tretaed timbers for a frame??

[hayton1960]

When you obtain your supply of timber, is it worth considering having the beams pressure treated with the copper/arsenic stuff (then brushing preservertive onto cut ends around mortices and tenons etc before assembling?) Is it worth the effort and cost; would it create any construction problems?
Cheers, Jonathan

[ARKANSAWYER]

 

  If the timber is going to be exposed then it will look different.  Some places do not allow pressure treated lumber exposed inside homes.  A major consideration in construction should be to keep the members in the dry or use something like walnut or black locust for sills.  When I lay members on concrete I use a foam pad under them and seal the bottom with tar.  I often coat the ends of timbers with linseed oil to help keep them from wicking up water should some get to the base of the timber.  Most brush on treatments have limited effect at best.

[Dan]

 Jonathan, I`m in the process of building the shed from Jack Sobon`s book, and I am using treated timbers for the sills (at the recomendation of my building inspector ;)). They were kind of pricey, almost double the price of untreated beams from the sawmill. They are also very heavy.  At least they were straight, in fact they were the straighter than any of my other timbers.

[Don P]

A treated 2x mudsill under everything is a possibility too and cheaper than going with a treated larger timber.
This link was put up on another thread the other day.
http://ohioline.osu.edu/hyg-fact/2000/2090.html
Borates are used fairly often, some people say the Shell-Guard type mix has been helping reduce checking as the timber seasons. It uses PEG that does have a waxy type finish and finishing issues. Borates do go deeper into freshly cut wood, travelling in by diffusion like salts.

[hayton1960]

Thanks for your comments Don 
That is an excellent idea, using a 2" sub sill.
Could I ask please-
What would be a good way to join the sub sill to the main sill of the frame?
Would you need a damp proof membrane between the 2 pieces of timber?
Cheers, Jonathan ;D

[Don P]

The connection would be whatever you need to the foundation. The house I'm working on now has only a 2x treated sill on a continuous foundation, no heavy sill. I'm blocking with 2x12s around the posts to 2x12 floor and rim joists to lock them in place atop the mudsill. That sill is bolted to the foundation every 2'. On piers with heavy timber sills and log joists we have put  the treated mudsill with anchor bolts onto the piers and lags run up from underneath beside the piers into the untreated heavy sill.  If you could spike them on first and then set over embedded threaded rod that would work too. I guess each situation just needs to be thought about.

I don't see any membrane necessary. We often use "sill seal" a 1/4" x 6" wide roll of closed cell foam. It goes between mudsill and foundation on continuous foundations, helping to seal irregularities.