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Question DetailsAsked on 4/1/2015

How much does it cost to finish an attic including HVAC, insulation, skylights

Just trying to get a +/-$5k idea, is this a 15k, 30k, 45k project. 1200 sq ft very open attic, in shape of a T, turned into a large open room, a side room, and a semi-finished storage area. Insulation, walls, ceilings, lighting, electrical, skylights, ductwork.

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At the higher end of your thoughts, I would say. Depends on your local building labor/ permit/ property tax costs of course, on how fancy you get with the interior, and particularly on whether you are doing anything with the roof or its structure like dormering or bumping parts of the roof up - but assuming this is a high-ceiling attic and you are going to use knee-walls or such to block off the low-headroom areas (or use them for low storage), I would say you are likely in the $40-70/SF range for simple knock-up walls with insulation and electrical - assuming no plumbing, and also assuming that the existing HVAC system can carry the added load so you are only adding a new zone to the existing system.

That may be an issue depending on how much of that square footage you actually include in the "HVAC envelope" - the conditioned space. However, if your house is not already highly insulated, it may be that with proper design and construction and a high level of insulation you may end up actually adding little new load to the HVAC system, because you can improve the house-to-attic interface insulation significantly in the process, potentially eliminating a lot of the existing air loss and thermal differential currently at the upstairs ceiling/attic floor level.

Clearly the place to start is an Architect who can help you with concepts as well as initia ballpark costs as you work toward a fully developed set of plans for Remodeling - general contractors to use to bid from, and then build from - possibly with an Energy Audit also if you have not had one in the past, to see where you stand on energy demand issues, because adding in a bit of thermal improvement elsewhere as part of the same job might allow you to avoid upgrading your HVAC system and in some cases can actually reduce your overall heating and cooling loads from current levels.

Be sure great care is taken with insulation and vapor barriers to properly isolate the HVAC envelope from the outdoors, and with maintaining excellent underroof/attic ventilation tp prevent moisture and air blockage issues - which will likely mean adding eave baffles and ridge vents if you don't already have them.

Lots more discussions, some in quite some depth, on attic insulation and ventilation in the Home > Roofing and particularly in the Home > Insulation links in Browse Projects, at lower left - as well as at websites like and

Answered 5 years ago by LCD

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