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What’s a ‘rule of thumb’ about how far to build a foundation from a good sized tree. My situation concerns a large fir tree (30″ Dia.). I’d like to put a foundation for a 2-story addition within about four feet of the tree.
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It appears you are going to kill about 1/2 of the roots and if the wind blows while the foundation is dug but not poured you may not have a tree.
This is not to say you cannot do it..
*we put a 4' foundation about 3' from a good sized oak...16 years later the oak is still healthy and thriving... i think it has some roots deeper than the foundation.. and i think we got lucky... usually anything inside the drip line is risky.
*I second George and Mikes comments - this sounds like a valuable tree, so if you decide to try to keep it, there a few things you can do to help - - - try to get a clean cut along the line of the hole - I'd think in terms of hand digging and chopping roots with an ax through the zone of the dripline - at least have the hoe operator dig with his bucket at 90* to the tree in this zone so the machine doesn't snag the roots and disturb them closer to the tree than the trenchline - - - keep machines off the ground within 10' of the dripline - don't pile dirt, change the grade, bury utilities, drive concrete trucks, wash out concrete trucks, compact the soil - etc etc - keep your impact on the tree to the minimum - -it would be preferable to dig in very early spring, and try to avoid disturbance during the shoot growth period of spring to summer - trees have a balance between the roots and top, possibly you could have 10-20% of the top removed to reduce the demand from the top for water and nutrients - I offer this with hesitation; this is a big tree, this strategy has to be carried out with b many small cuts, and most tree services are butchers - don't let anyone make a dozen 6" cuts - it'd be better just to remove the tree now - minimize water stress on the tree thru the next couple of years - b before it gets dry, sprinkle the area within the dripline and out 10'; think in terms of 1-2" of water every week to 10 days thru the growing season if there is not an equivalent amount of rainfall - use a can set on the ground to collect and measure the irragation so you know how much you are applying - this addition will alter the hydrology of the immediate area - is the roof run-off diverted away from the tree such that the area it's in will be generally drier than it is now? if so, irragation as decribed above should be maintained for several years - conversely is the run-off going to get channeled into the tree area? this too can be deadly - distibution of roots in the soil profile is affected by the nature and properties of the soil - Mike's oak might exist on a well drained, deep soil such that the project disturbed a smaller percentage of the roots than if the tree were on shallow soil with a spreading root system - hope you are lucky with the variables and your tree provides you with beauty and shade for many years to come - DOUD
*Bob - No way would I do this. You might get lucky and the tree wouldn't die. But I'd say the odds are better than 90% that it will. If it lives, you'll have to worry indefinitely if the tree is going to blow over on the house, or drop a branch through the roof in an ice storm, etc. And figure on cleaning out your gutters frequently. Think of how much it will cost to take the tree down once the house is completed. (When it dies)Check out this article at JLC:http://www.jlconline.com/cgi-bin/jlconline.storefront/3c6d07060079ef55271b401e1d2905ae/UserTemplate/82?s=3c6d07060079ef55271b401e1d2905ae&c=0fd2b71e50c3f13e9c7fbc1f27b94f0b&p=1
*Bob,We've been on many jobs over the years where they have built within 5-6 feet of a large tree - some considerably larger than what you have. The big issues seems to be keeping heavy equipment off the area within the drip line of the tree, making a clean cut of the roots and not allowing the cut bank with the exposed root ends to dry out.I checked my trusty tree reference guide and read that firs prefer to grow in moist soils to start with so a plastic drape (drop cloth) over the cut bank will probably do the trick to slow down the drying process of the root ends.The biggest concern that I could gather from the reference source was the potential fire hazzard that firs pose when not mature, and mature trees top out at 100' to 300'+ depending upon the species. Hmmm. It seems that these issues may be of greater importance than whether or not the tree will live.Keep us posted. I'd like to know what you decide and how it turns out.Cliff.
*Let's see;; a shallow rooted tree with root damage that grows very tall and generally rots from the core within four feet of the house. Not a pretty picture in my mind.But like they said: Let us know what you decide.
*It might be good to look for some tree experts instead of construction experts. Some species grow a branching root system that seeks water, and others grow what is called a taproot, a big root that goes straight down, kinda like a carrot on a grand scale.The trees that get blown down around here tend to be ones that have a branching root system, and have found most of their water near the surface from lawn watering. They resist getting pushed over about as well as a floor lamp with a heavy base. Taproots and deep branching systems do much better, they perform more like fence posts. To get a branching system to go deep, what you need to do is water the tree by filling a basin dug around it. This makes the water soak in and go deep, and the roots follow.-- J.S.
*Here's a link from Google:http://www.co.st-lawrence.ny.us/Cooperative_Extension/forestry/CONSTRUCTION_DAMAGE.html
*And don't forget the damage roots can have on foundations, especially block foundations for basements. (More danger with spreading roots systems, less with tap root types.)Rule of thumb no cloder than 5', but I personally think that;s too close. Crap falling on the roof, plugging the gutters and downs; moss growing on the roof, etc.
*Its best to try to stay out of the drip line.I had a large 10+ yr old, very large [80" dia] Maple within 10' of a large addition. This tree definetley suffered as a result of the digging and machine travel. Took three plus years before coming back full force.There was no way to avoid keeping the machine out of the drip line. Wish I could have.The tree dead pruned and fertilized the first three years. A new sprinkler system probably also helped.Take a pry type bar and poke 10" holes every 2' around the drip edge of the tree. Fill the holes with 10/10/10 fertilizer. The feeder roots are within the first 18". Let the rain do the rest.
*That should read 100 + year old tree
*Thanks for everyone's input. I'm back at the drawing board working on a revision of the house footprint that will provide more clearance between it and the large fir tree. Although there's certainly no shortage of big firs around here, its absence would be noticed in the neighborhood. There's plainly enough evidence against building too close to a tree - how close is up for grabs I guess, but I'm going to limit my foundation to the drip line of the tree.
*One more negative on the structure too close to the tree.I'm currently quoting a job where a massive root has traveled under the footer and slab of a house, raising it just over 1 1/2 inches, causing a severe crack in the footer and slab, a terrazo slab, no less, that travels diagonally completely through from the back to the front of the house. The fix is to demo the whole bedroom slab, remove the root structure, fill and treat as a new slab pour and then go out side, trench about 20' plus along the footer, cutting all the roots, apply a root shield along the length and then salt the trench before backfilling. The tree is not really expected to survive but you never know. There is extreme resistance to removing the tree, a mature oak.
*Bob:Before spending too much effort on saving the tree it would be a good idea to make sure it is healthy and has a remaining life expectancy long enough to matter. Lots of the firs, spruces, etc die from the inside. Also, I'm told by the experts that these species sort of die of old age; unlike most of the hardwoods.There has to be someone at your local Coop Extension, or something similiar who could help you on this.
*For what its worth, my house was built to nestle among and miss the bigger trees(love'em in place)with 8 foot to center of two close 30+ inch Douglas Firs, 6 foot to a couple more 20"ers off the SE corner, and 10 ft to a 3 ft+ dia off the NE corner. 30 years and no problems, did not cut any of the roots for foundation. Absolutely DO NOT leave a single big tree standing by itself if it grew in a cluster. As BobW said, the needles (crap) will be a BIG BIG problem requiring CONSTANT attention. Be sure your roof has copper or zinc strips. Had galvanized gutters that rusted out in 3-4 times a year. Have had to fix 2 "small" holes due to 4 in dia branches falling (obviously, they fall butt down) during storms. The trees are still worth it though. The garage is only 1 (one) foot from 3 different 24" + dia firs, but the foundation is only 12" deep, and was built with 6 ft + gaps in the wall foundation over known root branches with 4X10 sole plate over the gap. Driveway was built with 4 specific smaller sections meant to be replaced every 15 years or so due to root rise. Good luck.
*call the arborist. make sure it's healthy and worth planning around. get his recommendation on where it's considered safe to place your foundation and how to protect your tree. use a root shield to protect your foundation.once had a (very capable) landscaper check on trees that lined a street that ran down the middle of an apartment complex i supervised. he found half of them to be diseased.when i was a kid, we had an old oak growing about 5-6' from the house. thank god it fell away from the house!brian
*Art,Real nice to hear positive results and how you obtained them. Sounds like a very well executed plan to allow enjoyment of Mother Nature at her finest.Cliff.