Hello,

My wife and I recently (september) purchased a 44 year old home in Indianapolis IN. Prior to having the home listed, the previous owner had a pre-listing home inspection in Feb 2012 where the inspector noted a six-degree temperature difference between the rest of the house and a southern wing to the house. This wing is part of the original house, is one story, has about R44 attic insulation (we had it re-insulated upon moving in) and has three rooms: an office/den, a guest master bedroom with 4-piece ensuite bath, and another full bath. This wing is over a crawl space, which has no exterior wall crawlspace vents. However, due to storage equipment blocking the access to the crawlspace, it was never actually inspected. The original owner had her heating company evaluate the temperature difference, and they recommended a zone heating system.

Based on this information, I had a couple companies come by to give quotes on the attic insulation and zone system installation shortly after we moved in. By this point, of course, the crawl space access panels were unobstructed and we discovered that the ducts leading from the main supply trunk to those rooms in that wing had actually fallen apart. So, we figured re-connecting the ducts would solve the problem.

However, it did not. In the interim, my parents visited and my father suggested insulating the ducts themselves. My heating company did so and in the process found another duct in that crawl space which had actually been disconnected. However, despite that, there is still quite a bit of difference in temperature, sometimes ten degrees when it is exceedingly cold outside.

I have had several companies come in and offer contradictory suggestions on how to fix the problem, so I am looking for additional advice.

One major theme involves encapsulating the crawl space with insulation of the band boards. Most companies who offer that service CAN also install 4" foam board insulation along the concrete walls but recommend against this, as its cost savings are minimal without several years' worth of deep freezes. Of those who recommend band board insulation, some recommend foam board, some foam board with spray foam to anchor the edges, and some batt insulation.

Other companies recommend pulling off the insulation on our subfloor, pulling off the insulation we just installed on the ductwork, and adding a supply vent to heat the crawl space, with reinforcement of the band board insulation.

We don't really have a moisture problem at all, the crawl space is bone dry even when it is pouring rain outside, so with a 12 or even 20 mil piece of plastic encapsulating the crawl space I can't imagine it offers much in the way of insulating value. Furthermore, I'm not really sure I buy the "heat the crawlspace" theory, because, in effect, with the ducts disconnected, the crawl space was being heated in Feb and there was still a temperature difference.

So, what would folks here recommend? What solutions have you all found that help?

Thanks and have a great day!

Three questions:

1. Is there any insulation under the floor? How much?
2. With all the H/A involved, did any happen to run the loads on the system?
3. Also with H/A, is there adequate return flow from the cold areas?

From what you describe as the crawl space condition, I don't see where encapsulating will get you very much. Definitely do not heat the crawl space!

While a zone system is great and probably will solve your problems, it is rare to need a zone system for a single level house. Instead of investing thousands on a zone system, try to find H/A company who is willing to install dampers on your ductwork and who has the ability to balance the system to provide the needed airflow to these cold areas.

Since you just moved in this fall, you probably haven't had a chance to see how the A/C is working house-wide. If the cold-in-winter part of the house is also the warm-in-summer part, then your problem can probably be solved simply by directing more air to this section and less to the remainder of the house. If this section of the house is cold in both summer and winter, then you may have to seasonally adjust some dampers (or go with the zone system).

There are other factors like sun/shade exposure, number of windows and wind direction that will affect things, but those can be overcome by balancing your H/A system.

right on jaybee. good answer!
i guess you now know why the access was blocked to the crawl space, when your inspector was there. I would have, you should have. DEMANDED access to that crawl space.
or not bid on the house.

quote:

Originally posted by Jaybee:
Three questions:

1. Is there any insulation under the floor? How much?
2. With all the H/A involved, did any happen to run the loads on the system?
3. Also with H/A, is there adequate return flow from the cold areas?

Thank you so much for your response, jaybee.
To answer and clarify, the home is actually a two story home with a finished basement, and there are already dampers installed in the ductwork. There is some insulation under the subflooring, though I'm not sure how well it is performing since there are pieces that are thin or falling off. I don't believe there was a specific load testing done. No such test was listed on either the February inspection or my August inspection. We did have some time running the AC in September and early October due to the unusually high temperatures, but I didn't check the temperature difference back then. I can't recall it being nearly as noticeable as during the cold weather we have now.

Well, there you go: Part of the house is over a finished basement and part of the house is over unheated crawl space. Even if the finished basement is not really warm there will still be a huge difference in what it takes to heat the area above the finished basement vs the area over the crawlspace.

This increases the chance that the solution is to get more airflow into the area above the crawl space. You either open up dampers to this area, close off dampers to other areas or figure out a way to add another run or two to the cold rooms.