Guest User
7/3/2002
I am having a stone coated metal roof installed on my house that has a tile roof. Under the tile there is no felt paper or solid sheathing. There is only skip sheathing present. (The tile roof system leaks like a seive) The metal roof contractors are proposing laying the 30# felt paper directly over the skip sheathing. Then applying the wood grid for attaching the metal roof on top of the felt paper. Won't the felt paper begin to sag between the skip sheathing after while? Shouldn't they install solid sheathing under the felt paper? Should a different type of underlayment besides 30# felt be installed near the eaves and/or valleys? One last item. I have been looking at the ICBO web site. Does 30# felt meet the requirements of ICBO criteria AC08?
Allan Reid
Dura-Loc Roofing Systems, Inc.
7/8/2002
Your experience with a concrete tile roof system is unfortunate and most people do do realize that they are dependant on an underlayment. If yours was installed without one then you must of had quite an experience. I represnt a firm that manufactures a product like the one you mentioned although we prefer to call our products granular coated. Our panelized systems mount on either wood or metal strapping. The UBC buinding code and now the new IBC building code call for two layers of Type 15 or one layer of type 30 as a minimum underlayment for roof systems. Most manufacturers have their systems tested for open framed roof systems and ours for example then requires an upraded reinforced underlayment designed to be stable and span the open spaces. In your case it depends on the description of "skip sheathing". If it is a 1x6 laid every 9-10" as in wood shake, then #30 felt is quite adequate to span. If it is greater than this then I would ask your building official. As to the solid sheathing this is truly your call as it is an expense. Our type of systems are designed to be installed over skip sheathing, again with the appropriate underlayment. As to the eaves an valley treatment, the code soes call for an extra layer of #30 under the valley and in severe weather the eaves should be protected typically with cemented felts or with an ice and water shield. Not nowing your climate, I can't comment on the application in your case. As to #30 meeting AC08, I don't know as we have our systems tested to AC10 and included in our reports which includes underlayment. If you have any questions ask your local building department.
Guest User
10/15/2002
I am looking at a new house with a metal roof. A previous prospective buyer had the house inspected and the inspection revealed no felt paper under the metal roof. Also, some of the screws were tightened to the point there were indentions in the metal. According to the builder and real estate agent, the roof has been repaired, however, the roof was not taken off and felt paper applied, then re-roofed. Is this an appropriate application?
Guest User
10/18/2002
Find another house. Depending on the kind of metal roof panel, a 5/8 inch minimum thickness sheathing and 30 pound minimum tar paper is required. You can find installation information online, or order it from some metal roofing manufacturers. Many metal roofing installers have never read the installation instructions. I call this willful ignorance! Good luck!
Guest User
2/20/2003
I've read several postings here about underlayment and still wonder if there is a blanket "yes" answer to this question? I live in central Alabama and have seen several 5 V galvalume roof systems installed directly over 2x4 purlins (24 " o.c.) without underlayment. The roof pitches range from 7:12 to 12:12. The attics are well ventilated and insulated at the attic floor level. There does not seem to be any apparent problems with condensation on the underside of the roof. Is underlayment really crucial in this climate zone?
Allan Reid
Dura-Loc Roofing Systems, Inc.
2/21/2003
If you live in an area where the teperature drops below 50 degrees with average humidity there will be condensation forming. If you live in an area of high humidity and get sudden drops in temerature you will get condensation forming. In the more moderate climates a wood roof deck can act as insulation and absorb this condesation. leave out the wood deck and put a metal ron and you have elliminated the "blotter". Metal by nature transmits hot and cold faster than an asphalt shingle so it is possible in certain climates to get more dew point crossings an more condensation. The steeper the roof the better the air flow and the more lighly the condensation is to run down the sheets and out the eaves. Fact is many people are looking to cut the costs out of new home construction by eliminating the plywood deck and then do not know how to deal with felt underlayment that is not designed to span. First make sure the manufacturer of the metal approves and warranties it for this type of installation and there are a couple of high quality moisture barries such as Tri-Flex 30 that are designed to span rafters. Remember the intent is that you are installing a permenant roof system that needs to protect your substantial investment below it. The more corners you cut the larger the risk.
Guest User
2/25/2003
Hello, I plan to build a seasonal cabin in northern Minnesota and would like any comments on my plan for the roof. Roof trusses will be 4/12 or 6/12 pitch - 24" O.C., sheathing is 1/2" plywood with 30# felt over the top and a water barrier type self-adhesive material under the felt on all the edges. Vapor barrier of 6 mil poly in all rooms including ceiling. 6 1/2" of fiberglass batt insulation in the ceiling. The soffets will be vented aluminum and I plan to put additional vents in the gables. One half of the interior ceiling will be common trusses and one half will be scissor trusses for a vault. I'm installing channels on the underside of the roof sheathing so the batts do not block air movement. The roofing itself will probably be a standing seam type. Is this a sound plan? Thank you.
Guest User
3/10/2003
For a re-roofing with metal to replace existing shingles, I'd like to add a layer of exterior insulation (5/8" foil faced urethane foam board) above the 15/32 roof decking. My question is, do I need to add fastener strips to the decking and then attach the metal foofing to the new external strips (hat section) to allow for thermal growth. What would be your recommendation?
Allan Reid
Dura-Loc Roofing Systems, Inc.
3/10/2003
I would need more information to comment properly on your question. If you have an attic you do not need to add insulation. If you have a vaulted ceiling the new IBC/IRC states that you must have a minimum of 1" of vented air space under the roof covering. This may already be allowed for in your existing assembly and adding insulation over is of limited use. As to the attachment of the roofing, you did not specifically state what product type you had chosen. In roofing over, the strapping could easily provide the air space and the strapping provides a good solid base to fasten to. First though contact the manufacturer and get his recomendations.
Guest User
3/31/2003
I am building a 40 x 24 4 car garage (pole barn style) with a Gambrel roof. There will be an insullated room down the center of the second floor. We have 5/8 OSD sheeting on the roof. I was told that 1/4 fanfold (owens corning) would be better than the 30# paper for under the steel. What is your opinion?
Allan Reid
Dura-Loc Roofing Systems, Inc.
3/31/2003
The new building code calls for a 1" vented space between the insulation and the roof material. If you are not providing it between the OSB and the insulation then you must provide it above the OSB. This means choosing a system that will work on strapping and provide vertical air flow. As to the moisture barrier felt is all that is required however you are putting on a long term roof system so don't be afraid to invest in a good quality reinforced material. I am not familiar with this material however the best bet is to contact the manufacturer and get their recommendations.
Guest User
4/3/2003
We just had a metal roof installed and our contractor had put in his proposal/estimate that he would be installing Fsk Foil under the metal. He mentioned that tar paper isn't good to put under metal because it would sweat. Our roof leaks around the chimney and new fan over the stove - also, my husband looked under the metal and did not see any foil, just tar paper. We called the roofer and he said he would take care of it. I feel he tried to cheat us, should we trust him to re-do the roof?
Todd Miller
Classic Products, Inc.
4/4/2003
Hi Ann, thanks for buying a metal roof, and thanks for your question. Ultimately, I really suggest contacting the manufacturer of your roofing about this. First of all, different metals and different products will sometimes have different underlayment requirements. Also, if this installer has done something unethical here (and I obviously cannot say for sure that they have), I am sure that the manufacturer will wnat to know about it. 30-pound felt paper is used under metal roofing pretty regularly. Particularly in warmer climates, there is reason to use a slip sheet (such as red resin paper) between the underlayment and the metal when the metal roof has a low profile with lots of contact with the underlayment. This is to keep oils in the felt from causing it to stick to the metal. There are no real condensation issues with felt paper although, if your roof is solid zinc, there is reason to try to have some breathability on its back side. This can be achieved with some of the foil and foam spacer products. I doubt your roof is solid rolled zinc though. I think you need to confront your roofer about the felt vs foil issue. Right off hand, I do not know of a real good reason why foil should have been used but, again, ultimately that call needs to be made by the manufacturer of the roofing. As far as your leaks -- it sounds like improper flashings. I would sure ask the roofer to detail what he's going to do to remedy this situation. It should probably not be that he's just going to put some caulking up there. If you question what he is doing, consult with the manufacturer or a third party such as an experienced metal roofing installer or a roofing consultant.
Guest User
4/26/2003
I have talked with several metal roof contractors and each one gives me a different answer as to how the job should be done. One puts the metal directly on top of the existing shingles and screws it down. another puts wood strips horizontaly every three or so feet and attaches the metal to the wood strips. another want s to put down a 30 lb felt and the metal roof on top of that. I do not know who to believe.
Todd Miller
Classic Products, Inc.
4/26/2003
I would not suggest installing directly on top of the old shingles. Over time, the rough surface of the old shingles could be damaging to the back of the metal. 30-pound felt is a reasonable underlayment. However, especially in warm climates, I suggest either 30-pound felt with a "slip sheet" such as red rosin paper on top of it or else use a layer of one of the new polymer based underlayments. The risk of installing a long panel roof right on top of felt is that the felt might stick to the metal panels and then tear when the metal expands. Many metal roofs are designed for installation over solid decking or existing shingles (with underlayment). However, some others are designed for installation over lathe boards. I would suggest contacting the manufacturer of the roofing for their specifications on that issue.
Guest User
4/27/2003
Hi- I am considering metal roofing on my 80 year old Cape Cod. As of now, it has asphalt shingles over tar paper over the original wood shingles. The wood shingles are mounted on running boards in the traditional way, so there is no plywood decking. How should I proceed with the new metal shingles? thanks.
Todd Miller
Classic Products, Inc.
4/27/2003
Because building codes in many areas adhere to a two-layer maximum when it comes to roofing, you will need to first check with your building inspector to see if that is the case where you live. If it is, you should inquire as to whether exceptions are ever granted based upon the low weight and special design of certain metal roofing systems. In any event, of course, if there are any roof areas which are deteriorated form leaks, etc., those should always be addressed. Now, there are many metal roof system which can be attached over a base layer of wood shingles on spaced sheathing. These are typically metal shingles which would be mounted on top of new battens or metal shingles which have an option for side-fastening which would allow secure fastening into the original lathe board. The batten-mounted systems would probably require vertical battens first and then horizontal on top of those. If you do have to remove the old roofing, there are metal shingles which could be mounted right on top of lathe again or you could put down plywood followed by underlayment and the new shingles. If you choose some shingle styles you like and then work with the manufacturers, they can detail out all of the requirements for their products.
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