Joints in weather board

[Pord]

I'm at the stage of fitting the external weather board (aka shiplap, the t&g stuff) to my workshop. It's untreated and I've applied a single coat of Bedec Barn Paint to every board, front and back. I'll be butt joining the boards horizontally with a 45deg mitre cut.

Should I also apply a bead of glue/sealant at each joint? I'd also prefer to treat each cut end with the Barn Paint but it would drastically slow down fitting. Any thoughts?

 

[PAC1]

If you have gone to the trouble of mitring the joint (taking time), whilst it may slow it down further, paint the ends. no glue no sealant.

 

[MikeG.]

You MUST paint each cut end, but you don't have to wait for it to dry before fitting.

I don't think the mitre is a good idea. The philosophy with feather edge boarding is to assume water will get in, but allow it a way out. A mitre will trap water, which isn't a great idea. The best detail at a butt joint between two boards is to cut a strip of DPC and staple it to the batten behind the joint, dressed over the top edge of the board below but not visible below the joining boards. It should be long enough that the top of it is above the pair of joining boards. This will guide any water that gets in back out again. Obviously you should stagger joints so that they don't occur one above the other.

 

[Pord]

Thanks both. Painted ends it is, and I may just drop the idea of a mitre at each joint.

Mike, I'm using T&G weather board which means there isn't the same escape route for the water as described using feather edge board. Would you still advise using the patch of dpc behind each joint?

 

[MikeG.]

You're using T&G horizontally? If so, that has fundamental moisture retention issues and you can't expect a long life.

If you are using T&G horizontally, then there is no point to the DPC behind the join, as there is no where to lead water out from behind the boards to the outside. If you are using shiplap, with a half-lap joint at each board, then there is a way out and the DPC is a good idea.

 

[Pord]

Ok Mike, thanks.

 

[John15]

I think it should be shiplap rather than t and g.
+1 for square butt joints.

John

 

[Pord]

Cheers John, glad to ditch the mitred joints. The T&G was purchased long ago, and I'm happy enough with the choice.

 

[powertools]

Last summer I clad 1 side of my workshop with feather edge boards. I cut them all slightly oversized and painted them with barn paint.
At the joint I put in uprights and then cut the boards to length 1 at a time and painted the cut ends and fitted them while still wet and when finished I gave the whole lot another coat.
I still have the door trims and weather bars to fit.

 

[Pord]

Looks good - nice colour.

 

[sunnybob]

Paint each piece of wood twice before fitting. Install it with the tongue upwards, so that the groove does not hold water.
paint it all again once its installed.
Paint it each year.

 

[powertools]

Paint each piece of wood twice before fitting. Install it with the tongue upwards, so that the groove does not hold water.
paint it all again once its installed.
Paint it each year.

By the time you have given 2 coats of paint to each board before fitting that means that each joint will have had 4 coats of paint before fitting and they simply won't fit.
As for re painting every year life is too short.

 

[sunnybob]

Plan B. Dont paint it, replace it every other year.
Plan C (my own system) get the wife to paint it each year because i splash too much paint everywhere.

 

[deema]

For big projects or projects where appearance really matters get the T&G pressure treated initially. It’s not that expensive and when painted over means that it will out last you. If you don’t want the faff of getting it pressure treated an initial few coats of a wood preservative and then a single coat of paint is a good second best. T&G with the tongue upward as suggested will work without any issues and doesn’t trap water

 

[Some bloak]

Last summer I clad 1 side of my workshop with feather edge boards. I cut them all slightly oversized and painted them with barn paint.
At the joint I put in uprights and then cut the boards to length 1 at a time and painted the cut ends and fitted them while still wet and when finished I gave the whole lot another coat.
I still have the door trims and weather bars to fit.

What barn paint did you use on the feather edge boards? Thanks.