Ask Hannah Holmes

Hannah Holmes

Home Rx

Realtor/science writer/self-proclaimed “house geek” Hannah Holmes on outwitting squirrels in the attic, cost-to-build estimates in a frothy market, and more.

Illustrations by Christine Mitchell Adams

What is the average cost per square foot to build a new home these days? We’ve been quoted $250, but I’m seeing $100 to $200 online.

What is the average cost per square foot to build a new home these days?

Short answer: between $100 and $1 million per square foot. The long answer is very long. To start, the Northeast and West are the two most-expensive regions to build in, according to a 2019 U.S. Census Bureau report. At that time, the Northeast averaged $155 per square foot. But an average is nearly meaningless because houses are so complicated.

There are dozens of choices that go into construction of a house, and each affects the final price. A doorknob set can be had for $11 at a big-box store, or $259 online. A metal roof costs more than an asphalt one. Quartz countertops cost more than granite, which cost more than butcher block. Oil-fueled heating systems are cheap to install, but a pricey heat-pump system will cost less over time.

Factor in the recent volatility of building-material prices and it’s anybody’s guess what the overall cost might be. The closest you can get to an answer is to have a contractor review your house plans. He or she will work with a lumber yard to arrive at a cost for materials. But even that estimate is subject to change, because lumber yards can’t always guarantee their own pricing in these strange times.


When do you need a radon-mitigation system, and how effective is it?

When do you need a radon-mitigation system, and how effective is it?

When humans lived in well-ventilated caves, we did not worry about radon. Now that we build increasingly airtight homes, this naturally radioactive gas rises from the Earth’s bedrock and gets trapped inside. Maine is a radon-rich state, and trapped radon is responsible for quite a lot of lung cancer.

Radon’s natural concentration in the atmosphere is 0.4 pCi/L. Never mind that string of letters. What’s important is that if your indoor radon reading is 10 times that — 4.0 — the federal government advises that you address it. Maine’s state guidelines suggest remediation at just 2.0.

Remediation is usually simple: technicians bore through the basement floor or slab foundation and sink a pipe into the hole. A fan inside the pipe creates an area of negative pressure under the floor. Rising radon, choosing the path of least resistance, now migrates to the hole and is hustled out to join its free-range kin. A DIY radon test costs less than $20. The cost of the fan system is typically $1,000–$1,300 installed. Because radon is shifty and unpredictable, we are all supposed to test every few years to be sure it’s not sneaking up on us.

Any ideas for dealing with squirrels in the attic?

Any ideas for dealing with squirrels in the attic?

Know thine enemy. Squirrels have their own highway systems, and you must identify where they’re getting into the house. It’s often via a telephone line or an overhanging tree. But they may also shinny right up the corner boards to a front door they’ve chewed in your eave. Have a carpenter inspect the premises and formulate a plan for changing the locks, as it were. Then plan the eviction for a time when the critters are out on an errand. Squirrels are largely daytime creatures like we are.

In early spring, and again in late summer, there may be babies up there that you don’t want to lock in. Grit your teeth and wait until they join their parents on their daily rounds outdoors. One of the things you would hate more than squirrels playing in the attic is panicky squirrels trying to gnaw their way out of your attic. And failing.

Some methods that might help to expedite a squirrel’s exit include: harassment with a radio, harassment with a strobe light, and harassment with vinegar-soaked rags (they dislike the smell). The fact that there are so many suggestions suggests that none of them reliably works. Even professional pest control companies are sometimes outwitted by the little darlings. But persistence is key. Between their smelly pee and their destructive gnawing, they can do a lot of damage.


Some have suggested that we invite people to clear trees on our land in exchange for firewood. Is that a thing?

Some have suggested that we invite people to clear trees on our land in exchange for firewood. Is that a thing?

The Maine Forest Service strongly recommends that you begin this process not with a logger, but with a forester. Anybody with a sharp axe can kill a tree. But licensed foresters are trained to assess woodlands as a system, and guide you to creating a healthy and attractive version of your woodland vision.

Without that perspective, and a detailed contract, your back forty can be a minefield of misunderstandings. The logger may not realize where your trees end and your neighbor’s trees begin. He may not be familiar with shoreland zoning limitations on where trees can be cut. Or realize that you want to remove both the valuable trunks and the less-attractive “slash” composed of tops and branches. His heavy equipment may leave giant ruts in soft soil. A forester can also recommend reputable loggers to do the actual tree killing. Find a list of licensed foresters on

Hannah Holmes is a real estate broker at Keller Williams Realty Greater Portland and the author of four science titles, including The Secret Life of Dust and Suburban Safari. A veteran renovator of old houses, she blogs about humans and their territorial issues at