I have a 100 year old, two story ranch house, with NO insulation. Currently all that warms the house is one wall heater and one (seperate) A/C. I want to install a central heat and air unit. My question is: Do I need to install the central Heat and Air PRIOR to putting in insulation? Or can this work be done at a later (less rainy) time? There are no air ducts in the house, no basement and no attic, just small crawl apaces. Any assitance would be greatly appreciated. The house is approximately 2200 square feet total. Thank you.

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Originally Posted by Kirsten Slatten

I have a 100 year old, two story ranch house, with NO insulation. Currently all that warms the house is one wall heater and one (seperate) A/C. I want to install a central heat and air unit. My question is: Do I need to install the central Heat and Air PRIOR to putting in insulation? Or can this work be done at a later (less rainy) time? There are no air ducts in the house, no basement and no attic, just small crawl apaces. Any assitance would be greatly appreciated. The house is approximately 2200 square feet total. Thank you.

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Kirsten,

You can install insulation after installing the central heat and air, and you probably want to in this case, since the ducts will either be running in the attic or crawlspace, and for effiency sake the ducts better be insulated to. You can insulated everything at the same time.

Of course, keep in mind that until the insulation is in place, the central heat and air will be more expensive to run.

How are the walls constructed? They are conventional stud walls? Could they be the older, balloon frame construction? It has the same 2 x 4's running from the foundation to the roof. Much easier to run ducts up to the second floor. The full 4'' wall cavities will make things easier too. Today's 2 x 4's are 1 1/2 X 3 1/2. Modern construction uses 92 1/2'' high studs with base and top plates and a layer of floor for each story in the wall. Much harder to run a duct through.

Go with the heat and air conditioning first. It is much easier to run ducts through uninsulated walls. Where are you putting the furnace? I like my crawl space location, but it does complicate venting. You do need access for changing filters.

You need a vapor barrier and air infiltration barrier as well as insulation. You could have insulation blown into the wall cavities, but cold air could still blow through the outside sheathing, the insulation , right to your plaster, and then through any cracks or holes in it. Water vapor can go right through plaster and insulation, finding a point between the warm house and the cold outside where it condenses, running the insulation and maybe rotting the wood. Vapor barriers and air infiltration are difficult retrofits. You might look at injecting foam. I think the past problems with it have been solved. The older material with the out gassing problems have been banned. It is more expensive, but may be the only good solution to an older house. Otherwise, to do it right, you would have to strip off either the outside siding, or all the plaster on the inside. If it is a balloon framed house, you will have to seal each wall cavity top and bottom to hold the insulation in and stop air infiltration. Get more than one estimate if you can. If the contractor looks puzzled when you bring up balloon framing, find a more experienced one.

Don't set the air conditioner compressor near the dryer vent. The lint will clog it.