Thread: truss for different slope roof connection

this is the truss in a 13 years townhouse attic. I never seen this before. Is it ok?

Also, How to install the skylight over 24" wide on roof? Is it the only way to move the truss on each side to accommodate?

Merry Christmas

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Looks o.k. if there is, what we don't see in the picture, a bottom cord in tension. This looks fairly conventional to provide for a break in roof slope and rafter. I think a concern might better be toward the issue of how well these trusses are tied (clipped) to the walls and if there is sufficient fastening of roof sheathing to rafters (trusses) per the nail-down misaligned (i.e. picture shows nail fastener missing embedment in rafter). How much of this is going on with this roof? Could be in trouble in a high wind.

MERRY CHRISTMAS!

Oh, I remembered there was a second part to your question about mounting a skylight between truss rafters at 24" spacing but skylight was wider than the 22 inches. The quick and dirty, safe, way is to double up (build-up) on adjacent (to skylight location) trusses and bracket 2 x 6 purlins every 4 ft., outside area of skylight, between these 2 double-trusses in order to carry roof loads and prevent a sag in roof. Do this before removing/cutting out middle truss.

Are those trusses notched? It appears they may be... if so, that's not ok. Is that in a valley or porch roof? Hard to tell from the pics.

A truss can only be moved if designed for it. Moving it one way to allow for the skylight changes the load on it and the adjacent trusses (increased load on one and decreased load on another). Moving it an 1-1/2" really shouldn't cause a problem but none-the-less is would need to be designed for it.

I agree with the door guy, any modifacation to a truss should be noted, you can get convetional framing methods mixed in with trusses but that looks like someone tried to modify something.

Typically here in jersey, the owners association owns the truss and the owner owns up to the drywall, I would still note it for the owner selling to notify the association to inspect and certify.

The skylite framing also, you can usually tell on how the insulate the box of the shaft between the roof and the lower ceiling if the framer followed a detail, typically I dont see them done very well. How was the location of the skylite to the adjoining unit fire seperation wall?

1) It appears the truss was field modified not just notched. Note the nails in the joiner. Looks like someone pulled the joiner plates, cut out what they didn't want, maybe added another piece of lumber and nailed the plate back in place. Unless there is documentation on hand certifying the modification by a structural engineer or truss design professional, field modifications are not allowed and cannot be considered safe. Just because it has been there X years doesn't mean it has seen all the loading variables possible that can create failure conditions.

2) Get a skylight sized for the spacing present.

Nothing it that photo jumps and and says "truss modified in the field", the truss plates could have been loose and someone nailed them tight using nails.

Nothing in that photo looks "notched" either.

I've seen trusses similar to that where a sloped roof transitions to a flat (low slope) roof section.

Looks factory made to me - the only way to know for sure is to have the truss company either provide the engineering or do an inspection and say yea or nay.

Originally Posted by Jerry Peck

Nothing it that photo jumps and and says "truss modified in the field", the truss plates could have been loose and someone nailed them tight using nails.

Nothing in that photo looks "notched" either.

I've seen trusses similar to that where a sloped roof transitions to a flat (low slope) roof section.

Looks factory made to me - the only way to know for sure is to have the truss company either provide the engineering or do an inspection and say yea or nay.

I don't believe even the "Factory" can't nail pressed joiner plates that come loose.

Originally Posted by Stuart Brooks

I don't believe even the "Factory" can't nail pressed joiner plates that come loose.

Not following you???

Did you mean (changed the word in red) "I don't believe even the "Factory" CAN nail pressed joiner plates that come loose."?

If so, ... I did not say that it was correct, ... I only said that is what it looked like was done - and that IS what it looks like.

*I* don't know if that is allowed or not, or if the truss plates were NOT loose and some extra nails were installed, I'd need to ask the truss company about that.

Nonetheless, there is nothing (other than the obviously pointed out nails) which looks field modified - that is what I said and I'm sticking to it.

Jerry, those are two different trusses. It's not likely two truss plates popped off on two different trusses by accident.

The way the four 2X4 ends come together, it looks like it was banged up on the spot to me. Some generic truss plates were nailed on, different nail pattern on each.

I agree with the other guys, it needs the inspection and approval of an engineer. It may already be on the books, but I would call for confirmation.

BTW, Daniel M, we often see where nails for the sheathing miss the rafter or truss. It doesn't mean another nail was not fired in.

Originally Posted by John Kogel

Jerry, those are two different trusses.

Yes, I saw that.

The way the four 2X4 ends come together,

That is why I think they were made that way - you don't "fit" things together like that in the field and have the sheathing end up where you want it as that slop where it meets the flat part, and the pieces are all cut to fit at the various angles.

it looks like it was banged up on the spot to me. Some generic truss plates were nailed on, different nail pattern on each.

You don't press those truss plates into the wood with a hammer or those nails. Those were either done at the truss plant or with a hand press with someone who knew what they were doing, either way, they look designed that way to me.

I agree with the other guys, it needs the inspection and approval of an engineer. It may already be on the books, but I would call for confirmation.

I have not disagreed with that, I am only disagreeing on that they were 'made up in the field and nailed together' - I am saying they were designed that way.

And, yes, there probably is already a letter on the books, as you say, and that letter is in the truss engineering packet.

That is why I said:

Nothing it that photo jumps and and says "truss modified in the field", ...

Nothing in that photo looks "notched" either.

I'm voting for field modified due to the incorrect angle of cut evidenced in photo #1. Note the notched portion of the lower left 2X. It should be angled in such a way that the notched face would be tight against the right 2X and would not visible. Add to that the nails in the gusset plate.

Have a Merry Xmas!!

Originally Posted by Jerry Peck

Not following you???

Did you mean (changed the word in red) "I don't believe even the "Factory" CAN nail pressed joiner plates that come loose."?

If so, ... I did not say that it was correct, ... I only said that is what it looked like was done - and that IS what it looks like.

*I* don't know if that is allowed or not, or if the truss plates were NOT loose and some extra nails were installed, I'd need to ask the truss company about that.

Nonetheless, there is nothing (other than the obviously pointed out nails) which looks field modified - that is what I said and I'm sticking to it.

I don't think the nails mean the plates were attached in the field either. Nor do they suggest a modification of the truss. I have done residential construction for 23 and yes I have gotten factory built trusses with roofing nails in the gusset plates. Don't know why, didn't ask why. I would assume they added to increase holding power of the gusset? Pretty sure they weren't added to kill time at the plant. Jerry is right, you don't pound on a gusset plate in the field with a hammer and roofing nails. They are pressed on.

It appeared to me at first glance they were notched, if this is more than one truss, my guess would switch to be they were made that way.

Originally Posted by Bob Knauff

I'm voting for field modified due to the incorrect angle of cut evidenced in photo #1. Note the notched portion of the lower left 2X. It should be angled in such a way that the notched face would be tight against the right 2X and would not visible. Add to that the nails in the gusset plate.

Have a Merry Xmas!!

I actually have seen and used trusses with what was called a turbo web. All webs are cut on a raduis instead of an angle. This allowed them to be built quicker and less precise. It really didn't catch on... I didn't feel that you actually got much bearing on the webs as only a small portion of the 2x actually contacted the chords.

I must admit I have never heard of Turb-O-Web Truss.

None-the-less, all the joints for the truss in question here appear to be nearly perfectly cut at required angles except the bottom one.

spe

Originally Posted by Bob Knauff

I must admit I have never heard of Turbo Web Trusses. Here is a link to a company that makes the tool to produce them. I can't seem to make it a hyperlink today. Sorry. Index

None-the-less, all the joints for the truss in question here appear to be nearly perfectly cut at required angles except the bottom one.

I wasn't suggesting these were turbo webs... I guess I don't see the mis-cut web on the truss either. My eyes aren't as good as they used to be though.

Have a merry christmas too Bob

Happy Holidays to you too Door Guy.

I realize you didn't mean the trusses were Turb-O-Web type. I appreciate you bringing them up though. When I have more time I'm going to research them further. Ya never know when one will pop up in the field!

Here is the portion of the set up that appears to be incorrect. We should not see a vertical face on the left 2X. It should be tight against the right 2X.

I don't see a "mis-cut end", what I see is where the different truss webs meet offset from each other.

I've tried to drawing the edges of the webs aligning the red lines with the visible edges of the webs - looks like they meet pretty good to me, and you can see that there is no "mis-cut" at the bottom, just an offset between members.

Is there anyone here who as seen, and always sees, trusses with the members PRECISELY in alignment and they are never offset from each other?

I doubt I have ever seen trusses cut that way, in part simply because different angles create different length cuts and they simply do not match up perfectly and precisely.

Jerry, what program do you use to mark up your images?

Bob,

Jasc Paint Shop Pro 6.01, which I've had for ... well, it says "copyright 1991-1999" ... so I guess it's been over 10 years years.

I believe Corel bought them and made them fancier and gussied it up, but when I tried the new Corel program several years ago I did not like it, to complicated for what I use it for as I'm not into 'photoshopping' like some people are.

My version also has an animation program, but I rarely have done anything with that.

I searched ebay and found a newer version (but still OLD compared to the new stuff): eBay - photos border paint shop pro 9 learn color, Similar items search

Originally Posted by Bob Knauff

Here is the portion of the set up that appears to be incorrect. We should not see a vertical face on the left 2X. It should be tight against the right 2X.

Jerry's drawing elimates the issue of this truss being miscut. Guess that's why I didn't see it either. This is common of areas where webs meet as various angles produce various angle lenghts. The steeper the angle the longer the cut. If it is matching up against a shorter angle, the longer angle will hang over. I would like to see a pic of the outside or more of the flattened area of the truss, just to see why they were made that way.

Jerry's marked-up photo clearly shows the truss was not modified and that junction provides strong support in the way each section fits together.

A larger gusset wouldn't need the additional nails but since the actual surface contact area on each piece is so small, the nails were likely factory added, as the door-guy pointed out, for added strength and holding power of the gusset tabs, intended to reduce possible flex, twisting and loosening during handling and placement.