We have a small grove of Cedars (quite large...perhaps 80' tall) that has perfect space underneath them for a small shed. We're looking at putting a small one (less than 10x10') underneath them.

Would this in any way hurt the cedars? It's well within the drip edge, so it's usually pretty dry under them so assume that this wouldn't hinder water intake for the trees, and the root diameter (if it matches the branches) is at least 25' so the shed footprint would be fairly small in comparison.

I'd plan on using a loose rock foundation or, if preferable, some concrete post blocks.

BUT...we certainly don't want to put the health of the trees at risk, either.


What type of Cedar are you talking about? Where are you located? Is it a native species?

I know that native cedars in my area (Incense Cedar, Sierra Nevada foothills) are incredibly hardy, and will take just about anything that you can throw at them once they are established (I live in a mixed oak/conifer woodland). Also, Deodor Cedars in this climate, while not native, are very resilient (my mother did major grading work and a retaining wall five feet from a mature Deodor Cedar 15 years ago and it is still very healthy and happy). However, there are many of the Cypress Cedars (not native to this area) which are much more picky about their treatment, and a neighbor just had a large grove of them turn brown and die for no apparent reason.

My suggestion: go to your local nursery and ask about that particular species in your local area, and if they grow very well in your area (i.e. if they are a native species or are well adapted to your climate) then you are probably pretty safe with your idea of a small shed footprint and a non-intrusive foundation.


I can't foresee any problem to the trees by putting a shed beneath - there's probably more risk to the shed than to the trees over time from further root growth, but it should be just fine. I've always sited sheds under trees wherever possible, though usually at least 4 feet away from the main trunk, and even used a solid concrete slab as a base for small sheds without any problem to the tree/s.


In general trees like it just the way it is and do not like changes in grade or the ability to exchange air and water.

The issue is that roots absorb air as well as water and are close to the surface. If you cover more than one third of the root area, which is from the base of the tree to the drip line, then you could see some die back when the roots no longer have enough access to air. This is more likely if you use concrete slabs and less likely if you use large diameter round stones.

Some ways around this are to put the shed on posts or on a frame to minimize the surface area you are blocking. This does create a perfect place for small animals to live which may not be in your plans...

The "take no chances" approach would be to build a frame using 4" x 4" cedar for the walls to sit on. Place and level the frame on a thin bed of stone dust so the wood does not touch earth. Depending on the type of shed you may need further support for the floor. The best solution is to keep the floor supports integral to the frame or the shed so you don't have to worry about the ground settling over time and the floor sinking.

You will also get cedar duff coming down on the roof of the shed so what you gain in dryness you loose in the maintenance of keeping the roof clean.

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