Fixing a miss-drilled beam

[SteveBz]

I'm building a flat-roof extension on my house and I've got a guy helping me. Sadly he's miss-drilled the holes in the joists right next to the wall (within 70 mm) instead of .25 - .4 of the beam length. Actually, it looks very nice, but not in line with BRs. If we move the wiring (and pipes actually) to be in line with BR, how should I patch the holes? Can I put a steel plate over them? What to do.

Steve.

 

[Pete999]

I'm building a flat-roof extension on my house and I've got a guy helping me. Sadly he's miss-drilled the holes in the joists right next to the wall (within 70 mm) instead of .25 - .4 of the beam length. Actually, it looks very nice, but not in line with BRs. If we move the wiring (and pipes actually) to be in line with BR, how should I patch the holes? Can I put a steel plate over them? What to do.

Steve.

Probably need the advice from Building control

 

[SparkyChick]

Personally I would get a length of wood the same dimensions as the joist, running from the end of the joist to maybe a couple of feet past the last incorrectly drilled hole and then glue and screw it to the original.

But, as @Pete999 says, getting the advice of building control is probably the best option.

 

[ruston]

Personally I would get a length of wood the same dimensions as the joist, running from the end of the joist to maybe a couple of feet past the last incorrectly drilled hole and then glue and screw it to the original.

But, as @Pete999 says, getting the advice of building control is probably the best option.

Or even steel plate bolt and brace it.

 

[ruston]

Personally I would get a length of wood the same dimensions as the joist, running from the end of the joist to maybe a couple of feet past the last incorrectly drilled hole and then glue and screw it to the original.

But, as @Pete999 says, getting the advice of building control is probably the best option.

Or even steel plate bolt and brace it.

 

[Wilko]

Hi - I like steel too, this might do it . Wickes Galvanised Jointing Flat Plate 63x300mm | Wickes.co.uk - https://www.wickes.co.uk/Wickes-Galvanised-Jointing-Flat-Plate-63x300mm/p/152829

 

[sean_ork]

BCO will likely suggest a short sister joist spanning the hole.

 

[SteveBz]

Hi Guys, Thanks for this. It looks like a steel plate then, but check with building control.

Steve

 

[rsgaz]

I'd just cut some 12mm ply or OSB, the same height as the joists, spanning the holes a good distance and screw a piece on both sides. Don't forget, some joists are just an OSB web these days anyway, so it's certainly strong enough...

This is not a load bearing joist, it's just a flat roof. If the joists have already been over-sized/specced due to some insulation requirement, then see if BC will just let you leave it as is.

 

[ruston]

If it is the flat roof I agree with @rsgaz.
Pipes and wires made me think floor joists.

 

[SteveBz]

I'd just cut some 12mm ply or OSB, the same height as the joists, spanning the holes a good distance and screw a piece on both sides. Don't forget, some joists are just an OSB web these days anyway, so it's certainly strong enough...

This is not a load bearing joist, it's just a flat roof. If the joists have already been over-sized/specced due to some insulation requirement, then see if BC will just let you leave it as is.

Great answer. And I think they have been over-sized because of insulation. They're 150x50 with 100mm insulation.

 

[SteveBz]

If it is the flat roof I agree with @rsgaz.
Pipes and wires made me think floor joists.

Thanks for coming back and agreeing this answer.

 

[davesparks]

When the water clowns did this on one of our jobs the fix was to put short sections of joist timber on both sides of the joist covering the holes and coach bolted through.
This looked like overkill and may well have been the NHBC inspector making a point or just satisfying his own little power trip

 

[pirate]

Glueing and screwing a sister-plate will be fine, provided the correct glue is used. Something like WEST system epoxy, not Gripfill.The screws are really only needed to clamp up the sister until the glue sets. Most glued joints are stronger than the wood itself, and structurally there is no reason why you couldn't use this to beef-up a joist prior to drilling it to take pipes and cables in an area normally prohibited. Unfortunately, BC are not very inventive...

 

[Gavin John Hyde]

If the roof is not load bearing apart from the flat roof or tiles then i wouldnt worry too much brace it as others have said with additional timber or steel brackets/plates.

 

[rsgaz]

I think they have been over-sized

Check your span and centre to centre spacing against this table...
(taken from "Building Control Guidance Note, Subject: CEILINGS AND FLAT ROOFS, Timber sizes and construction details")



...to check if they actually are oversized first. (i'm guessing not, now, unfortunately for you.)

 

[Baddegg]

Knock up some wood dowels and hammer into holes with some PU wood adhesive let dry and trim off ends, then as sparky chick said glue and screw 18mm ply either side of the joist 500-600mm past the holes if possible,should be more than adequate for a flat roof

 

[SteveBz]

Check your span and centre to centre spacing against this table...
(taken from "Building Control Guidance Note, Subject: CEILINGS AND FLAT ROOFS, Timber sizes and construction details")

View attachment 43411

...to check if they actually are oversized first. (i'm guessing not, now, unfortunately for you.)

You're right, I've just checked. It's on the edge.

But I'm happy with the solutions suggested here.

 

[telectrix]

what size holes? if only 20mm or 25mm, i'd not bother doing anything. it' s not as if the joists were load bearing.

 

[sean_ork]

what size holes? if only 20mm or 25mm, i'd not bother doing anything. it' s not as if the joists were load bearing.

Why isn't it load bearing ?