British Columbia: Big trees in the yard

We have purchased a very small new home that has mature trees in the back yard- big leaf maple and a beautiful cedar. We put ad extension on the house to within about 20 feet of the cedar. Are we going to run into problems with the roots? We don't want to damage the tree. Any advice?

 

Yes, that very likely will damage the trees.

 

Get an arborist to check the Big Leaf Maple (Acer macrophyllum). Nearly all of them have crown rot (that's what I call it anyway) & heart rot (rotten interior of the main trunk) when they are mature. Not something would want too near my house. they are a large, fast growing, disease-prone, relatively short lived species in my experience. Great in the woods or in the "back 40".

 

I put a concrete retaining wall within 20 feet of a massive big leaf maple ( 5 foot diameter trunk x 100 feet tall) on my property a few years ago and have had no problems. The footings went at least two feet below grade and i encountered very few roots. At the time time I was concerned about the health of the tree because heavy trucks drove very near the tree as there was very little space to go around.

The tree showed no damage as a result, but I made sure I watered and fertilized it well to minimize the stress on it. I have removed many other large big leaf maples including their stumps and the roots go mostly straight down.
I wouldn't worry about it...

 

Note that you always want to put protective materials like a thick layer of wood chips over the soil near trees you want to keep BEFORE any construction activity occurs in the area. Ideally there is no driving and spillage over the roots of trees that are to be kept healthy, failing that (the driving, anyway) something that will be adequate to cushion the soil completely must be employed beforehand.

Since it has been a short time decline of the one maple may yet appear.