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  1. #1
    newsouth Guest

    Default Ridge Height and HAP

    Hi everyone. First we all need to say some prayers for the souls in the trade center. How tragic.

    I think I had a revelation last night and want to see if I am correct. I have been struggling with how to calculate the ridge height of a gable roof prior to installing rafters. I know everyone says just raise the ridge up with the rafters layed atop the ridge until the rafters slip into place, but my "inquiring" mind wants to know how to set a ridge that is in two sections/high up above the ceiling.

    Is it correct that to figure out the actual top of ridge height you figure out the "mathematical height" and then add the HAP to this dimension? Such as, a 10/12 roof pitch has a HAP of about 4 7/8". A 30' wide building at 10/12 would have a mathematical height of 150", but with HAP at 4 7/8" wouldn't that make the ridge height be 154 7/8"?? Is THAT right? Therefore if I was using a 2x8 rdige, then I would set the bottom of that ridge 7 1/4" below 154 7/8"?

    Thanks for all your help!

  2. #2
    Nick Guest

    Default Re: Ridge Height and HAP

    Don't forget to subtract 5/8" for half the width of the ridge board.

  3. #3
    newsouth Guest

    Default Re: Ridge Height and HAP

    Nick, deducting 1/2 thickness of ridgeboard from each side of the roof I know about. But that does not alter the HAP or the ridge height, does it??? I still need to know if the formula I wrote above is the correct formula for figuring the ridge height.

  4. #4
    John S. Cusick Jr. Guest

    Default Re: Ridge Height and HAP

    Actual ridge height =
    Mathematical height of ride + HAP - 1/2" ( for a 2x ridge)
    Good Luck

  5. #5
    Nick Guest

    Default Re: Ridge Height and HAP

    The final answer in your initial example should be 154 1/4". The only thing missing was the allowance for the width of the ridge board. John's formula is correct.

  6. #6
    newsouth Guest

    Default Re: Ridge Height and HAP *NM*

  7. #7
    newsouth Guest

    Default Re: Ridge Height and HAP

    ok, now I am confused! Why do you subtract 1/2" for a 1 1/2" thick ridge board?? That doesn't make sense to me! ???

  8. #8
    Nick Guest

    Default Re: Ridge Height and HAP

    Try reading this again, 'Don't forget to subtract 5/8" for half the width of the ridge board.'

    The ridge board is assumed to be centered on the peak with the top edge of the board square and flush with the top edge of the rafters.

    In order to calculate the distance to drop the ridge for the assumption listed above the following items were taken from your example:
    The pitch is 10:12. The run is 3/4", or half the width of a 2x.

    The resulting distance to drop the ridge to make the edge flush with the top of the rafter is 5/8".

  9. #9
    Glenn A. Davis, P.E. Guest

    Default Re: Ridge Height and HAP

    Nick and John are correct. If it is confusing, another way to look at it is that the sheathing rests on the top edges of the ridge but actually continue on until the touch each other which happens to be 5/8" above the ridge. so you have to lower the ridge this amount. to allow for it.

    The sad thing about it is that here in southeast NC, most of our framers don't know any of this. They set the ridge, then measure from the top of the ridge to the plate. Then cut the first rafter. Whatever it turns out is the pitch. Usually the pitch changes slightly because they didn't make the allowances. They didn't even know to make them.

    This is what we struggle with here. I have even seen a framer cut a 4 inch square hole near where the bird mouth needs to be on a hip because he couldn't figure it out. Then they siter it with a 2x4 to hold it at the right height. We did a Prime Time piece on a house where this was one of many problems. This is why we don't pay these guys much, and because we don't pay much, we can't get good framers to relocate here.


  10. #10
    Dick Guest

    Default Re: Ridge Height and HAP

    How do you put up with this? It looks like you're going to have to stand over them and teach them how to do it.

  11. #11
    rite coaster Guest

    Default Re: Ridge Height and HAP

    are these people carpenters? I cannot understand that where you are Glen that NOBODY KNOWS HOW TO DO ANYTHING.

  12. #12
    Joseph Fusco Guest

    Default Re: Ridge Height and HAP


    Whatever your ridge height is you must add to that the height of the H.A.P. As for what is the amount to subtract from this final number that depends on the roof pitch. You can get just about every angle on this if you browse the page I've linked to below. Since that page has all the answers to how, why and when to, I'm not going to re-type it here.


  13. #13
    Glenn A. Davis, P.E. Guest

    Default Re: Ridge Height and HAP

    Rite Coaster:

    It all relates to ones understanding of the best available technology. Those who are totally ignorant of good construction practices, are unable to articulate the defects in construction and think everything is fine.

    Others are located in an areas where there are qualified craftsman, so they cannot comprehend that there are regional areas in the United States where carpenters are people who either have no drivers license, an alcohol problem, no education-not even in their own trade, no intelligence, a drug problem or all of the above.
    They pawn their tools every other month to fund their habits, then steal someone elses and go back to work.

    I'm speaking of the subs. The majority of teh home builders/general contractors building homes, are brokers and know nothing about construction. So it is impossible for them to police the problems any other way except to convince the owner/buyer that everthing is OK. The genral contractors point the fingers at the subs. If the truth were known, most of the blame is related to the general contractors who can get hoodlums to do minimal acceptable work, and refuse to pay adequate wages for good craftsmen. As a result the craftsmen that move here end up moving back up north.

    Because most of my clients are lawyers or insurance companies for the last 21 years, I become aware of a lot of the problems on a wholesale basis.

    So, try to be thankful that you are either oblivious to this, or not exposed to it, instead of being critical of those who are and are trying to improve the situation. The first step in improving the situation is idntifying the problem.
    That is what you are hearing.


  14. #14
    Dick Guest

    Default Re: Ridge Height and HAP

    The problems you describe are not relegated to your area. Here in the San Francisco Bay Area we have similar problems. The Unions used to police the issues to some degree, but now their power is minimal. The trade has become specialized, we no longer have carpenters that can build a whole structure. Just look at the Forums: Exterior Details, Finish Carpentry, Lead Carpenter and Rough Framing. Contractors no longer can employ the best carpenters to build a building, they have to hire the specilized trades and coordinate them.

    Bright young men are not going into the trades, but are going on to become dot-com millioniares, or some other less demanding, more rewarding profession. The gap is being filled by immigrants (with language and legal problems) and the loosers that cannot join mainstream American business. The ex-cons and addicts have assumed the role.

    You can't really blame the contractors, because they would like to pay more and hire only professional craftsmen, but the consumer is always looking for the cheapest product (and they sue if they don't like it). America's fascination with the "Price at the Pump" (to use Paul Fisette's phrase) is to blame, and the contractor is caught in the middle. More diligent code enforcement can address only part of the problem, quality issues are difficult to address.

  15. #15
    Tim Hunsaker Guest

    Default Re: Ridge Height and HAP

    Glen, Good to hear from you again, no true'r words were ever spoken, as for Dick,s response that the General Contractors are not to blame is not right in the vast majority of cases, in my area N.W.Ohio most of the general contractors are doctors,lawyers and real estate people we even have lumber companies that are g.c. not to mention bar owners, bug exterminators,and car dealers if you haven,t noticed I didn't use proper punctuation in capitalizing the aforementioned " Professionals" because if you look at one of my previous responses refering to the fact that this was once an honorable profession is no longer, but it seems that all of these so called professionals want to be involved in the building industry for one reason only and it isn't for the satisfaction unless of course it's in the form of green paper. The thing that made me get out of the framing business is that these so called g.c. hire sub-trades knowing that they have no workers comp., unemployment, or pay S.S taxes on their " employees" but let this go on even though they know that it is against the law and that this is the way the majority of this industry works, their goal is to make as much money anyway they can, and if a problem arises which it alway,s do's they either close up shop or in the case of lawyers they know how to play the game and eventually it will go away. The town I live closest to is so bad that for the last 5 yrs. in the framing business I traveled an average of 60 k miles per yr. to go to areas where there was better money and for the most part where crafstmen were in demand and appreciated, I could go on all night about the problems in this industry but anyone that has been in it for any length of time faces these problems everyday and wonders why they still do it, the unfortunate thing is that most of us wouldn't make it in anything else because it takes a special person to succeed in this business. One final note I haven't been much involved in this forum until about a month ago but want to say that when people like Glen Davis and others with experience and intelligence share their views for all to read and hopefully benefit from, listen you might be suprised what you learn.

    One note on the tragic events of late we have all been asked to say a prayer for the victims and families isn't it ironic that probably the only time we pray is when we face a tragedy such as this I think we all need to pray more often MYSELF INCLUDED in light of all of this I suggest you read the first two verses of the 27 th Psalm and hopefully it will give you peace.

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