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-   -   Best way to repair rotted structural wood member? (http://www.diychatroom.com/f14/best-way-repair-rotted-structural-wood-member-123501/)

miamicuse 11-15-2011 01:11 AM

Best way to repair rotted structural wood member?
 
I have a piece of 2x6 about eight feet long.

This beam was badly damaged during a roof leak and possibly termites as well, was previously repaired by the former owner, by putting short pieces of 2x6s on both sides of it and nailed the three pieces together.

I was trying to repair some other framing in that area in the attic and attempted to reinforce the repair by driving more nails in, only to find out that the nail would just go right past the middle piece (the damaged piece) with no resistance whatsoever. Curiosity got the best of me and I decided to pry off the sister piece to inspect the damage. It was difficult to remove the sister beam because nails from above the roof deck were driven through it and I had to cut these nails off flush.

After removing it, and three other pieces of bracing connected to it, I was able to see the middle piece. I was SHOCKED at how badly it is rotted. This was previously fixed by someone when the roof was open because roofing nails were driven down and attached to all three pieces. Why they didn't take the time to fix it right when they had full access is totally beyond me. But now I am faced with this problem.

This is how it looks from below. The beam marked 1 and 3 are the short sister beams and the middle piece marked 2 is the damaged beam.

http://i173.photobucket.com/albums/w...ofP1010915.jpg

Now I have removed beam marked 3 and this is how badly rotted it is from the side view.

http://i173.photobucket.com/albums/w...ofP1010965.jpg

It is actually worse then it looks, because after I cleaned out the loose fibers with a wire brush, the rotted sections extends into the wood by another 4 to 6 inches.

http://i173.photobucket.com/albums/w...ofP1010969.jpg

http://i173.photobucket.com/albums/w...ofP1010968.jpg

This is BAD!!!

What is worse is I cannot replace this member. It sits below the roof deck and rests on top of the concrete team beam, and extends another 4 feet as part of the roof overhang structure. Also there are hurricane straps bolted this member down to the concrete tie beam, it is not going to come out in one piece.

Even if I can chop it off and remove piece by piece of this member, there is no way a new piece of this length can be maneuvered in place at this tight space in the attic without opening the roof deck up.

I am basically stuck with trying to repair this.

The good news is, the back side sister 2x6 is still there. I may be able to fill in the cavity with some structural epoxy? Not sure. Any recommendation there? and once I fix this middle piece, then a new piece but longer, that goes from the concrete tie beam to the other end will be added back, and all three pieces tie together with 1/2" bolts and Simpson hangers.

Any recommendation on how to repair this large rotted out cavity? I have heard of the Abatron system or the WoodWizard system that claim to restore structural strength. Any thoughts or ideas to replace this wood beam in place and restore structural strength would be greatly appreciated.

woodworkbykirk 11-15-2011 05:12 PM

with a peice of wood that severely rotted, id be replacing the entire beam and anything else that has rot.

only thing is this isnt a diy task, you should be contacting a contractor or experienced carpenter

miamicuse 11-15-2011 09:42 PM

Quote:

Originally Posted by woodworkbykirk (Post 771900)
with a peice of wood that severely rotted, id be replacing the entire beam and anything else that has rot.

only thing is this isnt a diy task, you should be contacting a contractor or experienced carpenter

That would be my first option, except there is no way to replace it without opening up the roof above. There is no access below because the room is extremely tight with a ton of conduits, and part of the beam is wedged into the roof overhang and bolted down to the concrete tie beam with hurricane straps. I can cut out a 3' section of it but that would not be a clean fix either.

Ron6519 11-15-2011 10:58 PM

What's the longest lumber you can get into the space? From the photos it looks like a hodge podge of framing.
Unless you can get some fairly large 2x's in there, you won't compensate for the damaged area.

miamicuse 11-16-2011 12:11 AM

I can probably wedge a 3.5' section in there, so that one end I can hang on a truss, and the other end extending to about 10" on top of the concrete tie beam.

The current "hodge podge" is that the rotted beam is being sistered on both sides by short beams. They are only long enough to cover the rotted section. I have removed one of the sister beam in order to see this.

But inserting a new beam in there to support the roof deck is not the problem. I can do that independent of the rotted beam.

The problem is if I cut out the rotted portion, then the 4' overhang on the other side of the wall will create a bearing. That's why the rotted beam is still serving a purpose. If I can somehow repair it and give it some strength, I can leave it in place, then put a new sister in front of it and longer.

kwikfishron 11-16-2011 06:48 AM

If the repair requires opening up the roof then that’s what you do, open the roof.

I’m looking at rotted sheathing too were you just going to leave that?

It looks like you still have wet wood. Has the source of the leak been dealt with yet?

sixeightten 11-16-2011 07:58 AM

You would be surprised by what a carpenter can do. Even opening up the roof is not always a huge deal. Probably a one day job with very little materials. You are beyond a bandaid fix there.

Ron6519 11-16-2011 08:22 AM

Quote:

Originally Posted by miamicuse (Post 772282)
I can probably wedge a 3.5' section in there, so that one end I can hang on a truss, and the other end extending to about 10" on top of the concrete tie beam.

I can't see that solving the problem.

Michael Thomas 11-16-2011 08:51 AM

Just had to solve this problem in one of my rental units, where they end of improperly pocketed beam supporting the gable end of the second story above had rotted out; because of the structural significance of this beam (around 30' long) and the way it intersected with various finished interior surfaces it would have been an absolute nightmare to replace.

The solution I came up with (and had blessed by an SE) was to open the floor 4 feet over from the interior wall, pour a footing, and support the beam above with a permanent steel column, with 12' of undamaged beam extending past the post.

I then cut out the entire damage section, correctly flashed the beam pocket, installed a replacement section, and bolted it to the projecting section of original beam extending beyond the post using steel plates on each side of the junction.

Finally, we build a wing wall out to the post location; as it happened the floor plan was such that the wing wall not only was not a problem at that location, but actually allowed us to build some additional badly needed closet space.

The point is not that you would want to do exactly the same thing, but that if you get a bit creative about it, there are often solutions to this kind of problem not apparent at first glance.

miamicuse 11-16-2011 04:07 PM

The leak has been addressed several years ago when they completely reroofed with new membrane and new tiles.

There is no more leak.

Why they didn't removed the rotted beam and replace it in it's entirety at the time, I have no clue. They obviously had removed the plywood because the sister beams have roofing nails driven into them from above the roof deck. They also used the old plywood.

The new "stain" you saw on the underside of the roof deck is not water damage. They are from some liquid wood compound I was experimenting with. They claim if you soaked the rotted wood with it it will harden and petrify the rotted wood back to structurally solid. I used a brush to brush a few spots just to see what it's like. Not too impressed with it. Feels similar to those "gorilla glue" foamy adhesive.

woodworkbykirk 11-16-2011 09:49 PM

kwik fish is correct. you cant fix a severed leg with a bandaid..

this rot issue needs to be addressed, to do so correctly it needs to be opened up to be worked on. theres no way around it

mrgins 11-17-2011 11:41 AM

Quote:

Originally Posted by sixeightten (Post 772383)
You would be surprised by what a carpenter can do. Even opening up the roof is not always a huge deal. Probably a one day job with very little materials. You are beyond a bandaid fix there.

This is correct. It also depends what that joist/beam is holding up. Is it possible to cut the joist back to solid wood, install a header between the two joists on either side, and then replace the rotted piece?

miamicuse 11-17-2011 09:39 PM

I actually located the roofing company that did the repair for the previous owner, and was able to talk to the contractor who did the work. He was able to tell me more about the previous repair.

When they did the re-roof they did open up the roof there to address the rotted beam, however, the beam even with the roof out of the way will not come out. The rot was localized to that one area which I photographed, the rest of the 2x6 beam is solid. However, this beam cantilevers out to the roof overhang and where it crosses the concrete wall, it is strapped down by a 1/4" thick metal tie down that embedded 8" into solid concrete.

After talking to him and I did a bit more poking around in the attic and on the outside overhang here is a sketch of what is happening.

http://i173.photobucket.com/albums/w...g/roofbeam.jpg

The rotted beam is shown in green. The rotted area is on the left where it looks like a shark took a bite out of it.

On the left it is attached to a double truss. Then it goes over the concrete wall, and this is where there is an "inverted U shaped tie down" embedding it into the solid concrete. Then it extends outside for 4 feet, there is another 2x4 beam attached to it from below, and below that a wood soffit panel. The end of the beam is attached to another 2x8 header, to which three layers of facial boards of different widths are nailed to.

The only way this beam is coming out is for the roof to come off, then cut in chunks, pull off the facial boards on the end, then the header, pry out the custom wood soffit panel, and remove the 2x4 beam below it. That would be the only way another piece of equal length can slide into position and pass through that thick metal tie down loop.

I am not going to do that with the roof not leaking and the beam rock solid on the portion on the outside of the concrete wall. There is no load sitting on this beam from the roof because the roof there is sitting on other trusses not shown and the roof goes on a different angle. That section that was rotted was basically there to provide a counter moment to the cantilever section. I can add bracing to distribute the roof load there, but what will be challenging is to find a way to relieve the uplift at the wall from the cantilever overhang.

Might have to consult a structural engineer to see how I can do that.

mrgins 11-18-2011 03:41 PM

Any way you could remove the fascia and slide in a new rafter? There must be a wood plate/sill on the concrete wall which could be notched at the same angle as the roof so that the new rafter would have more bearing on the plate. Then use a joist hanger on the left end of the rafter

Snav 11-18-2011 04:03 PM

Quote:

Originally Posted by miamicuse (Post 772702)
The leak has been addressed several years ago when they completely reroofed with new membrane and new tiles.

There is no more leak.

Why they didn't removed the rotted beam and replace it in it's entirety at the time, I have no clue. They obviously had removed the plywood because the sister beams have roofing nails driven into them from above the roof deck. They also used the old plywood.

The new "stain" you saw on the underside of the roof deck is not water damage. They are from some liquid wood compound I was experimenting with. They claim if you soaked the rotted wood with it it will harden and petrify the rotted wood back to structurally solid. I used a brush to brush a few spots just to see what it's like. Not too impressed with it. Feels similar to those "gorilla glue" foamy adhesive.

Call your insurance company and explain the issue - see what they say since it's related to previous damage. . . at the least they'd be able to point you in a direction of an insurance-company approved contractor to fix it.


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