Existing floorboards and joists have had to go due to rot and woodworm damage.
Underneath is an earth floor. Irregular granite and mortar walls go down to earth floor on both sides of the hall, which is 4ft wide, 17 long.
Originally, 2 x 3 joists were just placed on top of brick/slate/chewing gum columns and then floorboards nailed into the joists to form the floor and keep the joists in place; the accepted building regs for Cornwall in late 19th C. Joists were not tapered into the walls as you could not guarantee a mortar gap between granite pieces.
I think I need to form a concrete "sleeper shelf" along both walls upon which I would place a 2 x 4 rail and then cross nail 2 x 6 joists into this at 18" centres, with noggins between. PVC membrane to keep rising moisture in the earth floor, then nail a raft of T&G onto this.
My question is - can I place 7 Newton breeze blocks large face down on the bare earth and cement them together to form the concrete bed for my joists or should this be poured concrete? Which is stronger and which would be cheaper option? Also, would there be a damp problem doing it this way? Bearing in mind in these old granite houses, there is no damp proof course anyway!
These old Cornish houses are OK until a DIYer lives in it - certainly presents challenges.
How deep should this concrete shelf be to form a firm base for my joists?
Underneath is an earth floor. Irregular granite and mortar walls go down to earth floor on both sides of the hall, which is 4ft wide, 17 long.
Originally, 2 x 3 joists were just placed on top of brick/slate/chewing gum columns and then floorboards nailed into the joists to form the floor and keep the joists in place; the accepted building regs for Cornwall in late 19th C. Joists were not tapered into the walls as you could not guarantee a mortar gap between granite pieces.
I think I need to form a concrete "sleeper shelf" along both walls upon which I would place a 2 x 4 rail and then cross nail 2 x 6 joists into this at 18" centres, with noggins between. PVC membrane to keep rising moisture in the earth floor, then nail a raft of T&G onto this.
My question is - can I place 7 Newton breeze blocks large face down on the bare earth and cement them together to form the concrete bed for my joists or should this be poured concrete? Which is stronger and which would be cheaper option? Also, would there be a damp problem doing it this way? Bearing in mind in these old granite houses, there is no damp proof course anyway!
These old Cornish houses are OK until a DIYer lives in it - certainly presents challenges.
How deep should this concrete shelf be to form a firm base for my joists?
