Ridge beam end to end connection..sagging?

windowguy · 01-18-2010, 06:30 PM

How much should engineered lumber ridge beams be expected to "sag" at a connection? The total span is about 30 feet so call it two 15 foot 2X10's touching end to end. there doesnt seem to be anything fastening them together besides the weight of themselves pushing against each other.

The temporary (i presume) 2X4 to hold both ends up in the middle was left in place and it is bowing out about 2 inches. I'm guessing this is from a sag or settle of the ridge. the other picture is up close showing the 2 ends coming together, which sits on the 2X4.

Should there be concern about the 2X4 bowing? If i see that bowing i can't help but think there is tremendous weight on that 2X4... that 2X4 can't be structural i believe it was just there to support the ridge while the rafters were being put up..

how much "sag" is normal as a house settles? This construction is about 4 years old.. i admit i am not a pro when it comes to the framing and knowing how weight gets dispersed amongst the rafters..

thanks!

tpolk · 01-18-2010, 06:57 PM

that lvl should have had a plywood gusset nailed on both sides(minimum) should be no sag as rafters and coolar ties and ceiling joists should create a rigid triangle. have you held a straight edge along bottom to see if it is bowing. the 2x could just be warped from the heat

**Gary in WA** · 01-18-2010, 08:41 PM

Your LVL was used as a ridge board, not beam. It is not supporting the rafters, the walls and ceiling joists are. The 2x4 upright can be removed, it is non-structural. The engineered wood was used because it was as wide or wider, per code, for the rafters used. The connection between them may not be required because the roof sheathing is giving the roof system the shear flow, if properly nailed. If it makes you feel better, add some plywood gussets as mentioned. The ridge is material transferring forces down through to the walls with little pressure on the board itself.
Page # 242, figure 13.9: http://books.google.com/books?id=1fI...20ties&f=false

Be safe, Gary

jlhaslip · 01-18-2010, 09:23 PM

check the walls at the rafter ends to see if they are plumb.
is there any chance that the ceiling joists and walls are moving to the outside of their intended position?

as stated above, the ceiling joists act as a tension member which is supposed to stop the force from the roof rafters moving the walls outward. collar ties don't work to do that. if they are out of plumb even a little bit, have an on-site inspection done to confirm the stability of the structure. by a qualified structural engineer.

windowguy · 01-19-2010, 05:45 PM

I feel much more comfortable now knowing that the ridge beam does not carry the load per se. The joists do..

How would i check to see if walls are plumb? Go up on a ladder to the roof (2nd floor?) and hang a plumb bob down the outside? Or do i just put a level on the walls on the inside?

There is no signs of interior walls cracking or showing signs of distress in the sheetrock. (outside of the normal mouldings cracking from dry air in the winter).

CustomBuild · 01-20-2010, 12:31 PM

A lot of times the bowed 2x4 was used as an aide to installation of the rafters. What happens is all of the rafters are cut at the same time down on the ground to the same dimension. If, during installation, the framers notice the seat cuts are not fitting for whatever reason, they will cut a 2x4 1/2" longer than the height of the bottom of the LVL. They will put a massive bow in it and place it under the ridge. When the 2x4 attempts to straighten out, it extends, pushing the ridge upward with amazing force, enabling the next precut rafter to fit more snugly. Sometimes, all of the bow they put on this 2x4 doesn't get straightened out. Once the roof system is complete, the "jack" can be removed, and everything will stay in place.