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 ?

 

[SteveBz]

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

Max 25mm for 22mm water pipe.

 

[SteveBz]

Why isn't it load bearing ?

It's a flat roof, but I don't know if that is classified as load-bearing or not.

 

[sean_ork]

It's a flat roof, but I don't know if that is classified as load-bearing or not.

It is .....

 

[PEG]

Depending on the size and placement of holes,a clued up BC inspector,may well not require you to do anything.

Those advocating the bolting of plates,need to know more about the dynamics,of how a beam functions. You may make things worse,by drilling yet more holes,for bolts...

 

[Squid]

Who did the calculations for the beam?

 

[telectrix]

Beam me up, Scottie.

 

[Midwest]

Get the plasterboard up quick, before the BI comes round

 

[sparksburnout]

Get the plasterboard up quick, before the BI comes round

That's by far the most sensible advice yet given. It's just a few bloody holes for goodness sake. How the hell can a flat roof be properly load bearing, is someone going to put an outdoor Jacuzzi on it? You could have had the job done by now.....

 

[Squid]

That's by far the most sensible advice yet given. It's just a few bloody holes for goodness sake. How the hell can a flat roof be properly load bearing, is someone going to put an outdoor Jacuzzi on it? You could have had the job done by now.....

If you are going to do job properly the do it properly, no bodges allowed.

Maybe your customers should check on the amount of expanding foam and grip fill that you use ;o))))))

 

[Midwest]

If you are going to do job properly the do it properly, no bodges allowed.

Maybe your customers should check on the amount of expanding foam and grip fill that you use ;o))))))

You've never go to bed at night, without brushing your teeth?

 

[Squid]

You've never go to bed at night, without brushing your teeth?

 

[Squid]

I am perfect........

 

[andyb]

Just use the holes you've drilled, they're in the wrong place that's all. Why weaken the joists further by drilling more?

 

[sparksburnout]

If you are going to do job properly the do it properly, no bodges allowed.

Maybe your customers should check on the amount of expanding foam and grip fill that you use ;o))))))

Did I say I had done similar? I would have done the job properly in the first place, but if some fella without a "Part P" qually (joke) has gone and dared to drill a wee hole out of place, I would't fanny about with wooden pegs and sister rafters, complete waste of time. Have you seen the holes your average plumber puts through? never heard of a house falling down because of a few holes here and there, more PC BC non-sense.

 

[Squid]

Did I say I had done similar? I would have done the job properly in the first place, but if some fella without a "Part P" qually (joke) has gone and dared to drill a wee hole out of place, I would't fanny about with wooden pegs and sister rafters, complete waste of time. Have you seen the holes your average plumber puts through? never heard of a house falling down because of a few holes here and there, more PC BC non-sense.

Its all about liability, "if" something happens in the future then guaranteed someone somewhere will try to weasel there way out of paying for it or being screwed over for their decisions in allowing it.

Its like the 18th ed, most of its cack but you lot will adhere to it as it Electrical God's bible and if you don't you can and will be sued.

 

[sparksburnout]

This forum is full of people getting their knickers in a knot over being sued, setting houses on fire, being put in prison, electrocuting others and who know's what else for committing all sorts of minor misdemeanours, including this one. How many have you ever known get sued/prosecuted/imprisoned or anything else for such? It's plain common sense, a few miss-positioned holes in a non-load bearing component like a flat roof rafter or even a joist are not going to make a jot of difference and are completely wasting your time, or even make it worse, to try. Just stick the boards up and crack on!

 

[Squid]

This forum is full of people getting their knickers in a knot over being sued, setting houses on fire, being put in prison, electrocuting others and who know's what else for committing all sorts of minor misdemeanours, including this one. How many have you ever known get sued/prosecuted/imprisoned or anything else for such? It's plain common sense, a few miss-positioned holes in a non-load bearing component like a flat roof rafter or even a joist are not going to make a jot of difference and are completely wasting your time, or even make it worse, to try. Just stick the boards up and crack on!

Did you do the cladding on the Grenfell Tower BTW?

 

[sparksburnout]

Did you do the cladding on the Grenfell Tower BTW?

Well I didn't know it wasn't fireproof did I? At least the no-nails helpd up for a decent length of time. On a serious note, I bet no-one gets to go to clink for that either.

 

[pirate]

Rules and regs...all very well.
Commonsense...but that requires some idea of what is required for safety.
I don't care about splitting hairs, just putting a good job together...
However, putting a hole through a joist in the "wrong" place isn't a problem...if you realise what kind of joist you are tackling.
Honestly, common sense wins...if you have a brain.

 

[PEG]

...All that is required,for evil to prevail,is that good BC inspectors,do nothing...

 

[sean_ork]

....... in a non-load bearing component like a flat roof rafter ......

You appear to think that a flat roof rafter isn't load bearing, just for clarity, could you confirm this please.

 

[PEG]

If only for pedantic glee,i shall state that it will be load bearing,in the modern,BC submitted plans way...

It will be designed for both static and dynamic loads,to accept stress due to temperature change and age,for wind,snow,and foot traffic (maintenance purposes)

There are other anticipated loads,which may be intermittent,such as waterlogging or scaffold bracing.

Superfluous additions,rely on such guaranteed load bearing abilities,such as PV panels,whose mounting systems,are designed around expected,hidden certainties not that a number of photovoltaic,tile crunching apex monkeys care,as they paslode and velcro to whatever,willy nilly,and sail off to change business name three times and dissolve forever,leaving those with both knowledge and a conscience,to sort the casserole of nonsense...

Breathe in...breathe out...

 

[sean_ork]

Thank you PEG, well put.

 

[sparksburnout]

You appear to think that a flat roof rafter isn't load bearing, just for clarity, could you confirm this please.

Yes of course it is load bearing, as regards the boarding and outer layers, and as has been said any weight that needs to go on it, like a roofer. But putting a few holes in the supporting timber (that has probably been designed to take that into consideration) is not going to weaken it in any was that is worth worrying about. Any one that does worry is just suffering from a lack of experience. There are joists and beams in houses up and down the length of the country with far worse knocked through and out of them and they won't be going any place anytime. If is was supporting a massive corner bath I might give it a bit of thought but otherwise? Steel sister beams, whatever next....

 

[telectrix]

agreeee. if a hot tup was going on the roof with Vanessa Feltz in it, I'd be concerned. otherwise, just crack on.

 

[SteveBz]

Hi Guys,

Thanks so much for your input.

The engineer inspected it yesterday. He felt there was no problem. The joists are short enough for it not to affect it and he's going to write a note to BC saying so.

Thanks again,

Regards

Steve

 

[Paul P]

At last some one with common sense.

 

[Squid]

At last some one with common sense.

Maybe the OP should ask the engineer to join the forum..........

 

[Squid]

Plumber went in too deep through a few joists........ so make sure your liability insurance is paid up.........

 

[telectrix]

Hubble Bubble, Toil and Rubble. someone should have told Wally the window fitter to fit catnics.