scarf or butt joints- Caulk or without - cove style wood siding

[sharbin]

hello all,

I am in the process of installing horizontally a cove style rough white pine with semi transparent stain wood siding.

I need to know what to do with field joints: I read that making a 45 degrees (i.e. scarf) cut over a 1x3 strip to join the 2 sides of the joints is recommended. However I cannot find anywhere whether caulking that joint is necessary or any idea on how to prevent water from seeping in.

Also, I find it very difficult to do the 45 degrees cut and at the same time get a tight fit at corners and at other joints. Would butt joint be as good? and if so what to do to prevent water from entering the split.

Thanks,

Sharbin

[Don_P]

As good, no. Good enough, probably. Most siding is just butted at all joints. You can prime or stain cut ends prior to installing them. We flash behind joints and onto the overlapped piece on hardie siding to direct any leaks out, it wouldn't hurt to do it on all siding. Caulk really doesn't work in a zero gap. If something is to be a caulk joint leave about an 8d nail diameter's space for the caulk.

[sharbin]

Thanks Don_P for the reply.
So whether using scarf or butt field joints, do I need to caulk the joints? if yes, would that apply if I used flashing behind the joints? how about using Tyvek as flashing, would that work?

Thanks.

[Don_P]

I don't caulk siding joints, I butt them tight. Caulk in a tight joint is a waste of time and caulk. I do leave a gap between siding and verticals (jambs, corners) and caulk that. With Hardie we've made flashing index cards out of metal but I don't see why just about anything that will drain wouldn't work.