Repair/Replace/Sister 30 X 30cm Oak beam in French barn.

[GymBobby]

Hello all. I hope to get your thoughts on my problem.
First, the situation is I am on the last (of 9 beams) 30 X 30cm Oak beam repair or replacement, or sistering with Oak joists.
Of the 9, I have replaced 3, and repaired and sistered another. The remaining 5 have been OK.
So I am not phased by this stage of the project.
To allow you to get an overview of the problem, here is the overview. I have reduce it to like a Thumbnail size, but you can easily expand it again, I think.

The beam in question is the one on the right. It is supported along its length by the 100mm block wall, except for the doorway.
To the left the joist are all in and boarded, but the boards are not nailed down yet. I will nail them down when they have acclimatised. So the 3X2 across the hallway is purely to establish the level across the hallway, for upstairs. Although I was intending on creating a bridge over the hallway, at the far end of this photo. The room on the right will then be a bedroom, the room on the left will be a separate WC and a bathroom. There are two more bedrooms to the left.
That infilled doorway on the ground floor will become the main entrance.

The problem beam. Here is a few photos of close up the rotten far end of the beam. It has now been cleared of rotten wood and treated.

A wider view

And the other side:

And a wider view

I know there will be difficulties with repairing this with epoxy grout and rebar because I can see a hole right through, bottom to top

The other end of the beam is sound, again the 3X2 is just ascertain a level from the floor the other side of the hallway.

i seem to be having some difficulties with posting. I'll post this bit and then add another post.

 

[GymBobby]

So here is the view of the top of the problem beam

And a wider view

As I see it I have three choices:
1. Replace the beam entirely. The problem with that, and which I never had with the other three replacements, is that this one has the bottom of the crook frame attached to the beam ends, and there is a wall underneath the beam.
i am not phased with creating a mortise in the beam for the tenon at the bottom of the crook frame to sit in. although it would cause problems. It is more the wall underneath that creates the problem. Previously I have raised the new beam on a scaffold outside and a scaffold inside, and pulled the new beam through the wall and into place.
Now the wall would create difficulty in manoeuvering the beam (at about ½ ton maybe) along the top of the wall, or alongside and then sideways.
The tenon could be cut properly on the one end, and a one-sided tenon on the other end, with the cut-off piece replaced after the beam is in place. But the wall prevents any vertical movement.
I would have to remove at least the top course of blocks, maybe more.

Choice number 2.
I could splice a new piece into the worst affected part, about 3.3 metres, with a lapped joint each end of the splice.
Something like this, viewed from the top. I have some 10mm threaded bar in stainless steel.
And some some repair with epoxy grout and rebar. I am not phased by this. I have done it before. But this beam is in worse condition, and I am concerned about leakage of epoxy resin. There will be a lot of silicon caulking or hot glue gun and bits of wood required.

Choice number 3
Sister each side with Oak joists.
Again I have done this before, with the beam that I repaired with epoxy resin and rebar. That one was not supported except between walls.
Then I placed the first, lowest joist in situ, added a second one above it, and then a third one above that to get the right height for the floor.
Only the lower two were in pockets in the wall, not the top joist. that just sits on the other. This side will be visible, and there is a difference in the floor heights either side due to existing beams, hence the short length of threaded rod visible this side.
As shown here

The other side. You can just see the original beam peeping below the new Oak joists.

The length between the hall walls is 5.75 Metres.
Annoyingly I have 2 off 5.6 Metres in Douglas Fir. sitting in the other barn and another 5.8 Metre piece, all 210 mm X 70mm.

Other bits of information, i will be placing joists between the rotten beam and the beam to the left of it in the first picture. Whether those beams sit on a joist between the walls along the rotten beam, or sit in joist hangars fixed to a sistered joist doesn't matter.
Then there will be more joists for the floor of the room on the right, these will over shoot the new beam to the right of the rotten beam and either sit on a stone ledge, or in hangars on a leger board, fixed with bolts and epoxy to the end wall.

Surprisingly, the total replacement of the beam is probably the cheapest option, but the most difficult work, manly due to the weight of the beam. 30cm X 30cm X 6 Metres of green Oak, maybe about ½ ton, and the scaffold inside and out.

Any epoxy grouting will probably be the most expensive, at a minimum of £500 worth of epoxy resin + loads of hot glue gun, silicon caulking and maybe epoxy resin putty.

 

[StephenStephen]

I can't quite work out the function of the beam - is it to prevent spreading?