# Installing new metal roof question.



## Georgiadawgs78 (May 30, 2015)

I just had the metal delivered for my roof, 2000 Double wide with existing 15 yr old three tabs. I already plan on cutting in the ridge vent with mesh screen. My dad seems to think that with the 1x4 strips there is a lot more contracting and expanding and that the screws will wind up loosing up. He also thinks with the air gap the metal will condensate and create a moisture issue. 

But I'm in the air on whether or not to install furring strips or just installing the metal on the shingles. I think it's going to cost an extra $700 for the radiant barrier and furring strips. 

If furring strips I would roll out a radiant barrier then strip it out on 2' centers with 1x4s. I feel like with the radiant barrier and air gap

Otherwise I would just roll out some synthetic felt and lay the tin on top of that. 

So, is it worth the added cost and effort to go through with the strips and barrier or not. I figured I should see some difference in the ridge vent alone.


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## GA native (May 31, 2015)

Were it my roof, I would strip the shingles off. Then install the furring strips over the plywood deck. 

Reasons being: You lighten up the roof structure by several tons. You expose any existing water damage. You know you have good tight nails into the rafters.

*Do not screw the roof to plywood.* Plywood will not hold the screws. You will have leaks everywhere if you screw down to the plywood. 1x4s will hold the screws.

Some regular #15 roll roof felt will be a sufficient vapor barrier.


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## skiff23 (May 31, 2015)

screwing to the underlayment decking is not going to stayand 1x4 's is not enough either. The screw company recommends 1 "  of solid wood for the screws to bond properly. Neither of the 2 mentioned will doit. What happens is over a3-5 year period the screwswill start to back out and leak. if you want bit to stay put strip with 2x4's . If not you will regret it  . and the only way to fix it is take it off and do it again. 
 I have had to fix many of my competitors roofs because the customer went with the "cheaper Price" . A short cut or half way job will only cost you more in the long run.
And a 1x4 is only 3/4 " at best.

Do it right and use 2x4's screw them to the rafters. I have also seen a whole roof torn off still intact to thev1x4's laying in the front yard. make sure it is boned properly.
I have installed many of these roofs. Experience is well payed for .


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## jigman29 (May 31, 2015)

Agree with the above post. 2x4 all the way. Never put down without stripping the roof. Lay a piece of meyal on a piece of wood in the hot sun and see how much moisture develops in a few hours. Needs to be stripped to allow breathing room.


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## 1gr8bldr (May 31, 2015)

Ever been in a tent and the inside was dripping wet? Why is this? It is because of the condensation that forms because of a difference of temps. Any cavity usually has a different temp. If you lay down a piece of metal, then a 2x4, then a piece of metal, then a 2x4, then a piece of metal... you have 3 cavitys. In the sun, you will have three different temps in each cavity. Now lay three pieces of metal on top of one another. Likely, they will all be the same temp because the sun transfers heat as if they were one. I like to put my metal down after tearing off the shingles. Warranty usually says something about one underlayment or another. Fact is, it usually does not cover anything except color. Many manufactures are only covering color and not the metal itself, and certainly not anything to do with installation. So it is left up to experience to decide. I do agree that if you are going to strip it, use 2x4's. You may even consider pressure treated. This should be screwed down rather than nailed. Look under any open roof shed and you will see the discoloration of the wood due to the amount of condensation. You can see the water run lines down each rafter and stripping. This will now be trapped under your metal. Likely "damming" on each "strip".


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## 1gr8bldr (May 31, 2015)

Something else to consider. Under your ridge cap, get the widest they have, I make what I call a snow dam. I bend on the brake a 1 inch by 3 inch angle from metal coil and slide it under the top of the roof metal. I push it down until it seats. What happens, especially lower pitches, is that snow, and rain, but mainly snow gets pushed up the roof near the ridge due to wind. It will blow in your attic. You would be surprised at the amount of snow that gets in. Most people don't go looking around in the attic after a snow. Somebody may remember an old thread of mine with pics of buckets of snow in my attic. And I have shingle vent, not metal. Metal should be 50x more likely to do this. So, with the 1 inch lip sticking up, the snow would stop, backing up, blocking any more. Yet air can still move over the lip because the metal ridge cap usually has an extra bend up.


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## whchunter (May 31, 2015)

*Old*

Is it always better to remove the old shingles? Is there differences on a house vs a mobile home installation?


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## 1gr8bldr (May 31, 2015)

whchunter said:


> Is it always better to remove the old shingles? Is there differences on a house vs a mobile home installation?


I know metal installers who will not remove the shingles. They don't want to worry about rain. Leaving them on assumes you have no soft spots that need replacing.  It is cheaper to leave them on because of labor and dump fee. I think it is slightly better to take them off and deal with a good flat surface. But that is only an opinion. Of course it is based on much experience.... but none of that involves experience in the taking off of metal and looking beneath to see if any damage has occured with either way


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## 1gr8bldr (May 31, 2015)

whchunter said:


> Is it always better to remove the old shingles? Is there differences on a house vs a mobile home installation?


I have no experience in a mobile home application. Does the mobile home have shingles?


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## BriarPatch99 (May 31, 2015)

Be careful with the pressure treated lumber .... some of it will cause corrosion of the metal  ...depending on the treatment....


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## gobbleinwoods (Jun 1, 2015)

BriarPatch99 said:


> Be careful with the pressure treated lumber .... some of it will corrosion of the metal  ...depending on the treatment....



And warp no matter how well down it is screwed.


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## shakey gizzard (Jun 1, 2015)

I also agree with 2x4 "s over 1x. also a good habit to get on the roof and check for loose screws every couple years!


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## Georgiadawgs78 (Jun 2, 2015)

It seems there is several different ways with pros and cons to every one of them lol

So...say I take it back down to the OSB sheathing, I would then need to apply some sort of vapor barrier then strip it with 2x4s and metal on top of that. 

Now my question is would it condensate enough to rot the non pressure treated furring strips?

And would I just by new longer drip edge on top of the new 2x4 strips that would go all the way around the perimeter of the house? And do they make drip edge long enough to go over the 
2x4s and existing fascia metal or is that something I'm going to have to get a break and bend myself? 

Or do you just leave the 2x4s exposed?

I don't mind spending a little money and doing it the right way but all new drip edge, 2x4 furring strips, new vapor barrier, land fill dump fees/dumpster, and labor of ripping off shingles doesn't sound cheap.


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## skiff23 (Jun 2, 2015)

IF you do the steps you are talking about , that would be the best way . I like Titanium underlayment the best for several reasons. 
There is a trim called drip edge that is made to cover the 2x4's under metal and a Gable rake for the ends. Using these actually gives you a cleaner finish and "seals " the wood from exposure and makes it look complete.


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## whchunter (Jun 21, 2015)

*Vaulted Ceiling*

If you have a vaulted ceiling where the T&G is seen from inside and is covered by plywood. paper and shingles >>>> would adding bubble wrap be a good idea to add better insulation since you don't have FG insulation or airspace as insulation? 
And would this be more than good place to remove the old FG shingles?


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## whchunter (Jul 29, 2015)

*response*

any responses


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## 1gr8bldr (Jul 29, 2015)

whchunter said:


> If you have a vaulted ceiling where the T&G is seen from inside and is covered by plywood. paper and shingles >>>> would adding bubble wrap be a good idea to add better insulation since you don't have FG insulation or airspace as insulation?
> And would this be more than good place to remove the old FG shingles?


I would do a dense  foam board. But beware, you would need to stay off the metal. If you step on it and compress the foam, your washers on your screws will leak.


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## Nuttin Better (Jul 29, 2015)

You may want to check with the metal supplier. Metal roofs that I have installed would not have a warranty if they were not installed on furring strips. There needs to be a air gap between the new metal and the existing covering or decking to allow air to move under the metal to prevent condensation. I also agree with the 2 x 4 strips over the 1 x 4.


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## joey1919 (Jul 29, 2015)

There are lots of companies recycling shingles now, check with Asphalt companies in your area, you may be able to get rid of them for free instead of paying the dump fee


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## whchunter (Jul 30, 2015)

*More*

I had planned to use 2x4 furring strips but was thinking it would be nice to add some insulation. My thought was to install bubble wrap or dense foam (slightly less thick than 2x4 furring) between the furring strips. The furring strips would add insulation and my thought was not to put anything under the furring strips or over so no contact with metal. NO contact of added insulation should solve any condensation issues and also avoid any mechanical connection issues.

How do you feel about that and once again do you feel it would be better to remove the FG shingles above the vaulted ceiling?


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## whchunter (Aug 10, 2015)

*Anyone*

See above. Anyone got any answers or suggestions/comments ?


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## 1gr8bldr (Aug 10, 2015)

Your metal supplier should have some literature stating it's warranty requirements. Should check that out and then decide.


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## Firescooby (Oct 16, 2015)

Let me ask a question to this topic. 

I'm fixing to have a metal roof installed, 29g. 

The contractor said he uses 1x strips and runs screws through strips and existing shingles into roof decking. 

Adding 2x4's and 1.5" foam increases the cost nearly 50%. 

Would running the screws through strips into decking be adequate?


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## Firescooby (Oct 17, 2015)

Correction...NO strips. Uses 1.5" screws through metal, old shingles and into decking.


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## jimbo4116 (Oct 17, 2015)

Firescooby said:


> Correction...NO strips. Uses 1.5" screws through metal, old shingles and into decking.



Find another contractor.


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## 1gr8bldr (Oct 19, 2015)

Just so we know, When the sun gets in the right location, you can see every board when stripped with 2x's.


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