Posted on

Too Much Roof Snow?

Can my roof collapse from too much snow load? It’s possible, but highly unlikely.

Since about 1950, cold climate states must adhere to engineering principles that configure the structure of the roof. They are based upon the highest potential roof snow load in your area. The building code will then require the roof be designed and sized to safely meet or exceed those live snow loads. In Minnesota that load is 42 pounds per square foot north of a line that crosses the state just south of Hinckley. The south side of the line which includes Minneapolis and St Paul is 35 pounds per square foot.

How deep would the snow be if there was 35 pounds of snow per square foot on the roof?

Well…if it was light snow it would be 5 feet deep! If it was medium or normal density it would be 2.5 feet deep and if it was tightly packed, it would be more than 1.5 feet deep. The measurement by the way would be uniform over the whole roof. In the real world there will be places that are less deep or less dense. These include areas that are covered by roof overhangs, spots protected from wind, and behind chimneys and dormers. So, if your roof meets current code, you have little to worry about.

However, if your home is hundred years or so old or you have some reason to doubt that it has been built to code, you may wish to remove some snow. Remember though, if you are removing snow you are removing a very good insulator.

If you must remove snow use a roof rake with extension handles. Never stand on the roof or scrape the roof bare as this may damage the shingles. Be very cautious about letting someone who comes knocking on your door remove the snow from your roof. Check their credentials. Make sure they have insurance.

This could become a very expensive mistake!

Doug Hastings
MN Home Inspector, Minneapolis & St. Paul
ASHI certified inspector, ACI
Kaplan University, Home Inspection Lead Instructor

Rob ‘Pops’ Leslie
Kaplan Professionals, Retired

Posted on

Is Your Life Worth $25?

This very cold winter has been responsible for many accidents, including deaths from CO (carbon monoxide) poisoning. 

These disasters might have been averted if a properly located and operating carbon monoxide alarm had been installed. For just $25 a battery-operated or for $50 a hardwired alarm can be purchased and installed.

What is CO?  Carbon monoxide is a toxic gas that is tasteless, odorless, invisible, and none irritating gas. It also weighs approximately the same per cubic foot as the air in your house. If it is going to poison you, you won’t know anything about it!

What causes CO?  CO is a product of incomplete combustion due to an insufficient oxygen supply. This can occur by not supplying a fossil fuel burning appliance with enough air. Your furnace, water heater, fireplace, automobile either needs to be located in a wide open space or have an outside air supply. There are formulas for how big an open space is needed, but by installing an outside air supply you are assured of having sufficient air for complete combustion. Or carbon monoxide occurs when fossil fuel appliance burners are incorrectly tuned or when the burner exhaust system is blocked or leaking. In other words you are re-burning the original exhaust products. A safe appliance produces carbon dioxide (CO2). Only when there is not enough oxygen in the air or when you re-burn oxygen from the CO2 does the appliance become a CO producer.

All homes should have a CO detector within 10’ of all bedrooms.

What is the action level?  Obviously you would like to have zero CO in your house. But that may not be possible; you should expect a level of less than 15 ppm in your home. Exposures at 100 ppm (parts per million) or greater can be dangerous to human health. At this level the symptom would be a slight headache in 2-3 hours of exposure. People who survive CO poisoning and complain of low to severe headaches and nausea are lucky. They just got a relatively low dose of this insidious poisoning. Elevated levels of CO will simply kill you before you know anything about it.

All systems that burn fossil fuels… Oil, Gas, Wood… should be examined and tuned by an expert annually.

Doug Hastings
MN Home Inspector, Minneapolis & St. Paul
ASHI certified inspector, ACI
Kaplan University, Home Inspection Lead Instructor

Rob ‘Pops’ Leslie
Kaplan Professionals, Retired

 

Categories

BLOGS BY CATEGORY