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considering buying an old house--heating/cooling questions

Posted by tminn (My Page) on
Tue, Feb 24, 09 at 8:36

My husband and I are considering buying an old farm house. We can do basic home repairs on our own, but know that this project will be a learning experience for us as we will need to ask questions/get support in order to renovate most things this house will need. So we are trying to become educated about some of the basic things in order to help us make our decision. The house has a huge attic that we are wanting to turn into a rec room. We have heard horror stories about something called "ice dams" that can occur if an attic becomes too warm (I think). Is finishing this space (drywall, carpet, heat) even feasible in order to avoid this ice dam problem? Are there things we will need to do to make it possible? Secondly, we are afraid of being able to afford the heating costs (we are not sure even how much they will be)--currently forced air w/ propane. The house does have all new windows, but beyond that we don't know anything about the insulation, etc. Considering a corn burner, etc... Is there a way to estimate the costs? No one lives in there now. Any input would be appreciated.


Follow-Up Postings:

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RE: considering buying an old house--heating/cooling questions

Regarding ice dams, it is true that keeping the attic cold in the wintertime will prevent this from happening. The idea is to keep the roof cold, so the snow does not melt, and form ice where it refreezes over the eaves. If you were to heat the attic, it might be necessary to install those electric heating elements over the eaves, to prevent ice from forming at that location. The house you are considering probably was built with no insulation in the walls. This would have to be corrected before the house could be considered to be energy efficient. You might want to discuss this issue with a local insulation contractor before you make an offer on the house. At least get it looked at.


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RE: considering buying an old house--heating/cooling questions

Old houses are great, but they will require lots of rehab. What you can do in the attic may be based by the room you have. If there is room, you can leave an air gap, insullate bellow that and then finish the ceiling under that. Then there would be no worries about ice dams.

Here is a link from another board, so you will have someone to comiserate with when you see your heating bill:____ :) :) :)

Here is a link that might be useful: OMG... My heating bill is huge


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RE: considering buying an old house--heating/cooling questions

Yes, the idea of leaving an air gap between the roof and attic ceiling insulation is correct. Another alternative to prevent ice dams is to insulate between your rafters with spray foam insulation. This works when rennovating an attic where you are totally removing any ceiling material. This is the method we had to use because we did not have roof vents - so we could not use fiberglass insulation right under the roof. (We had just put on a brand new roof, sheathed with foam backed mdf - so we didn't want to create new roof vents). Anyway, between the foam backed sheathing and the sprayed foam between the rafters, we don't even have an icicle! It was expensive but the upstairs finished rooms are going to be sooo nice!


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RE: considering buying an old house--heating/cooling questions

Attics were usually not built to support loads equivalent to living space. So while you're looking at the roof, don't forget what's underfoot.


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RE: considering buying an old house--heating/cooling questions

The best thing you could do is have the house inspected by someone with expertise in old houses. This should give you insight into what major issues you'll be facing, best options for insulation and heating, etc., etc.

As far as ice dams are concerned, there are several ways of dealing with them. Perhaps the best is using an ice and water shield type membrane on the entire roof beneath the shingles. This does not prevent ice dams, but insures that water will not penetrate the roof. If the current roof needs to be replaced anyway, such a membrane is well worth any added expense.

Whoever provided the propane for the previous owners should have some record of their propane consumption; this would give you some idea of what to expect for heating costs. Forced hot air systems are more difficult than boiler systems to change over to solid fuels such as wood, corn, etc., but if there is a spare chimney/flue available, a woodstove or other device is an option.

I wouldn't worry overmuch about the attic floor supporting weight. The quality and size of lumber used in old houses was much greater than what's employed today. Just check to see that the spacing of the floor joists is reasonable: 16" to 24" on center.


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RE: considering buying an old house--heating/cooling questions

First before you start changing everything about the house, live in it for a year. Get to know it in all the different seasons.
You might find out the room you were thinking of using as a sewing room gets almost no sun while the other room your hubby was thinking of using as a dark room gets too much sun.
Get to know your house it's quirks.
Some old farm houses were built to maximize air flow by opening the doors. I know mine if you open all the doors that connect the rooms you don't need AC.
New windows aren't always a good thing. It's more important how the windows themselves are caulked, hung and maintained.
Take a hard look at your landscaping to see what there can be improved to give you maximum shade in the summer and sun in the winter.
A well placed tree can do more for your heating/ cooling bill than most insulation.
If you do decide to go wih a rom in the attic are you going to try and put in skylights? If you do that is a job BEST done when the roof is redone.


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RE: considering buying an old house--heating/cooling questions

"Ice damns" are basically just a term for when the roof gets warm enough to melt some snow in some areas. The water then can refreeze when it hits a cooler spot like at the overhang. That basically forms a dam that can hold water on the roof. Roofs are designed to let water run off them, not to hold water for any length of time. If the problem persists, the water can work its way up under shingles etc and leak into the house. Obviously, that can be a huge problem.

The way to avoid this is to avoid transferring too much heat to the roof during winter. A big open and vented attic accomplishes that in most instances. If you are going to enclose the attic, you will need an effective way of keeping the heat from rising up through the new room and to the roof. The "low tech" way to do that is to make a mini-attic above your new attic room. It doesn't have to be tall, just enough room to keep air flowing. For that to work, you need vents to get air between the roof and the ceiling of your new attic room. The heat needs a way to escape instead of through the roof. The "high tech" way to do it is completely shut off all air flow going up to the roof and insulate the heck out of it with expanding spray foam. That is a less reliable way to do it though because you are just counting on the insulation to keep heat from getting out of your room. If the insulation is compromised for any reason, you'll end up with hot spots on the roof.


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RE: considering buying an old house--heating/cooling questions

I wouldn't worry overmuch about the attic floor supporting weight.

If the floor feels "bouncy", you'll know right away. The romanticism about old homes never ceases to amaze me. I've torn apart several dozen of them and inspected many more. For every one built with 4x12s (really!) I've seen ten built with 2x8 floor joists (still legal) or even scrap wood.


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RE: considering buying an old house--heating/cooling questions

I certainly wouldn't dispute the 2x8 dimension sited by worthy. For a house more than 100 years old, however, a 2x8 is larger, better quality (in terms of old growth vs. new growth wood as well as the species)than run of the mill lumberyard wood today. I'd hazard a guess that a 2x8 from 1909 would have the strength of a present day 2x10 or 2x12. I haven't worked on dozens of old houses, but my experience with 10 to 12 of them is that they tended to be overbuilt rather than the opposite.


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RE: considering buying an old house--heating/cooling questions

I suspect a 1909 2x8 would actually be 2 by 8, not 1.5 x 7.5.


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RE: considering buying an old house--heating/cooling questions

"I wouldn't worry overmuch about the attic floor supporting weight."

We had an old house and the ceiling joists were 2x4s, 16" on center and spanned 12'. When we added a second story all new joists were laid next to the 2x4s


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RE: considering buying an old house--heating/cooling questions

We finished our attic, now called a third floor because it's so much nicer and did leave the air space between the new ceiling and the roof, added insulation and checked the floor joist and found they were much sturdier than a new house. No problem with condensation. I would have the house professionally inspected, but don't be afraid of old houses. They often are built better than the new ones. Just make sure it doesn't have structural issues.


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RE: considering buying an old house--heating/cooling questions

Allison1888--do you have any pictures of your 3rd floor attic space? Our house has a GIGANTIC walk-up attic and we were thinking of making 2/3 it into a family room/game room. I've just been looking around online trying to find pictures of renovated attics.

Thanks! (hope I didn't hijack this thread!! sorry!)

-Sarah


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RE: considering buying an old house--heating/cooling questions

One thing I do before buying a house, is call the local utilities and ask them what the previous bills have been (heating, electric, gas, water). No need to guess.

As far as finishing the attic. My attic is finished and no ice dams :-) Basically, you want cold air to enter low (soffit vents or pods)....flow up the underside of the roof (baffles under insulation)..and exit at the top of the roof (ridg vent or pod). You also want to keep warm air from the living space from exiting into the unfinished attic, etc. via electric outlets, hole for fixtures, etc. It's not brain surgery...just need to figure out how you want air to flow.

Call your local utilities company and ask them if they offer energy audits. They will give you lots of ideas on how to weatherproof your house, how to refinish your attic, $ saving tips, etc.


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