replacing floorboards with wider boards, notch problems



I plan to replace the original, and knackered after years of lifting/replacing due to plumbing and electrical work beneath, floorboards upstairs in one room. I'd like to put down some wider boards (PAR, not T&G) but I fear problems since the joists they will lay on have been 'notched to hell' (not by me I might add) and therefore the edges of the new wider boards are likely to sit on some of these wider notches.

Anyway got a clever way around this? I had considered laying hardboard/ply down first, and then to fit the new floorboards but this will mean if I ever do need to lift a new board to get to some pipework or wiring I'll likely have to lift up several boards. The other alternative I thought of was to route out each side of the notches and fit something to bridge the existing notches, but this means taking even more away from the joists and there is a LOT to do.

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Instead of covering the joists with ply or hardboard, why not cut the ply into strips the same width as the joists? Fix these on top of the joist first before putting new boards down. One problem with this is the fact that your now making the finished floor level higher than the original, meaning you'll probably take the skirting off and replace and the door will need trimming.
If you do decide to go down this route, just be careful when fixing the new boards down that you don't inadvertently nail through pipes or cables below.
24 Apr 2010
Reaction score
United Kingdom
I would use up scrap pieces of 3x4 ,say 10 inches or a foot long and place them alongside the notch.G-clamp this to the joist and tighten only after checking overall floor level and making sure that they are not pushing against pipes/wires below[notch if so].Pre-drill and screw to joist using number 5 screws and fully charged screwdiver-get them in tight[countersink if necessary].Now you have a stronger sub floor and new fixing points alongside the notches.

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