Joining joist question

[Ian H]

I did mine 600mm apart and alternate ones slightly higher and lower.

 

[tony1851]

@op; however you fix the new joists, don't fix the tops level with the top of the steel beam - set them slightly above. They will shrink and cause a hump where the steel is if you don't.

 

[Notch7]

So the reason I thought it wasn’t possible is because I tried before with crap bits and the literally just shrank before my eyes into nothing without leaving so much as a scratch. Cue quality bits and they went through it making a test hole like a hot knife through butter. So this is now a possibility; saving me around 6’ head height. Just need to ok it with BC as it’s not in the plan. The web is 175 and the joists are 200 so will need new timbers for it. Am guessing 600mm spacing m12 bolts would suffice?

The joists dont need to be the size of the web, if bigger just cut notches,

As Tony says always best to be higher than steel where a floor going above

 

[liamruairi]

@op; however you fix the new joists, don't fix the tops level with the top of the steel beam - set them slightly above. They will shrink and cause a hump where the steel is if you don't.

Good point; I will be setting them around 50mm higher anyway as there are m16 bolt heads on top of the beam where filch plates join 2 beams together anyhow

 

[liamruairi]

@op; however you fix the new joists, don't fix the tops level with the top of the steel beam - set them slightly above. They will shrink and cause a hump where the steel is if you don't.

I did mine 600mm apart and alternate ones slightly higher and lower.

Thanks! Are m12 enough?

 

[tony1851]

M10 would be fine - as long as the timber is seated firmly on the bottom flange.

 

[Ian H]

I used those big square washers too.

 

[liamruairi]

Thanks all. Spoke to BC who said fine no problem. M10 it is. That’s bought me a good bit of extra head height! Cheers