Oak door header in contact with galv lintel. Should I be worried?!

[Co1]

Should I be worried about the galv staining the oak? It’s a door header for a set of garage doors, so I will need to fix them to one another as the span it too wide to leave it be, but was thinking of spacing it off 5mm then grouting the gap. Am I worrying about nothing?!!

Also, any recommendations for fixings?

Thanks
Col

 

[okeydokey]

Could you put a 5mm gap of another timber glued to the oak and then just screw the galvanised header through both to fix. That will isolate the oak

 

[Co1]

Could you put a 5mm gap of another timber glued to the oak and then just screw the galvanised header through both to fix. That will isolate the oak

Great idea! Bloody obvious now you’ve pointed it out as well!!! Thanks a lot.

 

[HOJ]

I would leave a 5mm gap all round any way, give yourself some wiggle room, I use an expanding foam tape around my frames to make a good air and weather seal: Expanding tape and fit packers set back in from the the front face at the fixing points, (you could also run a strip of DPC along it if your really worried about a reaction).

With regards to fixings, your going in to a steel lintel, so that limits you options, I tend to use these type of fixings: Screws

 

[mwinfrance]

Umm, wont the screws in themselves be a problem long term with the oak.
I know the ones linked to say "zinc plated" but any damage to the plating and they are steel under it.

Interesting ( and depressing ) how much wider and better the available range of tools etc is in UK Screwfix compared to their french side Brico-depot.. The more up market part of that group here, Castorama, has better range, but is 200 km from me.

 

[Bingy man]

Similar to @HOJ are these from tech fast . I do find the hexagon heads easier to drive in but the head and washer sit proud

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[Fergie 307]

Umm, wont the screws in themselves be a problem long term with the oak.
I know the ones linked to say "zinc plated" but any damage to the plating and they are steel under it.

Interesting ( and depressing ) how much wider and better the available range of tools etc is in UK Screwfix compared to their french side Brico-depot.. The more up market part of that group here, Castorama, has better range, but is 200 km from me.

You could drill and tap the holes and then use stainless machine screws. If you get mushroom heads and pocket them flush it would look quite neat. Depends if the lintel is thick enough to take a thread.

 

[CaptainBudget]

You could drill and tap the holes and then use stainless machine screws. If you get mushroom heads and pocket them flush it would look quite neat. Depends if the lintel is thick enough to take a thread.

Do not do this please.

This will cause corrosion due to dissimilar metals being in contact (Stainless Vs Mild steel). This will cause the stainless to rust and the galv to fail prematurely.

I work in the structural steelwork sector and where you have this occurring you have to use nylon isolation washers under the head and isolation tape round the shank.

I'd drill the lintel and use decent wood screws personally (BZP finish to match the galv lintel). Oak staining should only be a problem around the screw shank, so if it's in the middle of the header and driven through the lintel flange into the top you'll never see it. (I am assuming its a proper rolled section lintel and not a folded piece of ~2mm pre-galv sheet; I somehow doubt it will be over that sort of span...

5mm packing shims made from nylon or timber under each screw to act as an isolator and grout the gap, or a full length timber strip as previously suggested will then isolate the oak from the lintel.