Protecting Trees on Site

While it’s important to protect tree trunks from equipment bumps (On the Job, 9/08), it’s more important to protect the roots from compaction due to equipment running over them. Compaction of tree root systems is the leading cause of tree decline and death on new construction sites, although the damage is not apparent right away. It can take years for the tree to decline and eventually die.

The proper way to protect a tree on a construction site is to fence it off to at least its drip line. We use snow fencing to make a barrier around the tree and make sure all equipment and materials stay outside it. In situations where access is needed closer to the tree, you can pile 10 inches of landscaping mulch over the root systems to minimize compaction, then remove the mulch after the work is done. If you do compact tree roots on a site, an air-infiltration tool can be used to literally blow air into the ground around the tree, breaking up the compacted soils. But the best protection is to stay away from the tree altogether.

Bruce Zaretsky

No Cover-Up Intended

I was surprised to see the cover photo of the August issue: The weather-resistant barrier does not fully cover the OSB or the rake trim boards — a condition I’ve written up many times in the field.

Rex Splitt

ABCO Construction Services Corp.

Centennial, Colo.

Author Trevor Kurz responds: We get a lot of wet weather here on Cape Cod, and we would never install roofing over a patchy substrate. Keep in mind you’re looking at an unfinished renovation project where rake trim extensions were added to the house. After the trim was installed, we folded back the existing roofing felt and ran a course of Ice & Water Shield up the rake to the outer edge of the cornice, then folded the paper back over the membrane. We also ran a soldier course of shingles all the way up the rake to cover the transition between the membrane and the felt. This is standard practice for our company.Also, that’s plywood roof sheathing, not OSB.

Radiant Heat Claims Revisited

I would like to respond to Lawrence Drake’s letter in the October issue. The “Canadian utility company” that published the “small, unscientific survey” that Mr. Drake criticizes is actually Canada Mortgage and Housing Corp. (CMHC), a federal agency. A summary of the study can be found at cmhc-schl.gc.ca/odpub/pdf/62675.pdf. While I admit that the 2001 survey was small (50 houses with radiant heating), it is curious that the manufacturers and distributors of radiant floor heating have not yet found a scientific study refuting the CMHC findings.

Don Fugler

CMHC Policy and Research

Ottawa, Canada

More Design Regulations Unnecessary

I fail to see where California SB 1312 addresses the “issue of protecting the customer,” as stated by Jack Smyer, AIA (Letters, 8/08). Isn’t that what our building codes do? Isn’t that why we have inspections? Certification never guarantees that a designer will absorb or apply the good practices he or she is supposed to be imparting to the public. But it does guarantee that designers who previously were not certified will have to charge more, which will only help to place critical design services out of the range of more people. I believe we have enough fees and regulation in place as it is.

Audrey Allen

Designer

Bend, Ore.

Pedal Power

Your October Backfill brought to mind a photograph I took not long ago while visiting China (below).

Ken Landes

Blue Springs, Mo.