Fixing corrugated sheeting roof

Calahonda52 · 13-02-2025 08:12AM #1

I have roof sheeted with 18 mm structural grade OSB and propose fixing sheeting to it with the self tapping fixing supplied.

Am advised that OSB shrinks and fixings become loose, need to fix to normal timber: eg 4 by 2?

Any thoughts?

Thanks as alway

FrancieBrady · 13-02-2025 08:50AM

https://www.boards.ie/discussion/2058396217/fixing-corrugated-sheeting-roof

Saw one done and roofer battened out the OSB with pressure treated 2x1 and then fixed through it with washer and hex head long enough to go through batten and into OSB.

Calahonda52 · 14-02-2025 05:00PM

Thanks,

this is ai view

Oriented Strand Board (OSB) can work well for screw fixings, but there are a few things to keep in mind:

Screw Holding Strength: OSB has a relatively strong hold for screws, though it is not as strong as plywood. If you use screws that are too small or don't pre-drill the holes, they may strip out or not grip as well.
Pre-Drilling: It is usually recommended to pre-drill pilot holes, especially for larger screws, to avoid splitting or weakening the board, especially in thinner sheets.
Type of Screws: It's best to use screws designed specifically for wood or OSB, such as wood screws or deck screws. These have better threading and will grip the material more effectively.
Thickness of OSB: Thicker OSB boards (e.g., 18mm or more) will hold screws more effectively than thinner ones (e.g., 9mm), as there’s more material for the screw to grip.

In general, OSB is good for screw fixings when done correctly, but care should be taken with the screw size, type, and the technique (e.g., pre-drilling).

The Continental Op · 15-02-2025 11:35AM

It's probably fine to fix to OSB but its not something I'd ever do. Tek screws into the rafters is the way I'd go and use something like these https://www.screwfix.ie/p/rawlplug-flange-self-drilling-screws-6-3mm-x-121mm-100-pack/339tk (OMG didn't realise how expensive they'd got). Normally centre punch the corrugated sheet so the screws don't slip when installing them.

Don't see why you'd predrill the OSB if you are using Tek screws but I'd experiment as not all Tek screws have the same wide "drill bit" on them. Straight into OSB I'd try https://www.screwfix.ie/p/easydrive-flange-self-drilling-roofing-screws-6-3mm-x-80mm-100-pack/5672p

Calahonda52 · 16-02-2025 11:02AM

Thanks CO

yes they are expensive.

Roof is on, front and back screws through OBS into 4by2

Sheets 4.8m long so screws at 1 m centres every 3rd ridge, we predrilled them upside down with pilot holes and counterpunched for the others

The Continental Op · 16-02-2025 11:09AM

Far to late now but its just occurred to me what about condensation? I've used a lot of CGI and one issue with it is condensation so I would guess even with good air flow you might get run off onto the OSB?

Calahonda52 · 16-02-2025 02:33PM

https://www.boards.ie/discussion/comment/123176461#Comment_123176461

Tyveck over the OSB.

GreeBo · 20-02-2025 06:07PM

I wouldnt worry about shrinkage, more about the holding power of OSB with self tappers.

Looks like you went through the OSB into rafters, which is exactly what I would have done!

Fixing corrugated sheeting roof

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