MortarThePoint Posted November 16, 2023 Share Posted November 16, 2023 Our fireplace has a 6ft opening with a 140(w) X 215(h) concrete lintel over. I'd like to dress this in Oak and there are places selling 3-4 year seasoned for ££ and others selling partially seasoned for £. I'm wondering if well seasoned is a red herring as it will always need to adjust to its new environment. My hope is to attach it to the concrete lintel and then plaster around it (11mm Hardwall plus 2-3mm MultiFinish). What are my chances of the oak not shifting and cracking the plaster? @nod do you ever do this and do you have any tips? Link to comment Share on other sites More sharing options...
Russell griffiths Posted November 16, 2023 Share Posted November 16, 2023 You have absolutely zero chance the oak won’t move and the plaster won’t crack. Can you build it in, in a way that the plaster does not but up to it, either a stop bead or mount the oak forward and the plaster sits behind somehow. Oak frame houses and plaster were always a problem, so they changed how they are boarded and the plasternow goes behind the oak so they are free to both move independently. I would look at this for maybe a solution. 1 Link to comment Share on other sites More sharing options...
joe90 Posted November 16, 2023 Share Posted November 16, 2023 (edited) Oak will always move but less so with well seasoned stuff. I would mount the oak on/In front of the plaster so it can move, even paint the plaster first if possible. Edited November 16, 2023 by joe90 1 Link to comment Share on other sites More sharing options...
MortarThePoint Posted November 16, 2023 Author Share Posted November 16, 2023 9 minutes ago, Russell griffiths said: You have absolutely zero chance the oak won’t move and the plaster won’t crack. That's my thinking too 10 minutes ago, Russell griffiths said: I would look at this for maybe a solution Was there a missing link? Link to comment Share on other sites More sharing options...
Conor Posted November 16, 2023 Share Posted November 16, 2023 Render over the lintel, paint, then fit the oak over. Buy the greener one and leave it in the room for a few months before fitting. 1 Link to comment Share on other sites More sharing options...
joe90 Posted November 16, 2023 Share Posted November 16, 2023 I actually used Oak as the lintel (given to me by my builder as he had it spare) even tho it was well seasoned it shrank about 5mm across its 200mm making it loose in the brickwork (bricks didn’t fall down) packed it with 5mm oak wedges underneath to keep it tight, stopped shrinking after 2 years. 1 Link to comment Share on other sites More sharing options...
nod Posted November 16, 2023 Share Posted November 16, 2023 1 hour ago, MortarThePoint said: Our fireplace has a 6ft opening with a 140(w) X 215(h) concrete lintel over. I'd like to dress this in Oak and there are places selling 3-4 year seasoned for ££ and others selling partially seasoned for £. I'm wondering if well seasoned is a red herring as it will always need to adjust to its new environment. My hope is to attach it to the concrete lintel and then plaster around it (11mm Hardwall plus 2-3mm MultiFinish). What are my chances of the oak not shifting and cracking the plaster? @nod do you ever do this and do you have any tips? I definitely wouldn’t use hardwall Sand-lime would be more suitable As there is very little shrinkage 1 Link to comment Share on other sites More sharing options...
MortarThePoint Posted November 17, 2023 Author Share Posted November 17, 2023 8 hours ago, nod said: I definitely wouldn’t use hardwall Sand-lime would be more suitable As there is very little shrinkage I'd been thinking more of the beam shrinking away from the plaster, but plaster shrinkage is a further risk Link to comment Share on other sites More sharing options...
nod Posted November 17, 2023 Share Posted November 17, 2023 9 hours ago, joe90 said: I actually used Oak as the lintel (given to me by my builder as he had it spare) even tho it was well seasoned it shrank about 5mm across its 200mm making it loose in the brickwork (bricks didn’t fall down) packed it with 5mm oak wedges underneath to keep it tight, stopped shrinking after 2 years. We planned to build oak in last time and the fitter said he wouldn’t certify Link to comment Share on other sites More sharing options...
MortarThePoint Posted November 17, 2023 Author Share Posted November 17, 2023 38 minutes ago, nod said: We planned to build oak in last time and the fitter said he wouldn’t certify The stove fitter? Link to comment Share on other sites More sharing options...
Redoctober Posted November 17, 2023 Share Posted November 17, 2023 (edited) @MortarThePoint Here are a couple of images showing how our oak beam was fitted. When installed, it came with two large "bolt" type "pins" protruding, which were then drilled into the concrete lintel. The surrounding area was then plaster boarded. I have to say in the past 5 years we have not suffered any shrinkage or cracking or either the beam or plaster. The beam was sourced and fitted by the approved stove fitter! Edited November 17, 2023 by Redoctober Tidy up 1 1 Link to comment Share on other sites More sharing options...
nod Posted November 17, 2023 Share Posted November 17, 2023 6 hours ago, MortarThePoint said: The stove fitter? The guy who sold it to me installed and certified BC will ask 😁 Link to comment Share on other sites More sharing options...
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