Roofing question for ya

[ABNAK]

Sometime late this Fall I'd like to get a metal roof. If the existing roof is in good condition, is it better to leave it in place and have the metal one installed over it (they use furring strips right?) or have it removed altogether?

Roof now on there was done in late 2010. No major defects, just heard it was better long-term to leave a decent shingle roof in place and then put a metal one over it, kinda like "double protection".

[Artos]

I reckon there would be too much weight with two roofs unless you got bracing out the wazoo...your roofer can confirm, but imagine they will want to go w/ metal only.

Replaced my roof in 2012 w/ basic shingles & would love to go metal on the next one...I bet current pricing is painful.

[mrbieler]

Metal roofs are pretty light so if you've got a decent roof in place now and local permitting allows for it, metal over asphalt shingles is fine. Provided your current roof doesn't have any moisture issues, you should be good to go. You are over the 1/2 way point for your current roof. Most are suggested to be replaced at the 20~22 year mark. Something to consider as well.

[jsbhike]

The only advice I can give after helping a buddy install his(I was a strong back) is to be super careful if you ever have to get on it.

The slightest temperature change can cause condensation to form and when that happens you are on a super slick and sloped surface. I figured it out from a slight temperature drop 30 minutes or so till sunset, but have heard something as insignificant as a cloud passing over can do it.

Other than that, I much prefer our metal roof to the shingles we had on, but I didn't watch the company install so no idea if they left the shingles on or not. Buddies roof(16+ years old and still ok afaik) was shingles on, but I can't recall any other details.

[Averageman]

Living in Central Texas a roof lasts about ten years due to UV damage and seasonal weather (We are prone to Gold Ball sized hail here) so we're used to replacing them fairly regularly.
If you have a question about if you'll have to have your roof replaced look under the gutter downspouts and see how much gravel from the shingle tiles has accumulated , if you've got more than a tablespoon, you need an inspection. Walk the edge of your roof looking for damage such as out of alligned shingles or "Dips" in the roof surface.
I will bite the bullet and put a metal roof on next time.

[Alex V]

As an Architect I would advise to have the existing roofing material removed, new ice/water shield laid down and have the metal roof installed as if this was a new build. In the few rare instances that I've designed home additions or reno work I always note to have the existing roofing removed down to the sheathing.

Encapsulating the existing assembly with a new one should only be done for ACMs.

Plus, removing the shingles and existing membrane may expose moisture issues you may otherwise not have known about. Why take the chance of installing a new roof over a less than ideal substrate?

[THCDDM4]

Roof overs are almost never a good idea, remove to sheathing, inspect sheathing, install new synthetic underlayment, ice and water, flashings, pipe jack boots, venting, etc.

Make sure everything is brought up to current code and you don’t have unknown issues lurking under the current roofing system- that’s always a better way to go than a roof over.

What type of “metal roofing” system are you looking to install? There are many and they all have pros and cons.

Water moves a lot faster on a metal roof than it does on an asphalt shingle. You should consider necessary modifications to your drainage needs with a new roof, 6” gutters and 3”x4” downspouts should be installed to handle the increased flow rate of rain on most metal roofing systems.

Also make sure and install snow stop over areas people will be walking/present below the roof if you live in an area that gets snow.

If you need a referral for a reputable roofer let me know, I own a home improvement business and have been in the roofing industry going on 20 years Colorado- one of the biggest roofing markets in the world.

I can ask my reps whose a good roofer where you are if you haven’t already selected one.

[ABNAK]

Roof overs are almost never a good idea, remove to sheathing, inspect sheathing, install new synthetic underlayment, ice and water, flashings, pipe jack boots, venting, etc.

Make sure everything is brought up to current code and you don’t have unknown issues lurking under the current roofing system- that’s always a better way to go than a roof over.

What type of “metal roofing” system are you looking to install? There are many and they all have pros and cons.

Water moves a lot faster on a metal roof than it does on an asphalt shingle. You should consider necessary modifications to your drainage needs with a new roof, 6” gutters and 3”x4” downspouts should be installed to handle the increased flow rate of rain on most metal roofing systems.

Also make sure and install snow stop over areas people will be walking/present below the roof if you live in an area that gets snow.

If you need a referral for a reputable roofer let me know, I own a home improvement business and have been in the roofing industry going on 20 years Colorado- one of the biggest roofing markets in the world.

I can ask my reps whose a good roofer where you are if you haven’t already selected one.

Just the simple "smooth" metal roofing, not the stuff made to look like shingles. Want kind of the "farmhouse" look (we live out in the sticks so.....).

[FromMyColdDeadHand]

Just the simple "smooth" metal roofing, not the stuff made to look like shingles. Want kind of the "farmhouse" look (we live out in the sticks so.....).

Standing seam?

THCDDM4-how much ventilation do you put under the metal so that the hot air can rise up and vent through the peak? The air-gap/flow seems interesting, but wondered about the ability to walk on it afterwards. Do you do roofs in Kynar or the soil-poly for residential steep slope?

[THCDDM4]

Standing seam?

THCDDM4-how much ventilation do you put under the metal so that the hot air can rise up and vent through the peak? The air-gap/flow seems interesting, but wondered about the ability to walk on it afterwards. Do you do roofs in Kynar or the soil-poly for residential steep slope?

My guess is abnak is going with corrugated metal panels based on his answers.

Kynar 500 coated panels for standing seam is my preference.

I look at ventilation on a case by case basis, lots of variables to consider to optimize for the specific home/structure.

Most important broad factor is net flow of 2:1 ratios of I take/exhaust- intake@soffit to exhaust@ridge.