one of your biggest investments, one of the ways to get you to groceries, gas, propane, building supplies, to safety in a forest fire is underneath it.  All you need is for one corner to go down and there could be damage.  

There's enough to worry about going wrong in a rural setting.

:-)