Help with cold room addition

6 years ago

Long post, please bear with me -- I have a circa 1950s addition on the north side of my 1941 house, built on a block foundation/crawl space. The heat duct comes through the former basement window and is only a few feet of run from the furnace. One wall has a large picture window, surrounded on both sides and below by built in cabinets and file drawers. The interior walls are pine paneling, and I am sure that there is no other interior layer under the paneling. There is no access to this attic other than the dormer vent, and no access to the crawl space without cutting the current LVT flooring and subfloor.

Over the years I have had the subfloor rebuilt with fiberglass insulation installed under it, vapor barrier on the dirt, and Great Stuff foam used to fill the gaps along the new floor edge (2006); urethane foam insulation in all the walls (25 years ago) at the same time as replacement double pane windows and blown in insulation into the addition attic; foamed around the supply and cold air returns in the walls; and in early 2018 had the aluminum siding replaced with insulated vinyl (over the original wood). I was told that a Tyvek type wrap was not needed with the insulated vinyl.

Still, this room is colder than the rest of the house, and this winter I am noticing it more - perhaps because it has been windier (like today). I am even smelling my neighbor's smoke in the room from time to time!

What would you do, what would you check, to warm this room up? I am going to buy carpet to lay over the LVT floor for sure. The replaced subfloor did not extend under the built ins, but the insulation should have. I can feel a small draft under the picture window sill, so I will pry off that bit of trim and caulk there. How would you look for other sites of air seeping in?

Could the urethane in the walls have deteriorated after 25 years, and need to be redone? Should I call the siding contractor back and ask for Tyvek on the addition? Is there a way to seal the joint between the structure and the foundation from the outside?

This is a comfort issue - the rest of the house is warm, and my gas bills are below comparable houses according to my gas company.

I'll appreciate any suggestions!

Featured Answer

DavidR

6 years ago

last modified: 6 years ago

I would start by contacting the local utility to arrange an energy audit. That should give you some idea of where your heat is going. A blower door test may turn up some air leaks.

Other than that, remember that you don't have a cellar under this room, and you have a big window in it. If there's no room above, you also have heat loss through the roof. You'll lose more through there than through the floor. How's the insulation?

I've known many people with similar problems -- room additions that are never as comfortable as the original house. I had such an addition on one of my own houses. The house was on a cellar, but the addition was on a slab, and at a lower level. In addition to the room's losses, all the house's cold air pooled in the addition. I installed a booster fan in the air ducts to that room, but it only helped a little.

The traditional answer to this problem is an inelegant one -- supplemental heat for the room. A minisplit heat pump would be a bit pricey to buy, but relatively inexpensive to operate, and would give you extra cooling in the summer as a bonus.

Alternatively, a room like that would benefit from hydronic underfloor heat, but I shudder to think what it would cost to install it.

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Comments (7)

littlebug zone 5 Missouri
6 years ago
last modified: 6 years ago
I agree - contact your utility provider first thing. They can tell right away where your heat is escaping/cold is entering, through an energy audit.
raee_gw zone 5b-6a Ohio thanked littlebug zone 5 Missouri
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kudzu9
6 years ago
If you're smelling the neighbor's smoke, you have major air infiltration issues that can be remedied by caulking, probably including around the receptacle boxes. I agree that a utility energy audit will be the best way to get answers and find economical solutions.
raee_gw zone 5b-6a Ohio thanked kudzu9
raee_gw zone 5b-6a Ohio
Original Author
6 years ago
Thank you all - I will contact the utilities about another audit -- I did have one, but he didn't do the blower door test because of old asbestos tape on the ducts (since remediated) and he didn't really go into that room.) He recommended air sealing, which was done in the main house, but not in the addition b/o lack of access.

I guess I should get the ladder out and try to see into the attic space through the vent, to see if there really is any significant amount of insulation.
kudzu9
6 years ago
raee-

One easy thing you can do by yourself is to get something called a "smoke pen" (probably $40). These emit a non-toxic little plume of smoke that you can use to easily find drafts in the room like around windows, doors, electrical switches, baseboards, etc. If you don't want to spend the money for a smoke pen, I've done this in the past by simply using an incense stick that put out a decent plume, and it cost me less than a dollar.
raee_gw zone 5b-6a Ohio thanked kudzu9
raee_gw zone 5b-6a Ohio
Original Author
6 years ago
Great Idea, Kudzu9 - I should have thought of that! I think my child has some incense sticks - I'll get one from her.
Elmer J Fudd
6 years ago
Why not have an HVAC tech look at the ducting and see if any leaks can be found. Especially common are ones around the boot that may let in outside (crawlspace) or attic air - these are easy to seal with tape.
raee_gw zone 5b-6a Ohio thanked Elmer J Fudd