Hi All Tried a search but nothing quite answered my question I am building a pergola, 3.6m square using 100x100 posts and 150 x 50 (6*2) timber crossbeams Using a hold digger that has a 16cm shovel width I have dug my holes around 60cm deep and at a 2.4m planned height the total post length will be around 3 metres. So have I dug them deep enough? Also using a post hole digger are they wide enough? I was planning to sink and then use postcrete. Im working around a deck frame I built so its getting tricky to get any deeper. Long story short we started with lets build a deck to lets add a pergola! Thanks
They're fine, the crossbeams will stiffen and stabilise the structure. Ideally you'd build concrete up higher at the bottom of the post and slope it away from the post to shed rainwater, but if the deck is locking the posts in it should be good for a long time.
600 deep is what you would do if it was for fencing panels subject to wind loads, your posts will be connected at the top so will be more than stable enough, as long as you can get concrete down the sides of the post and compact it no problem the neater the hole in virgin ground the better.
Thanks both that's given me a lot of comfort. Def plan to build up and haunch around the posts too. Cheers.