Sounds like it may need structural work as well as cosmetic replacement. I would not expect to pay less than $10 a square foot for just the material and install. Any prep work and especially structural work will be in addition to that. You did not give the square footage, but 10K+++ would not be out of line for all of the potential issues here.

A little late to the question but in case you still need an answer... Not sure about exact installation costs which typically do vary by installer by 10-30%, but without telling us specifically which Trex or Azac product, it will be hard to estimate material cost. Typically Trex will run somewhere right around $3.50 to $4.00 per linear foot. You will need to purchase 12 footers for your deck and you will need roughly 60 of them (not counting any stairs if any). The spacing between boards will be 1/8" so actually a few boards less. Always order several extra due to mistakes in cutting/measuring, etc. At $4.00 per linear foot that will cost you $2880 for just the deck boards without installation. That does not count screws or hidden fasteners. Hidden fasteners will be a couple hundred extra. Do your estimates include tearing up and removing the old deck boards? That might save you some money if you did that part yourself but I can't imagine the entire quote should be much more than $4000-$4500 (Just an educated guess based upon just building a large deck myself after receiving several estimates)

:) Yes, the exterior is ugly. I'll grant you that. We suffered from previous owners (circa late 1970s is my guess) and their desire to do asbestos tiles siding over the original. While I'd love to tear it off and put up new siding, there's not much reason to other than curb appeal, and we'd rather put our money into the interior and living spaces. We do have plans to paint, replace gutters, and we are replacing attic windows. Eventually we will replace all windows. Attic was replaced in 2010. Sure, the exterior isn't flashy and lovely and definitely won't win awards, but it is what is and it's what we've got. Maybe historic home isn't the best term, but it would be the terminology used in our town to describe our neighborhood and our house, for better or for worse. It's really what's inside in the interior that we like, along with the location and overall features of the home. Our home has all original oak floors, quarter sawn oak pocket doors and trim and 5 panel doors all original to the house, a huge chapel bench in the foyer that is built in, and none of it has been painted. Sure, it's not a grand historical home, but those are rare in general, and there's probably only 3 or 4 like that in our town. What is rare is the fact that we have all original woodwork, plaster walls in good condition, a few original decorative leaded glass windows, and a gorgeous brand new finished master suite. We have a 5 bedroom 3 bath house with a finished basement family room and playroom, plus a patio. In our town, that is a very rare find. But with all of that, comes the crappy original kitchen layout and back porch/bathroom hack. What we discovered when we looked at homes 6 years ago is that there were FAR worse. Mold, scary DIY electrical, refrigerators that couldn't be opened, and absolutely terrible upkeep and maintenance. It was bad...really bad. So when we found our house, trust me when I say this, it was a total steal and we loved it. Except the kitchen. :) Trust me, I get the rebuild idea. I get it. I'm sure many of you see this and read this and think, "Money pit! Run away!!!" :) But not all of us can or want to tear down houses or replace absolutely everything. If we actually tore down our house and rebuilt it, it would cost more than 2-3x the current value to rebuild it with the same quality and materials and finishes. I appreciate all the warnings and suggestions to consider that, but it just isn't going to happen.

I have been trying to keep the costs under $8500 and therefore I am down to two systems choices. I have model numbers on one and still working on a quote with model numbers for the other. Any thoughts? Trane XR16 Heat Pump 16 seer 4 ton single stage, 80% gas furnace single stage, new thermostat, matching ACoil, media cabinet fielder, clean flush and reconnect line set, remove and discharge all old equipment. $7600. 1 year "gold" member service plan, 10 year parts warranty from Trane Goodman DSZC180601 DSZC 18 seer 4 ton two stage heat pump GMVCB1005CN 80% variable speed two stage gas furnace CAPF4961 5 ton insulated A-Coil AM11 Media air filter CTK04 Thermostate, fossil fuel kit for heat pump with gas furnace, new pad, flush out freon lines, install new drain line, install new humidifier pad in existing, safety switch, pull vacuum on system and charge, remove all existing items $8,300 2 year warranty on all labor, 10 year on all parts, limited lifetime on compressor? I like both installers, they were heads and tails above two others I spoke with on the system. The Goodman installer (ex Trane dealer, ex Lennox dealer), did the most thorough job, measurements, inspections, questions, etc. I am leaning toward the Goodman because the systems seem night and day from each other, but I feel more confident in the Trane name. Unfortunately a similar Trane system is over $12k