Reuben's Home Inspection Blog

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How Much Snow Can My Roof Hold?

After the recent collapse of the Metrodome roof, the collapse of a hardware store roof in Glenwood, and a recent Super bowl commercial from Allstate, some Minnesota homeowners are starting to wonder if they should be worried about their own roofs.  In December, I even received a question on the Structure Tech Facebook page asking how much snow a roof should be able to hold if built to code.

The video below shows the Super bowl commercial; this is what finally inspired me to write a blog on this topic.
The required roof snow loads for Minnesota aren't clearly spelled out anywhere, but the numbers can be found by using Table R301.2(1) of the Minnesota Administrative Rules.  This table says that roof snow loads equal .7 times the ground snow load.  To find the ground snow load, we use section 1303.1700 of the Minnesota Administrative Rules.  The southern portion of Minnesota, which includes the Twin Cities metro area, uses a ground snow load of 50 pounds per square foot.
For the Twin Cities metro area, the ground snow load equals 35 pounds per square foot, or .7 x 50.
Bucket of SnowSo how much snow does this equal?  It depends.  As everyone knows, cold fluffy snow is very light, while wet snow can be extremely heavy.  I've heard that very wet snow could weigh up to 20 lbs per cubic foot, but we haven't received much of that this year.  I just checked a section of undisturbed snow in my back yard, where the snow is about 12" deep.  For the record, we've received over 60" of snow this winter.  According to my calculations, the snow weighs about 10 lbs per cubic foot, which conveniently equals 10 lbs per square foot.

If you have a properly constructed roof, you shouldn't have to worry about your roof collapsing, even if you get some big snow drifts on your roof.   On the other hand, if you know you have structural problems with your roof, this would be a good year to have some of the snow removed from your roof. 

Reuben Saltzman, Structure Tech Home Inspections

        

Comment balloon 53 commentsReuben Saltzman • February 08 2011 06:21AM

Comments

Good Morning Reuben, excellent input for home owners in snow country.

Posted by Dan Edward Phillips, Realtor and Broker/Owner (Dan Edward Phillips) over 7 years ago

Hi Reuben - This is really great information in a year when many of us are receiving record amounts of snow. I hit Suggest.

Posted by Judy Klem, Home Staging, Senior Move Management, Fairfield/New Haven counties (Transition Stage LLC) over 7 years ago

This is fascinating, and I enjoyed your research! Having worked in an elementary school, you'd be a wonderful guest for a science class at a local school!

Posted by Mara Hawks, Inactive-2012 REALTOR - Homes for Sale Auburn Real Estate, AL (First Realty Auburn ) over 7 years ago

Great blog, Reuben.  I was watching CNN yesterday and they were talking about the weight of snow on rooftops and how heavy the snow is per square foot, with room for error.  But still, it's heavy and blog-worthy.

Posted by Kimberly A Norgard (Devlin McNiff Halstead Real Estate) over 7 years ago

Dan - thanks, this stuff has been on a lot of people's minds.

Judy - thanks, the feature happened very quickly!  Much appreciated.

Mara - my high school physics teacher made me want to be a teacher when I grew up.  This is kind of close :)

Kimberly - I wish I would have seen that.  I'll have to try to pull up that video clip online.  Thanks for the info.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 7 years ago

Everyone's asking that question since the Allstate commercial!  As you point out though, different snow has different weights...reasons for a good home inspection before buying!

Posted by Laura Giannotta, Your Realtor Down the Shore! (Keller Williams Realty - Atlantic Shore ) over 7 years ago

Roof rakes are good investments...know what you don't know and be more safe than sorry !

Posted by Sally K. & David L. Hanson, WI Realtors - Luxury - Divorce (EXP Realty 414-525-0563) over 7 years ago

Laura - I guess this was good timing.

Sally & David - absolutely.  If you get a lot of snow, you should have a roof rake sitting in your garage.  Just in case.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 7 years ago

I would live in constant fear of a roof collapse if I lived up there. How does a roof rake work?

Posted by David O'Doherty, Clayton NC Homes, Raleigh, NC (Raleigh Realty Inc) over 7 years ago

Reuben, I find there can be great variation in the weight of snow, whether it is the heavy wet snow or the powdery light snow...

Posted by Chris Smith, South Simcoe, Caledon, King, Orangeville Real Esta (Re/Max Chay Realty Inc., Brokerage) over 7 years ago

My husband and I were talking about the math this weekend...thanks for the info Reuben.

Posted by Brin Realty Associates Team At Bean Group, Amherst NH homes and Southern NH real estate (Bean Group | Brin Realty Associates) over 7 years ago

Definitely a concern with all of the snow we have gotten this year (and last)!  What do you think of the "tablets" that you can throw on the roof to melt the snow?

Posted by Kathy Kenney, Realtor - Princeton & Central NJ Homes for Sale (Keller Williams, Princeton, NJ) over 7 years ago

Not completely off the subject, but did you know that not one snowblower can be found in the state of CT. 

This is very good information for people who live in the Northeast this year.... to include me.  I have a flat roof... not fun.  It has been shoveled, thank goodness.

Posted by Valerie Osterhoudt, ABR, Cromwell, CT Real Estate ~ 860.883.8889 (Johnson Real Estate, Inc.) over 7 years ago

Rueben, great post. I think as homeowners we just think the roof will hold. Maybe not with these record snows. Last year here in Virginia, we had snow that was upwards of thirty and fourty inches in places. We actually had to pay roofing contractors to shovel off the roof. It took four men three hours to get the job done! I'm glad we did, others nearby weren't so lucky.  Ice jams, water damage, gutters falling off. Better safe than sorry.

Posted by Peggy James, Woodbridge Virginia Area Real Estate Specialist (EXIT Realty Associates) over 7 years ago
Reuben, i guess the checking of choice should be the support of interior rafters and such & stay off the roof..keep to the ice melt in pantyhose i've heard is a great solution. Until I saw a story on the weight of snow on a roof, i had no idea...it's a worthwhile concern..thanks
Posted by Ginny Gorman, Homes for Sale in North Kingstown RI and beyond (RI Real Estate Services ~ 401-529-7849~ RI Waterfront Real Estate) over 7 years ago

Very timely advice.  In Massachusetts we have had over 90 incidents of roof collapse over the past several days due to high snowfall amounts, followed by rain & ice last week that made for very heavy roof loads.  Some schools and businesses are closed as a precautionary measure while structural integrity of some roofs is checked.

Posted by Christine Smith, Exclusive Buyer Agent & Attorney, Canton, MA (Buyers Brokers Only LLC - www.BuyersBrokersOnly.com) over 7 years ago

How much snow can my roof hold? is an excellent post Reuben.  Thank you for your research and insights into this very important question.  I have seen roofs collapse and when it happens, too often there is no time to escape.  It is sudden and merciless.

Posted by Dan Quinn, Dan Quinn (Berkshire Hathaway HomeServices PenFed Realty) over 7 years ago

Hello. as a fellow inspector here we don't have the snow problem. But I am from Michigan, there we do. I have always been keenly aware of the weight and the consequences.

Great post,

Clint McKie

Posted by Clint Mckie, Desert Sun Home, Comm. Inspection 1-575-706-5586 (Desert Sun Home, commercial Inspections) over 7 years ago

I have no desire to know that - which is why I moved from Michigan to Phoenix many years ago!

Posted by Tony and Suzanne Marriott, Associate Brokers, Serving Scottsdale, Phoenix and Maricopa County AZ (BVO Luxury Group @ Keller Williams Arizona Realty) over 7 years ago

Reuben, I know from first hand experience how heavy snow can get. Last year we had a roof buckle on a patio enclosure. Good info.

Posted by Michael Setunsky, Your Commercial Real Estate Link to Northern VA over 7 years ago

A very timely post Reuben. I love the 'Mayhem' guy. It's good to remind people that, in general, if they don't already have a weak structure, then snow is not going to be a problem. Houses were built to handle it, and then some.

Posted by Robert Butler, Montreal Home Inspector | Aspect Inspection (Aspect Inspection) over 7 years ago

I saw the title of the post and just new it had to be someone from MN.  Loads of snow on my roofs and everyone is sold out of snow rakes.  We had one ice dam removed but water leaked in and ruined one of our ceilings.  Now water is leaking into an upstairs bedroom and I know it is an ice dam causing the problem.  If I could just get the snow off the roof we culd make it through this. No worries about a roof colapse, ceiling colapses are more of a concern

Posted by Teresa Boardman (Boardman Realty) over 7 years ago

Every year there's the news story of the whatever that collapsed from snow weight.  That commercial is really funny, but pretty true!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 7 years ago

This is a great post to remind people how heavy snow realy is! In my area I have always told people if they have a low pitch roof they should use a roof rake to take some of it off. They don't need to get it all off just as far as they can reach with the rake. And don't climb up on the roof! As Valerie says, probably a better chance of hurting themselves falling off the roof!

Posted by Darryl Salls (Darryl Salls, Century 21 Energy Shield Realty) over 7 years ago

Great advice, especially for the folks who are getting 21 inches over night.:)

Posted by Traci Ferguson, Realtor, EcoBroker, LEED AP (San Luis Obispo Realtor & ecoBroker with Patterson Realty) over 7 years ago

Hi Reuben,  Great post.  As a Michigan transplant I remember shoveling snow off the roof to lighten the load.  We never really knew the stats but always kept an eye on the roofline.

Posted by Bill Gillhespy, Fort Myers Beach Realtor, Fort Myers Beach Agent - Homes & Condos (16 Sunview Blvd) over 7 years ago

I am glad we don't have to deal with snow here.  I have seen one structure in another part of the state that did have a roof that wasn't safe for snow.  See my post http://activerain.com/blogsview/1951278/diy-porch-additions-gone-wrong.

Posted by Loren Green, Phoenix Home Inspector & Designer (Greens Home Design L.L.C.) over 7 years ago

Hi Reuben - I've often wondered how a homeowner would calculate the snow load and am thankful for you pulling this together.  Even though our rating is most likely very different than those listed it is still great to know the basics of how roofs are rated.

Posted by Peter Clay - NoCo Home Team, Sell Smart, Buy Wise & Live Well in Nrthn Colorado (Fort Collins Realtor @ C3 Real Estate Solutions) over 7 years ago

I hope we don't have to think about such a hefty amount of snow anytime soon. But if I do, I know where I'm turning for my info!

Posted by Aaron Seekford, Ranked Top 1% Nationwide 703-836-6116 (Arlington Realty, Inc.) over 7 years ago

We've had many roof collapses here in MA. It's the first year I can remember this happening with such frequency.

Posted by Larry Costa, Realtor, Carver MA Real Estate (Century 21 Classic Gold, Carver MA) over 7 years ago

Great information, that many of us take for granted. Of course, here in Utah we have the "Greatest snow on earth", which is always of the light and fluffy variety...Thanks for the info!

Posted by Chris and Berna Sloan, Tooele UT (Group 1 Real Estate) over 7 years ago

Reuben, that collapse on the Metrodome was something else and structural engineers need to take into account the weight of snow.

Posted by Gary Woltal, Assoc. Broker Realtor SFR Dallas Ft. Worth (Keller Williams Realty) over 7 years ago

Great info. I grew up in NJ - snow caved in our garage years ago and we had it rebuilt!

Posted by Gerard Ladalardo (Black Ops Outfitters) over 7 years ago

Hi Reuben, great post.  You combine a current topic with a bit of science or engineering and common sense.  Thanks

Posted by Dale Ganfield over 7 years ago

David - you can see a photo of me raking snow off the roof of my old house here http://activerain.com/blogsview/2054140/preventing-ice-dams-from-the-exterior .  It's a great way to pull snow off your roof, but it's hard work.

Valerie Z - solid advice.  A local doctor died on Christmas day this winter when he fell off his roof, and there have been tons of trips to emergency rooms this winter as well.

Chris - definitely.  Through all of the freeze / thaw cycles, the snow on your roof will usually get more and more dense.

Rene - my pleasure.

Katherine - You can see how those tablets work here http://activerain.com/blogsview/2019235/how-to-get-rid-of-ice-dams.  They don't.

Valerie O - I have no trouble believing you're out of snowblowers in CT.  I've been getting far more web traffic from CT than anywhere else, and it's all about ice dams.

Peggy - wow, that's a lot of snow.  I wonder if the roofs in Virginia are designed for the same snow load?

Ginny - I actually did a little test of my own with the pantyhose salt thing - http://activerain.com/blogsview/2068588/ice-dams-pantyhose-salt

Christine - Ninety roof collapses?  WOW!  It's a pretty rare event up here.

Dan - I hope I never get to find out ;)

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 7 years ago

Clint - thanks!

Tony - I heard Texas got snow this year.  You're not off the hook yet... :)

Michael - bad news.  I'm glad it didn't collapse.

Robert - I love the Mayhem guy too :)

Teresa - I'm sorry to hear about your leaks!  I've been to a ton of houses with leaking water this year, and it's always a nasty sight.  

Jay - any idea what your roofs are designed for in Virginia?

Darryl - I agree with you.  Stay off the roof.

Traci - thanks, I bet you're not too worried about this yourself.

Bill - ever try a snowblower on the roof?

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 7 years ago

Loren - I just checked out your post; that's beyond laughably wrong.  

Danielle - glad to help.

Aaron - thanks!

Larry - I heard you've had over ninety.  I'd be worried.

Chris - that is great snow :)

Gary - I had to watch that video about five times in a row to really comprehend the magnitude of it.

Gerard - I bet it was a little stronger the second time.

Dale - thanks, my pleasure.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 7 years ago

Good reminder. Thanks for sharing.

Posted by Craig Hatcher (Georgia Residential Realty, LLC) over 7 years ago

Thanks a lot, Reuben.  Now I can say I learned something new today. 

Posted by John Meussner, #MortgageMadeEasy Walnut Creek, CA 484-680-4852 (Mason-McDuffie Mortgage, Conventional Loans, Jumbo Loans, FHA, 203(k), USDA, VA,) over 7 years ago

Reuben,

Excellent Post!  Definitely worthy of a feature.  Congratulations!  This is really great information for those who live in areas where they get heavy snow.  Since I live in CA I had no idea just how bad the snow can damage homes. Thanks for sharing this with us!

Posted by Linda D. Pufford, ASPM, Marin/Sonoma Home Stager (Stage with Divine Style - Home Staging) over 7 years ago

My family is in Oklahoma and my mom owns her home and they just had a lot of snow and I was wondering the same question especially once I saw that commercial....Great blog.

Posted by Stacey Smith, Your Orange County Beach Cities Realtor (Keller Williams Realty) over 7 years ago

Hi Reuben~  I can't believe how many stories of roofs collapsing from the snow have been on the news.  I have heard that you can hardly find a roof rake anywhere! 

Posted by Vickie McCartney, Broker, Real Estate Agent Owensboro KY (Maverick Realty) over 7 years ago

We have been lucky in WV so far this year, but I wondered last year how well our roofs would do, they did just fine. Can't way much for my garden gazebo...one last year, one this year. L must learn to take them down.

Posted by Jeanne Kozak, REALTOR and Broker/Owner in WV and VA (RE/MAX In Action) over 7 years ago

We have been lucky in WV so far this year, but I wondered last year how well our roofs would do, they did just fine. Can't way much for my garden gazebo...one last year, one this year. L must learn to take them down.

Posted by Jeanne Kozak, REALTOR and Broker/Owner in WV and VA (RE/MAX In Action) over 7 years ago

What is used here is 17/32" OSB and pre-mfg rafters on 24" centers.  What does that hold?  I don't know.  I have never seen a collapse and last year we had that 5' snow, which was exceptionally unusual (like every 100 years!).  All the roofs held up under it.

And until your posts I had never seen a roof rake.  So that is something not even sold here.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 7 years ago

Craig - thanks, my pleasure.

John - good deal.

Linda - rub it in ;)

Stacey - that's gotta be pretty rare for your mom.

Vickie - the roof rake manufacturers must be having a great year.

Jeanne - Your gazebo collapsed?

Jay - In other words, your roofs are designed well enough :).  I'm no engineer; I don't know what that comes out to either.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 7 years ago

My first question would be does homeowners insurance cover roof collapse resulting from snow.

Posted by Dave Halpern, Louisville Short Sale Expert (Keller Williams Realty Louisville East (502) 664-7827) over 7 years ago

Hey thanks for the great post today, perfect timing with all the snow everywhere!

 

{Patricia/Seacoast NH & ME

Posted by Patricia Aulson, Realtor - Portsmouth NH Homes-Hampton NH Homes (BERKSHIRE HATHAWAY HOME SERVICES Verani Realty NH Real Estate ) over 7 years ago

I spent three hours shoveling off a lake home, a farm porch. Tonight tackling a home porch. It slides off easier than having to snowblow out the inside when it caves in!

Posted by Andrew Mooers | 207.532.6573, Northern Maine Real Estate-Aroostook County Broker (MOOERS REALTY) over 7 years ago

Hi Reuben Saltzman,

Thanks for sharing this information.  I think you’re exactly right about this current topic.Snow loads for agricultural buildings in southern and western Minnesota are generally around 20 lb per square foot. This does not include the weight of the wood that makes up the truss or rafters, a ceiling if one is added to the lower cord of a truss, any equipment hung from the trusses or rafters, or wind loads. Many roofs for livestock barns and machine sheds are designed for a total load of 25 to 30 lb per square foot. Roofs should be able to handle this load if the building was properly designed by a registered professional engineer and constructed by a qualified builder who followed the design.

Do you use blog marketing a lot in your business?
Thanks again,
Lauren Stevens
http://www.smartblogcontent.com

Posted by Lauren Stevens over 7 years ago

Dave - if insurance doesn't cover that, Allstate is in big trouble.

Patricia - thanks!

Andrew - I hope you're not speaking from experience :)

Lauren - yes, blogging is almost all of the marketing that we do.  We do a little with LinkedIn, Twitter, Facebook, and newsletters, but it's all centered around blogging. 

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 7 years ago

There have been quite a few roof collapses here in CT this winter. Mostly flat roofs and barns. I did hear of a few residential roofs coming down. We set a record for snow fall in the month of January (just under 55 inches), which certainly explains the mayhem.

Posted by James Quarello, Connecticut Home Inspector (JRV Home Inspection Services, LLC) over 7 years ago

I bet the insurance disaster teams have flooded your area.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 7 years ago

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