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pressue blocking

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.
 
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?
 
The code does not address the issue of pressure blocking. Thus pressure blocking effectively cannot be used to show code compliance.
 
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.
 
I have approved pressure blocking if correctly applied instead of a hanger for floor and ceiling joist.
 
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.
 
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.
 
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.
 
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.
 
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.
 
Code Neophyte said:
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.
Click to expand...
I understand and agree. An engineering study would be in order.
 
Jobsaver said:
I understand and agree. An engineering study would be in order.
Click to expand...
You would require an engineer to approve pressure blocking in SFR framing?

Is the house engineered?
 
Bootleg:

I am probably not saying it right. I think it would be good if an engineering study could be done to establish, particularly in SFR, whether or not the practice of pressure blocking could be considered an alternative "accepted principle" to using hangers or a ledger to support joists.

Just about everybody in my state pressure-blocks. I haven't been personally exposed to any resultant failures. But, it remains the general consensus of many people in these forums more experienced than I that the practice of pressure-blocking does not meet code.

Further, there are apparently many places where nobody pressure blocks, and spends lots of $$ on metal. Seems like someone would want a study done.
 
Jobsaver, Keep in mind that not meeting a prescriptive provision of the Code does not automatically mean non-compliance with the Code.

An Engineer could review and provide detail for only those elements of the project that are not prescriptive, or a contractor, owner etc could provide the Reference Standard that shows that detail, if it exists.

That a Code Official has broad discretion, does not mean it should be used too freely. Those accepted practices are usually accepted (Engineering) practices. Just because it's 'been done that way for XXX number of years doesn't necessarily mean it's a good idea.

I'm less convinced that Simpson, TECO, etc sold us a bill of goods. They sold us options, alternatives to traditional methods. And the Codes allow the flexibility to use a wide array of options in design and construction.
 
Legality aside, pressure blocking, as pointed out if done correctly, is one of the best and strongest ways to connect certain wood members such as rafters to ridge boards.
 
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