Joist hangers - Minimum nails required?

[eveares]

Hi all; had an extension done recently and had a few issues with the kitchen floor dropping slightly that was determined to be caused due to weight by the heavy granite in the kitchen.

Now our builder fixed this a while ago by reinforcing the joists, however we have noticed that some floor boards seem springy and just want to be sure he has put enough nails in the joist hangers and that the lack of nails is not going to cause any problems such as like above.

The kitchen is downstairs and has a large granite island with more granite by the sink.

Are only a few nails required like shown; see the below pics for the joist hangers.

Untitled

• eveares
• 30 Jun 2013
• 1

Untitled

• eveares
• 30 Jun 2013
• 1

Untitled

• eveares
• 30 Jun 2013
• 1

Regards: Elliott Veares

 

[gregers]

the reason they have all the holes in them is so everyone has a nail in it.
only a couple each side then i would say something will fail over time.

 

[JimLoskot]

I have just repaired a floor using some simpson joist hangers and it states on the hanger itself what nails to use and how many in which part for top wrap or not top wrap.
My joists ar 3"x7" and I think it is (for top wrap) 4 nails into the joist, 8 nail into the face and 4 nails into the top wrap using 30mm x 3.5 square twist nails.
If the picturs are of your joists, there would appear to be too few nails in for a start.
The other problem could be that the joists are too small for the weight of your kitchen

 

[eveares]

Yea, the pictures are my joists in the kitchen; don't know the size of the joists of by heart. They have 1 nail in the top, 2/3 in the side and faces each.

Also the last picture is where the securing bolt into the block has cracked part of the end and has come out of the block at the end.

 

[JimLoskot]

measure the joists and the span. I would guess they aren't big enough for the weight on them

 

[tony1851]

Allthough all nails should be use as specified, too few would probably not account for the springyness.
As above, it's probably your island (in the middle of the floor?) being too heavy for the joists.
Although published tables give load/span relationships for domestic floors, unusually heavy permanent loads need special consideration.

 

[eveares]

Re all:

The springiness I think might be caused by the board it self, as it's corner is not supported by a another joist nor is it interlocked with anther board.

I have just checked the dimensions of the joists and they are 1 3/4 inches wide by 220mm (8.66 Inches) deep. The joists run across the kitchen width ways.

The joist hangers have on averarge 12 out of 27 possiable nails holes used, with the worst case scenario with only a 10 out of 27 holes used.

What is worse and shocking are the photos below, where the joist hangers are not bent over the top and only have 5 nails in per side. Quite a few are like this!

(This is where the side of the kitchen (towards the oven) that dropped originally, see second the picture of the reinforcement below that has been put in place since the original drop.)

Untitled

• eveares
• 30 Jun 2013
• 1

Untitled

• eveares
• 30 Jun 2013
• 1

Finally I have attached a picture of the granite worktops to give reference to the size of them. The main island is 47 1/2 x 85 inches, the kitchen side is 97 x 24 inches.

Untitled

• eveares
• 30 Jun 2013
• 1

 

[^woody^]

If the floor is springy, then its either natural, the joists are undersized, or they need noggins at mid point. It wont bounce because of nails in the hangers

 

[eveares]

It was springy on just one or two boards, and only slightly.

I really want to ensure it wont drop anymore and that the reinforcements and the lack of nails is fine. I am sure it is, or at least I hope so.

Just why do the joist hangers have all those wholes if they are not needed?

 

[^woody^]

Because whoever makes them says so to protect against any claims. They work it out on the chances of a nail shearing vertically, so more nails prevents shearing potential

Joists work in a load sharing way, so not all the load from the floor goes onto one end of any given joist, so a few nails in a few joists will not mean that the floor will collapse

There is some inherent movement in these hangers and it is often recommended to fit solid blocking (ie noggins) near to the hangers at the end of the joists.

Yes strictly, there should be a fixing in every hole, and the hanger strapped over the top of the timber it is fixed to. But I can't see that solving the floor bounce problem

 

[tony1851]

I have just checked the dimensions of the joists and they are 1 3/4 inches wide by 220mm (8.66 Inches) deep. The joists run across the kitchen width ways.

But what is the span of the joists?

 

[eveares]

The span between the joists is 14 inches.


Ignoring the issues of the springiness (as think it is just the board/s and not the joists themselves), would you say the the joists are sufficiently secured and that everything is up to standard?

Regards: Elliott

 

[tony1851]

The span between the joists is 14 inches.

That's the spacing of the joists; the span is the distance between the supports of the joist.
But if you don't believe it's the joists themselves, then that's of no consequence.

 

[JimLoskot]

if its just one or 2 boards that are springy then try screwing the boards down better with flooring screws.
What thickness are the boards (chipboard from the look of it)?
if its only 18mm I would suggest the boards aren't thick enough for the job.
Personally I wouldn't want a chipboard floor in the kitchen at all, I'd have 25mm marine ply minimum with all that weight.

 

[b21playa]

Everytime I've used joist hangers, I'll put a nail in every hole possible, using either square twist or ring shank nails