Big difference in decking screws?

[larsbj]

If 4,8x75 is too weak a screw, what do you recommend then?

90-100mm

 

[Finndjävel]

I go against the grain and claim that 75mm screws for 45mm fence slats are sufficient in all cases. It's not a construction that needs to withstand significant loads, and the screw goes 30-32mm into the material, which is 3mm more than, for example, regular 55mm decking screws go in when fastening the deck board. The threaded part of a regular decking screw is usually half the screw length and driving them further than that has no effect.

Personally, I would still go with 6x80mm regular electro-galvanized screws because it's the thickness and not the length that feels like the weakest point in this case. But even 4.8x75 should handle a few fence slats without issue.

 

[Pumba]

I work with screws... however, not decking screws, but there is a difference between suppliers, the good ones keep a fairly even pace with each other, but then there's always a number of manufacturers who produce nothing but junk. Most screws are made over in Asia, and they are not worse than the small selection made in the EU.

There is a big difference in hardness between stainless and hardened C4 screws, the stainless ones are soft and tolerate more movement, hardened screws are hard and when exposed to the movement of the wood, they don't keep up at all and when stressed they break when it gets too much. I would probably guess that there is some extent of hydrogen embrittlement when exposed to water, etc., over longer periods, depending on how hard the screws are hardened, it will also affect how many break. My theory, I don't know much about wood screws but work mostly with M10 and above for heavier industry.

 

[Anna1984]

I work with screws... not decking screws, but there is certainly a difference between suppliers, those that are good keep up with each other fairly well, but then there are always a number of manufacturers that produce nothing but junk. Most screws are manufactured over in Asia, and they are no worse than the small range that's manufactured in the EU.

There is a big difference in hardness between stainless and hardened C4 screws, the stainless ones are soft and can handle more movement, whereas hardened screws are hard and when they are subjected to the wood's movement, they don't hold up at all - when stress occurs, they break when it's too much. I would probably guess that to some extent hydrogen embrittlement occurs when they are exposed to water and so on for longer periods, depending on how hard the screws are hardened, it will also affect how many break.
My theory, I don't know much about wood screws as I mostly work with M10 and larger for heavier industry.

What is your opinion on the dimension? Do you think it is too weak?

 

[Pumba]

What is your opinion on the dimension? Do you think it's too weak?

I would probably say yes to that, it's a disappearingly small amount of money to buy a slightly longer screw to be on the safe side.

 

[GK100]

Or perhaps rather a slightly coarser as Finndjävel wrote it's in line with what I think and a bit longer for that matter.

 

[L-E]

SPAX?

http://www.spax.com/en/craftsmen/sc...tainless-steel/spax-specials/decking-screw-a4

If they are half as good as they suggest... Has anyone tried them?

 

[Pumba]

SPAX?

[link]

If they are half as good as they imply... Has anyone tried them?

That type of screw is mostly used for slightly more exclusive types of wood?

Spax is good stuff otherwise, but seems overkill for a fence?

Coarser screws create a greater need for pre-drilling.

 

[Anna1984]

Deck screws are traditionally 4.2-4.8x55-75. If you want thicker screws, like 5x100, what should you look for in screws then?

 

[larsbj]

Deck screws are traditionally 4.2-4.8x55-75. If you want to use thicker screws, like 5x100, what should you look for in a screw then?

I mostly use Essve for outdoor use. Available at Beijer.

 

[Pumba]

Deck screws are traditionally 4.2-4.8x55-75. If you want thicker screws, like 5x100. What kind of screws should you look at then?

I use byggmax (Heco), you should support companies located near you, Heco is about 2 miles from here.

 

[Anna1984]

I have now bought Essves outdoor screw in dimension 5x100. It should be fine.

 

[Mikael_L]

Have now bought Essves outdoor screws in the dimension 5x100. It will probably be good.

I think that was a much better choice than using any decking screw.

 

[f91jsw]

However, decking screws are recommended in pressure-treated wood precisely because pressure-treated wood is very corrosive. Even hot-dip galvanized nails are now said not to work in the long run in pressure-treated wood.

 

[mexitegel]

However, decking screws are recommended for pressure-treated wood precisely because pressure-treated wood is very corrosive. Even hot-dip galvanized nails are no longer said to work in the long run in pressure-treated wood.

Yes, that's the case, but it's like choosing between the plague or cholera if you don't choose stainless steel screws. Either it rusts or it breaks...