Size of coach screws for wooden frame

Lynne_H

Hello,
I am building a wooden frame that a summerhouse will sit on. The frame is 14' by 10' and the pieces of wood I'm using for the outside of the frame are 45 mm depth x 145 mm width. I will use coach screws to attach the four pieces of wood together to make the frame and coach screw sto attach the frame to wooden posts in each corner (the wooden posts are 10 cm x 10 cm). Please can someone advise what size of coach screw I should use to
a) go attach the corners of the frame together and
b) go through the wooden frame into the wooden post in each corner

Any help much appreciated!

Lynne

getmore4less

What's going to hold up the middle?

presumably you mean 145mm high for the frames and that is the long side attached to the posts vertically.

I would just attach to the posts,
A couple of M10x100/120 should do the job

I think your vertical shear loads should be OK with 16 bolts holding up the structure and people.