Inspecting a metal roof

(David C. Macy, CMI) #1

Did my first inspection of a metal roof.

Any tips on inspecting this type of roof would be appreciated.

Can you walk on this surface.

How do you determine the age or life expectancy.

How long do the areas of penetration last until they leak.

Is this chimney covering stucco?

Thanks.

Roof was stated as 3 years old, there were no gutters, skylight leaked, no attic.

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(Raymond E. Wand) #2

I would not walk it.
Its a standing seam roof, not a cheap installation.
As the vendor for any information on date and warranties on the roof.
It is likely a lifetime roof, but refer to the manufactures information if available. This metal roof may last anywhere from 40 years on, dependent on installation, weather, maintenance..

As to penetrations they should be rubber boot type, that flexes, and allows expansion and contraction of the metal roofing. From the picture it looks like a big gap at bottom of the stack.

Flashings finishings should be complete and neat and tight. From your picture that area of the roof looks good to me.

However I am not crazy about the metal roofing as a chimney cap.

Cheers,

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(Brian J. Zimbelman) #3

Hope that helps!

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(David P. Valley) #4

Inspecting metal roofs....You can absolutely walk the roof surface if it's considered safe to walk on. No snow or rain.

You should consider the following items when performing a roof inspection on a metal roof: A) panel corrosion B) loose fasteners at panel laps and C) seriously deflected panels.

An especially important area to inspect thoroughly is the system’s roof seams. The five primary components of the seam-fastened metal roof assembly are...

1) Horizontal panel seams

2) Vertical panel seams,

3) Panel fasteners,

4) Metal panels

5) Perimeter and penetration flashings.

Deterioration of one or more of these components is the most common cause of roof leakage. Horizontal seams occur where the bottom edge of a roof panel overlaps the top edge of the downslope panel. As panels expand and contract, sealants within these seams become brittle. Foot traffic, expansion, contraction and other forces deflect the panel seams, resulting in broken seals and open seams. Strong winds, negative building pressure or ice damming during periods of freezing and thawing might force water up the slope and into the building through these voids.

Vertical seams occur where the sides of adjacent panels overlap. Similar to horizontal seams, sealant deterioration and panel deflection also reduce a vertical seam’s integrity and allow water entry in conjunction with wind, negative building pressure, or ice damming.

Panel fasteners typically contain neoprene sealing washers to prevent water infiltration. Ultraviolet exposure and panel movement from expansion and contraction normally deteriorate these washers. The fastener holes also elongate from panel movement, and in some instances, the holes are larger than the washers. Overtightening fasteners during installation immediately damages the washers and increases their susceptibility to deterioration.

Loose, missing and rusted fasteners are common deficiencies, too. Steel panels, by their makeup, are susceptible to deterioration over time. Common deficiencies include rusting, kinking, puncturing and finish deterioration. If an inspector suspects leaks from panels’ end laps, make sure sealant is present and located in front of the fastener, not behind it.

Also, note if the sealant is cracked or dried. Inspect panel terminations at the eaves, ridges and valleys to ensure closure strips are in place. These strips are made of foam or rubber and fit under the panel to keep out water and animals. Also, inspect the trim pieces at the rakes to ensure they are sealed and fastened properly. Look for buckling or standing water at the laps of the panels, which indicates unusual movement within the system.

Perimeter and penetration flashings are common locations for leaks. The effects of panel movement are concentrated at these locations, thus accelerating deterioration of sealants, fasteners and other flashing components. Premature flashing problems can arise from poor design and installation. Quality workmanship and appropriate flashing material are vital to long-term flashing and roof performance.

While walking over the roof, you should make sure to inspect penetrations, the source of most leaks. you'll need to verify that the sealant is soft and pliable where the field and flashing meet. Fasteners should be tight, and neoprene washers should be in good shape, and not cracked or dried.

Metal systems typically are installed on a slope, so drainage is not a concern. But they usually drain via gutters, either exposed or concealed, so you should check gutters and downspouts to ensure they are free of debris and restrictions. If the roof slope is very shallow, you should look for ponding or restricted drainage in the roof field. Panel deflection sometimes can cause dips, which trap roof water.

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(David C. Macy, CMI) #5

Thanks for the response.

House had no attic.

Only soffit vents that were painted. I would think the heat created would require additional ventilation.

Where was the roof venting?

I advised to obtain documentation as the roof was stated as 3 years & cost about 20K. Skylight leaked and ventilation was inadequate as it was painted.

Would of liked a thermal camera on this one!!!

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(Roy D. Cooke, Sr) #6

Looks like a ridge vent on this roof to me shows on right of chimney .
In our area steel roof frequently loose their snow in one fell swoop and off go the gutters .
Did one where the lady left her car nose into garage and the snow took out both fenders hood windshield rad grill..
She had a new Mercedes Wagon and I understand it was about $25,000:00 damage
We always recommend avalanche guards to try and control the snow.
Many steel roofs done in this area are not done properly .
I am not inpressed with steel roofs and would not have one cost in this area is about 3 times the cost of asphalt and most people move every 8 years.
I do not walk Steel roofs.

.................Cookie

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(Linda J. Foster, TREC # 7654) #7

You have to be careful on steel roofing.

Early in morning, and in the afternoon as the dew starts to happen, it gets slick as all get-out. You don't want to exit the roof 'the fast way'. The landings are rather hard.

Linda

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(Raymond E. Wand) #8

David C.

Here are some photos from a homeowner who was taken advantage of by a roofer for $10k, on a century home.

See the difference quality makes? :wink:

MVC-012S.JPG

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(Roy D. Cooke, Sr) #9

Thanks Ray very typical to my area too.
Some are even worse then this.

...Cookie

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(Brian J. Zimbelman) #10

David -

Much better explanation then mine. :D

I agreed with everything you said except the staement about them typically being installed on a slope. It's very common practice down here to install them in flat roof situations, either on higher end new construction or in the case where the builtup or rolled roof has reached the end of it's life.

Oh, and I never see sealent between panels, do you? Typical installation down here is a non water tight approach, where the underlayment (felt or previous roof or whatever) is used to catch any water that gets under the metal and drain it off to the gutters/drip edge. Are they installed to be water tight up there?

-- bz

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(Michael W. Gault) #11

Very nice synopsis...

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(David P. Valley) #12

Brian,

We don't have many metal roofs out here in Massachusetts. When I do find metal roofing I find that most of the panels are rolled with a male assembly along one edge and a female assembly along the opposite edge that create the standing seam when they are snapped into place. One side of the snap lock usually has a factory-applied sealant along the leading edge to prevent any water penetration. I'm not sure if this sealant is applied in the snow zones only.

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(Raymond E. Wand) #13

http://www.alutuff.com/installation/grandrib3-alutuff.pdf

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(Brian J. Zimbelman) #14

David,

I think we are talking about the same thing. The standing seam (as you describe normally have a seal along the vertical edges along with the hidden screws. The others, which down here you can buy the panels at any HD, Lowes or other home improvement store normally do not have a seal along the vertical edge.

The instructions I've seen for both tell the home owner to have a weather barrier underneath, felt or otherwise. Many (most) roofers who install retrofits down here simply install these over their existing roofs and use that. Saves on tear off costs, and is usually as good as a new felt layer would be or better. Also keeps them from seeing the rotting sheathing, so they don't have to do anything about it :shock::mrgreen:

All the manufactures I've talked to say that these roofs just like comp shingled roofs are expected to allow a minimal amount of water into them and that water needs to be able to drain out somewhere. I've never seen any sealant where a higher panel sits over the top of a lower panel (horizontal seam) as that would stop water that had gotten in under the roof from draining out.

I was just checking to see if they were doing something differently up there.

I Frequently see these on barns and other buildings in ranchettes as well. On barns they frequently are over skip sheathing, usually every 3-4'. Make a he11 of a noise during a storm and the little woman is always amazed that their horses don't stay in the barns when it storms :shock::shock::shock: What rich people skimp on is always amazing.:mrgreen::mrgreen:

-- bz

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(Michael Kennedy, 49070) #15

Brian, Thank you for this information. I’m in the Coastal Carolina’s where Metal roofing is popular. May I share some of this information with my home owner?
Thanks, Michael Kennedy.

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(Roy D. Cooke, Sr) #16

This how some repair a steel roof ( I do not recommend this method )

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(Roy Lewis, CMI - North Florida Inspector) #17

I don’t see a metal roof…

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(Roy D. Cooke, Sr) #18

Many steel roofs do not have avalanche guards needed big time in snow country .

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(Roy D. Cooke, Sr) #19

Strange things people do,.

Its there kind of hidden with the tar and shingles .

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(Roy Lewis, CMI - North Florida Inspector) #20

I don’t see a metal roof…

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