# Thread: how much support on the end of a main beam is needed?

1. ## how much support on the end of a main beam is needed?

I have several documented sources stating that a main beam. In this case 3 2x10 planks fastened together, would need 3.5 inches of support on the ends. In this particular installation, I am assuming when they built the cavity for the main beam the contractor forgot to include the height of the sill plate. To make up the difference they added a 2 x 2 piece of lumber.

I called this out. All 4 walls had horizontal cracks and each wall have a verticle crack from the top to the horizontal crack.

An engineer was hired to evaluate.

Was is your opinion? Did I miss something?

3 inches

3. ## Re: how much support on the end of a main beam is needed?

Beam needs to be supported by entire surface provided by the pocket ( 3" )
AND if shimmed, the shims should be steel, the grain of the wood will compress, and will continue to compress as it ages.

4. ## Re: how much support on the end of a main beam is needed?

According to 2006 IRC R502.6, when bearing on wood, minimum is 1.5 inches.
However, those cracks don't sound too good.

5. ## Re: how much support on the end of a main beam is needed?

Originally Posted by John Arnold
According to 2006 IRC R502.6, when bearing on wood, minimum is 1.5 inches.
However, those cracks don't sound too good.
John I believe the 1.5 inches is for Joist. Girders need 3 inches.

6. ## Re: how much support on the end of a main beam is needed?

Originally Posted by David Banks
John I believe the 1.5 inches is for Joist. Girders need 3 inches.
It says "joist, beam or girder". The question is, does that lousy 2x2 constitute "bearing on wood"? It's 3 inches for masonry or concrete.
I'm certainly not saying the 2x2 is fine and good. Just trying to interpret the IRC.

7. ## Re: how much support on the end of a main beam is needed?

I think the 2X2 is a shim, not a bearing surface. Therefore it needs to be 3" minimum, but lets see what the code guru's have to say.

8. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Vern Heiler
I think the 2X2 is a shim, not a bearing surface. Therefore it needs to be 3" minimum, but lets see what the code guru's have to say.
Shim sounds good to me.

9. ## Re: how much support on the end of a main beam is needed?

That compression on the end of the beam in the second pic isn't good. I've seen beams that appeared to have adequate bearing support but still showed that same type of compression/crushing.

10. ## Re: how much support on the end of a main beam is needed?

That is bearing "on wood", and the minimum bearing for "on wood" is only 1-1/2".

Remember, that is "minimum". The loads placed on the girder, joist, beam, along with the species of wood of the girder, joist, beam, and the species of wood of the bearing, along with the orientation of the bearing, all would need to be checked against the strengths and load capacities of the species of wood, which would include the modulus of elasticity and the fiber bending.

It is quite possible that, to meet the latter two strengths, the bearing would need to be increased to greater than 1-1/2".

Should the HI have to (need to) get into deciding if the bearing was sufficient? No.

Should the HI use their knowledge and visible indications present (if any) that it might not be working as built? Yes, absolutely.

If it does not look right, or something looks amiss, it is the HIs job to write it up (that is what the HI was hired for).

11. ## Re: how much support on the end of a main beam is needed?

[quote=Jerry Peck;62689]That is bearing "on wood", and the minimum bearing for "on wood" is only 1-1/2".

It was a shim in a thread last week that had to be orientated with the fibers pointing in the direction of Meca! What makes this any different? If the 2X2 was metal it would be a shim!

12. ## Re: how much support on the end of a main beam is needed?

[quote=Vern Heiler;62782]
Originally Posted by Jerry Peck
That is bearing "on wood", and the minimum bearing for "on wood" is only 1-1/2".

It was a shim in a thread last week that had to be orientated with the fibers pointing in the direction of Meca! What makes this any different? If the 2X2 was metal it would be a shim!
Vern,

I'll answer that with some questions:

Does the wood girder bear on concrete?

If not, what is the wood girder bearing on? (I.e., what is the wood girder touching?)

If a "shim" is bearing on "concrete", and a wood girder is "bearing on" the "shim", and the "shim" is wood, what is the wood girder "bearing on"?

Then, does it matter what that piece of wood is called? Other than "wood"? It could be a "shim", a "bearing plate", a "support", or any other name you want to give it, but it is ... drum roll ... "wood", is it not?

13. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Vern Heiler
It was a shim in a thread last week that had to be orientated with the fibers pointing in the direction of Mecca!..
That's funny. I liked it so much I corrected your spelling of Mecca!

14. ## Re: how much support on the end of a main beam is needed?

Does the wood girder bear on concrete?
No, but the 2X2 wood does. Thus must have 3" of bearing on the concrete.

If a "shim" is bearing on "concrete", and a wood girder is "bearing on" the "shim", and the "shim" is wood, what is the wood girder "bearing on"?

I think the operative word is "bearing " meaning to support. The 2X2 would not support anything without the concrete that supports it. The 2x2 is a spacer to the bearing surface.

Last edited by Vern Heiler; 11-17-2008 at 08:03 PM. Reason: Quote got messed up!

15. ## Re: how much support on the end of a main beam is needed?

Jerry, if this is allowed all we would need is a 1 1/5" pocket in the wall and a piece of paint stick.

16. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Vern Heiler
No, but the 2X2 wood does. Thus must have 3" of bearing on the concrete.
Vern,

Two things regarding the above:

1) The code does not address how much bearing that ""shim", a "bearing plate", a "support", or any other name you want to give it" is required to have. Thus, you would need to address that based on its species, modulus of elasticity and the fiber bending characteristics.

2) *It does have* the 3" bearing you are referring to - how long does that piece of wood (whatever you want to call it) look to be? 1-1/2 blocks? That's about 24".

I think the operative word is "bearing " meaning to support.
The operative word IS bearing, however, its meaning is regarding how many square inches of support it is required to have, which all relates back to the characteristics I keep referring to "its species, modulus of elasticity and the fiber bending characteristics".

If you have a SYP, 2x10, its "bearing surface is 1-1/2" wide. The required minimum depth is 1-1/2", thus, its "bearing" surface is 1-1/2" x 1-1/2".

All the above is based on the codes "prescriptive" requirements, it is entirely possible that there are "engineered" requirements involved, and that those "engineered" requirements may exceed the "prescriptive" requirements.

For example, say the engineer has placed a greater load on the floor, and, to compensate has engineered in a 3" bearing (doubling the bearing, cutting in half the per square inch load on fiber bending). Would the minimum code requirement of 1-1/2" work or be sufficient? Probably not.

How would you, as a home inspector, know if this is built to the "prescriptive" minimums based on the loadings shown in the code, or, if this was built based on "engineered" loading? You would not.

The 2x2 is a spacer to the bearing surface.
No. There may be multiple bearing surfaces. In this case there are two bearing surfaces:

1) The concrete filled block: The 2x2 is "bearing on" that concrete filled block.

2) The 2x2: The girder is "bearing on" that 2x2.

You have to follow the load path down to the foundation, in this case that is from girder to 2x2 to foundation wall to footing which bears on the soil.

To follow that path, then, the girder bears on the 2x2, which bears on the foundation wall, which bears on the footing, which bears on the soil.

EACH must be able to support what bears on it.

17. ## Re: how much support on the end of a main beam is needed?

The operative word IS bearing, however, its meaning is regarding how many square inches of support it is required to have, which all relates back to the characteristics I keep referring to "its species, modulus of elasticity and the fiber bending characteristics".
I don't recall the code having "square inches" in it!

I know and appreciate that you use this forum to hone your skill of litigation consultant, but be honest, you wouldn't trot this pony in front of a half conscious judge in a darkened court room!

18. ## Re: how much support on the end of a main beam is needed?

This thought is in line with the picture but.....

What if the wood, shim, whatever that wood thing is....were scabbed parrallel with the beam...a regular 2X nailed to the bottom of the beam so that it was as wide as the beam and a couple feet long.

Would it make a difference then? You would still have a piece of wood used as a shim but then the weight of the beam would be bearing on the added piece of wood but it would be supported by the concrete and the bearing would be 3 inches.

Would you write that up?

19. ## Re: how much support on the end of a main beam is needed?

The photo shows lack of air space of a minimum of 1/2" at the butt end of girder.
The question that begs asking is; is the girder bearing on wood or a concrete block wall? (this should be fun?)

20. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Wayne Carlisle
This thought is in line with the picture but.....

What if the wood, shim, whatever that wood thing is....were scabbed parrallel with the beam...a regular 2X nailed to the bottom of the beam so that it was as wide as the beam and a couple feet long.

Would it make a difference then?
Only to the distance to which the wood bearing plate/shim was bearing on concrete/block.

You would still have a piece of wood used as a shim but then the weight of the beam would be bearing on the added piece of wood but it would be supported by the concrete and the bearing would be 3 inches.
Looks like it would be bearing on maybe more than 3 inches (that bearing surface on the block looks recessed i/2 a block (4") with the pilaster block projecting out 1/2 a block (another 4"), for a full 8" block (filled, of course) surface.

That would mean the wood bearing plate would have a bearing surface of 1-1/2" x 8". And that the girder would also have 8" of bearing.

21. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Vern Heiler
I don't recall the code having "square inches" in it!

The code does not have square inches in it. In fact, neither do the design manuals, however, those design manuals tell you what the strengths of the different species are, and then you need to make the calculations needed to determine how much bearing area is needed for a given species for a given load - i.e., it gets down to engineering, which is what I stated.

Do you "know" for a fact that this was constructed in accordance with the prescriptive code, or to "engineering"? I don't.

The point being, some of this stuff is way past what an HI is inspecting, or, rather, what the HI is addressing - the HI should be inspecting it all, then deciding on how and what to address. If it 'looks questionable', that is when the engineer is called in to "design appropriate repairs".

I know and appreciate that you use this forum to hone your skill of litigation consultant, but be honest, you wouldn't trot this pony in front of a half conscious judge in a darkened court room!
Depends on who's side I was on and what their position was. Yeah, I might pull out my old design manuals, look up the information in new editions of those design manuals, then walk the sleepy-eyed judge through the scenario of what excessive loading does on a species of wood which has insufficient and inadequate fiber bending strengths (you know those crushed ends of joists you see, yeah, those - that is from the fiber bending strengths not being sufficient to resist the load place on it with that size bearing area. Increase the bearing area square inches and you reduce the load per square inch, now the wood is not crushed).

22. ## Re: how much support on the end of a main beam is needed?

FWIW - IMHO that wall is a masonry wall, therefore I agree with Richard, David and Vern, 3 inch bearing is required per 2006 IBC 2308.7 and 2007 CBC 2308.7.
That piece of wood the girder is sitting on does not appear to be PT and furthermore they're called "post blocks" or "nailing anchors" in the trades. (West Coast)
The evil thing about this set up is what the moisture will do to the girder end sitting on a piece of wood providing less than 3 inches bearing without adequate clearance from the end of the beam. In my book it's a reportable item.

23. ## Re: how much support on the end of a main beam is needed?

agree with west coast jerry and others. needs 3" bearing on concrete minimum and 1/2" airspace. catch that at underfloor inspection before insulation and plywood installation.how is p.t. attached to foundation and beam?

24. ## Re: how much support on the end of a main beam is needed?

Brian
We used to drive 16d duplex headed nails into the bottom of redwood pier blocks (PPT) and set them in the pier pockets before we poured the forms or filled the concrete blocks. Of course this was the era when we had to post dinosaur look-outs and concrete pumpers where not even imagined.

(PTT – pre-pressure treated)

25. ## Re: how much support on the end of a main beam is needed?

brian: For genral building practice (i.e. without getting into all kinds code considerations) A pressure-treated 2x4 is plenty in my experience. There is compression involved just as there is compression from all the joists (live load,perpendicular load bearing walls, etc. Remember that a significant portion of the load is on the exterior foundation wall and sill plate as far as compression is concerned. I am curious about what apears to be a buttress as part of the pocket? I can't see where the cracks are. I would suggest that additional piece of wood be put in place, but that the cracks are the real point of concern. What do you think? Chris Bittner

26. ## Re: how much support on the end of a main beam is needed?

Jerry Peck

You do realize what you just said I hope/ won't even try to explain it but this is what you said.

"Depends on who's side I was on and what their position was."

Sounds like the Long Con and cannot be interpreted as anything else.

27. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Ted Menelly
You do realize what you just said I hope/ won't even try to explain it but this is what you said.

"Depends on who's side I was on and what their position was."
Ted,

This is what the question was:

Originally Posted by Vern Heiler
be honest, you wouldn't trot this pony in front of a half conscious judge in a darkened court room!
Originally Posted by Jerry Peck
Depends on who's side I was on and what their position was.
That question was referencing where I said "The operative word IS bearing, however, its meaning is regarding how many square inches of support it is required to have, which all relates back to the characteristics I keep referring to "its species, modulus of elasticity and the fiber bending characteristics". "

The answer, thus is (was) "depends".

The rest is posted above, as it "depends" on who was saying what and who I was speaking for.

One would not want to bore a judge with those details when not necessary - that is the "no" part of "depends", however, one would be foolish not to explain the reason for the requirements when it was necessary - that is the "yes" part of "depends".

Not sure if you get it now or not, but ...

Surely you would not say something which a dizzy judge might not understand and where it is not necessary, just as you surely would explain something to help your client should the judge not understand the reason for the requirement. True?

One part of being an expert witness is knowing when to shut up and let the other party ruin their own case. Another part is being able to explain the reasoning behind something should that become necessary.

28. ## Re: how much support on the end of a main beam is needed?

Ted,

Here is an example of one which actually happened.

I was testifying and the opposing attorney asked me if I had seen the Palm Beach Gardens Swimming Pool and Spa Code. I replied that I had not, that I was referencing the Palm Beach County Swimming Pool and Spa Code. One thing I did not say was that I knew the local code was, if there were any changes, required to be more stringent, thus anything he was going to point out would be in my client's favor.

That attorney held up the local code and said here it is, you are stating that you have not read this before, correct. To which I answered correct.

I then asked if he wanted me to look at it briefly, and, with full chest thumping he said yes, then gave me that code booklet (printed on 8-1/2 x 11 pages, about 30+ pages.

I flipped through it from back to front, then from front to back, then asked him if he would like me to read something from it.

Before continuing, the one issue (just one of hundreds issues) being discussed at that precise questioning was where the Palm Beach County Swimming Pool and Spa Code required a swimming pool and spa to be "at least 3 feet from a foundation of a structure", and the pool and spa were only 2 feet 9 inches (as I recall, may have been 2 feet 10 inches), meaning that the builder was trying to squirm out of being 2"-3" too close.

Okay, to continue, I read the title to the section I saw as I flipped through the local code - Location:, and under which it stated the following for the first requirement listed:

No swimming pool or spa may be located within 5 feet of a foundation of a structure.

Just like that ... BOOM!, the axe fell ... we were no longer discussing the pool being a mere 2" to 3" too close to the structure's foundation, we were now discussing that the pool was 2 FEET (plus that 2" to 3") too close to the foundation.

Before that attorney had a chance to gasp, I repeated it for him, giving the code section number, blah-blah-blah 5 FEET blah-blah-blah, followed by 'that means it is 2 feet closer than it is allowed to be'.

As I recall, that was my last question from that attorney, I think I remember him saying "no more questions".

At which time my client's attorney got back up and asked me to read that section again and to explain to him as he was not quite sure what it was saying (he did not need me to explain it to him, he *got it* immediately, I could tell by the look on his face when I read it and when he asked me to explain it to him, he just wanted to make sure the judge *got it* too).

29. ## Re: how much support on the end of a main beam is needed?

Jerry, the whole #16 post (too long to quote again) where you ramble on in the direction of saying that the 2x2 is ok, is the pony I was refering to.

Now you have come to the plate as a switch hitter, saying the surface is too small and will compress.

30. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Vern Heiler
Jerry, the whole #16 post (too long to quote again) where you ramble on in the direction of saying that the 2x2 is ok, is the pony I was refering to.

Now you have come to the plate as a switch hitter, saying the surface is too small and will compress.
Vern,

You've lost me there.

The 2x2, as I have said, MAY BE (i.e., "it depends") okay or it MAY BE too small.

According to the prescriptive construction in the code, it fulfills the "okay" size. However, and I keep repeating this, *IF* that is engineered, IT MAY be too small.

There is a difference between building to a prescriptive code, the engineering is 'conservative' versus building with an "engineered design", where the engineering is 'not as conservative', i.e., VE (Value Engineering).

A good example was pointed out by, I think it was Erby, when discussing a glass with water in it at the halfway mark.

The optimist says the glass is half full.

The pessimist says the glass is half empty.

The engineer know the glass is twice as large as it needs to be.

I had not heard that before, but it is true. And that applies to the difference in my two scenarios - you cannot take them both and apply them to one installation at the same time. If you are presuming it is "prescriptive", you must stick to that, if you are presuming it is "engineered", then you would need to see the engineering. Plain and simple.

I really don't know an easier way to explain it.

Here is another example:

Take a 2 foot 2x4 post, at that height, that 2x4 post will support a lot.

Take a beam and lay it across the top (end grain) of the 2x4 post.

Will the end grain of the 2x4 crush first with a load or will the horizontal grain of the bean crush first? The horizontal grain of the beam will crush first.

Now, though, add two 6" long pieces of 2x2 to the top of the 2x4 post - making the top of the 2x4 post 1-1/2" by 3" long; it does not strengthen the 2x4 post much at all, but it does double the bearing surface the joist is bearing on.

Now you have double the bearing surface, reduced in half the per square inch load on the joist at the bearing. The 2x4 post is still taking the same load, the joist is still taking the same load, the bearing contact area, though, while it is still taking the same TOTAL load, its per square inch load has been reduced by half. The joist grain will not crush now.

Does that help understand it?

31. ## Re: how much support on the end of a main beam is needed?

Now, though, add two 6" long pieces of 2x2 to the top of the 2x4 post - making the top of the 2x4 post 1-1/2" by 3" long; it does not strengthen the 2x4 post much at all, but it does double the bearing surface the joist is bearing on.
Jerry, I have fumbled a 2x4 with two 2x2x6's in my head like a monkey with a coconut, and I can't make the top of the 2x4 smaller than it was originally?

This thread has made me think about what the code requirement of 1-1/5" on wood and 3" on masonry is about. Never really gave it a lot of thought before.

If a joist or beam is bearing on masonry it is most likely not attached to a rim joist, as is the case here. If a joist or beam is bearing on wood it is end or toe nailed at the end of the joist or beam to another piece of wood, at least in every situation I have seen. End nailing and toe nailing do provide support, contrary to some belief, evidenced by the joist found in old construction that had only nailing to hold it in place. Not enough by today’s standards, but "surprise" the joist were not on the crawlspace floor! They hadn't moved for over 60 years.

If this was the line of thought in writing the code, additional bearing surface would be required to prevent crushing where nailing at the end was not used. The end of the beam at the beginning of this thread requires 3" of bearing surface for its full width. The fix is easy, no SE required, just insert another piece of 2X and satisfy code. The only question I would have is clearance as mentioned by WC Jerry, but the picture may be deceiving.

32. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Vern Heiler
Jerry, I have fumbled a 2x4 with two 2x2x6's in my head like a monkey with a coconut, and I can't make the top of the 2x4 smaller than it was originally?

Yeah, After I typed that and shut my computer down, I realized what I had typed, then said 'What to heck, I typed it, I'll let some point out that I just made it smaller, while saying I made it twice as large - and 'How to heck do you do that?

Well, the way I did that is by taking the 2x4 at its narrow width of 1-1/2" and adding the two 2x2 to it, but, if you are going to add the two 2x2, why would you not just turn the 2x4 to the wider dimension?

What I meant to say was ...

For WC Jerry:

"That piece of wood the girder is sitting on does not appear to be PT"

It looked like it was PT to me, but, then, I've been mistaken before, and will be again.

33. ## Re: how much support on the end of a main beam is needed?

Hey guys shouldn't there be some bridging right on top of that beam between the joists? Thanks.

34. ## Re: how much support on the end of a main beam is needed?

brian,
there should be solid blocking between joist at bearing in this situation. where is the insulation?

35. ## Re: how much support on the end of a main beam is needed?

That is what I figured, just wasn't sure that it HAD to be. Thanks Brian

36. ## Re: how much support on the end of a main beam is needed?

"How much support on the end of a main beam is needed?"

More than this?

37. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Michael Thomas
"How much support on the end of a main beam is needed?"

More than this?
Nah. That should be fine.
Run!

38. ## Re: how much support on the end of a main beam is needed?

Detail in a 1.2M home:

39. ## Re: how much support on the end of a main beam is needed?

Where in the IRC is the allowable shim material specified? The required side clearance?

- Thanks

40. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Michael Thomas
Where in the IRC is the allowable shim material specified?
Shims and supports are not addressed as such, they are address only along with all other load-bearing wood, after all, they are "load-bearing" by bearing on the surface they are on, and carrying the load of whatever is bearing on them, therefore they should be the same or greater strength as what is bearing on them.

From the 2006 IRC.
- R502.1 Identification. Load-bearing dimension lumber for joists, beams and girders shall be identified by a grade mark of a lumber grading or inspection agency that has been approved by an accreditation body that complies with DOC PS 20. In lieu of a grade mark, a certificate of inspection issued by a lumber grading or inspection agency meeting the requirements of this section shall be accepted.

The required side clearance?
- SECTION R319
- - PROTECTION AGAINST DECAY
- - - R319.1 Location required. Protection from decay shall be provided in the following locations by the use of naturally durable wood or wood that is preservative treated in accordance with AWPA U1 for the species, product, preservative and end use. Preservatives shall be listed in Section 4 of AWPA U1.
- - - - 1. Wood joists or the bottom of a wood structural floor when closer than 18 inches (457 mm) or wood girders when closer than 12 inches (305 mm) to the exposed ground in crawl spaces or unexcavated area located within the periphery of the building foundation.
- - - - 2. All wood framing members that rest on concrete or masonry exterior foundation walls and are less than 8 inches (203 mm) from the exposed ground.
- - - - 3. Sills and sleepers on a concrete or masonry slab that is in direct contact with the ground unless separated from such slab by an impervious moisture barrier.
- - - - 4. The ends of wood girders entering exterior masonry or concrete walls having clearances of less than 0.5 inch (12.7 mm) on tops, sides and ends.
- - - - 5. Wood siding, sheathing and wall framing on the exterior of a building having a clearance of less than 6 inches (152 mm) from the ground.
- - - - 6. Wood structural members supporting moisture-permeable floors or roofs that are exposed to the weather, such as concrete or masonry slabs, unless separated from such floors or roofs by an impervious moisture barrier.
- - - - 7. Wood furring strips or other wood framing members attached directly to the interior of exterior masonry walls or concrete walls below grade except where an approved vapor retarder is applied between the wall and the furring strips or framing members.

41. ## Re: how much support on the end of a main beam is needed?

So... just so I'm clear.. there really is no requirement that such shims be metal; it's certainly a Good Idea (especially as in this case when there is evidence - efflorescence and deteriorating mortar - of elevated moisture along that wall), but I really haven't got a leg to stand on in terms of code requirements, I just have to appeal to common sense.

So next question, I guess, is: how many people here would mention that shim as an FYI, how many would recommend its replacement on general principles, and how many we just let it slide given that there is no current evidence of deterioration?

I ask because of sort of a tricky one: the entire house (built '49, conventional concrete foundation, central girder with one post) is sagging and continuing to sag further toward the center of the house, and there will be an SE out looking at it.

Going down from attic through first and second floors I was convinced I would find an obvious explanation once I got to the basement, but the girder is if anything oversize, it's got no sag, there is no evidence of problems at the pockets or with the central column, the only thing out of the ordinary is the load bearing wall down the center of the first floor is running parallel rather than perpendicular the joists, but nearby joists don't seem to be sagging..

Given that the SE is going to be out there I want to have dotted every "I" and crossed every "T" in terms of potential structural issues, but now the whole thing has really got me questioning how to report wooden shims in masonry or concrete pockets, I've read many times in many sources that the should be steel, but now it appears this is a home inspection urban legend, and belief in such is a good way to end up looking to design professionals like a Complete Idiot.

Does anyone know of an authoritative source for the steel requirement?

42. ## Re: how much support on the end of a main beam is needed?

Some discussion on the ICC board:

ICC Bulletin Board: Shims

43. ## Re: how much support on the end of a main beam is needed?

Brain fade: what is this diagonal joint called - I keep thinking "lookout", but can't seen to GOOGLE up confirmation...

44. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Michael Thomas
Brain fade: what is this diagonal joint called - I keep thinking "lookout", but can't seen to GOOGLE up confirmation...
Other than miter cut I'm not sure what you are looking for.

In some instances it would be called a "fire cut".

45. ## Re: how much support on the end of a main beam is needed?

That's a beveled shoulder joint. Couldn't tell from the picture if there was a tenon in the horizontal piece - there usually is a tenon and peg to "keep" the joint although that's clearly missing from your joint.

46. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Corn Walker
That's a beveled shoulder joint. Couldn't tell from the picture if there was a tenon in the horizontal piece - there usually is a tenon and peg to "keep" the joint although that's clearly missing from your joint.
Yes, I do see a tenon in there, which would negate any effect of making a fire cut.

Usually, those are not at that great of an angle, not the ones I recall having seen in years past.

You are also correct in that there are no pegs in the joint to keep it tight.

47. ## Re: how much support on the end of a main beam is needed?

What's the minimum bearing at this type of joint?

Thanks.

48. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Michael Thomas
What's the minimum bearing at this type of joint?
I don't think there is a "minimum bearing." That question implies a structure "built to code" using calculated load and span tables. As such, an old timber frame house is likely to be outside of what the code might adjudicate and warrants consulting a SE, particularly one versed in timber frame construction.

49. ## Re: how much support on the end of a main beam is needed?

The code (IBC) does address timber construction as Type IV Heavy Timber Construction, the IRC does not address Heavy Timber Construction, but any Type in the IBC may be used instead of using the IRC provided it meets the minimum fire-protection and separation requirements.

The IBC does not give a lot of information on, or guidance to, Heavy Timber Construction.

50. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Jerry Peck
The code (IBC) does address timber construction as Type IV Heavy Timber Construction, the IRC does not address Heavy Timber Construction, but any Type in the IBC may be used instead of using the IRC provided it meets the minimum fire-protection and separation requirements.

The IBC does not give a lot of information on, or guidance to, Heavy Timber Construction.
Have you seen many residential buildings that meet the IBC Type IV specifications? In my area you're talking about apartments/condos above retail shops, and converted light industrial buildings, but not much else.

As you stated, the IBC doesn't give much guidance on Heavy Timber Construction, outside of defining minimum sizes to meet the requirements for classification and setting out the fire resistance ratings for structural components. I can't tell if the timber in the picture meets those minimum size requirements. I suspect it doesn't.

That said, figuring out the required bearing should be some fairly straightforward math, given the loads, species, and sizes of the members, for a SE to calculate.

51. ## Re: how much support on the end of a main beam is needed?

There is no inclined member, that is not a beveled shoulder joint.

Two half joints, both ledged.

Could be lapped or lipped half joints, might be bare-face haunch can't see.

What does this have to do with the OP?

52. ## Re: how much support on the end of a main beam is needed?

Originally Posted by H.G. Watson, Sr.
There is no inclined member, that is not a beveled shoulder joint.
If you rotate what you're thinking of 90° you'll get what is in the picture. Using this tool I found online called "Google" I was able to locate an architecture book with a section on heavy timber construction. On page 248 you'll find both a picture and a description of the joint in question, the latter of which I've taken the liberty of retyping for you (given the poor quality of the scan):

A beveled shoulder or housed joint is used to connect all load-bearing beams, such as bent and connecting girts and summer beams, to posts. Angled variations can be used when principal rafters join to posts or for diagonal braces. The depth of the shoulder depends on loading, torsion, other joinery in the area, and wood species.

One of my architecture books that details timber construction also refers to this as a beveled shoulder joint, but perhaps they're both incorrect. As I'm always looking to learn something, I'd appreciate any references you can provide that might set the record straight.

53. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Corn Walker
If you rotate what you're thinking of 90° you'll get what is in the picture. Using this tool I found online called "Google" I was able to locate an architecture book with a section on heavy timber construction. On page 248 you'll find both a picture and a description of the joint in question, the latter of which I've taken the liberty of retyping for you (given the poor quality of the scan):

A beveled shoulder or housed joint is used to connect all load-bearing beams, such as bent and connecting girts and summer beams, to posts. Angled variations can be used when principal rafters join to posts or for diagonal braces. The depth of the shoulder depends on loading, torsion, other joinery in the area, and wood species.
One of my architecture books that details timber construction also refers to this as a beveled shoulder joint, but perhaps they're both incorrect. As I'm always looking to learn something, I'd appreciate any references you can provide that might set the record straight.
Since you like on-line books I'll reply in kind.

The term "bevel-shoulder joint" is another name for an "oblique-mortise-and-tenon" joint or joinery.

From: "Handwork in Wood" By William Noyes, M.A.; Assistant Professor, Department of Industrial Arts. Teachers College, Columbia University, New York City; The Manual Arts Press, Peoria, Illinois, Copyright William Noyes 1910.; page 269.

Snipped from: Chapter VII, The Common Joints.

"No. 67. An oblique mortise-and-tenon or bevel-shoulder joint is one in which the shoulders of the tenoned beam are cut obliquely and its end is cut off at right angles. The cheeks of the mortise are correspondingly sunk. By these means the tenon prevents lateral motion while the whole width of the beam presses against the abutment. Thus a much larger bearing surface is obtained. The whole is bolted or strapped together. It is used in heavy truss work."

You can view the chapter on line, including the diagram(s) here (amongst other places, some scanned): Handwork in Wood 7 You'll see a housed joint, specifically a housed brace joint discussed and diagramed immediately preceeding.

From: "The Building Trades Pocketbook: A handy Manual of reference on Building Construction"

"A bevel-shoulder joint is a mortise and tenon used to unite inclined to upright or horizontal pieces. It is made by cutting beveled shoulders on the inclined piece and a corresponding sinking in the cheeks of the mortise of a post or beam."

You can get the book on Amazon, or view the section which contains the above and a Figure (see "a" in Fig. 5) at: Carpentry Joints

Regarding Timber Construction, you will find a great deal of information at the American Wood Council, including a number of (free to download) publications, technical papers, construction guides, etc.

However most joinery is common.

Last edited by H.G. Watson, Sr.; 04-12-2011 at 09:13 PM.

54. ## Re: how much support on the end of a main beam is needed?

It's not that I like on-line books, only that internet links are a bit more useful than "come by my place and take a look at these architecture books that show this."

Speaking of which, architects and timber frame builders seem to insist on calling it a beveled shoulder joint, seemingly because the shoulder in the mortise and tenon joint is beveled rather than square.

Also, I'm wondering what kind of "timber framing" would use "bolts" or "straps." Timber framing, as opposed to the more general post-and-beam framing, uses primarily the joints themselves (plus pegs or wedges as keepers) rather than mechanical fasteners and straps.

Try as I might, I can not find any reference to the particular joint in Michael's photo that does not identify it as a bevel-shouldered mortise and tenon joint. The 1910 definition not withstanding, the definitions I've found are not restricted to "inclined" members only (which appears to be a feature of the joint's use in furniture), choosing to include the joining of a horizontal girt to a vertical post as well.

55. ## Re: how much support on the end of a main beam is needed?

I just saw that pocket clearance detail somewhere recently, might have been in Code Check, not sure. If I can stay awake long enough I'll look it up. Really sick right now, spent Monday in the hospital. PIA Flu.
The 6x6 porch beam you show in the pic is traditionally called a 'lookout' in Chicago porch building. The end cut is typically called a fire cut or birds beak cut. Recess into the the 6x6 upright is typically 2" - 2 1/4".
If that's in the City repair is not an option unless they lie on their permit app. In that state the City wants full replacement. The old construction style no longer gets approved for permits. (except possibly in those odd interesting cases).

56. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Markus Keller
If I can stay awake long enough I'll look it up. Really sick right now, spent Monday in the hospital. PIA Flu.
Glad I have my anti-virus running

57. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Markus Keller
The 6x6 porch beam you show in the pic is traditionally called a 'lookout' in Chicago porch building. The end cut is typically called a fire cut or birds beak cut.
Do they call them fire cuts if they're not recessed into masonry walls? I am (was?) under the impression that fire cuts don't have tenons since the purpose is to allow the horizontal member to collapse (due to fire) without creating an upward or rotational force on the vertical member.

As for a bird's beak joint, that connotes something entirely different to me. In woodworking it resembles something of an open bird's beak.

58. ## Re: how much support on the end of a main beam is needed?

Originally Posted by Michael Thomas
What's the minimum bearing at this type of joint?Thanks.
None, it is not allowed in the City of Chicago to notch an upright (column) for bearing to "let in" or frame in a beam into an upright. Making matters worse it has been further framed and reduced the upper beam. The compound notch has also been overcut above - a sure condemnation even if the upright were for example simply spliced (which wouldn't be allowed so close to a beam anyway). The beam must be adjacent.

IIRC City of Chicago hasn't allowed "let in" beams or any column or post notching exposed to weather for quite some time (I'm thinking at least 2003 or thereabouts after a major porch collapse that made national news), and there is no "grandfather" provision having to do with decks, porches, overhangs, or the like - when seen old or new it is written up and required to be corrected. Steel angles fully supporting and bearing, no weakening of an upright with notching, and bolts not nails or pegs.

If you consult both the glossary and Appendix D (Unacceptable Details), contained in the attached document from the City, noting beams and columns I believe you will find mention of your lookout supporting beam. You will find expressly prohibited in Appendix D (Unacceptable Details) Figure D.1 (pg 35 of 29 of the attached pdf) of the document and an example of the forbidden pictured notch framing-in. Obviously the additional notching for the above member has further complicated and compromised.

I've always understood "lookouts" in your region to be joists, projecting out from the wall of the building, not the beams, girders, etc. which support them.

It took some hunting, as my old saved links weren't working, but I've found the summary page, checklist, and the approved design information on the city site - its here: City of Chicago :: Porch & Deck Information

The attached is the "Guide to Porch Design and Construction (Volume 1A of 2). Inspection checklists also make mention I believe.

HTH.

P.S. sure hope M.K. beats the bug, recovers soon and without complication.

Last edited by H.G. Watson, Sr.; 04-13-2011 at 09:23 PM.