Which joist hanger type and exactly where does it go?

[Notch7]

do you need to bolt the joists to the rafters for lateral restraint?

And since they are pairs that would mean bolting them together and making them overlap on the central wall.

 

[Doggit]

If you're working from the central wall, then you can cut and notch the joists, and then slip them into place. As Ian has said, the excess strap can't be nailed behind the wall plate, so just push it back, and ignore it. Look at the joist hanger, find the lowest hole, and you'll realise that that is the highest point you can set it; as long as that. Obviously, with 7" joists, you'll need to put in noggins for lateral stability, and it'll be good to nail them together where they meet on the central wall. You may find it best not to start nailing the hangers in till you've made sure that everything is working out level, and you may need to pack any gaps under the hangers with slate to keep things tight.

 

[antonyc]

Anything round the back will be spare, you wouldn't be able to nail it anyway.

I realise that, but what are the limits?

 

[antonyc]

do you need to bolt the joists to the rafters for lateral restraint?

And since they are pairs that would mean bolting them together and making them overlap on the central wall.

The SE made no mention of bolting to the rafters, he just said to run the new joists right next to the existing ones and fix them together.

The new joists will need to be bolted together and overlap the central wall though.

What has happened now is that he is for steel only. Having sent him my new plans, he said he recommends steel only. He doesn't seem to be interested in the job if it is timber... I suspect that is because there isn't much money in it? I don't know.

 

[Doggit]

I realise that, but what are the limits?

None that I can think of.

 

[antonyc]

If you're working from the central wall, then you can cut and notch the joists, and then slip them into place. As Ian has said, the excess strap can't be nailed behind the wall plate, so just push it back, and ignore it. Look at the joist hanger, find the lowest hole, and you'll realise that that is the highest point you can set it; as long as that. Obviously, with 7" joists, you'll need to put in noggins for lateral stability, and it'll be good to nail them together where they meet on the central wall. You may find it best not to start nailing the hangers in till you've made sure that everything is working out level, and you may need to pack any gaps under the hangers with slate to keep things tight.

Ok, so cut, notch and chamfer is acceptable in this situation.

I realise about the joist hanger strap, but is that allowed? Surely there has to be some limit? how can I find this limit?

Noggins, yes and nailing together yes. I was thinking about using bolts.

Thanks for the advice on packing out too!

Would you also rawl-plug them in from one or two of the bottom holes too?

 

[Doggit]

Where is the SE recommending steel though; we haven't seen any plans, but I can't see why a steel is needed.

Notch and champher in conjunction with the joist hangers is belt and braces, but it would be the BCO that accepts or d You'll nail into the joist from the sides of th hangers, and if you want to bolt the overlapping joists, then no problem. As to putting the new joists alongside the old ones, and then fixing them together, as the old ceilings coming down, you might as well take the old ceiling joist out as you go. And if you were to manage to keep the old ceiling in place, then fixing the new ones to the old ones, might cause the ceiling to flex and crack, so I'd make sure they were seperate, and a gap between the old ceiling.

 

[Ian H]

I realise that, but what are the limits?

On the posh ones it will say if your face fixing it use 20 nails of if your strapping it use 14. I'd just knock a twist nail in every hole you can see.

 

[Ian H]

He will be charging you the same money wether he designs it with steel or timber.

A steel might sit under your purlins and have a shorter span to the central wall.

 

[antonyc]

Where is the SE recommending steel though; we haven't seen any plans, but I can't see why a steel is needed.

Notch and champher in conjunction with the joist hangers is belt and braces, but it would be the BCO that accepts or d You'll nail into the joist from the sides of th hangers, and if you want to bolt the overlapping joists, then no problem. As to putting the new joists alongside the old ones, and then fixing them together, as the old ceilings coming down, you might as well take the old ceiling joist out as you go. And if you were to manage to keep the old ceiling in place, then fixing the new ones to the old ones, might cause the ceiling to flex and crack, so I'd make sure they were seperate, and a gap between the old ceiling.

He recommends two steels above the current ceiling joists to support the new floor and one steel below the ridge board. He is against timber it seems. I don;t know why, he didn't say.

I'm not sure if it's as easy as removing the old joists as they seem to form the roof structure. They're nailed to the rafters and nailed together too. Although I suppose I could.

The ceiling will need to come down as the new joists will sink down 4" below it!

 

[antonyc]

On the posh ones it will say if your face fixing it use 20 nails of if your strapping it use 14. I'd just knock a twist nail in every hole you can see.

Ok, I think I may be able to get 16 in, so that should be ok. I've got 25mm sheradised nails here somewhere.

 

[antonyc]

He will be charging you the same money wether he designs it with steel or timber.

A steel might sit under your purlins and have a shorter span to the central wall.

Unfortunately, this is true. It's £600 either way. I have an issue with that, but that's a different matter!

The steel plan is completely different, they span gable to gable, huge 5.5m things, split in two with splice things. The thing is that that is another £600 for the steel and then £200 for the timber.

Timber only design would cost just £300 in timber and I'm also much more confident with timber too.

 

[Doggit]

It's only a 3.4m span form the centre wall to the wall plate, so what's he bitching about. Now with the 4.4m span in steel, then you've got to bed it into the wall, engineered bricks to support it, party wall agreements unless you're a detached property; what is the guy up to. As the C16 wooden joist tables will show 3.5m at 400 centres, I can't see an issue, so run it past the BCO, and see what he'll accept. And appologies for suggesting the removal of the existing joists, yes, they'll be nailed into the rafters. But rather than just lay them alongside, look at the layout, and even put them the other side of the rafters. But no great shakes either way - common sense required here.

If you're going to suspend the joists, then nail through every hole, if you're notching them, then not so many nails needed, as they are just providing a degree of stability.

 

[antonyc]

It's only a 3.4m span form the centre wall to the wall plate, so what's he bitching about. Now with the 4.4m span in steel, then you've got to bed it into the wall, engineered bricks to support it, party wall agreements unless you're a detached property; what is the guy up to. As the C16 wooden joist tables will show 3.5m at 400 centres, I can't see an issue, so run it past the BCO, and see what he'll accept. And appologies for suggesting the removal of the existing joists, yes, they'll be nailed into the rafters. But rather than just lay them alongside, look at the layout, and even put them the other side of the rafters. But no great shakes either way - common sense required here.

If you're going to suspend the joists, then nail through every hole, if you're notching them, then not so many nails needed, as they are just providing a degree of stability.

It's a 5.5m span in steel! Yes, I know about the padstones and party wall, etc, it's also a far more expensive solution and messes with my staircase design. I don't know what he is up to. I assume it is easier for him to calculate, or better money or something.

No worries about suggesting removing the rafters!

Ok, advice taken on board!

 

[Doggit]

Do I assume that you haven't submitted the plans yet, and the SE wil only do the plans and cals based on the 5.5m steel he wants to use. Maybe you need to ask him to justify his reluctance, and see if he'll do both calcs/plans etc, and then suggest he allows BC to make the final decision. If you point out the problems his insistance is causing, he may (I do say may) relent, and be a bit more amenable.