Scaffold planks for carvel

I'm just curious as someone suggested using scaffold planks for the hull, i can't find anything on them so I'm guessing there's a good reason why they arnt. maybe weight, type of wood or price... Anyway just curious

Edit: just realised I wrote carvel in the title, it's just the first type of planking I thought of doesn't matter if it is or not.

 

Scaffold planks, on this side of the pond anyways, are typically made from southern yellow pine and have limited knots and grain run out. Possibly even a grain density, but not necessarily. They have to meet an OSHA standard to be a scaffold plank. The problem is they are flat sawn and would most likely not be a good choice for carvel planking. I having used them for planking, but have resawn them to get more vertical grain orientation.

I have also used them for structural components where their strength is an asset and their weight is low in the vessel.

 

AFAIK the scaffold planks (in the UK) have to meet a Euro/BS standard for loading and that's about it. I think it is stamped on the aluminium end strips. Personally I would not even consider this material as suitable for a boat. If you want to use cheap pine(s) or related species go to a big timber merchant who will let you select from their yard. This is not easy to do btw.
Then go through the stacks to find the best straight grain quarter sawn stuff with minimum knots. There's quite a bit of Baltic origin spruce/deal around for high quality cabinet making and this stuff can yield very suitable material.

Depending on what you want to build, how long you want it to last and the loadings, you should find something suitable. Also allow it to dry properly before using, you may need anything from a month to 6 to get the humidity suitable.

If you just want to nail something together for the kids to play in a local pond it might be different....