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New to woodworking and doing first project which is a garden gate. I am using pressurized 2x4 timber for the frame. To join the vertical and horizontal timbers together, I am using the half-lap joint (I am limited to a circular saw and combi drill for my tools).

My question is do I need to treat the newly exposed faces of the timber (I have bought some creocote) before gluing the lap joints together? Or can I just use the glue and ignore the creocote?

I am in the UK so rain and damp is a given for a large part of the year.

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    If you're glueing you can't really treat the joint surfaces as this will impede the formation of a proper glue joint. And if you form your joints well and use a fully waterproof glue the cuts are not at risk because they're sealed inside the joints. For exterior construction treating cut surfaces is considered good practice, but that's generally for nailed or screwed construction. Do treat any cut board ends however. – Graphus Sep 6 at 22:47
  • Further to that, if your only tools are a circular saw and a combi drill, I would suggest avoiding a glued joint - you really need some way to clamp the joint. You could clamp it by adding screws, but then you might as well leave out the glue, paint the cut surface with creosote and just screw. – Martin Bonner Sep 10 at 15:28
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When using pressure-treated wood for exterior construction treating any cut surfaces is considered good practice, but that's generally for nailed/screwed construction where even inside a joint water is assumed to be able to wick inside.

When you're using glue however the joint faces will be sealed by the glue so this doesn't apply, and any preservative or wood treatment applied there is likely to impede the production of a proper glue joint and isn't advisable anyway.

So if you're glueing you don't need to worry about treating the cuts you make for the half-laps joints (note, these are halving joints in traditional UK parlance). But do treat the ends of any boards you cut to length, especially if they are close to the ground or will be horizontal after installation.

  • Thanks Graphus - have gone with your answer. – wyc73 Sep 10 at 7:51
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    @wyc73 If this answer was helpful for you, be sure to upvote it (click the big up arrow) and accept it (click the big check mark below the down arrow). That helps others to know how helpful it was - not everyone reads all the comments. – FreeMan Sep 10 at 19:55

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