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installing my own metal roof
Hi folks,

Just a couple questions before I screw something up majorly on my roof. I am in the process of installing a metal roof on top of my existing roof. I currently have put 1x4's on the existing roof for the metal to sit on. i'm a little unsure where to start. should i start from one side?

also, i have a porch with a different pitch. is there anything tricky about making the transition? this seems like it will definitely be the hardest part.

finally, how far over the edge of the house should i start with the roofing...couple inches?

sorry for all the questions, just don't want to make too many mistakes...haha

taylor.. austin tx
The typical installation will occur from left to right.

Most pitch transitions will require a flashing that goes under the higher roof and over the lower roof. You may need the help of a local sheet metal shop to bend this flashing to meet your exact needs.

In most cases, you would start the eave end of the panels even with the edge of your drip edge.

I strongly suggest tracking down the manufacturer of your roofing and obtaining full installation details from them.

One of the best online sources of installation info that I know of is:


Good luck. All Best.
A HUD inspector in my area is requiring a min. 1" overhang beyond the drip-edge(metal-edge)when installing metal roof panel. This seems to me inappropriate, particularly on older structures which tend to be racked out of square. I maintain that since water/ice shield is also required, if the shield is installed on top of the drip-edge, (allowing a 1" reveal), and the metal roof laps over both (leaving a quarter to half inch reveal), then the drip-edge maintains a clean straight line from the ground point-of-view (square or not)and the installation should be frost protected and waterproof. If instead, the metal roof panels over hang the drip-edge, as the inspector maintains, they must be installed perfectly square or they will leave a sawtoothed edge when viewed from the ground, not to mention sharp edges and corners to hazzard when maintenence is required. It doesn't seem to me that this installation method would be any more waterproof or frost protective and rather defeats the purpose for requiring the drip-edge at all. There, I've made my arguement, now please tell me, what is the standard and why? David Patnode-general contractor-NY
There may be something that I am missing, but I
haven't a clue where this HUD guy is coming from. I
am not aware of any building code that requires what
he is asking for. Also, this is not in tune with
what I know any individual manufacturers to be requiring.

I would track down the manufacturer of your roof and
ask them to send this guy a letter explaining the
proper eave detail on their product. What he is suggesting, for most metal roof profiles at least, would be ugly, prone to possible wind uplift or other damage, and would interfere with drainage into gutters.

If anyone else out there knows something different from what I am saying, please add your two cents here!

I am in the process of installing my second metal roof using IMSA's Skyline 16" panels. I put my first roof on in 1996 over a 2 story duplex. That building's east facing roof has experienced fairly high winds in winter and spring annually, up to 80 mph, with no sign of uplifting. IMSA calls for a 1" overhang. The only exposed fastners on this roof are #14 x 1 metal to wood screws 8" O/C approximately 2" from the eave.

As for squaring the roof, I have not found this to be overly problematic. You simply start with a square edge off your gable end and extend it the length of the eave. Once you determine the extent of wandering along the eave you adjust the overhang. If overhang is particularly bad you can shim a drip edge fascia board the length of the roof to correct the problem.
I would like to know if I can place a metal roof over a 3/12 tar and gravel roof using 3/4inch styrofoam as a spacer-insulation.
The 3:12 pitch is fine for virtually all metal roofs.

However, in my experience most manufacturers will not approve of their product being installed over EPS (aka "styrofoam") sheets because the foam will compress when the roofing is walked on, leading to possible roof system damage.

There are some systems which could be installed over rigid urethane insulation sheets.

I am concerned about ventilation in this building -- is there a ventilated attic? Current building codes do require ventilation to avoid excessive heat and moisture build up in homes.

Using a "structural" style of metal roof which can be installed on battens and an airspace can be very effective from an energy standpoint because of the the ventable sirspace it creates. I would consider installing vertical 2 x 4 spacers and perhaps partially filling in between them with rigid urethane and then putting horizontal battens over that, followed by the roofing. You would need to work in a vent at the eave and then install ridge vent.

Find a manufacturer of a metal roofing product you like and then work with them to tell them what you want to accomplish. They will work with you to develop details for the product you want to install on your home.
Yes, I would like to know where to place the screws on the ridge or not.
Thank you David Brock
I assume you're referring to screw placement when fastening down 5V Crimp roof panels.

To the best of my knowledge, the major manufacturers say that the screws should not go into the valleys between Vs on the panels. Instead, they should go into flat areas or the peaks.

The manufacturers suggest pre-drilling fastener holes from the back of the roofing sheets.
The website you posted is not the correct website. It went to some other website that had nothing to do with metal roofs.
Oops! Well, I just tried it myself and I see what you mean.

However, the URL I have listed is correct. I think the problem is a result of the fact that it is actually linking to a .pdf file.

My suggestion at this point is to go to the manufacturer's home page of www.mtlsales.com and then link from there to download information on whichever of their product lines is of the most relevance to you.
is it possible to instal a metal roof over wood shakes without removing them. can this be done when the roof is wet.
A few manufacturers like ourselves have metal roofing systems designed, tested and approved to install over a wood shingle/shake roof.

I would wash the roof down first with a mild solution of bleach and sunlight soap to kill an loosen any fungus.

Typically wood roofs were installed on space sheathing and as such you need to first cut back the edges of the wood and block it up. Then install verticall strapping over the rafters, fastening down through into the rafters. Then install a moisture barrier, the horizontal strapping and the metal roof.

If you install a self venting system or ventilate the air chamber damp wood shingles will dry quickly however it is important to kill and fungus first.
I`m about ready to build a log house. roof beams are 24'' apart after i apply the sheeting , should it be 3/4 or 5/8, what is the next step i know i will need insulation what thickness. Is ther a book or digram showing the steps befor installing the metal roof?
First you need to choose a metal roof system that meets your needs. There are some that apply direct to the deck and some that apply on strapping.

Next you should consider your energy needs with an eye to insulation values and ventilation to the local code.

I would need more information to give proper advice and if you would like contact me directly and I will see what I can do to help
I would like to know if I have to put 1by4strips down
before i put my tin down over a shingle roof
I would like to know if i have to put 1x4 strips down before i put my tin down?
Metal roofing is available in many styles and substrates. We descibe it as vertical rib which can be through or concealed fastened, metal panels which are typically horizontal panels and metal shingles which are typically hooked together. They are generally made available in coated of bare Galvalume or Galvanized coated steel and aluminum. Tin plate has not been used for roofing for a considerable amount of years.

Some systems only fit over strapping, some one direct to deck and most can do either. I suggest that you consulte with the manufacturer of the product you have chosen.

Having said that you do need to watch if you are using flat sheets directly over shingles as the patterns can telegraph through and you should minimum put down a layer of 30 pound felt to separate the materials.
I would like to know if i have to put down 1x4 strips t
nail my metal roofing to ,i already have a shingle roof
It really depends upon what type of product you use. Some are acceptable for use over lathe or purlins and others require solid decking.
I just purchased a new "Manufactured Home" with a "Pro Panel" vertical rib metal roof. The metal roof overhangs the eave flashing by 1/16 - 1/8" this allows the frost melt in the morning to run directly down the facia board. When I questioned the home manufacturer about this I was told that the roofing manufacturer recomends no overhang to prevent ice damning between the roof panel and flashing.
I have never seen a roof with so little overhang over the facia boards. Having lived in a wet climate where the roof runoff cascaded down the front of the facia causing expensive damage to the facia boards, I find it hard to believe this is a proper installation.
ANy help will be greatly appreciated.
I have seen variances in recommendations for this overhang. Generally, 3/4" or so is common though.

Butyl tape can be used between the bottom of the panel and the roof leg of the drip edge to keep water from migrating uphill. This would probably avoid the situation that the home manufacturer has referred to.

If you add gutters to the house, slip the back edge of the gutter up behind the roof drip edge. Adding gutters may be the best answer to your situation.
Thanks for the information.
I will be installing gutters on the house and your insight into the installation behind the drip edge is very helpful.
need to refoof garage i was thinking metal a friend said he wouldPUT it it over shinges but i question its final APPEARANCE ROOF DECK IS VERY GOOD CONDITION FIVE EIGHTS PLYWOOD ALSO SHOULD I USE UNDER LAYMENT AND SPECIAL TREAT FOR ANY VALLIES
Many types of metal roofing are ideal for going over existing shingles, especially the horizontally-run shake, shingle, tile, and slate facsimile products.

In most cases, getting good fastening is not a question provided the existing decking is in decent shape.

With some vertical seam products, though, particularly if the old shingles are badly curled, going over existing shingles can cause a rippled appearance in the metal panels.

As far as underlayment, most manufacturers will suggest something such as a 30-pound felt or a poly-based underlayment. If you're putting down a flating standing seam system on top, you need a slip sheet such as red rosin paper between the metal and 30-pound felt.

The valley treatment is based upon the product you choose to install. The manufacturer, in many cases, will offer a pre-formed matching valley. In all cases, they should have instructions for valley installation.

I am putting on a roof made with 9"AG panel. I do not think they sent me the right flashing. Would you Email me the instructions on how to install it.
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