Building a porch swing...need advice

[Iansaws]

I am going to build a porch swing for some good friends who just had a large front porch added to the front of their house. Here are the on-line plans:

http://www.buildeazy.com/porchswing_1.html

I would like to build it half again as long as the swing in the plans. What kind of additional supports do you think would be required to do this? Do I have to use treated would as called for in the plans? Could I forgo the use of the hardwood and use all untreated pine if I planned on painting it?

[pelligrini]

Just thinking about it in some basic architectural statistics, increasing the size of the front and rear seat members wouldn't be a bad idea. A single 2x4 might be ok, but make sure it doesn't have any defects (knots and such). If your friends are large folks, I'd upsize.

I think more attention should be paid on how it fastens to the porch. Being a larger swing it'll have the potential to carry more people. Start them swinging and the load on the fasteners can be quite a bit.