DF probably won't last as long but, for me, particularly at the same cost, it'd be a no brainer. I'd use wood. Particularly for a classic house.

It takes more care and upkeep. But composites on craftsman make me sad.

But that's just me ...

I'll be the voice of dissent here. I think you should seriously consider the composite product.

Consider this, if your 1920 home is like any other 1920 home, there is probably a lot of deferred maintenance and repair it needs. The composite product will last a lot longer than real wood. And once it's in and finished, you will not have to concern yourself with the porch flooring for a very long time.

Douglas fir today is nowhere near rot resistant as Doug Fir from 1920. I guess you could saturate the wood with borates, and use some top shelf marine primer and prime all six sides of the boards. Then top it off with a good porch and floor enamel.

Listen, I'm no fan of composites. However, I'm also no fan of constant maintenance either. Sometimes you gotta take the easy path and focus in on other areas of the home to maintain authenticity.

A lot of my decision would be based on the climate. Its pretty wet where I live. At my home, the Doug Fir was all rotted on the under side. I replaced with cedar. I wish I would have used composite.

I'm so torn on this as well. We have a 1928 Chicago Bungalow and will have to replace our back porch next year. It was painted common wood (no idea on species or if it was even original to the house).

I'm a proponent of a composite product, as long as we could get the tongue and groove look. DH really wants wood, but I'm not a fan of maintenance or babying it (hello snow shovel) and worry about longevity. Our small yard is already bordered by a cedar privacy fence and I am afraid of the ski lodge effect.

About 10 years ago we replaced a composite floor on a newer house (1990) with a painted mahogany floor. The composite was believed at the time to be the most whiz-bang stuff, ended up in court and the homeowners ( a class-action full) got their floor replaced.

It's been so long I can't remember the brand name, but it was the kind made from plastic and wood flour, it swelled up at the edges just like particle board, despite the sanguine claims on the brochure.

Casey

Ouch - that's an expensive lesson, Casey. It sounds like fir might be the way to go! As I said, the prices are about the same but it sounds like real wood might be the way to go, even if it means more prep work initially. As much as I would like to stain the wood instead of painting it, I think paint on all sides is the correct way to do it (someone correct me if I'm wrong!) I would CRY if we spent $4,000+ on this project using composite only to find it wasn't all it was cracked up to be a few years down the road.

I should mention, too, that I am in Buffalo, NY. It is cold much of the year and we do tend to get a bit of snow. ;) Composite is appealing for those reasons (I don't want to shovel the porch twice a day 6 months out of the year!) but then again, I wonder if extreme weather like ours might cause it to fail more quickly, too. Hmm....

Even though I personally don't like composites on older houses, they shouldn't be ruled out on technical grounds today. I have a friend with a composite deck that's doing fine after at least a decade and a half. You just have to choose quality material.

"I would CRY if we spent $4,000+"

WHAT?? I can get tongue and groove VG fir T&G porch decking for something like $2 or $3/bf if I remember correctly.

How big is your porch?

Instead of Fir, maybe consider something that grows closer to home that is more rot resistant like white oak. You're paying a lot of markup for a "specialty" wood that is beginning to come back in vogue. Plus, fir is so pretty with a clear coat it's a crime to cover it in paint.

I occasionally run into salvaged old growth Doug fir at the local rebuilding center. Like a big lot of the same types of boards. Maybe that (or local trusty old wood) would be a good choice, if one can find it?

I re-read your question; you have heated/insulated rooms below a porch. Therefore, the wooden decking has no air movement underneath it, so it can never fully dry after rains. Any rain is able to penetrate through the many seams in the flooring and get the insulation and framing wet, and they can't dry out either.

You need to understand the construction details that are necessary for this situation. It consists of building a seamless flat roof, that is impermeable and drains water away from the house, then building a walking deck on top of it.

I have done three projects like this. The first one. we used a torch-down adhesive roll roofing, then 2x4 floating sleepers and a 3/4" traditional wood flooring.

Second one, a subcontractor put down a EPDM rubber roof (we had to tear off everything because the old rubber roof failed and ruined the decking and a lot of the framing) then we built modular, removable hardwood duck boards that fit into the space and were removable for cleaning underneath.

Third one, the metal roofer came in and built a flat copper roof, and we did a normal porch floor on sleepers as in #1, but this time in mahogany (more stable and rot proof) , painted.

I just wanted to point out that there are more issues in play than you may realize, and your path forward is not simply choosing the most maintenance-free finishes.

Casey

Hi Casey! That is the plan for the cold storage rooms below the basement - we are going to address that before we tackle replacing the porch. The cold storage rooms are original to the house and are, well, freezing, so unfortunately the PO, not knowing any better, insulated the rooms' ceilings. I suspect that is what caused the porch to rot. I appreciate you weighing in on this, as your knowledge and expertise were a huge help to me when I owned a different old house when I posted here a few years ago! The seamless flat roof idea is actually a more involved idea than our research had yielded, and it makes a lot more sense.

Re: the cost of the porch - it's a big porch, which normally is a good thing but in this case, not so much! The width of the original boards are an odd size (I can't recall offhand what it is) so sadly we will have to special order new material in order to replicate it. We priced out all the materials we'll need at between $3,500 - $4,000...sigh. But considering it's the one and only large project our 95 year old house needs, I guess I can't get too upset over it! ;)

its my understanding that Aeratis is NOT a composite but rather just made from PVC. And it is paintable, so it has all the benefits of the painted doug fir but not the downsides. In fact, I believe that it has been approved by many historic registries...

So you might want to take a look at it again.