DKenn

Thanks for the advice. The holes look like they were done by a wild animal; they are rough and far from straight. I would need to re-drill them to get a dowel in. I was thinking of a strong and flexible filler of some kind that would fill the uneven holes.

All true... I am a bit "belt and braces" with things like this - so it is more for piece of mind.

Hello... I am fixing down some loose floorboards to firm up a floor. I have found under one of the boards a row of rough (unused) holes (around 25mm) running through the joists. The holes are central in the 6x2 joists, so I am not too concerned about the loss of strength, but I would like to fill them anyway. Can you advise on a good filler to add some structural integrity back to these holes? Thanks.

I am pretty sure that I can reach using an angle drill. I was going to using a drill guide to get the hole started.

Ok, I can see the logic of smaller screw, I just didn't see a 10mm hole centred in the joist being a problem.

Love the on the fly illustration!

I can't see how using two pieces of plywood is less complicated that using one? Also, wouldn't the use of screws near to the top or bottom of the joist increase the likelihood of splitting?

Judging by what has been said, it looks like I might be overthinking this. So I am going to check and reinforce any "loose" floorboards and leave it at that. Just as an aside - can anyone see any any actual problem with my method of reinforcement with plywood fixed with timber connectors and carriage bolts?

The joists are 3.8m long and the joists are 150mm x 50mm. The holes are largely centred. The the two pipes/holes are 1.2m from the walls on either side of the room.

Hi saveasteading, The weight will be static; however, much of the movement will be at the end of room and either side of the bed. The bed and wardrobe are going to be following the line of the two pipes - see diagram.

Hi JohnMo, It's a bit rudimentary. But hopefully is helps.

So, do you feel that glue would be enough without screws or bolts?

Thanks for the replies. I have considered adhesive; however, I felt that the carriage bolt option allowed for a tiny amount of movement and reduce the risk of shearing that screws. I felt that one bolt per side of the patch might be less invasive that several screws. I was planning to drill 10mm holes for M10 bolts.

Hello everyone... I am about to buy a new bed and wardrobe which will add around 300Kg to the floor of a first-floor bedroom. Much of the weight will be distributed along the span of the joists, not against the joist ends. My concern is that while the floor has no discernable sag/bow or bounce, the two rows of 30mm holes (for the central heating pipes) in each joist (150mmx50mm, 6x2) might weaken under the increased load. The two rows of holes in each joist are around 1.5m apart, running the entire length of the room. I propose reinforcing these holes (as a precautionary measure) using 600mm x 140mm strips of 18mm external plywood bolted with timber connectors over the holes (which will need drilling to allow the pipes through). The two bolts would be spaced approximately 200mm on each side of the pipe hole, leaving an overhang of around 100mm on each end of the plywood. So, each 600mm x 140mm strip of plywood would be as follows: 10mm of plywood, and then; carriage bolt and timber connector, and then; 200mm of plywood, and then; the hole for pipe, and then; 200mm of plywood, and then; carriage bolt and timber connector, and then; 10mm of plywood. I have approximately 200mm of access above each hole to slide under the plywood and drill the holes (this is why the lengths of plywood are limited to approximately 600mm). I would prefer not to take up any more of the tongue and groove floorboards. I have read everything I can find on reinforcing bouncing and slagging floors, but little is relevant to this situation. I would appreciate any constructive advice or support from the community. PS. I hope this makes sense!