Planting distance of large trees from buildings

Discussion in 'Outdoor Gardening in the Pacific Northwest' started by Polar, Jul 15, 2017.

  1. Polar

    Polar Active Member

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    Hello,
    I've looked through the BC Landscape standards for what may be considered a large tree and for guidelines as to how far from a building's foundations one should plant large trees.

    The American Conifer Society describes a large tree as growing more than 25 feet over 10 years - somewhat helpful but is it not so that some trees grow quickly up to 25 feet or so and then broaden outward over time? On a side note, perhaps these are classified as 'large' along with other trees that reach 50 ft or more at maturity because their root structure is comparable?

    Does anyone know of an official standard for planting large trees near buildings and what is 'large' for that standard? Ideally the standard may also provide guidance for groups of large trees, for example, "avoid planting Weeping Willows within 50 feet of homes; Austrian Black Pines can be planted up to 20 feet" or whatever? I'd expect the source to use Latin names to sidestep misunderstanding.

    Is there a website or standards manual available to the public?

    I hope one of you in this grand community may know the answer!

    Thank you in advance.
     
  2. Daniel Mosquin

    Daniel Mosquin Renowned Contributor UBC Botanical Garden Forums Administrator Forums Moderator 10 Years

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  3. Michael F

    Michael F Esteemed Contributor Forums Moderator 10 Years

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    A lot also depends on soil type. Heavy 'shrinkable' clays are the worst - when deep-rooted trees with high water demand like willows or poplars take up water from them, the clay shrinks, leaving foundations unsupported and the building gets subsidence damage. In Britain, the minimum safe distance advised for poplars on shrinkable clays is 50 metres, unless you have very deep foundations (i.e., deeper than the maximum rooting depth). Sandy soil, which doesn't shrink if it dries out, you can plant trees considerably closer and not have any problems.
     
  4. Polar

    Polar Active Member

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    Thank you for your replies!

    So, some sites say 1/2 spread for large conifers (Calgary - above), others say 1 x height for large trees in regular soil, 1.5-2 x height for large trees in clay (UK), the society of Arborists of Quebec states trees taller than 20 m must be planted a minimum of 10 m from buildings. Assuming the soil here is sandy/rocky (class A soil) then which do I recommend? 1/2 the spread or 1 x the height or 10 m?!?

    Pines in Calgary likely grow more slowly than here where trees are active in winter at temperatures above 5 deg celcius (from what I've read but cannot locate again, anyone have horticultural research I can quote?). Dirr says Pinus nigra grows 50-60 feet x 20-40 spread which may be so on the east coast but here, they grow to 80 high by 40-50 feet spread in regular situations. Dirr also mentions these pines can reach 100 feet - how I wish he mentioned where he saw these. Another frustration is the spread here seems to vary amongst west coast online nursery plant profiles. Vancouver Trees does not provide mature height and spread - just lists size after 45 yrs - I'd like to recommend plantings that are reasonable for the life of the tree and avoid passing on huge expenses early on because of poor choices made now.

    So if 1/2 anticipated spread for Pinus nigra is safe in Calgary, is that transferable to here?... UK's weather is more comparable to us ... but that's a UK standard, for whatever reason may not be transferable to BC.... And is Quebec's guideline transferable to here?

    Any West coast research papers anyone may have on this topic?

    I'd like to have something I can quote and back up with research.

    A tall order! But if anyone can help, I'm listening. Thanks.
     
  5. Michael F

    Michael F Esteemed Contributor Forums Moderator 10 Years

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    Pinus nigra has reached 46 m tall in Britain (info & photo), and can get more than that in the wild. But it doesn't have a bad reputation for invasive roots, you can plant it much closer to buildings than you can e.g. willows, poplars or oaks.
     
  6. Polar

    Polar Active Member

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    But how close?

    Still looking for a west coast guideline too...
     
  7. Polar

    Polar Active Member

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    Oh yes, I have found different guidelines for deciduous trees (particularly willows and that sort) but I'm looking for guidelines for large conifers...
     
  8. Michael F

    Michael F Esteemed Contributor Forums Moderator 10 Years

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    I've seen a 20-25 m tall Sequoiadendron planted within a metre of a house with no evidence of damage. I'd not recommend that, though!

    I'd say in general, for large conifers on non-shrinkable soils (sandy, etc., but not heavy clay), you should be able to get away with 6-8 metres, possibly a little less.
     
  9. Polar

    Polar Active Member

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    Thank you Michael!

    Curious about the house next to the sequioadendron ... small, big, old, new, built before or after? Was the trunk large.... 1 m, wow, those trees get huge trunks - over not too much time the trunk will be touching the house!
     
  10. Michael F

    Michael F Esteemed Contributor Forums Moderator 10 Years

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    Checked up on google street view, it's not as close as I remembered (the angle of approach along the road makes it look closer), but still pretty close, about 4 m, at most 5 m. Trunk I'd guess about 1.2-1.5 m diameter. Hard to know which is older, I'd guess probably the house.
     
  11. Polar

    Polar Active Member

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    Have you seen reports that the house has no damage? Just incredible.... if it's on a slab, the roots are probably reaching underneath the house, probably working their way to the other side, but receiving moisture from the tree's system. You'd think the land beneath the house would be too compacted and oxygen poor to allow the roots to grow immediately beneath.... if the soil is too compacted immediately beneath or if the house has deep foundations then the roots will likely reach the foundation and continue along the underground perimeter of the house. This could make for an unstable tree...

    My understanding is conifers don't only have a tap root (though some don't have a tap root) but also lateral roots - one set occurring in the first meter (with the majority within the first third) and often a second set occurring at about 2 meters deep, again growing out laterally from the taproot. Perhaps the tree is putting out a secondary set and that is going underneath the house and stabilizing the tree.... depends on oxygen availabity? In a forest, the secondary set likely receives water through the soil above and as the soil hasn't been compacted, there's sufficient oxygen...

    The diameter of this species' trunk has been seen to grow to 26 feet wide - though less in garden situations perhaps? Hard to fathom a trunk 7-8 meters in diameter! I hope the tree will get to stay...
     
  12. Michael F

    Michael F Esteemed Contributor Forums Moderator 10 Years

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    There's no visible damage in the pics, but I've not consulted the owners to find out if there's been any problems. I'd doubt the house is on a slab, more likely it'll have good deep foundations (particularly if it is old), in which case the roots won't be going below it. Older traditional-built houses in Britain (before the post-WWII cheap housing boom) usually do have deep foundations.
     
  13. Polar

    Polar Active Member

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    Interesting! Thanks for sharing!
    I love the house in your picture - not something we see much in the Canadian west coast countryside... I so enjoy your countryside every time I get to visit it.

    Best regards,
    Sonia
     
  14. Georgia Strait

    Georgia Strait Active Member

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    I suggest you look at the BC Hydro website - they have planting page on website - here are two links

    https://www.bchydro.com/content/dam...corporate/safety/planting-near-powerlines.pdf

    and this is back a couple of clicks from that PDF (above) - more helpful input
    Planting trees and plants

    ===============
    I know the two locales shown on your profile - if you haven't already planted --- here are some further ideas

    do consider water use - obviously BC (Pac NW) summers are far drier than ever in recent memory - and why waste water on introduced garden plants. Whole topic there!

    future plans for the property --- everything from parking an RV to adding a chicken coop.

    And tree root invasiveness - on your building foundations --- I know you've asked about that - but you must also consider utility lines above and under ground (gas, sewer, power, water etc) ---- and most importantly (and expensively) - your septic system if out in the rural area.

    Tree litter on your gutters and on your roof and cars and deck furniture --- how much moss will grow on your roof as a result of tree litter and shade etc

    Also as you know -- interface wildfire is a significant risk in all parts of BC --- so read up on the guidelines -- I bet your property insurance company has info --- otherwise Wildfire BC - the govt website --- here's one place to start (link below)
    Wildfire Prevention for Your Home & Community - Province of British Columbia

    Which way are the prevailing storm winds ? Does your insurance policy cover this? (potential branches and tree falls)

    Will any branches or other tree litter affect your neighbors property or view? This is a big factor in view-hungry BC ... that's why people come out west coast - mainly for a view lot.

    remember that if you do proceed, some of the coast's best planting times are in the late fall when it's naturally wet (rain) and going in to more rain --- versus - when the plant sales nursery is full of fresh treasure in May - and the coast is going in to its heat and drought.

    and YES - My rule of (green) thumb - I never plant anything I can't later manage myself ;)

    (take a drive and it's easy to tell the homes that planted that cute little Christmas tree "x" number of years ago - or those crazy blue spruce Xmas trees (Okanagan esp)


     
    Last edited: Sep 10, 2017
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  15. Georgia Strait

    Georgia Strait Active Member

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    one more thought - have you looked at Sunset.com garden book

    it's a really useful book for gardening in WESTERN North America ---

    I believe technology allows it to be online now too.

    (make sure you read their proprietary gardening climate zones - and - that you're consulting a most recently updated version (edition) of the reference book)

    The New Sunset Western Garden Book
     
  16. Polar

    Polar Active Member

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    Just in case anyone else is looking for similar guidance, the following is a distillation of some of my research on this topic. In the end, I will play safe and until research clearly debunks the guidelines put forward by theses 'authorities', I will use this to guide my present decisions.

    It comes right back to right plant, right place!

    1. Canadian Landscape Standards Association, in written correspondence:

    "[regarding large growing conifers] If you want to really be safe, the rule of thumb is to keep a distance of half the dimension of the tree crown... As an example, a tree with a canopy of 10 meters would not be planted closer than 5 meter from the foundation, never over a pipe line, of any kind, mainly because if maintenance is needed on the conduits."


    2. Society of Arborists of Quebec states "Trees over 20 m must be planted 10 m from buildings."

    "Arbres de plus de 20 m de hauteur
    Des grands arbres peuvent être plantés [mais] il faut toutefois s’assurer qu’ils n’obstrueront pas la vue des voisins ou qu’ils ne feront pas d’ombre sur leurs parterres. Il faut planter les grands arbres à environ 10 m de la maison, et ce, pour permettre aux racines de se développer tout en minimisant les risques de dommages à la maison ou à l’immeuble."
    See: "Arbres et services publiques": https://www.siaq.org/media/1245/arbres-services-publics.pdf


    3. FortisBC

    "Trees and other plants near gas lines:
    "Trees growing over or near gas lines can interfere with routine maintenance surveys and have the potential to damage the protective coating on the buried pipe."

    "Hazardous trees or other plants on private property:
    If you’re planting a new tree on your property, follow these steps to avoid having to cut down or trim your tree later on:
    1. Avoid planting trees or bushes near gas lines. ...
    2. Consider the root span of the tree. As it grows, the roots may present a hazard to gas lines. Plant trees in an area where they will maintain a safe distance from the gas line when fully grown."

    See: Gas line maintenance > FortisBC


    4. International Society of Arboriculture publishes "Trees are Good", an educational tree care website for homeowners:

    "Tall Zones:
    Trees that grow 60 feet (20 meters) or taller can be used in the area marked “Tall Zone.” Plant large trees at least 35 feet (11 meters) away from the house for proper root development and to minimize damage to the building(s)."

    "Large trees are also recommended for parks, meadows, or other open areas where their large size, both above and below ground, will not be restricted, cause damage, or become a liability."

    See: http://www.treesaregood.org/portals/0/docs/treecare/Avoiding_Conflicts.pdf

    5. National House Building Council, UK

    "ZONES OF INFLUENCE All trees have radial 'zones of influence' on buildings, that diminish the further away from the tree the construction takes place. As a rule, it is recommended that properties be built at least a distance equivalent to the tree's height away from that tree."

    From: "The second in our series of NBS Shortcuts examines the effects of tree-root systems on building design", www.thebuildingregs.com
    Resource: National House Building Council (2006) 'Building Near Trees', Chapter 4.2; BS 5837 (2005) 'Trees in Relation to Construction. Recommendations.'


    6. Ministry of Agriculture, Food and Rural Affairs, Ontario

    (Supplemental information available under: "How tree roots grow in the soil", "How tree roots plug drainage tiles")

    "Avoiding Plugged Drainage Tiles:

    "Trees:
    Drains that are within 15 m of trees and that carry water for prolonged periods during the growing season may become plugged with tree roots. If possible, remove all water-loving trees, such as willow, soft maple, elm and poplar, for a distance of 30 m from the drain. Give other trees a clearance of 15 m. If it is not possible to remove the tree or reroute the drain, use continuous non-perforated pipe for a distance of 15 m on either side of the tree."

    See: Farm Tile Drains and Tree Roots
     
    Last edited by a moderator: Nov 14, 2017 at 9:28 AM
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  17. Polar

    Polar Active Member

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    Thank you Georgia Strait - all excellent points to consider!! The 'planting distance' issue is one small factor (though important) amongst the many other considerations you pointed out!


     
  18. Georgia Strait

    Georgia Strait Active Member

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    ... and? did you choose a tree? for which planting locale (rocky Pender Hrb or urban NVan)?
    it'll be interesting to learn of your progress - and what you'd do again or maybe not ; )

    ps - for a short tree (up to approx 12 feet height and approx 6 foot spread), does well in drought once established, native planting at the BC Coast - I have stated on this website several times - I swear by Acer circinatum (Vine Maple) - in the ground and in really large containers. Yes they make a messy leaf drop in the autumn but it's small leaves - easy to clean up if near deck or stairs etc. (and I can maintain it myself~)
     
  19. Polar

    Polar Active Member

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    I've been looking at Acer circinnatum (which I too really like) but resisted because what I've read says it does well with drought if in a shadier location. My spot is full sun... it may also get too large?

    So I was looking at Morella californica (evergreen), the compact Arbutus unedo (evergreen and nice flowers/fruit) but now also exploring shrubs with fall colour (Cotinus coggygria 'Ancot' or other 'chartreuse' forms) or summer/winter interest shrubs such as the seedless (but not flowerless!) Buddleia 'Asian Moon' - but maybe not big enough. Amelanchier alnifolia too but wonder if it might look too straggly throughout the winter?

    Was exploring Chilopsis linearis but suspect it isn't cold hardy to here though Dirr rates it in our zone. But local sites rate it as USDA 8-10.

    What about Vitex agnus-kastus?

    I'm also looking at Cornus mas but wonder how drought tolerant it really is in full sun... is it interesting enough to be a specimen/focal point plant? Wonder what it's mature height becomes here on the coast...

    If you or anyone reading this has had experience with any of the above growing on an oceanside property with little access to water, please let me know what you witnessed. We can water the plant until established but after that our bylaws do not allow further watering!!

    So I'm still looking. Wishing for a tick on all these traits:
    - drought tolerant
    - mature size under 15 feet
    - fast growing to mature height and then spread/breadth can be accomplished over time
    - low maintenance
    - specimen for focal points (ideally with multi-seasonal interest)
    - no foul scents (i.e. some viburnums)

    ... and so it goes. What a tall order I'm placing!!!!

    Some of the sites I look at:

    Select a Tree: UFEI - SelecTree: A Tree Selection Guide

    Great Plant Picks:
    View Plant | Great Plant Picks

    Vancouver Trees app

    Monrovia

    ...to mention a few coastal ones.

    Cheers!


     
  20. Georgia Strait

    Georgia Strait Active Member

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    re: Acer circinatum (Vine Maple) --- at a previous home, I had a vine maple beside the house foundation and it made a nice screen across a 2nd story house window and outdoor balcony - aside from leaves falling off and sometimes having to trim a branch in the way - it was pretty and seasonal too (I put warm-white LED lights on it for winter interest)

    i would again estimate that the height was 12 feet - and - spread approx 6

    at the current house at the coast nr you - I have several vine maples --- one was planted 7 yrs ago in crusher dust gravel and some decent soil - it's about 10 feet tall and narrow (because I have trained it and also trimmed it discreetly)

    I find that once they are established - then the drought like we had at coast since (late?) June 2017 to approx a week ago (rain) is ok. I think I put the hose to dribble on it once or twice - that's it. This tree I describe is in HOT early morning sun (faces due east) til approx 4 pm at this time of year.

    they withstand ocean salt air and the usual deep freeze that we get for that week in the winter with the sudden freezing outflow temperatures

    it looks really nice with salal planted around it - and then I hang a shade hanging basket from it (like a fuchsia or amazing begonia from John on Pell Road in the Creek) from one of the stronger branches to add some decorative color (and hummingbird snacks) --- this is a normal subdivision town small garden (not an acreage)

    vine maples are sometimes hard to find in the nursery - esp if you want ASAP results! - I find that Suzanne at Jardin de Flores also on Pell Rd in the Creek off hwy 101 is very helpful at finding a special order like that. She's great.
     
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  21. wcutler

    wcutler Renowned Contributor Forums Moderator VCBF Cherry Scout 10 Years

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    I don't belong in this conversation at all, but will mention a beautiful vine maple cultivar I just learned about from Douglas Justice's August blog: Acer circinatum 'Monroe'. I posted a few photos at August 2017 in the Garden - Acer.
     
  22. Polar

    Polar Active Member

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    Thank you Georgia Strait! Such useful information. Thank you for sharing your direct experience of the vine maple. I have two spots for one in each - as I wish to bring the eye along from one area to the next using the same plant. The first area gets a lot of sun.... the plant would be out in the open - buildings nearby do not provide shade at the height of summer sun. The other spot has shade until about 11 a.m. and then summer sun until 7 or 8 pm. I'm still hesitating.... would like to have this mostly vase-shaped, almost yr-round interest plant to soften edges and buildings in view and also provide a bit of privacy during busy summer months.... I like the flowers/samaras in spring, the leaves' shape, their lime colour in spring, the yellow-orange colour in fall.... and that it is a BC native though not to the Sunshine Coast (I understand that the A. glabrum is supposed to be the smaller native maple here and that it needs more moisture and/or shade - have you or anyone reading this had experience with this latter plant?

    I'll let you know what I do!

    Also thank you for advice re: nurseries here on the coast :-)
     
  23. Polar

    Polar Active Member

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    I looked at: Elbert L. Little, Jr. (1971), Atlas of United States trees, Vol. 1, conifers and important hardwoods:
    U.S. Department of Agriculture Miscellaneous Publication 1146, 9 p., 200 maps.


    Now I'm confused as to what is native to the coast... the above reference shows both A. glabrum and A. circinatum as occurring here (but not unique to here). But I'm also reading otherwise on the forum....

    Did Little base his mapping on what he saw growing here or did he actually find specimens in the wild? Or was it that specimens were introduced to the coast much earlier on and may have seemed 'wild'? After all 1971 is quite late in the evolution that was already occurring here through tourism, logging, farming, fishing... just boat out to Hardy Island or Desolation Sound to find St John's wort and laburnums having escaped from nearby abandoned homesteads....

    I merely find this interesting but nevertheless, coast natives or not, these maples are close neighbours to the coast.

    My concern remains finding a plant that has sufficient attractive features (to fellow humans :-) to be a focal point and that will take full sun, tolerate salt air and drought, grow to at most 15', grow quickly upwards and fill out laterally/ broaden or thicken over time..

    Yes, I am chuckling at myself - I love plants and do not want to plant something that will die too soon or have to be removed within 30, 40, 50 years or so because it has outgrown its space. 'Old trees' are such a pleasure to have, they have such character when placed in a well chosen spot and allowed to mature.

    Cheers!
     

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