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
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.
ABCO Construction Services Corp.
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
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.
CMHC Policy and Research
More Design Regulations
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.
Your October Backfill brought to mind a photograph I
took not long ago while visiting China (below).
Blue Springs, Mo.