Extending Ceiling Joists

[cjard]

ps, stud work timber, as in 2x4, it's about 1.20 a metre

 

[leevis]

This one is becoming a bit of a nightmare really. I can't replace these timbers because there is the loft extension built on top of them although the extension is on steels, for some reason a lot of the timber work is directly on top of these meaning that its going to be very very difficult to get them out.
The problem i am having at the moment is i cannot attach the extension pieces to the steelwork as there is not enough space for the hanger to attach (too close to an already positioned hanger.
The only thing that i can think of now is to attach a ledger to two of the walls and then hang another timber onto these which would be similar to using hangers. Just to recap on the lengths, the length of the room is 2.3 meters and the joists are 1.8 meters cut, then 50mm then the steel, with another gap on the other side of the steel.
Cant think of a way out of this at the moment. I probably could screw some timber into the gaps in the steel to give me something to attach a hanger to but i don't think that this is going to be strong enough to hold it. Ledger is all i can think of with some M12 rawlbolts all along the wall with some 6x2 taking the weight of the existing joists

 

[endecotp]

Photos!

 

[leevis]

Uploading some pics right now, the stud ceiling is definately a go-er, all i need to do is work out how to secure these joists so i can knock down the wall

 

[leevis]

the brown joists are the ones that i wish to extend into the timber, these joists are 50mm short but i cannot work out how to extend a joist which i want to attach to the existing one into the timber in the steel. the hangers i have will not fit (unless i trim them a fair bit which means that they are likely to be held with less screws). But saying that if i attach a timber to the existing there totally won't be enough space in the steel to attach it. I really don't think that it is possible due to the fact that i cannot install an hanger. The only thing i can think of would be to attach a ledger to each wall and then using a joist hanger, hang a long length of timber across the room kind of like a timber steel which will carry the ends of the timber joists.

 

[leevis]

Heres another pic. Here is the new joist next to the old showing there isn't space to hang

 

[cjard]

Can you take a photo from a bit further away? Showing the entire ceiling for example. It looks to me right now like you could just rip out the old brown joists because you've fitted new ones above them!

I'm also not really getting the problem. Get a nog of wood, 50mm thick and attach a large hanger to it. Insert it into the 50mm gap between old timber and new steel, pound nails into the nog so it becomes attached to the wood that packs the steel. Or drill the entire thing and bolt the nog to the steel

 

[cjard]

A sketch too might help, showing a 2d section slice through the old beams, and another showing a slice through the newer looking ones (your descriptions of stuff are a bit garbled)

 

[leevis]

I will try and take some more pics tonight and hopefully it will be clearer as to what my problem is. In my mind, I don't have the space on the timber which is in the steel to connect a hanger, if there were L shaped hangers this might do it as one side is relatively clear (all the ones I have seen have been U shape - for a reason). I will also attempt to draw what I have.

 

[switch33859]

Hi All
Opening an old thread I know but have a very similar issue I'm trying to solve.

I have a supporting wall (stud) I plan to move. This wall currently carries one end of 150mm deep flat roof joists that are currently 2650mm in length (clear span).

By moving the wall I will need to extend each joist by 260mm so their clear span then becomes 2910mm.

As I'm only extending by 260mm I'm sure I could go over board with something like 1200mm sisters and several M12/M10 bolts and all would be ok, but I would prefer to design them and also know how to do the design for future reference.

@RonnyRagun - you said (several years ago ) you would do a check. Did you do this by calculating the BM and shear in the new length spliced beam at the splice location, then independently spec TPCs to deal with shear and bolts to deal with bending ?

Any guidance on the right way to calc would be appreciated.

D

 

[RonnyRaygun]

@RonnyRagun - you said (several years ago ) you would do a check. Did you do this by calculating the BM and shear in the new length spliced beam at the splice location, then independently spec TPCs to deal with shear and bolts to deal with bending ?

Any guidance on the right way to calc would be appreciated.

D

The bolts (or the Tooth Plate Connectors) are designed for shear only. The TPCs give a larger area of bearing between the timber and the fixing, therefore increasing the overall shear capacity.

So what you need to do is work out what the shear is at the bolt nearest the end of the existing joist (that’ll be the worst case).

Then you have to look in the relevant section of the relevant British Standard to find the capacity of the bolt or TPC.

In this instance, TPCs will allow for a shorter overlap than using bolts alone. It’s an iterative process to work out what is most efficient.