Replace traditional shingled roof with metal roof? Experiences?

[rtimgray]

I love screw-down metal roofing for barns, shops, outbuildings, etc. where a little leak every now and then will be of no great consequence. I know that everytime I've been working in my shop or barn from morning until afternoon I can hear the expansion/contraction of the metal as the sun warms it (squeaks/pops/etc.). Everytime this happens, those gaskets get a little looser. It's been built 10 years or more, and it might have just a couple of dripping leaks, nothing to worry about in the shop - but I don't want it in my house, that's for sure.

I've helped my father in law replace all the screws on his roof - he had metal screw-down roofing installed my laying it directly over the old shingles - no purlins, no tear off, no nothing. Most of the screws we removed were rusted/rotted out and we had to remove one small piece of metal and it was rusted underneath.

I think a lot of folks like the metal for the looks, and a lot like it for the cost, because they feel they can skip the tear-off of an old roof. My opinion on roofing is that if the roof is in bad enough shape that it needs to be replaced, it needs to be removed. I hate doing roof tear-off too, but as others have said, the first step in a good roofing system is proper preparation, no matter what type of roof you're installing.

If I were to install a metal roof on a residence, it would be standing seam, but I prefer the looks of asphalt shingles. Additionally, I've only had one small portion of shingles that has ever blown up, and that was during a hurricane-force wind event (and we don't get those often in KY).

Whatever you choose, good luck and take care.

 

[Oaktree]

I've helped my father in law replace all the screws on his roof - he had metal screw-down roofing installed my laying it directly over the old shingles - no purlins, no tear off, no nothing. Most of the screws we removed were rusted/rotted out and we had to remove one small piece of metal and it was rusted underneath.

I think a lot of folks like the metal for the looks, and a lot like it for the cost, because they feel they can skip the tear-off of an old roof. My opinion on roofing is that if the roof is in bad enough shape that it needs to be replaced, it needs to be removed. I hate doing roof tear-off too, but as others have said, the first step in a good roofing system is proper preparation, no matter what type of roof you're installing.

Timely discussion, I was planning on putting a metal roof on my garage this summer. Main reason for going with metal was that we get a lot of snow here, enough to warrant shoveling off the roof once or twice in the average winter. I'm in my mid-60s now, and don't really want to be shoveling a roof when I'm in my 70s if I can avoid it (one side you can get with a roof rake, but the land on the other drops off too much). Currently has 40 year old asphalt shingles which have seen better days. Really don't want to strip the roof if I don't have to...shingles aren't warped or anything, just old, brittle and losing granules. Would 1x4 strapping do the job for purlins?

 

[rtimgray]

If it was me doing it, I would tear off the shingles and install 2x4 purlins - that's how I would do it, but that doesn't make it right. I would say the vast majority of installations that I have seen in my area, just driving down the road, is that they are installed without removing the shingles and without purlins at all (just like my FIL did).

1x4s would be better than nothing, but I doubt there is an appreciable cost difference vs. 2x4s and the labor will be a wash. I think Eddie mentioned the pro of removing the shingles helps to make sure that the purlins lay flat and attached strongly to the rafter.

In the end, its your dollars and your roof, so do whatever is within your budget and what you think is the best for the situation.

Good luck and take care.

 

[doxford jim]

I think that using 2x4 purlins would better allow air to circulate under the metal roof and hopefully, carry away moisture and condensation due to weather conditions.

 

[MAN IN BLACK]

Timely discussion, I was planning on putting a metal roof on my garage this summer. Would 1x4 strapping do the job for purlins?

Exactly what I did to my house 5 years ago now, right on top of shingles.
Black

 

[CalG]

I've redone my house with metal. Snow shedding was a strong consideration in the change.

A "cold roof" was also one of the desired features. I was advised that placing metal on mineral shingle would result in rusting of the metal as the thermal expansion "worked" the metal against the stone.

With a cold roof in mind, 2X4 sleepers were added on 4 foot centers, ridge to fascia. On those, 1X3 perlins were laid on two foot centers. The "built in ladders" were a welcome feature when putting up the metal

Fascias and rake boards were trimmed to the new grade of the perlins. I use drip edge all around with black paper rolled out over all the added structure as the metal went down.

It's been about 20 years now. Details around openings are a bother. Actually all details are a bother in metal. (two chimneys and a dormer for me). A few screws pull and need replacing every couple of years. Though more costly, I switch out to the internal wrenching "Low profile" screws for all replacements.

Do I like it?

I do when 3 feet of snow slides off in a rumble and I can feel the entire house take a fresh breath with the load removed.

 

[DaveOmak]

We just replaced our roof with metal.... Remove the old roofing and underlayment.... inspect the old sheathing etc... the old materials add additional weight to the rafters etc... in the event of a house fire, you can't get to the old shingles that burn really good.... Installed ice and water shield and a breathable roofing fabric similar to house wrap..... and a ridge vent.... Installed 1x4 purlins across the rafters/sheathing.... If your existing roof has any dips or valleys, tight string the purlins during installation and shim with wedges where necessary to get a straight run.... metal roofing will not conform to a wavy roof line...
If the roof panels are extremely long, say over 16', consider laying 2 sheets... 9 & 8' lengths.... I have had experience with screws pulling or screw holes egging from the expansion and contraction of the metal panels.... and ensuing leaks from same.... That creaking, popping etc. folks hear when the sun shines on the roof is the metal expanding and later contracting.... It does cause problems....

 

[MH8675309]

We had an Amish friend of mine do ours. The roof is 21 squares and it cost us $5500. He used 4" ring shanks to put down the 2x4s. I had certainteeds on and they were a 30 year shingle that were only 16 years old (good luck collecting on that warranty). It went on quick and is doing good so far - and we live in a kinda windy area.

 

[PILOON]

I have done a fair number of metal roofs as well as repaired a few.
Screws on top of ridges, water runs down the flat.
Metal sweats, so purlins a must for circulation, never on sheeting. ( once repaired a 10 year roof that was screwed to sheeting and underside was totally rusted)
Valleys on steep pitched roofs will be a problem as rushing water will cross over to the other side and leak as the velocity drives the water up and under the adjacent tins.
There are qualities and gauges in roofing. You want galvinume as a primed tin and not the thinner stock either.
Pre drilling makes for a much nicer finished product.
Never use nails, only screws.
If you are in a snow climate you will need snow brakes as when that roof sheds the load it can kill you and or your pets.*
The attic need to be very well vented as otherwise the condensation can and will soak your wool and even damage the plaster ceilings.**

*Last winter one owner's roof shedded and took out all his porch railings!
**One person over heated in his absence and now needs to re plaster his ceiling in a few places. (Poor designed cathedral ceilings and inadequate ventilation)

My 2 cents.

 

[adventure bob]

Heres the thing that dissuaded me from a metal roof: Insurance guy. He said that in a hail storm your shingled roof will be damaged and need replacement. A metal roof however, will have cosmetic damage and still perform. So I asked "What does it take for you to replace a metal roof?" He said the it would have had to destroyed a seem line to the point of leakage and then they'd replace the panels on either side of the seam. I asked what if the finish was coming off from the impacts? He said again if it wasn't leaking its still a good roof.