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Joists....Have I boobed?


Dee

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7 hours ago, saveasteading said:

Not quite all. the notch is out of the bottom, and that is the bit of ply that needs to be fixed hard. a few more screws down there, if you can.

 

Sorry, I don't understand?

I had nothing to fix to below the bottom of the joist? Please expand what I should have done? Appreciate the advice 

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I mean that the notch is what needs to be spliced, so put some screws in the lower area of the ply splices.

When load  is applied to the joist, the bottom goes into tension. The ply can take that tension at the bottom , holding it stiff across the gap. It will do that most efficiently if there are fixings lower down ( unless there are and I'm not noticing them).

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So, giving the bathroom ...and you guys, a rest while I figure out the heating system which seems to have developed a mind if it's own!

I have 18 rads, of which 6 decided not to heat up atall.

So I turned off fully the 12 hot rads, and all 6 cold rads heated up .

One by one I turned the 12 back on and after a few days all rads were still lovely and hot....until 2 gradually went cold and despite my best efforts have remained so.

I have tweeked and twiddle the LS valves on those pipes that I believe to be effecting the 2 duds but no improvement.  All rads bled, recently drained system when boiler was replaced...totally foxed!

 

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Yeh, I have properly balanced the whole system a few years ago, down to using a multimeter to get the temp to 12⁰ across the pipes....took 2 days. I was hoping for a quick fix this time!

What I don't understand is that on all the hot rads the LS is literally barely open, not even 1/4 turn, even those the farthest away from the boiler.

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  • 2 weeks later...
On 10/12/2023 at 10:52, saveasteading said:

Not quite all. the notch is out of the bottom, and that is the bit of ply that needs to be fixed hard. a few more screws down there, if you can.

What’s screws would you use?

interested as I thought you should only use nails to prevent shear?

 

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Nails perform at their best when resisting shear force (force pulling sideways) while screws are designed to resist withdrawal force (force pulling outwards).

 

I have heard that but what you have done is fine in my opinion along with glue.

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Ahem. An interesting statement.  Yes screws perform well in pullout, but they all have shear resistance based on how much shank is there. 

But nails hold things together too, and are not easy to pull out.

A good interview question....when would you choose a nail or a screw?

I prefer screws because I'm rubbish with a hammer, and there is a second chance.

 

In this case the advantage of screws is in ease of fixing.

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I remember a thread here a long time ago where someone used screws in joist hangers and was told it should have been nails because they work best in shear 🤷‍♂️. I guess it depends on the type of metal and diameter.

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2 hours ago, SteamyTea said:

That makes them bolts.

No,  A bolt is a non-tapered fastener that uses a washer and nut to hold objects together. A screw is a tapered fastener that mates with an existing thread or creates its own thread in a material as it turns.

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5 hours ago, joe90 said:

No,  A bolt is a non-tapered fastener that uses a washer and nut to hold objects together. A screw is a tapered fastener that mates with an existing thread or creates its own thread in a material as it turns.

 

so what's a set- screw then?

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