Glueing window boards

[Barnboy]

I've got to fit some timber window boards that I've made, the plasterer wants them fully sealed and in before he skims.  I've read on here about gluing them down instead of screwing but can't find the thread now. 

My question is.. is glueing a good method ? I was thinking something like sikaflex or no more nails with a couple of weights on them for a few days.

Also if they're oiled both sides to seal them from the moisture when skimming, will sikaflex, or any other glue adhere to the oiled surface at all?

[SteamyTea]

Not really sure what you mean by 'window boards' (assuming you mean internal window sills), but it does not matter much.

When using an adhesive, the surfaces you are sticking together is the important part.

Generally they need to be compatible with the adhesive used.  This may sound a bit obvious, but there are some quirks.

The traditional 'silicone sealant' does not stick that well to rough surfaces, and does shrink away over time.

Polyurethane adhesives work in a different way and like to grip mechanically, so need a solid substrate i.e. not flacking off.

 

Oils, paints and other treatments can cause problems, all really depends on the chemistry.

 

So how to get around this.

Quite simple, knock up some samples and try them.

 

My 'go to' adhesive is low expanding polyurethane.  It expands a bit to get a better contact surface area, sets fully in a reasonable time and can be painted over.

[Russell griffiths]

If you oil the underside you will struggle to get anything to stick to them. 
 

you have two choices 

1 screw them down and use a matching wooden plug to fill the holes. 
2 paint the underside, not oil, I painted the underside of all my oak worktops before fitting. 
do a dry fit, then flip them over and mask up a straight line on the overhang bit, two coats of a good quality exterior paint to seal the surface, let it dry and then stick them down with a good quality no nails type thing. 

[garrymartin]

Whilst it depends on whether the gap between the window boards and the substrate is sufficient, another option is to sink screws into the bottom of the board so they get enclosed by the adhesive to give it some more strength. As an added plus, they can be screwed in and out at various positions to give you a very solid, level surface; in essence, the screws get used as levellers too.

[Barnboy]

@Russell griffiths Thank you, i seem to over think everything and you've just given me the simplist most obvious answer that I never thought of.

The window boards / internal sill boards are to be fixed down to some solidly fixed marine ply, the underside will hopefully never be seen again so as you've suggested, I'll give them a coat of paint on the underside which the adhesive will stick to nicely.

Thank you.

[Russell griffiths]

9 hours ago, Barnboy said:

@Russell griffiths Thank you, i seem to over think everything and you've just given me the simplist most obvious answer that I never thought of.

The window boards / internal sill boards are to be fixed down to some solidly fixed marine ply, the underside will hopefully never be seen again so as you've suggested, I'll give them a coat of paint on the underside which the adhesive will stick to nicely.

Thank you.

Make sure you mask off the overhang, you will want to oil that bit. 

[bassanclan]

Low expansion foam or adhesive depending on what you are fixing to

[Barnboy]

19 hours ago, bassanclan said:

Low expansion foam or adhesive depending on what you are fixing to

It's timber sill boards on to marine ply, I've got some low foam adhesive left from other tasks but don't mind using a adhesive of that would work better. The timber boards have a slight cup in them so will need a little weight until whatever I use grips them. Do you have a recommendation for an adhesive ? , no more nails, pink grip ,sikaflex ?? 

Thanks

[SteamyTea]

10 minutes ago, Barnboy said:

I've got some low foam adhesive left from other tasks but don't mind using a adhesive of that would work better.

These are usually a PU (polyurethane) base adhesive, so about as good as you can get for timber.

11 minutes ago, Barnboy said:

Do you have a recommendation for an adhesive

My favourite is Lumberjack

https://www.ebay.co.uk/itm/355101195139

 

Get a tube and try it out on something, you need a lot less then you think.

[joe90]

1 hour ago, SteamyTea said:

My favourite is Lumberjack

I agree, brilliant stuff and if you make the wood damp it foams more.

[Barnboy]

Thanks, I'll try and get some to try.

[bassanclan]

7 hours ago, Barnboy said:

It's timber sill boards on to marine ply, I've got some low foam adhesive left from other tasks but don't mind using a adhesive of that would work better. The timber boards have a slight cup in them so will need a little weight until whatever I use grips them. Do you have a recommendation for an adhesive ? , no more nails, pink grip ,sikaflex ?? 

Thanks

Glue is a better bet in this instance.

https://www.ebay.co.uk/itm/364771798768?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=ov-2yzu-rew&sssrc=2349624&ssuid=sZUbc1BTTHO&var=&widget_ver=artemis&media=COPY

Foam would have been ideal if you were fixing to bricks etc where there might be frogs etc.