Metal roofing over shingles questions

Swamp_Yankee

New Member
Oct 18, 2018
59
Hunterdon County, NJ
I have an 1880s era farmhouse that sits back in the woods-I can't see any other homes and they can't see me so we're not worried about how our house "fits with the neighborhood." The house underwent a major renovation/addition in 1998 which added a lot of space to the second floor. Most of the roof is new construction with 2x8 rafters. There is one section of the house that is older but not original-I believe it was added in the 1920s that has 2x6 rafters and a shallower pitched gable. In 1998 all of the old roofing was torn off of that section, the new roof deck was tied in, and new 30 year three tab shingles were applied to the entire roof, so there is only one layer of roofing. These shingles are now in the last third of their life so we are looking toward going over them with steel. This is the basic idea I was looking to follow:


Granted this was done on a mobile home but the same principles would apply-furring strips screwed directly into the rafters and then metal roofing right on top of that. I wouldn't bother with any insulation the way they did as my attic is very well insulated already. I'd like to hear from others who have done it this way, what to look out for, etc...
 

Swamp_Yankee

New Member
Oct 18, 2018
59
Hunterdon County, NJ
Local guys did mine the same way. No issues that I've seen with it after 8 years.
I think it's rediculous but my wife is worried about noise-do you find it any noisier in a hard rain than a shingle roof? I think we will be fine because we have plenty of attic space and insulation between us and the steel panels.
 

festerw

Feeling the Heat
Nov 16, 2009
409
Cambridge Springs, PA
I think it's rediculous but my wife is worried about noise-do you find it any noisier in a hard rain than a shingle roof? I think we will be fine because we have plenty of attic space and insulation between us and the steel panels.
Not noticable at all. Our bedroom is under the shortest part of the attic crawlspace we've got 16 inches of fiberglass over top and don't hear anything.

Even in my shed where there's only OSB under the metal it's not very loud.

Shingles are a lot of weight. Remove them and then put down the metal. That's from a Mainer thinking of snow load weight.
Snow load could be a concern but there's also plenty of houses out there with 2 layers of asphalt. Nice part with metal is if there's any kind of slope as soon as the sun comes out it pretty much clears itself.
 

xman23

Minister of Fire
Oct 7, 2008
2,056
Lackawaxen PA
To you guys who know. What about the void between furring strips. When you walk on the roof doesn't the roof bend?
 

festerw

Feeling the Heat
Nov 16, 2009
409
Cambridge Springs, PA
To you guys who know. What about the void between furring strips. When you walk on the roof doesn't the roof bend?
There may be some but nothing easily noticable in my case. Only part I don't like about it is it needs to be 100% dry to walk on or your ending up on your butt.
 
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bholler

Chimney sweep
Staff member
Jan 14, 2014
21,007
central pa
To you guys who know. What about the void between furring strips. When you walk on the roof doesn't the roof bend?
Yes it does bend a bit but that doesn't matter. But if you have much slope at all you won't be walking on it anyway
 

Gearhead660

Member
Dec 20, 2018
227
WI
I have an 1880s era farmhouse that sits back in the woods-I can't see any other homes and they can't see me so we're not worried about how our house "fits with the neighborhood." The house underwent a major renovation/addition in 1998 which added a lot of space to the second floor. Most of the roof is new construction with 2x8 rafters. There is one section of the house that is older but not original-I believe it was added in the 1920s that has 2x6 rafters and a shallower pitched gable. In 1998 all of the old roofing was torn off of that section, the new roof deck was tied in, and new 30 year three tab shingles were applied to the entire roof, so there is only one layer of roofing. These shingles are now in the last third of their life so we are looking toward going over them with steel. This is the basic idea I was looking to follow:


Granted this was done on a mobile home but the same principles would apply-furring strips screwed directly into the rafters and then metal roofing right on top of that. I wouldn't bother with any insulation the way they did as my attic is very well insulated already. I'd like to hear from others who have done it this way, what to look out for, etc...
If there is a space between the steel roofing and the old roof below, that's what creates the "metal roofs are noisy" complaints. You can remove the existing shingles and lay down tar paper before installing the metal roofing, no need to put down furring strips. Or you can put down furring strips. I have seen both done. I have done the tar paper without furring strips. With minimal attic insulation, it was no louder than shingles in a downpour.
 

MTY

Feeling the Heat
Jan 9, 2019
303
Idaho
I did this in 84 or 85. Furring strips nailed into the rafters through the shingles. I have been past the house in the last year and the same roof is on the house. It is 12/12, so not much snow sticks. On this roof I only walked the ridges, but on a metal roof of 6/12 or less a good pair of tennis type shoes on dry metal will allow you to walk without slipping. Step near the screws, and you will be stepping on the furring strip.

Current roof is metal on felt paper on plywood. I do nor remember the furring stripped roof being any louder than this one in a heavy rain storm.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
21,007
central pa
As someone who is on roofs allot I absolutely hate metal roofs. They are dangerous to walk on. Ridge ladders scratch them. They are a pain to flash.
 

zrock

Minister of Fire
Dec 2, 2017
835
bc
If your going to do a roof do it right and remove the previous layer first... I have a tin roof and no issues with noise
 
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firefighterjake

Minister of Fire
Jul 22, 2008
19,053
Unity/Bangor, Maine
There might be a little more noise, but I haven't found it excessively noisy in any way. Our contractor laid down sharkskin under layment and then attached the standing seam metal roof. We left the shingles in place.
 
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semipro

Minister of Fire
Jan 12, 2009
3,750
SW Virginia
To you guys who know. What about the void between furring strips. When you walk on the roof doesn't the roof bend?
I have a metal roof over 2x4 purlins on our barn and I just walk on the screw heads so I don't bend chance bending the metal.
 

firefighterjake

Minister of Fire
Jul 22, 2008
19,053
Unity/Bangor, Maine
I really wanted to do standing seam but it was 3 times the cost for my roof from every contractor.
We ordered on line from a company in Tennessee and it was just a little more expensive than the screw down metal roofing. The seam kinda locks together . . . and I guess it would be more fair to say it has a hidden fastener system vs. true standing seam.
 
I have an 1880s era farmhouse that sits back in the woods-I can't see any other homes and they can't see me so we're not worried about how our house "fits with the neighborhood." The house underwent a major renovation/addition in 1998 which added a lot of space to the second floor. Most of the roof is new construction with 2x8 rafters. There is one section of the house that is older but not original-I believe it was added in the 1920s that has 2x6 rafters and a shallower pitched gable. In 1998 all of the old roofing was torn off of that section, the new roof deck was tied in, and new 30 year three tab shingles were applied to the entire roof, so there is only one layer of roofing. These shingles are now in the last third of their life so we are looking toward going over them with steel. This is the basic idea I was looking to follow:


Granted this was done on a mobile home but the same principles would apply-furring strips screwed directly into the rafters and then metal roofing right on top of that. I wouldn't bother with any insulation the way they did as my attic is very well insulated already. I'd like to hear from others who have done it this way, what to look out for, etc...
I think it's best to bring the shingles down.
Then work the metal there.
Not too heavy. More information.
 

peakbagger

Minister of Fire
Jul 11, 2008
5,146
Northern NH
We ordered on line from a company in Tennessee and it was just a little more expensive than the screw down metal roofing. The seam kinda locks together . . . and I guess it would be more fair to say it has a hidden fastener system vs. true standing seam.
I would be interested in the name of the company. My brother has a large new roof currently covered with high temp ice and water shield for the winter. He would like metal on it. The few contractors that do this work in the area seem to be franchises of Affordable Metal Roofing somewhere in Mass that buys the coil stock and rolls in pattern and delivers it. They charge quite a premium. They claim its Chinese tariffs as only the Chinese make the coil stock. Not sure if I believe it. My guess is high labor costs and good housing market means its time to make a good profit on every job.

Its an ideal roof for metal no valleys one chimney and I will convince him to run the vents up to the near the ridgepole to cut down on the need for crickets.
 

semipro

Minister of Fire
Jan 12, 2009
3,750
SW Virginia
Its an ideal roof for metal no valleys one chimney and I will convince him to run the vents up to the near the ridgepole to cut down on the need for crickets.
With some planning, the vents might be relocated so they don't fall on seams which make for a cleaner installation and will help prevent future leaks.
 

firefighterjake

Minister of Fire
Jul 22, 2008
19,053
Unity/Bangor, Maine
I would be interested in the name of the company. My brother has a large new roof currently covered with high temp ice and water shield for the winter. He would like metal on it. The few contractors that do this work in the area seem to be franchises of Affordable Metal Roofing somewhere in Mass that buys the coil stock and rolls in pattern and delivers it. They charge quite a premium. They claim its Chinese tariffs as only the Chinese make the coil stock. Not sure if I believe it. My guess is high labor costs and good housing market means its time to make a good profit on every job.

Its an ideal roof for metal no valleys one chimney and I will convince him to run the vents up to the near the ridgepole to cut down on the need for crickets.
I honestly don't remember the name as this was several years ago.
 

peakbagger

Minister of Fire
Jul 11, 2008
5,146
Northern NH

MTY

Feeling the Heat
Jan 9, 2019
303
Idaho
Mastic is darn cheap. The roof on the current build has mastic on every seam. Probably as important as any other aspect of a screwed down roof is the size of screws used. Many use the 1/4" head screws. The various manufactures I have bought metal from require the more expensive 5/16" head screws. The tapered end is also supposed to protrude through the sheating or furring strip. Contracton and expansion of the metal will pull the smaller shorter screws loose.
 

PaulOinMA

Minister of Fire
Oct 20, 2018
505
MA
… Definitely. Take it from someone who went through the multiple layer disaster. Finally decided to tear everything off and do it from scratch the right way. Very glad I did …

Yes. You may have to remove the old roof for a warranty on the product being installed. You may want to look into it.

I asked the roofing company if they were going to leave on the old roof, as I just had one layer of shingles. They said that they have to remove the old shingles and inspect the roof before installing the new shingles. The manufacturer require it for a warranty on their product. The product must be installed on an o.k. roof.

Nextdoor neighbor did the cheap and slapped shingles on her roof. All removed in a few years and a new roof put on.
 
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