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Plan How to Install an Exterior Combination Unit
Intro to Combination Units
This video explains how exterior combination units use doors, sidelites, and transoms as flexible building blocks to fit almost any exterior opening. The goal is to design a custom solution that avoids costly changes to your home’s existing structure.
- Combination units fill exterior openings both vertically and horizontally using doors, sidelites, and transoms.
- Custom sizing allows you to use your existing opening instead of resizing brick, siding, or stucco.
- Single doors, double (French) doors, and sidelites accommodate increasing opening widths.
- Transoms can span the full width or be configured with smaller “flanker” transoms alongside doors.
- All glass used in doors and sidelites is tempered for safety.
- The video series walks homeowners and DIYers through designing and ordering a custom-fit unit with minimal construction.
Arrangements
This video explores the different arrangement options for exterior combination units and how to choose the right design for your specific opening. It shows why the best arrangement balances aesthetics, building codes, and the size and purpose of the space.
- Combination units can be arranged using single or double doors, with zero, one, or two sidelites, and optional transoms.
- The chosen arrangement should always match the shape, size, and function of the exterior opening.
- Smaller or oddly sized openings may limit options due to space constraints and building code requirements.
- Larger openings often work best with double doors to reduce the width needed for sidelites.
- Finding the right arrangement may take some trial and error before identifying a design that fits properly.
- Once an arrangement is selected, all components can be precisely sized and ordered using provided guides and templates.
Bottom Row
This video explains how to design the bottom row of a door and window combination unit by balancing door size, sidelite space, and installation clearances. It focuses on making choices that look intentional and allow for proper fitting during installation.
- The bottom row of a combination unit consists of a door area and a remaining fill area.
- The door area can use a single door or double doors, while the fill area is made up of sidelites.
- The size of the selected door directly determines how much space is left for sidelites.
- To fit two sidelites, at least 10 inches of fill space is needed on each side of the door.
- Choosing an oversized door can make sidelites look too narrow and unbalanced.
- A small gap (about 1/4 inch per side) is intentionally left for leveling, shimming, and proper installation.
Top row
This video explains how to design the top row of a door and window combination unit, building on the decisions made for the bottom row. It shows how transom height and width are calculated to create a balanced, well-aligned design.
- The available height for the top row depends entirely on the fixed height of the bottom row.
- The bottom row always extends 81 3/4 inches from the finished floor, determining how much space remains for transoms.
- About 10 inches of clear height is typically needed to add a transom; smaller gaps can be handled with trim instead.
- For the best visual result, top-row units should align in width with the door and sidelites below.
- “Unit dimensions” refer to the actual width and height of each building block and are used to coordinate top and bottom rows.
- The bottom row is always sized first, since it drives all measurements for the top row, including intentional installation gaps.
Window Unit Dimentions
This video explains the difference between ordering dimensions and unit dimensions for windows and why jambs are essential in building a properly fitted combination unit. It focuses on how window units are constructed and sized to fit within exterior walls.
- A window sash or door slab is the core component used for ordering, defined by its width and height.
- Exterior walls are thicker than windows and doors, so jambs are added to adapt them to the wall depth.
- Adding a jamb turns a sash or slab into a window or door unit, increasing its overall size.
- Window jambs are made from 3/4-inch material and add 1 1/2 inches to both the width and height of the sash.
- Sash dimensions are used for ordering, while unit dimensions are used to size and assemble the full combination unit.
- This sizing method is an industry standard that allows compatibility across manufacturers and simplifies planning.
Door Unit Dimentions
This video explains how to determine door unit dimensions for combination units, with special attention to differences between single and double doors. It also covers standard door heights and how doors align with sidelights and transoms in the opening.
- A door with a jamb is called a door unit, and the outside-to-outside measurement is the unit width.
- Single doors are straightforward: the jamb adds 3/4" per side, making the unit width 1 1/2" wider than the slab.
- Double doors with a T-astragal vary by manufacturer, so unit width can differ depending on whether slabs are reduced to compensate.
- The most reliable way to get an accurate double-door unit width is to measure the unit on site from outside jamb to outside jamb.
- Industry standard places the top of the door jamb at 81 3/4" above finished floor, based on an 80" door slab plus jamb thickness.
- Sidelights should match the door height (80") and align flush with the door jamb, with transoms filling any space above.
Measure Your Rough Opening
This video walks you through how to accurately measure an exterior rough opening so you can design a custom door and window combination that fits without modifying your existing exterior finishes. By taking a few careful measurements, you can work with the opening you already have.
- Measure the rough opening width stud-to-stud, checking multiple points and using the narrowest measurement.
- Always measure to the nearest 1/16 inch and keep the tape perfectly square across the opening.
- Measure the height from the unfinished floor to the top of the rough opening, again using the shortest measurement.
- Convert to finished-floor height by subtracting the thickness of the finished flooring (e.g., 3/4" for hardwood).
- Use these final width and height measurements to plan doors, sidelights, and transoms that fill the opening without exterior rework.
- The next step after rough opening size is determining jamb depth, the final key measurement needed for design.
