Posts Tagged ‘window’

Window sill replacement

Friday, August 27th, 2010
Written by Marcus de la fleur

The beauty of remodeling is that you think you are done with one job, only to find out that you are not.

I proclaimed that we had taken care of the basic masonry repair in the basement and around the windows. That was before I took a close look at the window sills of the two basement bathroom windows.

The sills, once one nice piece of carved limestone, were pointing and sloping in all sorts of directions, and were a lit wobbly and cracked into three pieces. A situation that was incompatible with the installation of new windows.

I still had salvaged limestone sills in the yard from a nearby tear-down that I could use for the replacement. First, though, I had to remove a lot of concrete that was poured all along the western edge of the house, presumably to keep water away from the foundation wall.


Removing the old sill pieces was comparatively easy. I also removed some of the loose limestone from the foundation wall under the sills and mortared them back into place. This should provide the sills with a firm footing. Last but not least, I fitted and placed the new sills, making sure that they were level across the window, but had a slight slope outward into the yard.

Does that conclude the masonry repairs? I am afraid not. The list of minor and major masonry repair works is still growing.

The old window bars, which are let into the masonry wall, have rusted so much that they have begun to push the brick work out. We would like to install new bars and at that time repair the brick around the outside window opening.

We also have the issue with the cement parging around the bottom of the house. The parging covered up water-damaged brick, which actually made the problem even worse because it prevents the masonry from drying out. We would like to remove the parging  and replace all the water-damaged brick.

Then there is the foundation wall that we will need to re-point once we start excavating for the footing drain and insulation. Cathy and I know that we will not shoulder that task again but will have a pro on the job.

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Bucking, sort of…

Monday, August 16th, 2010
Written by Marcus de la fleur

Back to the basement windows! The basic masonry repairs are taken care of and I would like to get the final measurements, which allows me to get a final bid on the windows.

First, though, I have to frame out the masonry opening with what is called a buck. The buck is the wooden frame that sits inside the opening of the brick and holds the window in place.  I will get the final measurements for the window from measuring the interior of the buck.

buck-01

My friend Ben from the 168 Elm Ave. project was kind enough to stop by and offer his advice on the buck installation. He pointed out that nine out of the 16 window openings were almost the same size. Rather than tailoring each individual buck, he recommended that I pre-assemble nine of the same size for those openings.

I have a bunch of lumber to cut, although ending up with a number of same sized window bucks expedites the process.


The basement windows are rather close to the ground, therefore close to moisture sources such as splashing rain water. To add to the longevity of the window buck, we purchased 2 by 6 treated lumber for the sides and top, and 1 by 6 composite lumber for the sill plate.

buck-02

The sill plate will have the most severe exposure to moisture, thus our decision to use the composite lumber, which provides an excellent rot resistant material.

The hardware also influences the longevity of the assembly. I have to use coated screws to put the buck together. Uncoated screws would corrode in the treated lumber.

The lumber is cut and I’ve got the hardware; time to put the bucks together.


It is important to assemble the buck as square as possible. To add rigidity and keep it square while I am moving it around, I stiffened the top corners with triangular plywood pieces and added another plywood piece along the bottom.

Here is another subtle detail that helps with moisture management and should increase the longevity of the buck assembly.

I cut the bottom of the two sides at a two degree angle, which gives the sill plate (the composite lumber piece) a slight slope outwards. This, so I hope, prevents any water from sitting on the sill plate or at the bottom of the window.

buck-03

It’s time to install the buck.  I set it into the masonry opening and shim on all four sides. While doing that, I check several times that the assembly is level, plumb and square. The easiest way to check for square is to measure diagonally across the buck from corner to corner. Both diagonals must measure the same distance.


This is somewhat important as the window units will come perfectly square, and we want them to fit into the buck opening.

The last step requires attaching the buck with ¼ inch masonry screws into the brick opening.

Once that is done we can take a closer look at how it all fits.

buck-04

Yes – what you see there is a gap between the brick opening and the buck – and it is intentional.

The triple-glazed windows we are about to install will have a U-value of 0.20, which is about R-5. The assembly surrounding the window should meet, or preferably exceed R-5. If not, we will have paid good money on high efficiency windows but lose energy through the sides, defeating the whole point of the investment.

The pressure treated lumber (pine) has about an R-value of 1 per inch. The gap gives me a thermal break between the masonry and the buck, which I can spray out with foam to increase the thermal resistance to an R-5 or greater. This is a subtle detail that will have a significant impact on the thermal comfort.

All right, now I am ready to take the final measurements and get the bids for the windows. I hope we won’t end up cost-shocked again!

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L’arc de triumph

Saturday, July 31st, 2010
Written by Marcus de la fleur

Repairing the masonry work on the inside around the hole in the wall – namely the one added basement window – is less than half the story. Dealing with the exterior repairs is much more interesting.

All original windows have proper stone window sills. This one had not. It was half-heartedly set on the limestone foundation wall with plenty of nooks and crevices for critters, water and air to get in and out.

I fixed that by removing some of the limestone to make room for a salvaged cut stone sill.

Then, as with the inside, I deconstructed the edges around the window back to the original brick work and rebuilt it from there with salvaged brick and the right type of mortar.


The work around this added window was bad, but at least it was consistently bad.

The window had no header on the inside, nor on the outside. Adding the outside header was a little involved.

We took our cues from the architecture around the original windows, which all have a two layered segmental brick arc. This construction is structurally super sound, and something that has been used for centuries. Just think of arched cathedral ceilings.

To install my modest arc header, I build a template that I fitted into the window opening. It allowed me to mortar in place the two segmental brick arches. Once the mortar was cured – a couple of days later – the template could go.

From the removal of the original windows to the small masonry repairs at every window, this was a bigger task and accomplishment, which we began to refer to as our little l’arc de triumph.

I like to think that its sustainable impact could also be somewhat triumphant. So many thinks that are done or that we do around our buildings are often executed with so little thought, which can lead to long term damage rather than adding to the longevity of a structure. It is about the other side of green.

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Fixing a hole in the wall

Monday, July 26th, 2010
Written by Marcus de la fleur

I removed the old basement windows and now have repair work in the masonry opening ahead of me. There is some moisture damage to take care of as well as filling the recesses of the old wooden window sill and head in the top and bottom corners.

One of the windows is an unusual case and requires a little more tender-loving care.

We discovered during our basement deconstruction that it is not an original window, but had been added sometime later.

bsmt-win-04

This is a curse as well as a blessing as with most other things that had been added later in this building. We don’t mind having the extra window in the basement, but we now have to deal with shoddy masonry work around the edges, which was done with the wrong mortar. But worst of all, this window had no header and thus no support for the two floor joists. Instead, they were just resting on the window jambs – not something you can call a structurally sound solution.

That said, this setup obviously has worked for a number of years. Nevertheless, I got increasingly nervous each time I looked at the window and decided quickly to shore up the non-supported floor joists.
I now could safely remove the shoddy masonry work around the window edge, deconstructing everything back to the original brick work.


After everything was cleaned out, I began to rebuild the masonry opening with salvaged common brick and the right mortar (type O). I finished the job by crowning the window with a 4 by 6 old growth header, the same kind of header we have over all other basement windows. This set-up has a 100+ year successful track record … enough to convince us that this is the way to put it back together.

This takes care of the inside work. Next step is to get the outside part of the window fixed.

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Basement windows

Friday, July 23rd, 2010
Written by Marcus de la fleur

I got on a roll—the window roll, that is. And I’d better be, because there is still a lot to take care of regarding the windows…specifically the basement windows.

bsmt-win-01 bsmt-win-02

Some of them are the original 100-plus-year-old windows, which are falling apart. Some have been replaced once with single pane double hung windows, but the jambs are still original, and show a lot of rot. There is nothing to salvage here. I have the privilege to rip out the entire window assembly down to the brick opening. The job involves a sawzall to cut the jambs, and a hammer, pry bar and a lot of dust.


What are we putting back into the opening? High efficiency double hung replacement windows.

I would have preferred casement or awning windows, because they usually have a lower air leakage rate and better energy performance. The problem is that both those styles open outwards, which would interfere with the exterior security guards.

bsmt-win-03

Hopper or tilt-and-turn windows would have been another option, but I couldn’t find these styles as high performance windows or at the right price point. So we are settling on the double hung which do not interfere with the guards.

Our research led us to Uniframe and Serious products, which fall within our energy performance parameters.

Once I have framed the brick opening with a new buck and once I can take the final measurements for the replacement windows, I will request pricing for both and take it from there.

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Highly-Insulating (R-5) Windows and Low-e Storm Windows Volume Purchase Program

Tuesday, July 20th, 2010
Written by Marcus de la fleur

Here is another incentive that may help us with the replacement window decision. This time it’s not a tax credit but a program by the Department of Energy (DOE) called the “Highly-Insulating (R-5) Windows and Low-e Storm Windows Volume Purchase Program”. I stumbled across it in a GreenBuildingAdvisor blog post.

“The aim of this volume purchase initiative is to work with industry and potential buyers to make highly insulated windows more affordable.”

… states the DOE web site. Hey, great! This is right up my alley. Anything that could make this big investment less hurtful on our pocketbook is welcome!

So, how does this program work? There are 30-plus vendors that qualified for the DOE volume purchasing program – vendors that sell “high performance windows” with U-value of 0.22 or less.

The windows volume purchase web page allows the user to browse through different window types for new construction, retrofit windows, patio doors and low-E storm windows. I can select my window size range (listed in unit inches [UI]) and get access to a list of participating vendors.

This program can be a real big time saver. Rather than going from vendor to vendor to find out if they have high performance windows, I have a preselected list right at my fingertips. The program is also an excellent resource to quickly find local vendors of high performance windows.

I began to call around to see how much savings I could expect from the program. This is where it got interesting. It was officially launched on May 27, 2010 and some participants are organized, others are not.

With some vendors, I communicated with a sales person who was designated to just deal with the DOE program sales, while others had no clue what I was talking about. I literally had to point them to the web site so they could see their name in the participating vendor list. Some had to get in touch with their corporate headquarters to investigate what this was all about.

This made it rather difficult to get my hands on the pricing information. I had to be very explicit and persistent that I was only interested in the DOE volume purchase initiative pricing structure, the same structure that had been submitted to and approved by the DOE.

Despite all the confusion I caused with my inquiries, I eventually got some pricing that appeared to be in line with the DOE program.

Because we are about to replace the basement windows, I used their size range (up to 70 UI) for my inquiry and got a price spread of $138.00 to $328.00.

window-matrix-01

I am not sure, but my gut tells me that some of the prices are not that different from the regular sales prices, which puts into question the objective of “making highly insulated windows more affordable”.

But so what? I still can get a 70 UI high performance window for under $200, right?

Well – you have to look out for the air leakage (AL) rate. Like I contemplated earlier, the insulation value of a window can be negated by a high AL rate. If we would like to keep the AL below 0.05 cfm/sf, we are looking at more than $200.00 per window.

As helpful as the DOE program is, it is important to remember that there are windows that are even more efficient than those included in the program. That is why I kept the Uniframe double hung by Great Lakes Windows in my list.

The question now is if the price delta to the next runner up (the Serious Windows product) can be justified by additional energy savings.

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Tax credit folly?

Sunday, July 18th, 2010
Written by Marcus de la fleur

We stepped deep into window research, but we still have to make a decision on what windows to use. Because they will be a very big investment, any type of rebates, financial incentives or tax credits will influence this decision.

Federal Tax Credits for Consumer Energy Efficiency

… or, more commonly known as the $1,500 tax credit that expires on December 31, 2010.

The total of $1,500 can be applied across a range of energy efficient upgrades, such as furnaces, water heaters, insulation, doors and – yes – windows. This made us very happy as we were convinced that we could claim the $1,500 in a heartbeat on our new windows … until I looked at the fine print.

Qualifying windows must have a U-value of 0.30 [LINK] and Solar Heat Gain Coefficient (SHGC) of 0.30 (see also ‘The world of windows’ post).

This is a federal tax credit, available nationwide, from Alaska to Florida and Southern California to Maine, intended to stimulate the economy and improve the energy efficiency of existing homes.

Now, wait a minute, how can that energy efficiency thing work with this one requirement (U-value of 0.30 and SHGC of 0.30) across a number of different climate zones? Down south, a very low SHGC is probably of interest while the U-value would not matter that greatly. It would be the reverse up north, where the insulation value (U-value) counts and passive solar heat gain (high SHGC) may actually be desirable.

Take our house in Chicago. I ran a quick window analysis for the 1st and 2nd floor with the RESFEN model. The only variable in the analysis was the SHGC.

  • Scenario 1: SHGC north 0.25, east 0.25, south 0.25, west 0.25
  • Scenario 2: SHGC north 0.51, east 0.51, south 0.51, west 0.25

Allowing for passive solar heat gain (high SHGC) through the windows on the east and south side could bring the annual heating load down as much as 10%, even though our building has a north-south orientation. The more a building has access to passive solar, i.e. lots of windows in the south elevation, the greater the potential to lower the annual heating load.

That said, any window slated for passive solar heat gain (high SHGC) would need proper summer shading or otherwise the winter heating savings may be lost in summer cooling needs.

Even the Energy Star program recognized the importance of the different climate zones and has structured the qualifying criteria for windows, doors and skylights accordingly.

Why the federal tax credit for consumer energy efficiency did not take the same approach is a mystery to me. I guess the intent is good but the execution is poor.

As for the $1,500 – we may not claim it on the windows alone, because we would like to benefit from passive solar heat gain. But we have the boiler, insulation and doors that will help us to claim the full amount.

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The world of windows

Thursday, July 8th, 2010
Written by Marcus de la fleur

Out of all items I have researched, looking into windows has taken by far the most time. And I am not talking about hours. I have spent days on figuring out what to do.

Why? Windows are a critical component in the energy efficient building envelope we would like to create. The objective is to have the window efficiency somewhat correspond to the R-value of the walls, which would make each investment worthwhile. To get there, we have to look at triple pane windows.

But they are a very big, if not the biggest, investment component in the building shell. Initial prices ranged from $400 to $1,300 for a 100 UI window. I suspected that the $450 must be a “too good to be true” case, while a commitment to the $1,300 window requires a level of obsession that I am lacking.

UI = unit inches (window width + window height = unit inches)

Looking at the energy performance helped me to narrow the field and get products organized. Four performance metrics of the NFRC ratings (National Fenestration Rating Council) help in that process.

U-value

The U-value is an expression of the heat transfer coefficient (or insulation value) and is determined according to the NFRC 100 test.

I initially used a U-value of 0.25 for the energy model, but hope to get it below 0.20, which would correspond to an R-value of 5 or greater. A window with a U-value of 0.20 or less would feel comfortable even during a cold winter day, as long as it is air tight (see also below).

Solar heat gain coefficient (SHGC)

SHGC reflects the heat gain in a space through a window and is determined according to the NFRC 200 test.

Solar gain can be a double sided sword. It could be desired in the wintertime for passive solar heat gain, but not so during summer. We would prefer passive solar heat gain through the east and south windows (SHGC of around 0.5), which we can shade during the summer months to prevent overheating. All westward facing windows should have a low SHGC, such as 0.25 or less.

Visible transmittance (VT)

VT is the amount of visible light that passes through the window and is determined according to the NFRC 200 test.

Some light will be blocked by the window frame and by various glass coatings. We would like to keep the VT at or above 0.4 to allow enough daylight into the building.

Air leakage (AL)

AL is a measure of air infiltration through and around a window (in cubic feet per minute per square foot [cfm/sf]) and is determined according to the AAMA/WDMA/CSA test.

Air infiltration is often overlooked but is rather critical to the window performance. What is the point of having a window with good U-value (say 0.20) if plenty of cold (or hot) air constantly leaks through the window.

The Efficient Window Collaborative recommends windows with an AL of 0.3 cfm/sf or less. That said, I have heard a number of times that 0.3 cfm/sf can feel uncomfortably drafty on a cold winter day. We would prefer an AL less than 0.05 cfm/sf.

See also:

Existing Homes: Selecting Energy Efficient Windows in Illinois

Questions About Replacement Windows & Energy?

Styles and materials

I learned that different styles of windows have different energy performance characteristics, although it really comes down to air leakage.

Double hung windows, the most common style, and sliders typically have a greater air leakage when compared to single hung, casement, awning and picture windows.

Because double hung and slider windows have two operable sections, outside wind pressure may push air in between the two sashes. Casement and awning windows are pressed into the jamb gasket when subjected to outside wind pressure, resulting in an even tighter seal.

Picture windows are non-operable and as such should not have an air leakage issue, unless they have a shoddy frame.

An item that influences the pricing of windows is the frame material. Vinyl is the most common and least expensive, but has an unfavorable environmental footprint and suffers from expansion and contraction with temperature change.

Aluminum frames need a really good thermal break to prevent heat loss or gain. Another option is a wood frame with aluminum cladding on the outside. These are very nice looking windows in my humble opinion.

Composite material frames (mixture of wood and plastics) are another higher end option and are sold as being virtually maintenance free. So are fiberglass frames, which have the reputation to last a long time.

Who sells high efficiency windows?

Good question. There are European models and a number of Canadian manufactures. I searched a lot for more local manufactures, with limited success. I did build a small product list, bit by bit, through recommendations, web searches and the reading of other green blogs.

Triple pane windows with a U-value of 0.20 or less seem a rarity in the U.S. market. The ones I found (U.S and Canada) were available with vinyl or fiberglass frames.

Return on investment (ROI)

I needed help to put the price of a window into the context of its energy efficiency and probable energy savings. The Efficient Window Collaborative has a very helpful web site that explains the basics and provides a window selection tool.

http://www.efficientwindows.org/selection.cfm

I found additional help in a simple to use energy model called RESFEN. It allowed me to input the performance metrics of the windows around the building and calculated the estimated energy costs or savings.

I now have accumulated a pretty good knowledge base, have a number of products, have an idea about the potential ROI, but still have to make a decision.

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