Paint undercoat

[caretaker]

I have just finished replacing my lean-to roof but my next job will be to paint the inside, I have used OBS2 boards and have brought a big tin of Dulux gloss white.
Do I need to use an under coat or will I get away with say a couple of top coats of gloss.
This is for the inside of roof.

 

[otter]

If you're going gloss, deffo undercoat it first. And primer.

Personally, for OSB I wouldn't gloss it. The natural rough finish of OSB will make glossing a right puppy IMO. I'd just emulsion it personally (you can add PVA to it to add a slight sheen and toughen it up if you wish*).


*Old theatre stage floor trick

 

[Flynnwood]

Being a "lean-to roof", it must be outside, so don't use PVA or emulsion.

Use a suitable primer.

 

[otter]

Being a "lean-to roof", it must be outside, so don't use PVA or emulsion.

Use a suitable primer.

I understood the OSB to be an interior skin, rather than the actual external roof material?

 

[ColeyS1]

A good primer, then undercoat, then 1-2 coats of gloss depending on coverage. The first coat will be a pain filling all the voids in the boards but it'll get easier with each coat.
Might be worth trying 'bedec multi surface paint' if you have a similar future project. It's waterbased, drys quick, covers really well and is an all in one paint- I'd have thought two coats of that would cover the osb o.k.
I never really get on very well with gloss and much prefer satin paint- that doesn't need an undercoat which is one less coat of paint

Coley

 

[Roughcut]

I think I would try an Acrylic Eggshell.