I’m doing some work on the double-hung wood windows in my house which involves making new jambs, heads, and in some cases sills and sub sills as needed. The existing windows are over a century old and are showing their age, especially the jambs, which have extensive water damage where they meet the sill. The jambs and heads are doug fir and the sills are redwood.
The jambs run down into a dado in the sill. The dado is angled a few degrees to shed water to the outside of the window. The parting bead groove runs the full length of the jamb including down into the dado in the sill. The parting bead itself dies at the top of the sill. This leaves a little cavity below the parting bead and I suspect this is the reason that the bottoms of the jambs deteriorated, as water could get down below the parting bead to the end grain of the fir jambs.
I realize that wood windows won’t last forever and also that some joints are inherently reliant on caulk/putty and paint to prevent deterioration, but the parting bead is something that is likely to be removed somewhat regularly and it would be frustrating to need to repaint every time it comes out.
What is the ‘right’ way to deal with the parting bead groove where it meets the sill? I see three options:
– Stop the groove short of the sill and relieve the parting bead to match
– Run the groove all the way down the jamb and notch the parting bead to fit down into the dado with the sill to help occupy the little void
– Replicate the existing design exactly
I’m doing all of the woodwork here so I have the flexibility to follow any of these options (or others I didn’t think of). I’d appreciate input from people who have personal experience building/repairing windows.
Thanks!
Henry
Replies
To mitigate water damage in double-hung window jambs, consider running the parting bead groove down to the sill, notch the parting bead to fit into the dado, and replicate the existing design. This approach helps prevent water intrusion and maintains the integrity of the window structure.
you might try glueing a small filler piece in the parting bead slot before assembly. Dry fit the jamb into the sill, mark the jamb to get the exact length of the fill in piece and glue it in before assembling the frame. Notching the bottom of the parting bead could make future removal difficult especially after many layers of paint have been applied. Resist the urge to nail the parting bead in place as it will be destroyed when it is time to remove it to repair a sash. The next guy will be faced with a custom woodworking job.Been there.
Thanks Mike! I will follow your advice.
When I build a window buck I extend the sill under the side jambs instead of having it between them like your drawing shows.
I also just use one piece of wood for the sill. I’m not understanding the sill and sub sill.
I like to get rough sawn Cedar and bevel and plane it myself. Something like a big thick 2” x8” wide board. I like to bevel it at lucky 13 degrees and put a drip kerf about 1/2” in from the front bottom edge.
A double-hung window features a vertical frame that supports two sashes which slide up and down. Important elements of this design include:
Jamb Liners: These are vertical tracks, often made of vinyl or metal, that facilitate smooth movement of the sashes and provide insulation.
Sash Balances: These are mechanisms, such as spring balances or counterweights, that help hold the sashes in place at any height.
Weatherstripping: This component is applied to the jamb liners to ensure a tight seal, preventing air and water infiltration.
Pocket: This is an area within the jamb that conceals the sash balances and allows for the insertion and removal of the sashes.
These components work together to ensure that double-hung windows are functional, easy to use, and energy efficient.