yong wrote: ↑Mon Mar 12, 2018 1:02 pm

bolueeleh wrote: ↑Mon Mar 12, 2018 12:49 pm what is the quick way to test or know if the screws are good?

Besides what I mentioned to reply you on shear failure there is another element of corrosion. So like I'd said before a good screw must have the ability to bend and one can clamp it on a vice and bend it 15 degree to one side and then the other side. Now here I am talking about long screws more like 50mm and above to be fixed to the crest of a roofing profile.

Corrosion is another big problem for any roof as corrosion sets in the screw the rust from the screws can cause the roof to be ugly with rust stains but much worst is that it is almost impossible to remove the screw for replacement. So a good corrosion resistant capability is very important for any roofing screw if the screw is exposed. A shiny screw from electro-zinc plating (yellow colour or bright silver colour) will not last more than 2 years in the best condition and in worst condition if the installation is close to the sea or industry area rust could set in within a year. One have to op for coated screws rather than electro-plated screws. Then of course there are good coating screws and there are bad coating screws.

bolueeleh wrote: ↑Mon Mar 12, 2018 2:03 pmi just want the screws on my roof in this project of mine to withstand the elements as this project is near the sea, which the corrosion factors will be multiplied, what is a good roofing material for seaside project as well? i dont like the usual khmer style roof, im looking for a one sided roof and positioned it to the morning sun, so that i can maximise my solar panels

yong wrote: ↑Mon Mar 12, 2018 3:51 pm

Generally if it is close to the sea carbon steel material should not be used so this include metalsheet and carbon steel screws. Anyway if you are far away some of the items can be use so if you could let me know which category you falls in in the table I can advise you.

In any case if its severe marine and no carbon steel material should be use you always have the choice of tiled roof which will not corrode and since its tiled screws will not be expose so basically any screws can be use although I prefer you to go for coated screws instead of plated screws. In the case the screws need to be exposed then recommendation will be 300 series stainless steel screws, never go for cheaper 400 series as 400 series is meant for indoor only.

bolueeleh wrote: ↑Mon Mar 12, 2018 10:56 pm thanks bro, im category 3 (mild and moderate marine), will look at tiled roof so as not to expose the screws