New joists

[James-the-doubter]

Hi all,

first time poster here.

move been embarking on planning an extension project, which will be a new sips structure connecting to my existing house.

as part of the project I need to replace my existing stairs and enlarge the opening. After months of planning I had my first weekend of real work and installed the long length trimmer, which is a double joist bolted together. All generally went well with a number of hiccups on the way, but nothing insurmountable.

Anyhow, now I’m completely paranoid about not having fixed the joist correctly. I have attached some photos and wondered if any one could have a look and put my mind at rest- or confirm my fears .

thanks all.

 

[Deleted member 174758]

Looks OK to me. All the holes in the nail-set joist hanger have twist nails in them and your bolt centres look to be 600mm or less (although the middle one is still missing a washer and a nut - photo 8 ). I'd probably have put a nail into the side of the zip hanger (the one in the masonry), but that's about all

 

[James-the-doubter]

Thank you so much for looking and commenting. I was tying myself up in self doubt despite having planned the work for ages.

I’ll get the missing washer added and will add the nail to the zip hanger. I couldn’t think how to get the hammer onto a nail in the small gap, but having thought about it since, I’m going to try hammering onto a flat bar resting on the head of a nail, which will hopefully get it in.

 

[Deleted member 174758]

That or use the flat cheek at the side of the hammer head

 

[tell80]

Maybe you know all this but.
The pipes need clipping to backings and the cables need sorting and clipping too. No cable should touch a pipe.
The obvious tape wraps need junction boxes. fix the J/B's to a backing dont leave them floating.
For down lights see the sparkies forum.
Bolt on Timber connectors dont seem to have been used - before closing up the ceiling give the nuts a last tweak.
Put some bouncy weight, yourselves, on the floor above to test for squeaks or movement.

 

[Deleted member 174758]

Bolt on Timber connectors dont seem to have been used - before closing up the ceiling give the nuts a last tweak.

By "bolt on timber connectors" do you actually mean coach bolts? Whilst these can be more convenient and are generally specified do you really think it will make any difference on a single trimmer?

 

[James-the-doubter]

Maybe you know all this but.
The pipes need clipping to backings and the cables need sorting and clipping too. No cable should touch a pipe.
The obvious tape wraps need junction boxes. fix the J/B's to a backing dont leave them floating.
For down lights see the sparkies forum.
Bolt on Timber connectors dont seem to have been used - before closing up the ceiling give the nuts a last tweak.
Put some bouncy weight, yourselves, on the floor above to test for squeaks or movement.

Thanks for the comments - yes, much of this is on the radar. The tape wraps and existing cabling pipework will be replaced in the next phase of works.

Will also do the bounce test and give the nuts/bolts a last little nip-up before closing up.

 

[James-the-doubter]

By "bolt on timber connectors" do you actually mean coach bolts? Whilst these can be more convenient and are generally specified do you really think it will make any difference on a single trimmer?

In theory I can readily drop a couple of bolts through the connections if this is felt to be more robust - if i understand the point being raise, i can pilot through the bolt holes on the joist-joist hanger and then enlarge the hole from the opposite side of the joist. Obviousy if it makes no difference i won't waste my time, as there's lots on the to-do list.

 

[Deleted member 174758]

In theory I can readily drop a couple of bolts through the connections if this is felt to be more robust - if i understand the point being raise, i can pilot through the bolt holes on the joist-joist hanger and then enlarge the hole from the opposite side of the joist. Obviousy if it makes no difference i won't waste my time, as there's lots on the to-do list.

Under no circumstances should you ever drill extra holes in joist hangers (if it were necessary, I'm sure that firms like Simpson Strong-Tie would have done it in the factory). Their strength is calulated and drilling extra holes can weaken them, especially as they are only thin metal. You should, however, fill every hole with a twist nail, as this is specified by all manufacturers

AFAIK what engineers mean by timber-to-timber connections is generally a coach bolt and nut and square washer with a dog washer placed in between the two joists. My understanding is that coach bolts are specified for ease, as they only require one spanner or wrench to tighten, whereas an engineering bolt requires two. In circumstances where we have not been able to source appropriate size coach screws they have accepted conventional bolts with two washers.

The one thing not mentioned prior to this is that if the new trimmed joist is below existing flooring, then that flooring will need to be fixed to the joists, but I'd have thought that was self evident

 

[James-the-doubter]

Under no circumstances should you ever drill extra holes in joist hangers (if it were necessary, I'm sure that firms like Simpson Strong-Tie would have done it in the factory). Their strength is calulated and drilling extra holes can weaken them, especially as they are only thin metal. You should, however, fill every hole with a twist nail, as this is specified by all manufacturers

The one thing mot mentioned prior to this is that if the new trimmed joist is below existing flooring, then that flooring will need to be fixed to the joists, but I'd have thought that was self evident

Thanks - I wasn't thinking of drilling extra holes in the hangers - just using the large bolt holes that are there (there is one on the flange on either side). My thinking was that drilling large holes in the joist would weaken the overall joist - hence my use of twist nails only.

yes, noted and agreed on the existing flooring.

 

[Deleted member 174758]

Thanks - I wasn't thinking of drilling extra holes in the hangers - just using the large bolt holes that are there (there is one on the flange on either side). My thinking was that drilling large holes in the joist would weaken the overall joist - hence my use of twist nails only.

A lot of joist hangers don't have them at all and they are very rarely specified as to be used, about the only instances I've ever seen them called for by an engineer have been where one trimmer is being carried by another trimmer or where the floor is to be subjected to heavy loading (as in a commercial building). In that case you don't use twist nails on that face, just bolt it on - it's one or the other, not both.

 

[James-the-doubter]

I think photo 3 is the clearest one showing the holes. I've gone down the route of twist nails, so i'll stick with that and will elave the bolt holes empty

 

[tell80]

No i dont mean coach bolts. Bolt-on timber connectors are jagged washers that prevent any slippage movement betwen the connected pieces. See Simpson M12. Should always be used with Bolt-ons.

 

[Deleted member 174758]

Ah, timber connector washers, or "dog washers" (see above)

 

[cdbe]

Looks good to me, I think it's an "either/or" with the nails/bolts for the hangers.

You might find this interesting:

And it's actually something you buy, not a hanger cut up!