03 Nov 2010

greenHILLhome: Winterize

The wrong way to insulate a window.

Colder temperatures are upon us, and it will just get colder (well, until sometime in 2011).  Many of us spend time turning off exterior water supplies and covering patio furniture, but how many people take a few hours to winterize their homes each fall?  Spending some time sealing cracks and topping off (or replacing) insulation can make your home much more comfortable in the winter and may save you some money on your utility bills too.

This past weekend I spent a morning putting new insulation into the addition to our house.  The previous owners had installed some paper-faced batt insulation (you know, the pink squishy stuff) between the floor joists, but over the years the insulation had fallen out or sagged and last winter we definitely felt the lack of insulation in our toes when the temperature dropped.  The insulation was also installed upside-down, with the paper on the exterior.  The paper facing had all but disintegrated in most locations.  So before Jack Frost arrived again I purchased some insulation and installed it properly against the underside of the exposed floor.  The EPA provides some guidance on selecting the proper thickness and R-value for insulation.  DC falls in climate zone 4, with a recommended R value of between 25 and 30 for floors exposed to outside air.  A building wrap product (such as Tyvek) will complete the installation.  You don’t want to cover the insulated area completely as that may trap moisture in the space—a breathable material is recommended, or at least exterior sheathing with a vent at the perimeter.

Most local home improvement stores don’t carry a slew of options for batt insulation, but you can find insulation made of recycled denim fiber (it’s blue as opposed to the normal pink) and there are also soy-based products as well.  Even if you go with the fiberglass pink stuff, look for products that carry the Energy Star logo.  Materials such as batt insulation, weather stripping, and caulk are eligible for the Energy Star federal tax credit, which allows you to claim 30% of the purchase price up to $1,500.

Ripping down walls to re-insulate may not be cost effective or convenient, and original exterior walls on Hill rowhouses aren’t thick enough to install batt insulation.  If there is a wall cavity at all, blow-in insulation may be an option for you.  Installation usually requires cutting small holes at the top of each wall (below the floor or roof decking) and using a commercial blower to push insulative material (fluffy stuff) into the wall cavity.  Green options for insulative material are available at many home improvement stores, including product made of recycled fibers.

A tube of sealant (caulk) and a candle will cost you about $5 but can save you a lot of lost heated air over the course of a winter.  Use the candle to check for air infiltration around windows and doors.  Make sure to move curtains and shades out of the way first.  Move the candle slowly around the joint between the window and the wall; if the flame moves as if being blown, you have an air leak.  There’s an old builder’s tool called a smoke pencil that does the same thing but without an exposed flame; surprisingly no one at Frager’s had heard of it and I was asked repeatedly why I wanted to smoke a pencil.  Frager’s does have a good selection of sealants in the paint shop, however, in a wide range of applications and colors.

Most sealants can handle cracks and gaps up to about 3/8” without looking too messy.  For larger cracks and gaps in walls you can purchase an expanding filler material that conforms to the space you spray it in.  These products are also fairly inexpensive (about $4 a can at Home Depot) and some can be sanded down to a smooth finish.  Expandable fillers are ideal for basement walls or gaps in brick walls that are too small to patch with a brick unit.

Finally, you may want to consider installing weather stripping around doors or windows where drafts occur.  If you can feel cold air coming in around a door or worse can see daylight between a door and its frame, installing a continuous line of weather stripping can mitigate the loss of heat.  There are a number of types of weather stripping, with self-adhering foam being the easiest and least expensive to install.  The foam tape comes in a roll and can be cut to the size needed.  Many newer doors and windows may have a sort of integral weather stripping installed so evaluate each opening in your wall individually.

Many of these home improvement projects are small and may not seem overly noticeable but can have an actual impact on heat loss and thus how much money you spend on replacing the lost heat in your home.

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  • jmt321


    I was wondering if anyone did a write up on the DC rebate listed below? I have talked with so many neighbors that never heard of this credit, and at 50% up to $1000 for weatherization, it can make a huge difference…and that is on top of the Federal credit.

    I had a new front door and transom window that qualified and my total cost came to $2143, but after the $1000 rebate only cost me $1143.

    There is still a few hundred thousand left in the program and it closes once the funding dries up, or DC Council re-appropriates the money.


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