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Building a Patio or Deck Around Trees

by Keith Brown
October 26, 2009

Quite opposite of the typical instinctive thought, putting a patio around a tree can be very beneficial to the tree. I will cover the fundamental benefit the tree receives from a patio and discuss the pros and cons of different construction materials / techniques.

The significant benefit that a tree gets from a patio is reduced soil compaction to its root zone. If there is no buffer between your feet and the soil, then the compaction that takes place over years of foot traffic becomes a very real stress factor to the tree. A patio can either reduce soil compaction by distributing the weight of your foot steps or eliminate compaction entirely by getting you completely off the ground.

Pavers are a popular choice for construction materials. They do a good job of letting soil and air penetrate the soil and do a fair job of distributing weight load to reduce soil compaction. The bigger each individual paver, the better job it will do distributing weight.

Concrete slabs do a much better job of distributing weight. Because the slab is one big piece, each foot step gets distributed over a larger area. Concrete becomes a problem in two scenarios. One, if you are covering more than half of the root system you might run into water and air exchange issues. And, if your slab requires you dig footing trenches around the edges the trenching might cut roots. However, if you slab is covering a small portion of the trees root system, then you can actually help water retention (remember that trees roots go out 4-5 times as far as the branches). Whenever it rains, the water moves laterally once it gets in the soil. So, water does get up under the concrete. However, as the sun and air dry up the water, the concrete slab will protect the soil underneath and act as an oasis of moisture after exposed soil has long since dried. I have heard and read about concrete buffer soil pH to deadly high ranges, but I have never experienced this on my projects.

The best patio construction material to use around trees is wood. Elevated wood decks get footsteps completely of the soil. And, if you provide small gaps between the boards, water and oxygen will easily access the soil and roots. In addition, the trees leaves will be able to slip through the cracks to the soil surface and retain a natural litter layer that recycles nutrients back into the soil. This is, hands down, the best way to go.

Whatever your approach, remember to leave enough room around the trunk for growth. You don’t want your patio girdling the tree trunk. And, if you have to dig piers or footers be careful. So, carry on, be careful and rest assured you are doing your tree a favor.

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  • Donna McNelis says:

    I am interested in extending my deck around a mature sycamore tree. The trunk root circumference is 51″. How far away from the tree should we stay with the decking and what precautions need to be taken with the footings?

    • Keith says:

      Give yourself as much room as you can live with so the tree has room to grow before you have to alter your decking. The answer to this question is a product of time vs. altering the decking. I’d want to keep at least 6-8″, if not more. Regarding the footings, use an airspade to dig. An airspade is a high powered air compressor that blows away the dirt without cutting through roots. That way you can be sure to avoid cutting very large roots.

  • Stan Mays says:

    I have a 100-year-old Live Oak out in Round Top and want to have some kind of patio/ground cover underneath to support a table and chairs. Would a combination flagstone and crushed granite be ok in terms of water and oxygen getting to the roots?

    • Keith says:

      This should be fine. I’ve not experienced tree problems when patio grade ground covers are installed. Just make sure you are not excavating roots to or building dirt against the trunk to level the area.

  • Cissy Olderman says:

    We are going to have a stamped concrete patio poured in our backyard, and have a locust tree and a small maple tree in the yard. How much room do you recommend for us to leave around the circumference of the tree trunks? Thanks!

  • George Austin Lewis says:

    I live in Pflugerville, and want to build an island around two trees about 12-14 ” round. The islands were going to be about 8′ x4′ around each tree with a fake brook of Marble stone going from one corner of the front yard , under a bridg between each island and a small pond in fromt close to the side walk. the islands were going to be about 12 – 14″ high because of root compact, making it impossible to plant anything at ground level. Now I hear that I should build a area around the tree to keep it clear because of rotting at the trunk area. Just how far should this area be, or should I just cancle this project and leave it bare, grass only. I had plans to make a Gnowm and Farie land under the trees sorounded by flowers that would be imppossible to plant without the islands. Should I cancle my project as a danger to the trees?

  • Erin says:

    We are building a paver patio and yesterday (Aug 9) the builders cut 2 medium roots and one med-lg root. They also compact the gravel with a machine under the paver area. Is our Chanticleer Pear in doomed? (10 years old, 30 feet tall, zone 5b)