Saturday, July 26, 2014

Draft Roof and Attic Design Guide now Available for Review

Posted by Webmaster on 1. December 2010 16:55

NOW ACCEPTING COMMENTS: A draft of our New Roof and Attic Design Guide for Hot Climates is now available for review.  These guidelines give homeowners and builders the tools to make informed decisions on the most economical and best practices for renovating a home’s roof and attic.  The guide includes information on new designs and conventional strategies for saving money by improving your roof and attic.

We are now seeking input from our stakeholders on this draft guide.  If you would like to comment, please do so by December 17th.  Your input is important for improving this guide  and can potentially save homeowner’s more money on their energy bills!

Draft_Roof-attic_design_guide.pdf (1.87 mb)PDF

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  • Scott Kriner said,

    Section 5 covers three roof types but is inconsistent in how the cost information is described for each type of roof. Suggest that the same topics related to cost be covered for each section 5.1, 5.2 and 5.3 (ex. initial cost, estimated service life, life cycle cost, installation cost, material cost, etc.)

    Section 5.1 is subjective and speculative to say "... may be the most economical..."

    Section 5.2 should include modified text as follows:
    Prepainted metal roofing is the fastest growing residential roof material and is capturing more of the commercial market as well.  The initial cost of prepainted metal roofing can be 2-3 times that of asphalt, but the estimated service life of most metal roofing is more than 40 years resulting in a very low life cycle cost.  States that charge fees for the disposal of shingle debris in landfills would have different cost differential between metal and shingle roofing.  Metal roof has a wide range of color options, durable paint finishes that resist fade, chalk and loss of solar reflectance, high strength to weight ratio, fire resistance, wind uplift resistance, and resistance to hail damage.

    ORNK simulated steep slope roofs ...

  • Dennis Mathes said,

    When is the final version planned to be published?

  • lvremodeling said,

    I am a contractor here in Las Vegas where as you know temperatures in the summer can reach over 110 degrees. My company has instituted a program we call our 5 Star Energy Efficiency Program. It is a program where we use open cell polyurethane foam throughout our new home construction, guest houses and closed cell foam on all room additions. This, we believe is the best insulation or thermo construction the industry has to offer. In addition we always use Energy Star windows and doors. We use this foam in the attic on the roof deck, at the joist , gable ends or rim joist, creating conditioned air in the attic and eliminating the need for attic ventilation. All the roofs we install are usually concrete or slate tile over 5/8" ply. In addition our exteriors are 1" foam board 7/8" stucco, and in most cases 3/8" or 7/16" OSB exterior sheeting. I believe there are a couple of other major builders doing the same only with batt instead. Fresh air in the home is provided by the A/C system, so the home is allowed to breath.
    Polyurethane foam creates a total seal (totally draft stopped) in the walls and attic. We also draft stop the garage (usually attached, 1 or 2 story)completely from the rest of the home, which we believe is another big plus.
    I would look forward to any recommendations that you or the EPA have to this type of construction method.    

  • Liquid Roof said,

    Thanks for posting, i am really happy to check out this, i am sure it will be beneficial for all of us, i am also looking forward for the final view.

  • Bob Goodhart said,

    Figure 2 on page 2, and discussion on top of page 4 - is the asphalt shingle cool granulated?
    Bottom of page 3 does not show page number
    Table 1 does not pull out individual effects, such as what is done in Section 5.
    Section 3.3 mentions a Dade County, FL roof attachment test. Which test was it?
    Section 4.2 title states "Ceiling" insulation. to be consistent this should be changed to "Attic floor" insulation.
    Section 4.3 - the second sentence and last sentence seem contradictory
    Section 5.1 - 7th sentence should say, "OSB with a foil facing can be ..."  OSB without foil facing would not provide an additional low e surface.
    Section 5.1, page 8 - the text above Table 3 makes no mention of the shingle color or type

    Table 3 - needs a column for Above Sheathing Ventilation, and in column for "assembly" need to indicate whether or not it is cool technology. Example, is "asphalt shingle" cool, is cool colored metal installed with ASV, EPS insulation, etc.)
    Section 5.2 - second sentence, strike "and" between durable and fade
    Section 5.3 - add text at end of first paragraph, "The advantage of clay tile is that it takes a long time to heat up. By "solar noon" it is still not nearly as hot as asphalt shingles or metal would be. It is a disadvantage in warm climates for the timle to stay warm at night."
    Section 6 - bottom of page 9 - the reference at the link shown does not look at tools to see if individual effects are quantified.
    Top of page 10 - 4th sentence in first paragraph, add a comma between "climate" and "and your input..."
    Section 7 - Add a line break between 5th and 6th listed reference.
    Page 13 - Above Sheathing Ventilation - 2nd sentence, change "removes" to "remove"
    Page 13 - figure at bottom. Need labeling to indicate that top row are cool colors and lower row are conventional formulations.
    Page 16 - after first paragraph, insert the next paragraph from the Radiant Barrier Fact Sheet starting with "A closely related material property is the reflectivity..." (source: DOE/CE 0335P Radiant Barrier Fact Sheet
    Page 21 - last sentence of first paragraph under Metal Roofing Field Data. The 0.35 emittance is presumably from unpainted Galvalume surface on bottom side. If so, it should state this.
    Page 23 - Figure A6 - what is the purpose of perforating the foil?
    Page 25 - first sentence under Thermal Simulations - change "ASTM 2004" to "ASTM C1340-04"
    Figure A8 - page 25 - if the benchmark is R50 then there should be only one data point on the graph.
    Page 26 - top paragraph -  the numbers in the text do not match the data on the graph on page 25  
    General comment - could there be some text regarding the potential negative impact of some of the proposals in the document on the life of the roof. for example, could radiant barriers increase the surface temperature of shingles thereby reducing their life?

  • lvremodeling said,

    This was very informative, but I believe that polyurethane is still the better of the alternatives for homeowners. The climate in Florida is not as dramatic in the summer as here in Las Vegas, NV. The summer here can reach 105+ May, June, July, August and September the attic temperature can reach 150+. By sealing off the attic with 6"-7" of polyurethane foam (open cell)to the roof deck, you can get an R-24-28 and create a conditioned air environment in the attic. For example: a 2000s.f. home if the living area is kept at a comfortable 75 degrees, the attic temperature is only about 90-95 degrees. We have used thermo foil OSB and do like it's benefits, there is a noticeable reduction in attic temps, about 30 degrees in the summer. But even with that application you still are allowing the attic to ventilate and may be the wrong approach. As for cost, to retro a 2000 s.f. with polyurethane foam is about $1.70-$1.75 per foot, which translates to about $3500+-. For a 2000 s.f. home your energy costs run about $350 a month, based on a balance power home (gas-heat & electric cooling) out of that you are probably looking at $225 a month for cooling costs and visa-versa for gas heating. If you factor in a 30% savings (conservative) roughly $67 a month, maybe more, polyurethane foam retro may pay for itself in 4 years, assuming power rates stay the same. Then think about the comfort level of the home year round, what is that worth. In addition the batt insulation is removed from the attic floor or the ceiling of the home, otherwise a hot-box situation is created in the attic. I welcome your comments

  • insulated panels said,

    Delivering a successful roof involves two distinct phases. The first phase is the design process. In this phase, the architect needs to have a basic understanding of roof assembly materials and system options, and an understanding of roof design considerations.

    The second phase is construction contract administration. In addition to the traditional activities, such as submittal review and field observation, the architect should also inform the building owner about the importance of semi-annual roof inspections and routine maintenance.

  • lvremodeling said,

    Here in Las Vegas or Phoenix for instance, most new homes have concrete or clay tile roofs. The metal roofs sound great for shingle re-roofs and I shall inquire as to the cost here with my roofing sub-contractor. But I fear the additional cost for homeowners looking to re-roof will be a hard sell, also those style homes are older, much older as well.

  • attic ladders said,

    Reviews are important to be a framework in the decision making in terms of attic design or house design in general. There are things that we have to consider if we are planning to design our attic. Function is one important factor.

  • Vin-Check said,

    Thanks for opportunity to check these guides! They are valuable for a great number of homeowners not just for roof and attic improvement and saving money but for some envirinmental issues too! Regards, Vin.

  • Oliver said,

    Eric, thanks for engineering and offering this draft and for your efforts. I have two questions: 1) Is this construction strong enough to stand up a tornado? 2) Can it be combined with solar panels?

  • Walter Zalis said,

    Hello Oliver -

    Below, please find answers to your questions:

    1) Is this construction strong enough to stand up to a tornado?

    ASCE-7 (American Society of Civil Engineers) has developed wind uplift requirements for roofs, and uplift loads vary across the country especially for coastal regions. Roofs are rated to about 90 mph wind speeds and assume the wind flows parallel to the roof not the swirling winds typical in tornadoes. Tornadoes can have wind speeds in excess of 150 mph, therefore ASCE code does not handle the wind strength or the swirling wind effect seen in many tornadoes. A metal roof is more resistant to wind uplift.

    2) Can it be combined with solar panels?

    That is exactly what we plan on working on in FY12. We believe the answer is yes, but we have not done it yet.

    Thanks for the questions!

  • plr articles said,

    I don't think that this construction is strong enough to withstand a tornado. I say this because, tornadoes usually have a wind speed in excess of 200 mph and that kind speed is usually outside the bearable range of any construction. Although I don't know the answer to your second question as to whether these constructions can be combined with solar panels.

  • Natural Stone said,

    These guidelines are really interesting is it OK to link to your site?

  • Walter Zalis said,

    It is always appreciated when others link to this site. Thanks!

  • Silverfish said,

    Looks like everyone else has already found the sections that I saw.  When is the final version supposed to be released?

  • Katy Roofing Contractor said,

    Bob and Scott seem to be on the ball with all the updates! Smile  I sure would want them on my team of I was having to make changes to this draft...

    This is great stuff!!  I can't wait to see the final revision!  Better roofing design and materials sure make our job more easy these days compared to the old days.

    Has the final draft come out yet?

    Thanks again Eric

  • Houston Roofing said,

    I'm in Old-Timer in the roofing industry so to see actually data is great.  I knew removing the ducts from an non-climate controlled attic would reduce energy costs, but never knew it was as much as the data shows.

    Down here in Houston, we are in Zone 2 on the map of Figure 1 and consumer energy costs are huge, especially in the summer.

    One gentleman above mentioned Tornadoes, but down here we have to deal with Hurricanes and after "Ike" a a few years ago we have been swamped with repairs and renovations and information like this helps stay up with the newest techniques and information.

    One a side note, I'm a little surprised the Dark Colored shingles outperformed the Cool Colored shingles. Wouldn't the cool colored shingles reflect more light back as opposed to absorbing the energy?

  • Melissa said,

    Have you not considered utilizing solar energy at all? There should be a sub section in the guide on how to install solar panels, solar water heaters. Or am I wrong?

  • Phoenix Painters said,

    A section on solar panels would definitely be beneficial for those of us out here in the Valley of the Sun. Thanks for posting the information and I'm looking forward to learning some more information on this topic.

  • Stink Bug said,

    That one looks good to me, but it's been a while.  Do you have the final draft available yet?

  • Whitco Roofing said,

    Thank you for the guidelines. As a roofing contractor this guide can be a valuable tool when properly used. I'll be sure to share it at our next meeting.