I am building with an Insulated Concrete Formwork system, my walls are filled with 40MPa concrete. The engineer has specified that the top plate should be chemset every 600mm. I installed bolts at the same centers into wet concrete and was going to chemset the remainder, not enough time to get them all in.

My roofing guy told me that usually the tie down is done with hoop iron down several coarses and in some cases threaded rod that goes all the way down to the foundations. There is a problem with chemsetting as the top coarse is a bond beam and has 12mm reo running all the way around - hard to miss while drilling and to divert from the centre brings you a little close to the edge.

I'm going to go back to the engineer but also wanted some opinions here, we are in a very windy location and if there are any doubts on the roof hold down I would prfer to install some hoop iron. Its not too late as I can strap it through the polysyrene under a few coarses.

Also - is hoop iron tightened somehow over the top plate ie under tension? How is it achieved?

Many thanks


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