building on wood

[stevegreen]

Hi, i'm fitting an 8' x 8' oak beam above a fireplace and would like to carry on above with blocks, has anybody had any experience in building on oak, The oak beam has been outside for some time, but i suspect is not completely dry and will move, split and shrink once in position and subject to the heat from the wood burning stove. The question is do i need to bed the blocks on some form of flexible joint to accomadate for the movement.
thanks

 

[^woody^]

IIRC, the Tudors had a lot of experience with building on oak. It seems OK to do

An 8" oak beam may shrink by about an inch as it dries. The blocks above may stay in place with just a gap between the beam and the blocks or they may crack in a stepped crack up all the joints.

To prevent this, either put a concrete lintel above the oak beam or put some expanded metal in the blockwork bed joints. Then when the oak shrinks, you will only need to repair the joint and plaster immediately above it

It might take three months or so before the oak stabilises to the room

 

[stuart45]

They used to build in lime mortar, and this helped accommodate any movement.

 

[geraint]

depends on the size of the fireplace.. old oak will not move too much.. so put it in and enjoy.. what, if there is any movement, you will not notice..