I'm planning a single storey extension on the rear of my house (semi-detached), pretty much like this (grey walls = existing house)
My question is about options to do with the existing opening shown with the dotted red line in the sketch. In the other, deeper half of the extension the existing opening for the back door will remain a doorway, but on the side with the wider opening, which currently has patio doors, it will end up a through room and I would like to have minimal intrusion at the side from a pier, and nothing protruding below the ceiling.
Viewed from the inside, the elevation of the existing rear wall and opening is this:
The opening is essentially as it was when the house was built nearly 60 years ago. I've not removed the plaster to check, but from my experiences of trying to drill into the wall above the opening I reckon there's a concrete lintel there.
Above the opening is the rear wall of the upper floor, which is 9" brick. and then a hipped roof.
What I want is to do away with the lintel, and part of the return on the LHS, and have a steel put in:
The idea being that the joists (which do run in the right direction) would be extended and would sit in the web of the steel, thus giving me a ceiling running from the existing room through to the extension with no visible beam across it.
SO - questions at last.
1) What, approximately, would this be likely to add to the cost of construction compared to doing nothing, leaving the opening as it is, and putting up with a 420mm protrusion below the ceiling? Not looking for free design work here, just trying to decide if I think it is worth doing, and therefore if I want to engage an SE to do the calcs.
2) The existing joists (6x2s) would need extending - not sure by how much (it's been a while since I had the boards up in the room above), but at a guess by around 300mm. Is it feasible to do this by sistering? Would not relish having to have them replaced.
My question is about options to do with the existing opening shown with the dotted red line in the sketch. In the other, deeper half of the extension the existing opening for the back door will remain a doorway, but on the side with the wider opening, which currently has patio doors, it will end up a through room and I would like to have minimal intrusion at the side from a pier, and nothing protruding below the ceiling.
Viewed from the inside, the elevation of the existing rear wall and opening is this:
The opening is essentially as it was when the house was built nearly 60 years ago. I've not removed the plaster to check, but from my experiences of trying to drill into the wall above the opening I reckon there's a concrete lintel there.
Above the opening is the rear wall of the upper floor, which is 9" brick. and then a hipped roof.
What I want is to do away with the lintel, and part of the return on the LHS, and have a steel put in:
The idea being that the joists (which do run in the right direction) would be extended and would sit in the web of the steel, thus giving me a ceiling running from the existing room through to the extension with no visible beam across it.
SO - questions at last.
1) What, approximately, would this be likely to add to the cost of construction compared to doing nothing, leaving the opening as it is, and putting up with a 420mm protrusion below the ceiling? Not looking for free design work here, just trying to decide if I think it is worth doing, and therefore if I want to engage an SE to do the calcs.
2) The existing joists (6x2s) would need extending - not sure by how much (it's been a while since I had the boards up in the room above), but at a guess by around 300mm. Is it feasible to do this by sistering? Would not relish having to have them replaced.