How much growth to expect from a Garry oak

We are fortunate to have two large Garry oaks in our yard in Victoria. It's been estimated that they are about 100 years old. One with two main stems is growing very close to the house--within inches of the eaves on our covered deck. We need to repair the deck and want to leave enough clearance without compromising our interior space too much. Anyone have a ballpark figure to determine how much expansion in diameter to expect per year? The trees have been cared for by an arborist and recently had some cable bracing added in the upper branches to provide added stability, with permits from the City of Victoria. Your thoughts are appreciated.

 

From: Quercus garryana Dougl

I would guess your tree is more likely in the slower-growing end.

 

Thanks Daniel, Am sorting out the lingo and the numbers you provided. So if there are 6-8 rings per centimeter, that's roughly 3 mm diameter growth per year? I also just remeasured: the tree is a meter diameter at the base, and immediately splits into two stems, 12 meters high. So at dbh on a slower growing oak, I can expect each stem to expand by the slower rate 3mm/year? Attached are two more pics. You can see why I'm concerned. Planning to rebuild the deck and want to make space for the tree. If the arborist's estimate of 100 years old is correct then it has grown an average of 10 cm diameter a year, which seems a bit much.

 

At breast height, 4.5 ft above ground level, it appears that your tree has already split into 2 trunks; so the diameter of each should be measured. Assuming that the individual diameters are around a half meter, then the growth rate would be 0.5 cm diameter per year, corresponding to 4 rings per cm (counted on the radius), which is within the ranges mentioned in the article.

 

Thanks vitog, Very helpful indeed.