east20, I hesitated to jump on your post in case others had some good ideas for you. We did use a barrier between the HFGH steel base and our pressure treated lumber, but only out of an abundance of caution, after reading here that others did so.

I will say after four years our HFGH base still looks like new, so we are pleased with how the (powder coated?) finish has held up. Also, I try to check various garden forums online for HFGH issues, and haven't seen any posts regarding the problem of corrosion between the base and pressure treated lumber.

I get a pretty good number of comments and questions posted to my blog about building our HFGH, and so far nobody has posted a comment about any steel base/treated lumber/ corrosion issues either, so I'm hoping you won't have any troubles.

I'm guessing that corrosive processes happen faster when moisture is introduced. Our base sits high on our wood, above the soil level, in a dry climate. If your base sits at or below ground level, in a wet climate, your mileage may vary, but based on things I've read, my two cents is not to lose much sleep over it.

Maybe someone else will pop in here with a preventative idea for you, but I'd tend to I'd just keep an eye out for problems, while you enjoy your greenhouse.

Building our HFGH

Thank you for the reply, it is a relief to know that this shouldn't be much of a problem.

Here's another thought. If you think it would help you sleep better at night, get a zinc sacrificial anode block like they use for small fishing vessels. Attach the block to the steel base with heavy copper wire and bury the zinc in the ground near the base of the greenhouse.

Should last quite a number of years, and if you go poking around after a few years and find out that the block is essentially intact, even better!

The current building code requires hot dipped galvanized fasteners into the pressure treated lumber or ACQ treated fasteners. I plan on buying a HFGH this weekend and I will use a cedar 1x4 nailed to the top of my pressure treated foundation and sill foam between that and the greenhouse base. I've read all of mudhouses directions and many people owe her gratitude for her hard work on sharing. I have even been thing of other ways to make the roof stronger. I'm a building inspector so I think I will come up with a couple good ideas to share.

That's an interesting idea Steve, thanks for that!

Bulamatari, I hope you will post back here with any ideas you come up with. I know the roof is a weak point for folks who have snow load problems. I often think this kit is mainly a good starting point for folks who want to apply their own ideas and creativity, based on what they need to accomplish, and I'm sure your experience would help others.