Chapter 7:                      Windows and Doors

This chapter presents specifications and procedures for improv­ing the airtightness and thermal resistance of windows and doors.

Use lead-safe weatherization methods for all tasks relating to window and door weatherization, repair, and replacement. See EPA RRP Requirements

7.1   Storm Windows

A storm window is an additional window installed outside or inside the primary window.

7.1.1   Exterior Aluminum Storm Windows

Exterior storm windows can save energy and preserve old worn primary windows from destructive weathering. You can attach exterior operable storm windows to the blind stop or exterior window casing of a double-hung window. Or, attach a fixed storm to any flat surface of a window frame or sash if the win­dow is fixed or if a movable sash can support the extra weight.

Metal exterior storm windows are the best choice if they are well designed and installed properly.

•       Choose operable storm windows to install on operable windows. Choose fixed storm windows to install on fixed windows or on sashes that open along with the movable primary window.

•       If operable, make sure that the storm window opens and closes to allow the maximum amount of ventilation and egress area.

•       Measure the storm-window dimensions according to where you’ll attach the storm: blind stop, window casing, or sash.

•       Storm-window frames should have sturdy corners so they don’t rack out-of-square during transport and installation.

•       Sashes must fit tightly in their frames.

•       The gasket sealing the glass should surround the glass’s edge.

•       Consider selecting a hard-coat low-e glass for the storm window, which should face the primary window to protect the low-e coating.

•       The storm window should be sized accurately and should fit tightly in the opening.

•       The storm window’s sashes should be removable from indoors for cleaning.

Installation of Exterior Storm Windows

Follow these guidelines when installing storm windows.

✓     Seal storm windows around the frame at time of installa­tion with sealant tape or caulk.

✓     Don’t allow the tape or caulk to interfere with the weep holes at the bottom of the frame. If weep holes aren’t man­ufactured into new storm window, drill weep holes or leave at least 2 two-inch spaces in sealant to allow water on the sill to escape.

✓     Don’t allow storm windows to restrict emergency egress or ventilation through movable windows.

See also "Mobile home double window" on page 483.

7.1.2   Interior Storm Windows

Interior storm windows are usually more airtight than exterior storm windows because they must be airtight to avoid conden­sation and icing on the primary window during winter. Interior storm windows are usually a metal or plastic frame enclosing some type of plastic glazing.

Consider these specifications when selecting interior storm windows.

•       Don’t install fixed interior storm windows on egress win­dows.

•       Interior storm windows should have an airtight edge seal to prevent warm moist air from passing by the interior storm window and condensing or icing the interior of the glass on the primary window.

•       Interior storm windows should be easily removable for storage.

•       The home should have a safe place to store the storm win­dows seasonally.

•       Consider using low-e glass or plastic for glazing to increase thermal resistance.

7.2   Window Repair and Air Leakage Reduction

With the exception of broken glass or missing window panes, windows aren’t often the major source of air leakage in an exist­ing home.

Window weatherstripping may solve comfort problems around windows, even though it may not be cost-effective. Avoid expensive or time-consuming window repair measures that are implemented to solve minor comfort complaints if the weather­ization budget is limited.

7.2.1   Double-Hung Window Weatherization

Re-glazing window sashes in a quality manner is time consum­ing. This task is best accomplished as part of a comprehensive window rehabilitation project. Re-glazing wood windows may not be a durable repair without thorough scraping, priming, and painting. Use lead-safe work practices when working on win­dows. See this locaiton.

Repair measures may include the following.

✓     Replace missing or broken glass. Use glazing compound and glazier points when replacing glass in old windows.

✓     Caulk the window frame where appropriate to prevent air leakage, condensation, and rain leakage. Use sealants with adhesion and joint-movement characteristics appropriate for both the window frame and the building materials sur­rounding the window.

✓     Replace missing or severely deteriorated window frame components.

✓     Fill damaged wood with epoxy, before priming and paint­ing.

✓     Adjust window stops if gaps exist between the stop and jamb. Ensure that the window operates smoothly follow­ing adjustment.

✓     Weatherstrip large gaps between the sash and the sill or stops. Weatherstrip the meeting rails if needed.

✓     Replace or repair missing or non-functional top and side sash locks, hinges, or other hardware if this significantly reduces air leakage.

7.2.2   Weatherstripping Double-Hung Windows

Window weatherstripping is mainly a comfort retrofit and not a high weatherization priority.

Paint is the primary obstacle when weatherstripping double-hung windows. Often the upper sash has slipped down, and is locked in place by layers of paint, producing a leaking gap between the meeting rails of the upper and lower sashes.

✓     To make the meeting rails meet again, either break the paint seal and push the upper sash up, or cut the bottom of the lower sash off to bring it down.

✓     To lift the upper sash, cut the paint around its inside and outside perimeter. Use leverage or a small hydraulic jack to lift the sash. Jack only at the corners of the sash. Lifting in the middle can break the glass.

✓     Block, screw, or nail the repositioned upper sash into place.

✓     To weatherstrip the window, remove the lower sash. Cut the paint where the window stop meets the jamb so the paint doesn’t pop off in large flakes as you pry the stop off. Removing one stop is sufficient to remove the bottom sash.

✓     Scrape excess paint from the sashes and the window sill.

7.3   Window Replacement Specifications

The purpose of these specifications is to guide the selection and installation of replacement windows. Improper window installa­tion can cause water leakage, air leakage, and noise leakage.

Existing window openings may have moisture damage and air leakage. Repair these conditions before or during window replacement.

Included here are specifications for two special window safety considerations.

1.      Windows in high risk areas, such as around doors and walkways, must have safety glass.

2.      Some bedroom windows function as a fire escape (egress). Recognize and accommodate this egress func­tion.

7.3.1   Window Energy Specifications

Installing new windows incurs a large labor expense so they should be as energy-efficient as budget allows.

1.      Replacement windows must have a U-factor less than or equal to what is required by New Hampshire standards. Lower is better, especially in cold climates.

2.      Replacement windows facing east or west in air condi­tioned homes should have a solar heat-gain coefficient (SHGC) that is equal to or less than what is required by New Hampshire standards. Lower is better in hot cli­mates.

7.3.2   Removing Old Windows

Remove existing windows without damaging the home’s interior finish, siding, exterior trim, or the water-resistive barrier (WRB) if possible.

1.      Protect the interior of the home from construction debris. See EPA RRP Requirements

2.      Remove window sashes, jambs, or siding, depending on the window-replacement method chosen.

3.      Repair moisture damage to the rough opening before installing the new window.

7.3.3   Installing Replacement Windows

The most important considerations for installing new windows is that the window installation is watertight and airtight.

Water leakage deteriorates building components around the window. To prevent water leakage in frame buildings, the win­dow must be integrated, if possible into the home’s water resis­tive barrier (WRB).

7.3.4   Replacing Nailing-Fin Windows

Install replacement windows with nailing fins in the rough opening after removing the existing window frame and exterior trim. Fasten the nailing fins directly to the house’s sheathing or framing, but support the window’s weight on the sill with or without shims before fastening the window to the building.

Water-Resistive Barrier (WRB): Designers and builders assume that some rain water penetrates through the siding. The WRB is the building’s last defense against water. House wrap and asphalt felt are the most common WRBs. Window replace­ments that expose the home’s WRB must incorporate the WRB in the window installation. Install a sill pan below the window and flashing on the side fins. Use flashing to connect the win­dow opening to the WRB so water that penetrates the siding, trim, or window exits the building by way of the WRB.

Windows are exposed to wind and rain. Install replacement windows so water that penetrates the siding or trim drains to the outdoors. If water leaks underneath the existing WRB or the new flashing, the water eventually damages the building. With proper flashing, the fins and flashing create a drainage system that drains water to the outdoors rather than relying on caulked siding and trim to prevent rain water from penetrating the building’s surface.

Follow these steps to install a nailing-fin window in the rough opening.

1.      At the sill, insert the flashing underneath the existing siding, over top of existing building paper, and under the bottom nailing fin of the window.

2.      Use flat shims to provide a level surface and support under the vertical structural members of the new win­dow frame. Don’t allow the fins to support the window’s weight.

3.      Use fasteners with heads wide enough in diameter to span the holes or slots in the window fin.

4.      Avoid over-driving the fasteners or otherwise deform­ing the window fin.

5.      Flash the window around its perimeter with 15-pound felt, house wrap, or a peel-and-stick membrane.

a.  Flashing procedures may vary. However, always install flashing materials to overlap like shingles.

b.  Insert the new building paper or flashing underneath the existing siding and underneath existing building paper on the sides and top of the window opening.

6.      Windows that are exposed to wind-driven rain or with­out overhangs above them or without WRB integration should have a rigid cap flashing (also called head flash­ing) to prevent rainwater from draining onto the win­dow. The cap flashing should divert water away from vertical joints bordering the window with an overhang or dam.

7.      Tuck the cap flashing up behind the WRB or exterior siding. Metal cap flashing must have downward bend­ing lip of at least ¹/₄ inch on the front and ends.

8.      Thoroughly caulk all filler and trim pieces surrounding the replacement window.

7.3.5   Block-Frame or Finless Windows

Contractors install windows using a block-frame or finless installation when they can’t remove the existing window frame or in a masonry window opening. Block-frame windows rely on caulk or rigid flashing to create a weatherproof seal around the window perimeter. Take care when installing caulk so that it is durable and effective for as long as possible.

Comply with the following requirements when installing block-frame or finless windows.

1.      Block-frame or finless windows may require a suffi­ciently wide gap between the new window and the existing window frame or masonry opening to allow for the following.

a.  Allowing for a slightly out-of-square opening.

b.  Leveling the window.

c.  Insulating the gap with foam.

2.      Access the window-weight cavities, remove the weights, and fill the cavities with insulation, and seal the cavi­ties.

3.      Protect the existing sill with a metal or plastic sill pan or rigid sill flashing if necessary for drainage and to pro­tect the existing sill that protrudes from the exterior wall. Or, install a new sill as part of the window replace­ment.

4.      Support block-frame or finless windows under their main vertical supports with shims that level the win­dow.

a.  Use flat shims for support if the sill surface is flat.

b.  Use tapered shims or a sill angle for support if the sill surface is sloping.

5.      Windows without fins must be secured to the rough opening within 4 inches of each side corner and a mini­mum 12 inches on center along the remainder of the frame with one of these fastening methods.

a.  Screws fastened through the window frame. Use screws that are designed for fastening block-frame windows if available.

b.  Jamb clips or plates that are fastened first to the window and then to the opening in separate steps.

6.      Fill any gaps over ³/₈ inch that are between the exterior siding and the block-frame window. Install backer rod in all exterior or interior voids over ³/₈ inch in depth or width before caulking.

7.      If possible, flash block-frame windows between the opening and the replacement-window frame and extend the flashing out far enough to slip under or into the siding.

a.  Tuck the flashing up behind the exterior siding at least 1 inch.

b.  Sill and cap flashing should have a downward bending lip of at least ¹/₄ inch on the front that sheds water away from the building.

7.3.6   Flush-Fin Window Replacement

Flush-frame windows are replacement windows that fasten to the window opening and mount directly over the flat siding sur­rounding the window opening. Replace windows in stucco walls using windows with flush fins, also called stucco fins, that have no nail holes. Flush-fin windows work well for any window opening with a flat water-resistant finished surface surrounding the window opening.

This flush-fin window-replacement technique is similar to block-frame window installation.

1.      Support the replacement window on the existing sill with one of the following materials.

a.  A flat or tapered continuous wood support.

b.  Flat shims under the window’s main vertical supports.

c.  Tapered shims under the window’s main vertical sup­ports if the sill is sloping.

2.      Apply a sealant that remains flexible to the back of the flush fin of the replacement window in order to seal it to the surface of the exterior wall. Interrupt the caulk­ing at the bottom fin for one inch on each side of the window’s weep holes.

3.      Fasten the flush-fin window to the window opening by driving screws through the replacement window’s frame.

7.4   Window Safety Specifications

Windows have special requirements for breakage-resistance in areas that are prone to glass breakage, and for fire escape in bed­rooms.

7.4.1   Windows Requiring Safety Glass

Safety glass is required in locations that the IRC 2012 considers hazardous to the building’s occupants. Safety glass must be either laminated glass, tempered glass, organic coated glass, or annealed glass bearing a permanent label identifying it as safety glass, manufactured in compliance with CPSC 16 CFR 1201 or ANSI Z97.1.

Instead of safety glazing, glazed panels may have a protective bar installed on the accessible sides of the glazing 34 to 38 inches above the floor. The bar must be capable of withstanding a hori­zontal load of 50 pounds per linear foot without contacting the glass and be a minimum of 1¹/₂ inches in diameter.

Safety glass or a protective bar is required in the following haz­ardous locations.

✓     Glazing wider than 3 inches in entrance doors.

✓     Glazing in fixed and sliding panels of sliding doors and panels in swinging doors.

✓     Glazing in fixed or operable panels adjacent to a door where the nearest exposed edge of the glazing is within a 24-inch arc of the vertical edge of the door in a closed position and where the bottom edge of the glazing is less than 60-inches above the floor or walking surface. Excep­tion: If there is an intervening wall or permanent barrier between the door and the glazing, safety glass isn’t required.

✓     Glazing adjacent to the landing of the bottom of a stairway where the glazing is less than 36 inches above the landing and within 60 inches horizontally of the bottom tread.

✓     Glazing with a bottom exposed edge that is less than 36 inches above the walkway surface of stairways, landings, and ramps.

✓     Glazing in any portion of a building wall enclosing show­ers, hot tubs, whirlpools, saunas, steam rooms, and bath­tubs where the bottom exposed edge is less than 5 feet above a standing surface or drain inlet.

Glazing in an individual fixed or operable panel that meets all of the following conditions must also have safety glass:

1.      An exposed area of an individual pane greater than 9 square feet, and

2.      An exposed bottom edge less than 18 inches above the floor.

3.      An exposed top edge greater than 36 inches above the floor.

4.      One or more walkways within 36 inches horizontally of the glazing.

7.4.2   Fire Egress Windows

Windows are the designated fire escape for bedrooms and should offer a minimum opening for a person’s escape. If the window installation requires a code-approved egress window, observe these specifications.

1.      Each bedroom must have one egress window.

2.      Egress windows must provide an opening that is at least 20 inches wide and at least 24 inches high.

3.      Egress windows must provide an opening with a clear area of at least 5.7 square feet except for below-grade windows, which must have at least 5.0 square feet of opening.

4.      The finished sill of the egress window must be no higher off the floor than 44 inches.

5.      You may install security bars, screens, or covers over egress windows as long as these security devices are easily removable from indoors.

7.5   Door Replacement and Improvement

Exterior doors suffer a lot of wear because they function as entrances to buildings. Doors need adjustment or repair when they’re malfunctioning or damaged.

Install flashing around doorways according to the specifications inInstalling Replacement Windows.

7.5.1   Door Replacement

Door replacement may be completed as an efficiency measure if the cost is justified. Use RRP & LSW methods to ensure occu­pants and workers aren’t exposed to lead dust during door repair measures. See EPA RRP Requirements

Observe the following standards when replacing exterior doors.

✓     Replace the door using an exterior-grade insulated door-blank or a pre-hung steel insulated door, unless the door opening isn’t standard width or height.

✓     Don’t replace an exterior panel door with another panel door.

✓     All exterior replacement doors must have three hinges.

7.5.2   Door Adjustment and Repair

Door operation affects building energy-efficiency, security, and durability, so doors are sometimes an important weatherization priority. A leaky door may be an important comfort problem, and weatherstripping it can be a high-value energy conservation measure. Perform all door adjustment and repair in a lead-safe manner. See EPA RRP Requirements

Evaluating Exterior Doors

Before weatherstripping a door, evaluate the door’s operation.

•       Does the door bind or scrape against its jambs, indicating a need for hinge adjustment?

•       Does the door close tightly and evenly against its stops or is there an uneven space between the door and stop when the door is latched?

•       Can you move the latched door back and forth against its stops, indicating a need for latch adjustment?

•       Can you move the open door up and down, indicating loose hinges?

Fixing Binding Doors

You can adjust binding doors by moving the door within its opening. Moving the top and middle hinges in, or moving the bottom and middle hinges out moves the door’s top latch-side corner upward and back toward the top hinge. Moving the top and middle hinges out drops the door down and moves the door away from the top hinge.

•       If the hinges are loose, tighten the hinges and add longer screws if necessary. Longer screws can even move the door jamb a little, when necessary, if the screws penetrate the stud next to the door.

•       If the gaps at the top latch-side corner are uneven, rotate the door in its opening by adjusting the hinges. Chisel the hinge mortises a little deeper or install cardboard shims between the hinges and door or jamb to move the door to create an even space around the door.

•       If the house has settled and the opening is out-of-square, plane or power-sand the door so it closes without rubbing or binding against its jambs.

•       If paint has built up and reduced the door’s operating gap, plane or sand off the excess paint. Planing and sanding are a last resort, so try the previous suggestions first.

Adjusting Latches and Stops

If a door won’t latch, inspect the door stops and weatherstrip­ping to see if they’re binding. If there’s no obvious problem with the weatherstrip or stops, move the strike plate out slightly or use a file to remove a little metal from the strike plate to allow the latch to seat itself. The strike plate is mortised into the door frame that receives the latch.

✓     Tighten loose door knobs, face plates, and strike plates.

✓     If the door is warped and doesn’t fit well against its stops, adjust the stops by moving them against the door or plan­ing them so door closes snugly against its stops.

✓     Move the strike plate to hold the door evenly against its stops if necessary. Use toothpicks to fill widened screw holes. Use longer screws if you have to move the strike plate.

Weatherstripping Doors

Consider these suggestions when weatherstripping doors.

✓     Use a durable stop-mounted or jamb-mounted weather­strip to seal the door’s side jambs and head jamb.

✓     Seal the back of the weatherstrip to prevent air from leak­ing behind the weatherstrip.

✓     Install thresholds and door sweeps if needed to prevent air leakage at the door bottom. These air seals should not bind the door. Thresholds should be caulked underneath and on both sides of the door sill.

✓     Install corner seals to close the gaps at the bottom corners of the door jambs.

✓     Seal gaps between the stop and jamb with caulk.

✓     Install a door sweep if you don’t install a door bottom.

✓     The door must operate smoothly in the locked position after you weatherstrip it.

7.6   SWS Alignment