I discovered that problem also on my recently erected 6'x8'. I think squaring to 124" would have been just right. Fortunately I had pre-assembled part of the frame and noticed it was a little off, but not completely trusting my measurements, I squared to 123 3/4". The back overhangs a little, but was able to get bolted to my wooden frame okay. Perhaps you can overlap a little on each side.

This is why my son insisted on assembling the floor plates before constructing the foundation. We sometimes kid him because he's so cautious ... but sometimes it pays off, and he's too gracious to say "I told you so." Perhaps by posting your experience you will save someone else the same problem.

If I'm understanding the problem correctly, would it be possible to find some 1" think lumber to attach (very securely) to the outside of the foundation (probably at the rear, away from the door) to extend it out so you don't have that floor plate sticking out? It probably need not extend all the way to the ground; just something to securely support that aluminum strip. I don't think I'd split the difference and allow even a half inch of the plate to protrude out below the doorway - too great a chance it might get bent down.

Good luck with the rest of the assembly - I hope it's relatively trouble-free for you. Take your time ... I know that's difficult when you want to see it completed and start fitting it out and filling it up! If you haven't done so already, do a search for conifers' photo documentation of the assembly process ... it was a Godsend for us!

Diane

When I built my 10X12 HFGH I never even bothered reading the dimensions I assembled the base and measured it then built my foundation to fit.

Well, the instructions were wrong. The dims should have been 99 inches length instead of 97.5. I went ahead and assembled the base and measured. All I am out is 8.00 for another board. Thanks, James