Have a remodel home (built in 1920s) that the HVAC cannot keep up with extreme cold or heat. Have minimal insulation in attic & no vapor barrier or insulation in crawl space (pier & beam).

Looking to add spray foam to roof decking to encapsulate attic & subfloor. Would this aid the HVAC or should i spend money to replace brand new 3ton unit? Also any recommendations for local contractors?

Home is about 1300 sq ft.

Sorry for multiple posts. Got errors when trying to post the 1st try

Can you give some more info ?

Gas furnance ? Electric heat ? Heat pump ?

What kind of windows are in the house ?
Single pane original wood ones?


Is there any insulation in the walls ?


I've seen retro attic foam result in a too small hvac that previously couldn't cool house under 80 when it was 100 degrees. After the foam it would cool down to 72 at 100 outside.

No wall insulation as well as no insulation in crawl space or vapor barrier.

Electric everything with no heat pump. House struggled in winter to keep up in cold fronts. Right now i lowered the thermostat for the heat to 75 & stays fairly close but humidity level is hovering around 60% with 3 dehumidifiers running.

Original windows in older section of home, single pane on wall with most sun exposure

I'm going to go with blown in insulation in the attic for the winter months once I'm done rewiring. Once installed, good luck ever walking up there again easily.

$500 a month to heat this sucker in the winter!

I'm not going to spray foam the attic rafters because there is no solid decking for it (It's stringers, then the original cedar shakes then a very old metal roof . It would wind up attaching directly to the underside of the cedar/metal in places making eventual replacement of the metal "interesting." I did do a radiant barrier, because it was cheap and easy. I have no idea if it was worth it.

I've looked at spray foam for the crawl space, but I hesitate to do so due to moisture issues. These houses aren't vapor-barriered so I'm worried about trapping moisture against the wood. (It's the reason I did not do the exterior walls.

A good quality weather stripping should help with the windows, as will making sure they're tight to each other when latched and the glazing is in good condition. I'm currently looking for a set of motorized blockout shades for the front to help with cooling in summer. The addition of ceiling fans helped immensely over the winter to keep the heat closer to floor level (11 foot ceilings) and has made the few hot days so far much more pleasant.

If it makes a difference, I have a 4 ton for 1100 sf due to the ceiling height.

Adding insulation will definitely help.

Adding insulation usually provides the best value when starting without any to begin with. Once you hit a certain point you will see diminishing returns.

Even if you replace the HVAC; I would insulate first. Make sure and get a manual J. Many installers will include it for free if you purchase a system from them. With all that new insulation you may be able to run a 2.5 ton system @ 1300 sqft. The manual J will tell you for sure.