I need to replace a floor, existing joists are very old and have suffered from wood worm, the floor above is very bouncy and bows in the middle (there are no noggins, which does not help). They are currently spaced at 600mm and the span is 4m, going into a solid sandstone wall.
By using the rule of thumb I got from here, I would need 8X2 (rest of measurements in inches). I would like to use the existing holes and we want to leave them exposed and I was wondering if I could get away with 7X4 as we prefer the look of wider ones and would appreciate the extra inch it would give us in room height. We want to plasterboard between them so the noggins would not be the full depth of the joist, will they still stiffen and prevent twisting if they are only 2X2? I was thinking I could do three or four rows across the span so we have better purchase for the plasterboard. We would then fit some Kingspan between the plasterboard ceiling and the T&G boards for the upstairs floor.
Does that make sense or have I missed something? Also I know I should use WPB plywood to board it down but what depth should I use and what are the advantages this has over T&G pine floorboards (apart from cost). The floor above will be solid oak 18mm T&G boarding laid floating.
Cheers.
By using the rule of thumb I got from here, I would need 8X2 (rest of measurements in inches). I would like to use the existing holes and we want to leave them exposed and I was wondering if I could get away with 7X4 as we prefer the look of wider ones and would appreciate the extra inch it would give us in room height. We want to plasterboard between them so the noggins would not be the full depth of the joist, will they still stiffen and prevent twisting if they are only 2X2? I was thinking I could do three or four rows across the span so we have better purchase for the plasterboard. We would then fit some Kingspan between the plasterboard ceiling and the T&G boards for the upstairs floor.
Does that make sense or have I missed something? Also I know I should use WPB plywood to board it down but what depth should I use and what are the advantages this has over T&G pine floorboards (apart from cost). The floor above will be solid oak 18mm T&G boarding laid floating.
Cheers.
