Sistering oak beams urgent help please

[stevesmith18]

We have supported our rotten oak beams with sistered oak beam supports alongside and now need to infill the holes in the walls. Its tricky to put the granite stone all the way to the back of the hole where the original beams have rotted out, so the builders are recommending sand-and cemment and then facing this with granite and lime mortar at the front of the hole as you see it in the room.
Their argument is they can fill up all the gaps in the middle of the wall so it acts like stone. It wont touch the new oak beams (they will be packed with the granite and lime. The sand and cement will be just used to pack the back of the hole. However im concerned about the use of sand and cemment - any thoughts

 

[aockenden]

It’ll probably be fine as long as the rest of the wall is done with proper lime and the wall as a whole is remaining nice and dry. I would definitely insist that it’s not in direct contact with the joist though. Our post-war renovation era joist-ends are fully bedded into cement that was packed into the original wall pockets at the time of installation. In addition the joist ends themselves are wrapped in a bitumen paper / tar fabric. They are perfectly sound, especially now that we’ve replaced the rest of the cement, plastic paint and gypsum on the inside and outside of the wall with lime.

Edit: don’t get me wrong, it’s a dumb reason that makes no sense, but then you’re dealing with a modern builder here, whose general approach to every problem under the sun is a drooling slack jawed muttering of “uhhhh, let’s put some cement on it”. So you need to temper expectations and settle for solutions which are good enough OR do it yourself.

 

[Toby Newell]

We have supported our rotten oak beams with sistered oak beam supports alongside and now need to infill the holes in the walls. Its tricky to put the granite stone all the way to the back of the hole where the original beams have rotted out, so the builders are recommending sand-and cemment and then facing this with granite and lime mortar at the front of the hole as you see it in the room.
Their argument is they can fill up all the gaps in the middle of the wall so it acts like stone. It wont touch the new oak beams (they will be packed with the granite and lime. The sand and cement will be just used to pack the back of the hole. However im concerned about the use of sand and cemment - any thoughts

View attachment 12327

Where is the sistering? I see a broken beam but no sistering, I see a split beam and tiny bits of wood stuck to the top. If you wrap the beam ends you can use cement but as aockenden says you want to make sure the whole wall is breathable

 

[stevesmith18]

Thanks - yeah the photo was taken before the sistering started. I’ve had a word with the guys and they are now infilling with granite and lime so the c&s wont be touching the beams.
Appreciate you and aockenden’s time coming back to me.

 

[aockenden]

Thanks - yeah the photo was taken before the sistering started. I’ve had a word with the guys and they are now infilling with granite and lime so the c&s wont be touching the beams.
Appreciate you and aockenden’s time coming back to me.

Good news. No worries.

 

[Toby Newell]

Thanks - yeah the photo was taken before the sistering started. I’ve had a word with the guys and they are now infilling with granite and lime so the c&s wont be touching the beams.
Appreciate you and aockenden’s time coming back to me.

Yeah I was slightly worried for a moment there!