Avoiding Pitfalls & Getting The Biggest Bang For Your Buck
(With Lots Of Project Photos At The End)
In this blog, we’ll look at a new window installation, emphasizing ways to sidestep common pitfalls to realize your objectives.
This past summer (August, 2014) Connolly Construction Co. was hired to remove and replace the original windows and interior/exterior casing from a four bedroom colonial in Rowayton, Connecticut.
The Historical Context And Owner Objectives
The work inquiry originated as a referral from another client who had hired Connolly Construction to replace all of their windows in 2010. Satisfied with our work, our previous client had given our contact information to their neighbor, who reached out to us in May, 2014. At the first meeting the owners told us their home, built in the late seventies, was drafty and cold in winter. ‘Could anything be done?’ they inquired. After chatting awhile, we poked around and here’s what we found.
We noticed the front door needed weather stripping and a new storm door, which we ordered and installed shortly after our first visit. This is always low hanging fruit. If deficient, you’ll get your biggest and most immediate bang for your comfort and energy saving buck by starting here.
From there, it was clear that the original single pane windows and the storm/screen window contraptions that were added later weren’t working very well. There were lots of air leaks, evident by natural light shining through wobbly portions of the aluminum storm window frames. When operated, some of the wood windows would jamb in the open or closed position. Others wouldn’t stay open, slamming shut when unattended. Given the age of the home, about 35 years, we surmised that the windows were neither insulated nor air sealed nor flashed very well around the perimeters, particularly where the window frames were fastened to the house framing. Based on our experience, water and air leaks were likely within and around the window assembly. Following the first visit, we were reasonably certain window replacement using good installation techniques would eliminate the homeowners’ headaches and discomfort.
Start With A Budget When Faced With Seemingly Endless Possibilities
With hundreds of windows and installers to choose from, where do you start? To sidestep the paralysis of analysis, start with a budget. If you do this, you’ll know in short order where to start and where to go. Your wallet will cut through the cloud of unknowing real fast. You might wonder: ‘how can I develop a budget when I have never shopped for windows before?’ Here’s how.
The Material Budget: Watch Those Options
First, determine how many windows you want to replace and about how much you want to spend on average for a window, not including installation labor. In Southwestern Connecticut, the possibilities generally converge around the following average values per window (good quality material only) on a whole house replacement job: $200, $375, $575 or $875 each. And each price point will tend to point you in three or four specific manufacturer directions. Obviously, the cost numbers will be refined as the process unfolds. But at least these figures will get you going at some realistic starting points with some realistic price ranges. (There are new windows available below the lowest price point, for $50-$150 each on average, but I generally shy away from these. Contact me if you want to know why: firstname.lastname@example.org)
On the Rowayton house, the owner wanted to replace 19 windows. After discussing the various manufacturers and features available at each price point, an initial material budget of around $375 per window or $7,000 total was identified as within the buyers’ comfort zone. At this price point, we zeroed in on the Andersen and Marvin manufacturer brands.
Buying windows is like buying a new car. There are lots of options on any given model and these influence the final cost (eg. millwork elegance and appearance, sash thickness, number of glass panes – generally 2 to 4 panes – and nature of gas/air between the panes, nature of exterior claddings/finishes and related maintenance requirements, energy performance ratings such as “u-factors” which measure resistance to heat/cooling loss, sliding mechanism in the jamb, nature of the lites/ grilles, aesthetic characteristics of the hardware, etc). After weighing the pros and cons of various alternatives, our client elected to upgrade into the $10,000 total budget range for the window material alone. They purchased highly energy efficient windows with maintenance free exteriors, upgraded interior millwork and simulated divided lites…a gorgeous package that would be a pleasure to install.
The Labor Budget: Include All Steps So You Don’t Fumble Quality Or Budget
One rule of thumb is to take 50% and 150% of the material cost to get the low to high labor cost range on a whole house installation. Then select the quality level of the installation. I’ve seen installations that range from the low end: with virtually no prep work or flashing – and units simply popped into the opening, neither leveled nor squared, and barely nailed into place…..to the high end: works of art with elaborate layers of lead coated copper flashing and expensive flashing tapes, weather resistive membranes, and complex trim assemblies. You and your installer need to discuss where in the range you’d like to be, make your selections, then put it all in writing. Getting it all down can be tricky. Here is some guidance.
There are a lot of moving parts that need to be specified. Homeowners and contractors usually miss parts, which leads to budget surprises or leaks or both later. To avoid these, try to align with a good experienced contractor . For tips on how to find a good home improvement contractor to do your window work, click on this link to Connolly Construction’s four part article entitled “Ten Steps To Choosing the Right Home Improvement Contractor”. Expect a thorough contract to be 10-20 pages long.
Here are some key installation components that will need to be on your radar when discussing the scope of service and labor quality level with your contractor prior to putting it all in writing:
- Is there a special condition: eg. waterfront, high wind, hurricane zone, etc?
- What is the nature of the new trim, both interior and exterior (eg. wood, pvc, other)? Will trim installation be part of the window installation contract?
- Is painting required on any portion of the window or trim?
- Is framing labor required to modify the rough opening dimensions?
- Is sheetrock repair and/or painting required around the windows? Is the painting a patchwork/blending or a complete repaint of the walls adjacent to the new installation, both inside and out?
- Is a sloped sill pan desired?
- What is the nature and extent of the drainage plane and flashing around the exteriors: tyvek, tar paper, flashing tapes, aluminum/copper flashing, etc.?
- If there is an existing drainage plane on the sheathing, is it in good condition? How will the windows and related house wrap and flashing, sill pans and drip caps be integrated into this drainage plane?
- Are siding repairs required? Who will paint the repairs and how extensive will it be?
- Is there a way for the old to be removed and the new to be installed while minimizing damage or eliminating the need for repairs to or painting of the existing work adjacent to the new work?
- Do the wall cavities around the windows need to be air sealed and insulated? If yes, how?
- How will damaged and /or rotted framing members be dealt with?
I’ll stop here so you are not overwhelmed. The point is there is more to consider with this type of work than meets the eye. Virtually every tool in a carpenter’s van will be used. So it’s important to align with an installer who knows what to look for and has done it all before so you don’t invite incomplete or shoddy work that gets covered up, financial trouble (cost over runs) and leaks (both air and water).
A Colossal Rip Off: Expensive Energy Efficient Windows That Waste Energy Every Time
The headline here is to make sure the installer air seals, insulates, flashes and integrates around new windows well. If you don’t pay for this to be done well, you’re wasting money when you buy so-called ‘energy efficient’ windows. If installed poorly, which means failing to prevent leaks and drafts, expensive double or triple pane windows waste almost as much energy as forty year old single pane windows because the r values on new windows aren’t all that much better than old windows. It’s all for nothing if the new window installation is not done well. More on this later.
Good Performance Metrics Need To Be Combined With Good Installation Techniques
Before we elaborate on the need for good installation techniques to realize energy savings and comfort, let’s take a slight but important detour to examine the metrics you’ll find on window stickers placed on every window and that are directly related to the cost of a window. The tricky part: which of the bells and whistles are worth the extra money ?
The stickers represent a standardized way for you to compare the energy and other performance measures of any new window. The NFRC (National Fenestration Rating Council) label on every new window certifies that it has been independently rated and usually displays the following information:
By my lights, this is the most important metric. It is a measure of heat flow due to temperature differences through windows and skylights and is measured on a scale of 0 to 1. The lower the U-factor, the lower the heat flow for a given temperature difference. Since you don’t want heated or cooled air to “flow” through or vanish through your windows, a low U-factor is good. A high U factor is bad.
Complications in heat flow ratings arise due to significant differences in heat flow rates between the center of glass, edge of glass and frame portions of a window. Heat flow ratings are further complicated by the size of the air gap between panes of glass, the coatings on the glass, the gas fill between glazings, and the frame construction. The U factor incorporates all these differences into a tidy statistic that can be used to compare one aspect of the overall energy performance of every new window.
To simplify, another way I look at the U-factor is to recall that it is simply the inverse of the “R-Value”, a more familiar rating you may have already seen on insulation and other building materials. For example, some fiberglass BATT insulation has an R value of 12, which is not all that great of an R-value. On the other hand, an R-value of 12 implies a U-factor of the inverse of 12, which is 0.083. This is a really fantastic U-factor for a window. However, no window comes close to this u factor. (Later, we’ll address ways of looking at this seeming contradiction – great window U factor relative to other windows, not so great R value when compared to walls.)
Always bear in mind that the higher the R-Value, the higher the resistance to energy loss. High R values are good. They save you money and may make you more comfortable if combined with good air sealing. Low R values are bad.
- Solar Heat Gain Coefficient.
This represents the percentage of solar radiation incident upon a window or skylight that ends up in a building as heat. It is a measure of the ability of a window to resist heat gain from solar radiation. It ranges from 0 to 1, with 1 representing no resistance and 0 representing total resistance. Typically, residential windows range from 0.2 to 0.9. What’s a good Solar Heat Gain Coefficient rating and a bad rating? The answer varies depending on your circumstances and objectives. For example, if you want solar radiation to heat your home, a high rating (ie no resistance to solar heat gain) is good and a low rating is bad. On the other hand, if you live in a climate where the air conditioner is on for most of the year, a low rating (ie. high resistance to solar heat gain) is desirable and a high rating is bad.
- Visible Transmittance.
This represents the percentage of incident light (and only the spectrum of light that is visible to the human eye) at a normal angle of incidence that passes through a particular glazing. The higher the visible transmittance, the greater the daylight transmission. The transmittance is influenced by the color of the glass, the coatings, and the number of glazings. The ratings range from 0 to 1, with higher numbers meaning that more light is transmitted. Which end of the scale is better? Again it all depends on your objectives. How much light do you want to make its way through your windows and into your home? For example, as you add additional panes of glass to the window, increasing energy performance, the visible tranmittance declines. Triple pane windows, for example, let in less light than double pane glazing.
- Air Leakage
This is the rate of outdoor air infiltration between various components of a new window and its frame measured under constant conditions-usually under pressure of a 25 mph wind with the windows locked. High performance windows, such as those used in coastal zones, tornado alleys or hurricane zones, may be tested at higher pressures. Note that this rating, which ranges from 0 to 1 with 1 being maximum leakage, does not measure air leakage between a window frame and the structural framing to which the window is attached. This latter gap will be addressed later in this blog. Also note, as windows age, weather stripping deteriorates. Thus higher rates of infiltration may be expected with older windows that have been operated often even if they had a low air leakage rating when new.
- Other: To cut this short, we won’t elaborate on the other metrics or descriptive information that you’ll find on the sticker, which are: Low emittance (low-e) Coatings, Selective Transmission Films, Inert Gas in the Air Gap, Superwindows, and Shading. For more information on these topics, contact Connolly Construction Co.
“Better” performance ratings usually mean higher window costs. But caution is advised when weighing these ratings. Sometimes you can pay a lot incrementally (at the margin) to improve the energy performance ratings of your windows and yet have very little incremental improvement in the overall R value of the wall assembly or your comfort, particularly if the installation is “lousy”. In other words you should try to avoid paying a lot for energy efficient window features and get little or nothing in return. Examples of this and other potential traps follow below.
To understand the traps better, let’s first look only at the estimated R-value, or resistance to energy loss, of the Rowayton home’s wall assembly and windows. (Don’t forget a simplified rule of thumb: the higher the R value, the more energy efficient the material/wall assembly.)
The Wall Assembly Components and R-value:
Approx. R Value
- Cedar shingles: ½” thick at base x 14” high, random widths………………0.87
- 5/8” particle fibre underlayment…………………………………………..0.82
- 30 pound felt paper to exterior side of sheathing……………………………0.06
- ½” cdx plywood sheathing………………………………………………..0.62
- 5 inch thick fiberglass Batt insulation with paper facing………………11.0
- ½” gypsum board attached to 2 x 4 douglas fir stud framing……………..0.45
Estimated Total R-value of Rowayton solid wall…………13.82 (See note 1 below)
Note 1: The actual r value of the wall was probably much lower than 13.82 because the installation of some, not all, wall components was not good. Insulation was packed tightly in spots, absent, or not spliced correctly around pipes and wires in the wall cavity. Also, there was no air sealing of any gaps and crevices within the wall cavity or around electrical switches, outlets and light boxes. This is not intended to be a criticism of the home’s quality or its builder. “Not good” in the categories examined here is the norm throughout all domestic housing markets.
Comparison of Window U-factors (and related R-values):
Window Description U-factor R-value
- Old Rowayton Windows
(single pane, wood, clear glass) ………. 0.89 1.12
- New Rowayton Windows-Marvin,
Energy Star Rated
(double pane, wood/clad, low e glass,
Argon gas)………………………………. 0.30 3.33
- Hypothetical Conventional Wood Window
(triple pane, clear glass, no gas)………… 0.34 2.94
- Hypothetical Wood Superwindow
(triple pane, low e glass, krypton gas)…… 0.15 6.67
The window performance statistics above reveal the following:
- A solid wall, with an R value of around 14, is about 12 times more energy efficient than those portions of the wall that have only single pane windows (calculated by dividing the wall r value of 13.82 by the r value of the single pane window of 1.12 = 12.3). In other words there is colossal heating/cooling loss through a single pane window. From a heating or cooling loss perspective, single pane glass is almost like having an open window year round.
- Caution must be exercised when comparing the options and related costs of windows. Some conclusions may be contradictory or counter intuitive. In the examples above, we see that some triple pane windows without low e coatings and no gas between the panes (r value = 2.94) perform worse than double pane windows with low e coatings and argon gas (r value= 3.33). Typically, triple panes cost more than double pane windows. Why buy triples if they perform worse than their double pane and less expensive cousins?
If we look at the triple pane superwindow (r value = 6.67), we see that it leads the pack with respect to energy performance, about twice the performance of the double pane windows with low e glass and filled with gas (r value =3.33). And yet the price for the superwindow is more than twice that of the double pane window. Is it worth it? Perhaps. Although an r value of 6.6 on the superwindow isn’t all that great. There’s still a lot of energy loss associated with it. And the superwindow is only half as energy efficient as a wood framed wall with fiberglass batt insulation.
Weighing the costs and benefits of the various options in order to narrow the field to an optimal choice can be a relatively straightforward process. And it can be an inconclusive process. The important take away is that by undertaking the analysis you will make decisions with your eyes wide open rather than half or completely shut.
- The new Rowayton windows almost tripled the resistance to heating/cooling loss when compared to the single panes they replaced (calculated by dividing the r value of the new @ 3.3 by the r value of the old @ 1.12 = 2.94). While this is good increased energy performance in percentage terms (300% increase), in absolute terms when compared to a solid wall the new windows are only about one fourth as energy efficient as a solid wall (which is derived by dividing the new window r value of 3 by the wall r value of 13.82 = 0.24). There is still a colossal amount of heating or cooling loss through the new R-3.3 windows, depending on the season. Double pane windows with low e coatings and argon gas are 3 times better than single pane windows. Yet the double panes still aren’t much better than if you were to keep the window open slightly all year.
- So why buy new windows (which may increase the r values from a”1” to a “3”, as illustrated in point #3 above) when the energy performance results are not all that spectacular? Why bother to go through the expense and hassle of buying more or better energy performance if there is still a colossal waste of heated or cooled air through the new windows?
Here are some reasons to replace the old windows even if the r values on the new windows aren’t impressive.
- A small r value improvement over what’s there is often better than no improvement at all, particularly since solid exterior walls everywhere is not an option. No one wants to eliminate natural lighting from a home. Since using windows to illuminate is a given, accepting that most new window r values are relatively lousy is a given too. The “lousy-ness” is relative and a matter of degree.
- Air leaks through cracks between the window sashes and abutting window frames will be mostly eliminated on new windows. We like this one. On new windows the individual components are “tightened up”. Thus, one of the two main sources of drafts will be eliminated.
- New windows will improve the aesthetics and operations.
- New windows usually experience decreased condensation on the inside surfaces.
- Most important of all, you’ll have an opportunity to open up the wall around the old window to properly air seal and insulate it thereby stopping drafts and improving comfort. This leads us to the final topic of this blog: the importance of opening up, examining and remediating wall conditions when necessary.
Similar To Furnaces, Windows Must Be Installed Well To Be Energy Efficient
The stickers on a window in the showroom never remind consumers that the window never sits in isolation. It always and only performs in context. It must be integrated well and in an energy efficient manner with all of the planes that intersect with it: solid, liquid and gaseous. And only a good installer who is paid to so integrate can ensure the overall energy efficiency of the window unit . If it isn’t well integrated, the performance ratings on the stickers do not provide an accurate reading on the overall energy performance of the window area. Installed improperly, you may still have drafts, leaks and discomfort after new windows are installed. New windows are no guarantee of more comfort or lower energy bills because the areas of the wall surrounding the windows are usually problematic. To understand more on this, let’s look at furnaces.
Energy efficient windows are a lot like expensive energy efficient oil or gas fired furnaces. A new “green” furnace with a 95% efficiency rating (also known as an AFUE rating) installed unprofessionally can easily result in a reduction in the AFUE rating to around 65% , an efficiency range typical for furnaces in the 1960’s. A sub par installation, poorly tuned with leaky/poorly insulated ductwork and partially commissioned, can easily eliminate any operational savings projected prior to purchase. The well intentioned consumer who wants to reduce consumption of fossil fuels and who therefore spends 20%-40% more to get the 95% efficient furnace may only realize 65% efficiency following installation because they skimped on the installer. The question then arises: if you’re going to skimp on the installation, why pay more for the more efficient furnace? By skimping on installation labor, there may be neither a reduction in the consumption of fossil fuels nor an increase in the related financial, environmental, and comfort benefits with the newer more expensive furnace.
The same principles illustrated above for a new furnace also apply to new windows.
How Does An Installer Ensure That Energy Efficient Windows End Up Energy Efficient?
Typically, a window sits in a square, rectangular, or round space known as a rough opening that is framed out of wood, steel or masonry. The space, or gap, between the window frame and the surrounding wood, steel or masonry substructure to which it is fastened needs to be plugged up in the right way using the right materials so air, water, or water vapor will not pass through the gap from the inside to the outside or vice versa in unwelcome ways that compromise the overall energy efficiency of the installation in all seasons. By preventing warm air, for example, from moving through the gap in the wrong way at the wrong time of year, you can reduce your heating or cooling bills. Not dealing with the gap correctly, or at all, is the leading cause of uncomfortable drafts and higher energy bills in most houses. Now for an example to illustrate the principles of this paragraph.
On the Rowayton job, which was similar to almost every house we’ve observed , the gap between the window frame and the abutting structural framing was stuffed intermittently with fiberglass batt insulation. I say intermittently because in about half of the windows, there was no insulation or anything else in this gap. Air could flow through the gap unobstructed. This condition is analogous to leaving your front door slightly ajar all year long. Would you ever want to do that? Of course not. Yet this condition obtains in just about all wall cavities that we examine.
The word stuffed is used in the previous paragraph to indicate that the batt was tightly packed in the gap, thereby reducing or nullifying any insulating properties. For Batt insulation to work, it cannot be compressed. It must be relatively fluffy so that interstitial air pockets within the material itself will be present in the final resting place of the batt. Air pockets in the batt are what make it work . Get rid of the air pockets, with water or compression, and the insulation will not perform to the level of the “r” value typically stamped on the batt.
Even if the batt insulation in the foregoing example had been installed properly, in a fluffed up manner, there would still be a problem. Batt does not prevent air or water in liquid or vapor form from whisking through it.
Packing batt tightly into the gaps doesn’t stop air flow exchanges between the inside and the outside. It neither air seals (ie. it doesn’t stop air from whisking through it) nor insulates properly when compressed. Yet most installers continue to pack batt into the gap. Don’t let them. Tight packing techniques do not stop drafts. Tight packing wastes energy. In your contract, specify better ways to plug the gaps.
To prevent air, water and water vapor from passing through the wall cavity in the vicinity of the window frame, the space must be air sealed prior to being insulated. The sealing part can be done by applying spray foam to all cracks and crevices, particularly at intersecting vertical and horizontal planes within the wall cavity. Spray foam can also be used to fill all or part of the wall cavity around the window to insulate it, though I do not advocate foam insulation for the entire wall assembly. Fiberglass batt, cellulose, or any of a number of other insulating alternatives can be used to insulate the wall cavity space. With the proper air sealing and insulation of the gap, the likelihood of an energy efficient window ending up being energy efficient overall in the field will be increased. And air drafts and water related leaks will be eliminated at the points so treated.
There’s more to consider on the topic of energy efficient window installation, such as proper flashing, shimming and fastening techniques and the integration of these techniques with existing drainage planes and weather resistive barriers, vapor barriers and other membranes and retarders that may pre-exist or be specified on the new installation. To cut this blog short, we won’t address these and other topics, such as interior and exterior trim selection, installation, and painting.
The main point of this lengthy blog is there are a variety of moving parts that need to be considered when buying and installing energy efficient windows. Hopefully, there are enough tips here to help you get started and ultimately realize the biggest bang from your new window buck.
New Window Installation Photos In Rowayton, Connecticut
- Front Of The Home
- Back Of The Home
- Side Of The Home