I’d highly recommend getting an energy audit through BGE’s Home Performance with Energy Star program.

Getting an energy audit (which is subsidized down to only $100) then qualifies you for rebates on insulation/air-sealing, and even HVAC upgrades. The audit report should give rough estimates on how much the work will cost, how much BGE will pay, and how much energy you’ll save going forward.

I plan on it but am curious if anyone has insight. I have part of my ceiling opened up right now for renovations so it would save some trouble to insulate above the ceiling while it’s still open

A lot of time with these rowhouses, the only “roof insulation” sits in the top floor’s ceiling, with the roof itself having none. Also, the attic or crawl space or whatever you want to call it between the ceiling and roof is often unvented, so it gets super hot in the summer and pretty cold in the winter. I remember on really sunny and hot summer days, sometimes I could feel the heat radiating off the upstairs ceiling.

Two years ago, I got a white membrane roof with 4 inches of insulation. It was expensive, but I really wanted a high quality roof after so many years of gross layers of tar and leaks. The upstairs no longer feels like it’s broiling in the summer. I will say though that there are so many other places in the house that are poorly or not at all insulated, including the sides of the attic, which is barely separated from the neighbors’ broiling attics, that it reduces my shiny new insulation’s effectiveness…but I could address those areas in the future. After I got the new roof, my energy use decreased a little bit, just in time for energy costs to go up.

That’s what I’m worried about, because there is no insulation above my ceiling. So it may be 100% in insulated. There is insulation that’s as added in the non shared walls at some point

I think it’s common to get insulation blown into the attic space, so that there’s a deep pile of the stuff. I think that’s supposed to be pretty effective and low cost, at least compared to a new roof.

Same issue. Contractors have quoted me 2k to blow in and seal attic spaces. You can rent a machine at HD and do it yourself for under 500. This winter has been mild so haven't affected us much. But definitely get it done by spring or you will be baking first heat wave in the summer.

Is the rental machine blown in insulation or foam insulation?

Rental machine is for blown it.

Before you install insulation, you should also figure out your attic venting situation. Without proper venting condensation will build up and cause mold.

I just did blow in insulation at my house, around 900sqft worth of roof, because of the slope we couldn’t hit the same r value throughout, but used around 30 bails of cellulose insulation. Was around $600. Venting, installed by a roofer will be another $700.

I assume you’re in a rowhome? Flat or shingled roof?

Yeah. Flat roof.

Blow in foam. Mine is a sloped shingle roof. But will probably wait till spring to get it done. No rush now.

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How old is your house, and do you still have any knob and tube wiring? Be aware that it is a fire hazard to have insulation touching knob and tube. We still had knob and tube up there, so that had to be replaced before we could have insulation blown in. It did make a noticeable difference in winter.

It was built between 1900 and 1920. There are some remnants of the old knob and tube but it’s not active. I plan on pulling it out while I’m up there

I got an energy audit - they told me they couldn't really tell if the roof was insulated or not, and that I would have to hire someone to drill holes to see.

That is not ideal. Usually they will ask permission to drill, poke around with a probe, or use an infrared camera. Luckily it seems the OP has the ceiling open already.