1. ATTENTION returning members. If you are coming here from the old forum for the first time, you will need to reset you password. However, we had an email problem getting password reset links set out to a lot of the email addresses. That problem is temporarily rectified but IF you still have an issue, email me direct at info@thebuildingcodeforum.com and I will give you a temporary password.
    Dismiss Notice
  2. Welcome to the new and improved Building Code Forum. We appreciate you being here and hope that you are getting the information that you need concerning all codes of the building trades. This is a free forum to the public due to the generosity of the Sawhorses, Corporate Supporters and Supporters who have upgraded their accounts. If you would like to have improved access to the forum please upgrade to Sawhorse by clicking here: Upgrades
    Dismiss Notice

pressue blocking

Discussion in 'Residential Structural Codes' started by Jobsaver, Oct 14, 2010.

  1. Jobsaver

    Jobsaver Sawhorse

    Joined:
    Oct 12, 2010
    Messages:
    851
    Likes Received:
    0
    Pressure blocking: allowed or not?
     
  2. pyrguy

    pyrguy Moderator

    Joined:
    Oct 16, 2009
    Messages:
    474
    Likes Received:
    18
    Saver

    Please elaborate. I do not recognize that terminology.
     
  3. ajweaver

    ajweaver Bronze Member

    Joined:
    Oct 27, 2009
    Messages:
    41
    Likes Received:
    0
    It depends.

    Ha. I learned that from the ICC.

    Pressure blocking:

    From my understanding, and this is folklore to me...before hangers-the pressure block would be cut larger than the gap between the ceiling joists and hammered into place then toenailed.

    A lot of what I see is not pressure blocking, in that there is no pressure. I can see a gap.

    Other times they face nail the block to a band joist, then nail the end of the face of the ceiling joist into the cut end of the block.

    I always ask them first if there is a reason why a hanger cant go there?

    My interpetation of the code is that floor joists require 1-1/2" of bearing per 502.6

    And Ceiling joists per 802.6.

    I interpet that to mean if they didnt have the min. req. bearing they would need a hanger.

    I do not enforce this on short spans < 4' in closets etc..if there isnt significant load.

    A MCP/CBO from this area refers to the "framing of openings" and doesnt require hangers until lengths exceed 6'.

    But we both agree, always on floor joists.

    I am curious too as to what people enforce.
     
  4. Jobsaver

    Jobsaver Sawhorse

    Joined:
    Oct 12, 2010
    Messages:
    851
    Likes Received:
    0
    I am trying to pick-up on an old thread off the ICC bb archive having topic as Framing Anchors. There are good posts there with illustrations: I am not as good at describing things as many others in these forums, but basically in is a method of sideloading girders, beams, or walls with floor joists/ceiling joists by attaching blocking to girder, beams, or walls and then nailing the joists to the blocking.

    Anybody out there good at posting illustrations?
     
  5. Jobsaver

    Jobsaver Sawhorse

    Joined:
    Oct 12, 2010
    Messages:
    851
    Likes Received:
    0
    ajweaver: 802.6 - Where is the bearing of the top end of a common rafter? Against the ridge or on top of the ridge? This gos back to an unfinished debate: is bearing contact with another member or

    does bearing require a member to set on top of the other?
     
  6. Mark K

    Mark K Platinum Member

    Joined:
    May 12, 2010
    Messages:
    1,433
    Likes Received:
    96
    The code does not address the issue of pressure blocking. Thus pressure blocking effectively cannot be used to show code compliance.
     
  7. Code Neophyte

    Code Neophyte Silver Member

    Joined:
    Oct 17, 2009
    Messages:
    269
    Likes Received:
    1
    802.6, as Ajweaver said, is for ceiling joists, not rafters. Rafters do not have the same requirement for bearing.
     
  8. Jobsaver

    Jobsaver Sawhorse

    Joined:
    Oct 12, 2010
    Messages:
    851
    Likes Received:
    0
    Code Neophyte:

    My book says: R802.6 Bearing. The ends of each rafter or ceiling joist shall have not

    less than 1 ½ inches of bearing on wood or metal . . .

    Mark K:

    R502.6.2 does allow for “approved framing anchors” as an alternative to ledger strips.

    Under definitions, Section R202: Approved: Approved refers to approval by the building official as a result of investigation and tests conducted by him or her, or by reason of acceptable trade principles or tests by nationally recognized organizations.

    I’m stupid. But, it seems to me that despite what many of the old timers on this and other forums say, BO’s can make a call on this either by acceptable trade principles, or, by tests conducted. In other words, traditional practice plus proven performance = prescription to the IRC.
     
  9. Code Neophyte

    Code Neophyte Silver Member

    Joined:
    Oct 17, 2009
    Messages:
    269
    Likes Received:
    1
    You're correct. A preceding section, R802.3, addressed rafter connection at ridge, hips, valleys.
     
  10. Bootleg

    Bootleg Silver Member

    Joined:
    Apr 5, 2010
    Messages:
    333
    Likes Received:
    0
    I have approved pressure blocking if correctly applied instead of a hanger for floor and ceiling joist.
     
  11. Jobsaver

    Jobsaver Sawhorse

    Joined:
    Oct 12, 2010
    Messages:
    851
    Likes Received:
    0
    Still. R802.6 applies to those same connections described in R802.3. So, what do they mean by bearing?

     
  12. Jobsaver

    Jobsaver Sawhorse

    Joined:
    Oct 12, 2010
    Messages:
    851
    Likes Received:
    0
    Ditto.

    I believe Simpson and the other framing connector manufacturers have duped our entire industry, including very very smart people using these forums, I don't get it.

     
  13. Code Neophyte

    Code Neophyte Silver Member

    Joined:
    Oct 17, 2009
    Messages:
    269
    Likes Received:
    1
    My 2-cent answer is that, going back to R102.1 "Where there is a conflict between a general requirement and a specific requirement, the specific requirement shall be applicable.", the upper end termination of a rafter is specifically addressed in R802.3, so it would apply at that location. In all other locations (i.e. lower end of the rafter), R802.6 would apply.
     
  14. Jobsaver

    Jobsaver Sawhorse

    Joined:
    Oct 12, 2010
    Messages:
    851
    Likes Received:
    0
    Code neophyte:

    Good answer. Thanks. What is your 2-cent answer to the legality of pressure blocking joists?
     
  15. Mark K

    Mark K Platinum Member

    Joined:
    May 12, 2010
    Messages:
    1,433
    Likes Received:
    96
    The building official can approve alternates in accordance with Section R104.11. From a practical point of view there are few limits on the building officials decision.

    Neither Section 104.11 orthe defination of approved say anything about acceptable trade principles. in my experience I have found a number of situations where what is presented as trade practices all to often has little foundation. This does not necessarily mean that they are unsafe but I would be more careful when basing a decision on what I understand to be normal trade practices.

    You can, and we have all done this, decide not to notice a code non-compliance.

    Test data would be a good basis for making the decision. I am not aware that there is any test data dealing with the effectiveness of pressure blocking.

    While you could load test a particular situation. I would be concerned that the performance would be dependent on workmanship thus making it difficult to extrapolate to other situations.
     
  16. Code Neophyte

    Code Neophyte Silver Member

    Joined:
    Oct 17, 2009
    Messages:
    269
    Likes Received:
    1
    IF....I understand the concept correctly (so the floor or ceiling joists are side nailed into the end of a 1-1/2" block?), then I think it does not meet the prescriptive requirement of R802.6, and could not be accepted without engineering. From a practical standpoint, however, I can't see how it is much different than the 2x2 ledger strip that's allowed by code to be used to provide bearing. Both depend heavily on only a mechanical nail connection and no direct bearing loadpath.
     
  17. Bootleg

    Bootleg Silver Member

    Joined:
    Apr 5, 2010
    Messages:
    333
    Likes Received:
    0
    Jobsaver,

    I'm not sure what you question is but in framing you can use pressure blocking any where it is needed if done correctly.
     
  18. Jobsaver

    Jobsaver Sawhorse

    Joined:
    Oct 12, 2010
    Messages:
    851
    Likes Received:
    0
    Mark K:

    I stand corrected. The definition states "accepted principles" rather than "accepted trade principles".

    I am now faced with the truth that I sometimes (accidentally) add or subtract a word here and there to try and get the code book to say what I want it to say.
     
  19. Jobsaver

    Jobsaver Sawhorse

    Joined:
    Oct 12, 2010
    Messages:
    851
    Likes Received:
    0
    I understand and agree. An engineering study would be in order.
     
  20. Bootleg

    Bootleg Silver Member

    Joined:
    Apr 5, 2010
    Messages:
    333
    Likes Received:
    0
    You would require an engineer to approve pressure blocking in SFR framing?

    Is the house engineered?
     

Share This Page