Hi,

I'm looking to replace most of the boards on a large wooden car deck on a sloping section. 90% is made up of 200x50mm boards with quite a few dry and cracking and not safe for a car.

At the moment my plan is to start from the worst and start gradually replacing with the same size boards. The deck is on poles with adequate bracing that looks structurally sound. So question is, do I actually need structural H3.2 for this, or could I use H4 boards of the same size (appears to be much cheaper and am I right in thinking will be less impacted by the wet and then dry?)

Second question is am I doing the right thing by replacing them with the same size board? It's hard and expensive to get anything thicker with that width, probably because of the weight and practicality. Is there benefit in going smaller, say twice as much 100x50? Or should I be going to a bigger extreme and looking at 100x75?

Thanks in advance for the help.